We consider models of telecommunication systems that incorporate probability, dense real-time and data.
We present a new formal abstraction method for computing minimum and maximum reachability
probabilities for such models. Our approach uses strictly local formal abstract steps to reduce both the size
of abstract specifications generated and the complexity of operations needed, in comparison to previous
approaches of this kind. A selection of large case studies are implemented the techniques and evaluate,
which include some infinite-state probabilistic real time models, demonstrating improvements over existing
tools in several cases. The capacity of metro and access networks are extended the reach and split ratio of
the conventional Long - Reach Passive Optical Networks (LR-PONs). The efficient solutions of LR-PONs
are appeared in feeder distances around 100km and high split ratios up to 1000-way . Among many
existing approaches, one of the most effective options to improve network performance in LR-PONs are the
multi-thread based dynamic bandwidth allocation (DBA) scheme where several bandwidth allocation
processes are performed in parallel is considered. Without proper intercommunication between the
overlapped threads, multi-thread DBA may lose efficiency and even perform worse than the conventional
single thread algorithm. Real Time Probabilistic Systems are used to evaluate a typical PON systems
performance. This approach is more convenient, flexible, and lower cost than the former simulation method,
which do not need develop special hardware and software tools. Moreover, how changes in performance
depend on changes in the particular modes can be easily analysis by supplying ranges for parameter values.
The proposed algorithm with traditional DBA is compared, and shows its advantage on average packet
delay. The key parameters of the algorithm are analysed and optimized, such as initiating and tuning
multiple threads, inter -thread scheduling, and fairness among users. The algorithms advantage in
numerical results are decreased the average packet delay and improve network throughput under varying
offered loads.
Mobility and Propagation Models in Multi-hop Cognitive Radio Networksszhb
Cognitive radio networks allow unlicensed
(secondary) users to opportunistically utilize the idle
resource of a licensed network for communication
without affecting the quality of service being offered to
the primary or licensed users. This paper investigates
the effect of mobility on performance of multi-hop
cognitive radio network under various propagation
models. MPEG4 video; a bandwidth intensive traffic, is
tested over these network conditions for secondary
users and results are validated using NS2 simulations.
Performance metrics used for evaluation include
throughput, delay variations etc.
Congestion Control in Manets Using Hybrid Routing ProtocolIOSR Journals
As the network size increases the probability of congestion occurrence at nodes increases. This is
because of the event driven nature of ad hoc networks that leads to unpredictable network load. As a result
congestion may occur at the nodes which receive more data than that can be forwarded and cause packet losses.
In this paper we propose a hybrid scheme that attempts to avoid packet loss due to congestion as well as reduce
end to end delay in delivering data packets by combining two protocols- Destination sequenced distance vector
routing (DSDV), which is a table driven or proactive protocol and Improved Ad-hoc on demand vector routing
(IAODV) which is an on-demand or reactive protocol that reduces packet loss due to congestion. The strategy
adopted is use DSDV for path selection and if congestion occurs than switch over to IAODV. The routing
performance of this model is then compared with IAODV and DSDV in terms of end to end delay, throughput
and packet delivery fraction
ROUTING IN OPTICAL MESH NETWORKS-A QOS PERSPECTIVEijasuc
Wireless Ad-Hoc Mesh Networks are characterized by static nodes connected in a mesh topology. A routing
protocol discovers and maintains the route for successful transmission of data in a network. The routing
protocol should also provide load balancing and fault tolerance for improved network performance. In
Free Space Optical networks (FSO) line of sight (LOS) should be maintained between the two
communicating nodes. In a multihop scenario maintaining LOS during routing is a challenge. In this paper
we propose a routing protocol Quality of Service-Directional Routing Protocol (QDRP) - which assures a
certain level of performance to a data flow in terms of delay and implemented on FSO MANET. Through
simulations it is observed that QDRP chooses the path with the least delay and performs satisfactorily
under varying node densities and transmission rates achieving end to end delay of .14 s and packet delivery
percentage of 96% when simulated for an area of 1300 m *1300 m for 100 nodes. This work explores the
potential of the proposed routing protocol for free space optical mesh networks. QDRP is compared with
ORRP (Orthogonal Rendezvous Routing Protocol) and AODV (Ad-Hoc on Demand Distance Vector), a
reactive protocol which is also implemented in free space optical environment. We support our conclusions
that QDRP gains in terms of packet delivery percentage, end to end delay and goodput.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Novel Position Estimation using Differential Timing Information for Asynchron...IJCNCJournal
Positioning techniques have been a common objective since the early development of wireless networks. However, current positioning methods in cellular networks, for instance, are still primarily focused on the use of the Global Navigation Satellite System (GNSS), which has several limitations, like high power drainage and failure in indoor scenarios. This study introduces a novel approach employing standard LTE signaling in order to provide high accuracy positioning estimation. The proposed technique is designed in analogy to the human sound localization system, eliminating the need of having information from three spatially diverse Base Stations (BSs). This is inspired by the perfect human 3D sound localization with two ears. A field study is carried out in a dense urban city to verify the accuracy of the proposed technique, with more than 20 thousand measurement samples collected. The achieved positioning accuracy is meeting the latest Federal Communications Commission (FCC) requirements in the planner dimension.
Optimized Cluster Establishment and Cluster-Head Selection Approach in WSNIJCNCJournal
In recent years, limited resources of user products and energy-saving are recognized as the major challenges of Wireless Sensor Networks (WSNs). Clustering is a practical technique that can reduce all energy consumption and provide stability of workload that causes a larger difference in energy depletion among other nodes and cluster heads (CHs). In addition, clustering is the solution of energy-efficient for maximizing the network longevity and improvising energy efficiency. In this paper, a novel OCE-CHS (Optimized Cluster Establishment and Cluster-Head Selection) approach for sensor nodes is represented to improvise the packet success ratio and reduce the average energy-dissipation. The main contribution of this paper is categorized into two processes, first, the clustering algorithm is improvised that periodically chooses the optimal set of the CHs according to the speed of the average node and average-node energy. This is considerably distinguished from node-based clustering that utilizes a distributed clustering algorithm to choose CHs based on the speed of the current node and remaining node energy. Second, more than one factor is assumed for the detached node to join the optimal cluster. In the result section, we discuss our clustering protocols implementation of optimal CH-selection to evade the death of SNs, maximizing throughput, and further improvise the network lifetime by minimizing energy consumption.
EFFICIENCY ENHANCEMENT BASED ON ALLOCATING BIZARRE PEAKSijwmn
A new work has been proposed in this paper in order to overcome one of the main drawbacks that found in
the Orthogonal Frequency Division Multiplex (OFDM) systems, namely Peak to Average Power Ratio
(PAPR). Furthermore, this work will be compared with a previously published work that uses the neural
network (NN) as a solution to remedy this deficiency.
The proposed work could be considered as a special averaging technique (SAT), which consists of wavelet
transformation in its first stage, a globally statistical adaptive detecting algorithm as a second stage; and
in the third stage it replaces the affected peaks by making use of moving average filter process. In the NN
work, the learning process makes use of a previously published work that is based on three linear coding
techniques.
In order to check the proposed work validity, a MATLAB simulation has been run and has two main
variables to compare with; namely BER and CCDF curves. This is true under the same bandwidth
occupancy and channel characteristics. Two types of tested data have been used; randomly generated data
and a practical data that have been extracted from a funded project entitled by ECEM. From the achieved
simulation results, the work that is based on SAT shows promising results in reducing the PAPR effect
reached up to 80% over the work in the literature and our previously published work. This means that this
work gives an extra reduction up to 15% of our previously published work. However, this achievement will
be under the cost of complexity. This penalty could be optimized by imposing the NN to the SAT work in
order to enhance the wireless systems performance.
Mobility and Propagation Models in Multi-hop Cognitive Radio Networksszhb
Cognitive radio networks allow unlicensed
(secondary) users to opportunistically utilize the idle
resource of a licensed network for communication
without affecting the quality of service being offered to
the primary or licensed users. This paper investigates
the effect of mobility on performance of multi-hop
cognitive radio network under various propagation
models. MPEG4 video; a bandwidth intensive traffic, is
tested over these network conditions for secondary
users and results are validated using NS2 simulations.
Performance metrics used for evaluation include
throughput, delay variations etc.
Congestion Control in Manets Using Hybrid Routing ProtocolIOSR Journals
As the network size increases the probability of congestion occurrence at nodes increases. This is
because of the event driven nature of ad hoc networks that leads to unpredictable network load. As a result
congestion may occur at the nodes which receive more data than that can be forwarded and cause packet losses.
In this paper we propose a hybrid scheme that attempts to avoid packet loss due to congestion as well as reduce
end to end delay in delivering data packets by combining two protocols- Destination sequenced distance vector
routing (DSDV), which is a table driven or proactive protocol and Improved Ad-hoc on demand vector routing
(IAODV) which is an on-demand or reactive protocol that reduces packet loss due to congestion. The strategy
adopted is use DSDV for path selection and if congestion occurs than switch over to IAODV. The routing
performance of this model is then compared with IAODV and DSDV in terms of end to end delay, throughput
and packet delivery fraction
ROUTING IN OPTICAL MESH NETWORKS-A QOS PERSPECTIVEijasuc
Wireless Ad-Hoc Mesh Networks are characterized by static nodes connected in a mesh topology. A routing
protocol discovers and maintains the route for successful transmission of data in a network. The routing
protocol should also provide load balancing and fault tolerance for improved network performance. In
Free Space Optical networks (FSO) line of sight (LOS) should be maintained between the two
communicating nodes. In a multihop scenario maintaining LOS during routing is a challenge. In this paper
we propose a routing protocol Quality of Service-Directional Routing Protocol (QDRP) - which assures a
certain level of performance to a data flow in terms of delay and implemented on FSO MANET. Through
simulations it is observed that QDRP chooses the path with the least delay and performs satisfactorily
under varying node densities and transmission rates achieving end to end delay of .14 s and packet delivery
percentage of 96% when simulated for an area of 1300 m *1300 m for 100 nodes. This work explores the
potential of the proposed routing protocol for free space optical mesh networks. QDRP is compared with
ORRP (Orthogonal Rendezvous Routing Protocol) and AODV (Ad-Hoc on Demand Distance Vector), a
reactive protocol which is also implemented in free space optical environment. We support our conclusions
that QDRP gains in terms of packet delivery percentage, end to end delay and goodput.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Novel Position Estimation using Differential Timing Information for Asynchron...IJCNCJournal
Positioning techniques have been a common objective since the early development of wireless networks. However, current positioning methods in cellular networks, for instance, are still primarily focused on the use of the Global Navigation Satellite System (GNSS), which has several limitations, like high power drainage and failure in indoor scenarios. This study introduces a novel approach employing standard LTE signaling in order to provide high accuracy positioning estimation. The proposed technique is designed in analogy to the human sound localization system, eliminating the need of having information from three spatially diverse Base Stations (BSs). This is inspired by the perfect human 3D sound localization with two ears. A field study is carried out in a dense urban city to verify the accuracy of the proposed technique, with more than 20 thousand measurement samples collected. The achieved positioning accuracy is meeting the latest Federal Communications Commission (FCC) requirements in the planner dimension.
Optimized Cluster Establishment and Cluster-Head Selection Approach in WSNIJCNCJournal
In recent years, limited resources of user products and energy-saving are recognized as the major challenges of Wireless Sensor Networks (WSNs). Clustering is a practical technique that can reduce all energy consumption and provide stability of workload that causes a larger difference in energy depletion among other nodes and cluster heads (CHs). In addition, clustering is the solution of energy-efficient for maximizing the network longevity and improvising energy efficiency. In this paper, a novel OCE-CHS (Optimized Cluster Establishment and Cluster-Head Selection) approach for sensor nodes is represented to improvise the packet success ratio and reduce the average energy-dissipation. The main contribution of this paper is categorized into two processes, first, the clustering algorithm is improvised that periodically chooses the optimal set of the CHs according to the speed of the average node and average-node energy. This is considerably distinguished from node-based clustering that utilizes a distributed clustering algorithm to choose CHs based on the speed of the current node and remaining node energy. Second, more than one factor is assumed for the detached node to join the optimal cluster. In the result section, we discuss our clustering protocols implementation of optimal CH-selection to evade the death of SNs, maximizing throughput, and further improvise the network lifetime by minimizing energy consumption.
EFFICIENCY ENHANCEMENT BASED ON ALLOCATING BIZARRE PEAKSijwmn
A new work has been proposed in this paper in order to overcome one of the main drawbacks that found in
the Orthogonal Frequency Division Multiplex (OFDM) systems, namely Peak to Average Power Ratio
(PAPR). Furthermore, this work will be compared with a previously published work that uses the neural
network (NN) as a solution to remedy this deficiency.
The proposed work could be considered as a special averaging technique (SAT), which consists of wavelet
transformation in its first stage, a globally statistical adaptive detecting algorithm as a second stage; and
in the third stage it replaces the affected peaks by making use of moving average filter process. In the NN
work, the learning process makes use of a previously published work that is based on three linear coding
techniques.
In order to check the proposed work validity, a MATLAB simulation has been run and has two main
variables to compare with; namely BER and CCDF curves. This is true under the same bandwidth
occupancy and channel characteristics. Two types of tested data have been used; randomly generated data
and a practical data that have been extracted from a funded project entitled by ECEM. From the achieved
simulation results, the work that is based on SAT shows promising results in reducing the PAPR effect
reached up to 80% over the work in the literature and our previously published work. This means that this
work gives an extra reduction up to 15% of our previously published work. However, this achievement will
be under the cost of complexity. This penalty could be optimized by imposing the NN to the SAT work in
order to enhance the wireless systems performance.
A MANET is an autonomous collection of mobile users that communicate over relatively bandwidth constrained wireless links. When designing mobile ad hoc networks, several interesting and difficult problems arise because of the shared nature of the wireless medium, limited transmission power (range) of wireless devices, node mobility, and battery limitations. This paper aims at providing a new schema to improve Dynamic Source Routing (DSR) Protocol. The aim
behind the proposed enhancement is to find the best route in acceptable time limit without having broadcast storm. Moreover, O-DSR enables network not only to overcome congestion but also maximize the lifetime of mobile nodes. Some simulations results show that the Route Request (RREQ) and the Control Packet Overhead decrease by 15% when O-DSR is used, consequently. Also the global energy consumption in O-DSR is lower until to 60 % , which leads to a long lifetime of the network.
ANALYSIS AND STUDY OF MATHEMATICAL MODELS FOR RWA PROBLEM IN OPTICAL NETWORKSIJEEE
Blocking probability has been one of the key performance to solve Routing and Wavelength Assignment problem (RWA) indexes in the design of wavelength-routed all-optical WDM networks. To evaluate blocking probability different analytical model are introduced.
Implementing packet broadcasting algorithm of mimo based mobile ad hoc networ...IJNSA Journal
With the rapid growth of wireless communication infras,,tructure over the recent few years, new
challenges has been posed on the system and analysis on wireless adhoc networking. Implementation of
MIMO communication in such type of network is enhancing the packet transmission capabilities. There
are different techniques for cooperative transmission and broadcasting packet in MIMO equipped
Mobile Adhoc Network. We have employed a model network in the OPNET environment and propose a
new scheduling algorithm based on investigating the different broadcasting algorithm. The new
broadcasting algorithm improves the packet transmission rate of the network based on energy
performance of the network and minimizes the BER for different transmission mode which is illustrated
in this paper. The simulations are done in MATLAB and OPNET environment and the simulated result
for the packet transmission rate are collected and shown in the tabular form. Also simulate the network
for generating a comparative statement for each mobile node. And performance analysis is also done for
the model network. The main focus is to minimize BER and improve information efficiency of the
network.
A Cluster-Based Routing Protocol and Fault Detection for Wireless Sensor NetworkIJCNCJournal
In Wireless Sensors Networks (WSN) based application, a large number of sensor devices must be deployed. Energy efficiency and network lifetime are the two most challenging issues in WSN. As a consequence, the main goal is to reduce the overall energy consumption using clustering protocols which have to ensure reliability and connectivity in large-scale WSN. This work presents a new clustering and routing algorithm based on the properties of the sensor networks. The main goal of this work is to extend the network lifetime via charge equilibration in the WSN. According to many errors with sensing devices and to have greater data accuracy, we use a quorum mechanism. The proposed algorithms are evaluated widely and the results are compared with related works. The experimental results show that the proposed algorithm provides an effective improvement in terms of energy consumption, data accuracy and network lifetime.
Design and analysis of routing protocol for cognitive radio ad hoc networks i...IJECEIAES
Multi-hop routing protocol in cognitive radio mobile ad hoc networks (CRMANETs) is a critical issue. Furthermore, the routing metric used in multi-hop CRMANETs should reflect the bands availability, the links quality, the PU activities and quality of service (QoS) requirements of SUs. For the best of our knowledge, many of researchers investigated the performance of the different routing protocols in a homogeneous environment only. In this paper, we propose a heterogeneous cognitive radio routing protocol (HCR) operates in heterogeneous environment (i.e. the route from source to destination utilize the licensed and unlicensed spectrum bands). The proposed routing protocol is carefully developed to make a tradeoff between the channel diversity of the routing path along with the CRMANETs throughput. Using simulations, we discuss the performance of the proposed HCR routing protocol and compare it with the AODV routing protocol using a discrete-event simulation which we developed using JAVA platform.
PERFORMANCE ANALYSIS IN CELLULAR NETWORKS CONSIDERING THE QOS BY RETRIAL QUEU...IJCNCJournal
In this article, a retrial queueing model will be considered with persevering customers for wireless cellular
networks which can be frequently applied in the Fractional Guard Channel (FGC) policies, including
Limited FGC (LFGC), Uniform FGC (UFGC), Limited Average FGC (LAFGC) and Quasi Uniform FGC
(QUFGC). In this model, the examination on the retrial phenomena permits the analyses of important
effectiveness measures pertained to the standard of services undergone by users with the probability that a
fresh call first arrives the system and find all busy channels at the time, the probability that a fresh call
arrives the system from the orbit and find all busy channels at the time and the probability that a handover
call arrives the system and find all busy channels at the time. Comparison between four types of the FGC
policy can befound to evaluate the performance of the system.
Design and implementation of new routingIJCNCJournal
Energy consumption is a key element in the Wireless Sensor Networks (WSNs) design. Indeed, sensor nodes are really constrained by energy supply. Hence, how to improve the network lifetime is a crucial and challenging task. Several techniques are available at different levels of the OSI model to maximize the WSN lifetime and especially at the network layer which uses routing strategies to maintain the routes in the network and guarantee reliable communication. In this paper we intend to propose a new protocol called
Combined Energy and Distance Metrics Dynamic Routing Protocol (CEDM-DR). Our new approach considers not only the distance between wireless sensors but also the energy of node acting as a router in order to find the optimal path and achieve a dynamic and adaptive routing.
The performance metrics exploited for the evaluation of our protocol are average energy consumed, network lifetime and packets lost. By comparing our proposed routing strategy to protocol widely used in WSN namely Ad hoc On demand Distance Vector(AODV), simulation results show that CEDM-DR strategy might effectively balance the sensor power consumption and permits accordingly to enhance the network
lifetime. As well, this new protocol yields a noticeable energy saving compared to its counterpart.
An Efficient and Stable Routing Algorithm in Mobile Ad Hoc NetworkIJCNCJournal
Mobile Ad hoc Network (MANET) is mainly designed to set up communication among devices in infrastructure-less wireless communication network. Routing in this kind of communication network is highly affected by its restricted characteristics such as frequent topological changes and limited battery power. Several research works have been carried out to improve routing performance in MANET. However, the overall performance enhancement in terms of packet delivery, delay and control message overhead is still not come into the wrapping up. In order to overcome the addressed issues, an Efficient and Stable-AODV (EFST-AODV) routing scheme has been proposed which is an improvement over AODV to establish a better quality route between source and destination. In this method, we have modified the route request and route reply phase. During the route request phase, cost metric of a route is calculated on the basis of parameters such as residual energy, delay and distance. In a route reply phase, average residual energy and average delay of overall path is calculated and the data forwarding decision is taken at the source node accordingly. Simulation outcomes reveal that the proposed approach gives better results in terms of packet delivery ratio, delay, throughput, normalized routing load and control message overhead as compared to AODV.
A Novel Path Tracing Scheme In All-Optical Networks Using Benes NetworkCSCJournals
A novel path tracing scheme is described in this paper which is known as Prime number encoding scheme using Benes network. In this scheme every data packet consist a label which is default 1 and every node consist of a prime number tag, as this data packet pass through the network label will be multiplied with the tag of the node. Prime number multiplication is done with encoder. At the receiver end factorization is done which gives the information of travelled path. In this scheme optical cross connects (OXC) is replaced with the Benes network which gives the better result than OXC. System having Benes network gives less attenuation than OXC and complexity of the system also decreases.
Mobile Primary User in Cognitive Radio State of the Arts and Recent Advancesjosephjonse
The processing of primary user mobility with static or mobile secondary user in the context of cognitive radio (CR) has recently been the subject of several studies and discussions all over the world. These studies are seeking to broaden the horizons of CR implementation beyond the formalism described in the diverse existing standards. The mobility of primary users is likely to reduce the overall performance of the Cognitive Radio Network (CRN) and affects the different phases of the cognitive cycle. Said mobility alters the network’s topology, the channel’s availability, and affects spectrum sensing. This makes any endeavor aiming to implement CR technology complicated. This paper is devoted to the analysis and discussion of the scientific literature that has addressed the issue of the primary user’s mobility.
Analysing Mobile Random Early Detection for Congestion Control in Mobile Ad-h...IJECEIAES
This research paper suggests and analyse a technique for congestion control in mobile ad hoc networks. The technique is based on a new hybrid approach that uses clustering and queuing techniques. In clustering, in general cluster head transfers the data, following a queuing method based on a RED (Random Early Detection), the mobile environment makes it Mobile RED (or MRED), It majorly depends upon mobility of nodes and mobile environments leads to unpredictable queue size. To simulate this technique, the Network Simulator 2 (or NS2) is used for various scenarios. The simulated results are compared with NRED (Neighbourhood Random Early Detection) queuing technique of congestion control. It has been observed that the results are improved using MRED comparatively.
Routing in Cognitive Radio Networks - A SurveyIJERA Editor
Cognitive Radio Networks (CRNs) have been emerged as a revolutionary solution to migrate the spectrum
scarcity problem in wireless networks. Due to increasing demand for additional spectrum resources, CRNs have
been receiving significant research to solve issues related with spectrum underutilization. This technology
brings efficient spectrum usage and effective interference avoidance, and also brings new challenges to routing
in multi-hop Cognitive Radio Networks. In CRN, unlicensed users or secondary users are able to use
underutilized licensed channels, but they have to leave the channel if any interference is caused to the primary or
licensed users. So CR technology allows sharing of licensed spectrum band in opportunistic and non-interfering
manner. Different routing protocols have been proposed recently based on different design goals under different
assumptions.
ADAPTIVE HANDOVER HYSTERESIS AND CALL ADMISSION CONTROL FOR MOBILE RELAY NODESIJCNCJournal
The aim of equipping a wireless network with a mobile relay node is to support broadband wireless communications for vehicular users and their devices. The high mobility of vehicular users, possibly at a very high velocity in the area in which two cells overlap, could cause the network to suffer from a reduced handover success rate and, hence, increased radio link failure. The combined impact of these problems is service interruptions to vehicular users. Thus, the handover schemes are crucial in solving these problems. In this work, we first present the adaptive handover hysteresis scheme for the wireless network with mobile relay nodes in the high-speed train scenario. Specifically, our proposed adaptive hysteresis scheme is based on the velocity of the train. Second, the handover call dropping probability is reduced by introducing a modified call admission control scheme to support radio resource reservation for handover calls that prioritizes handover calls of mobile relay over the other calls. The proposed solution in which adaptive parameter is combined with call admission control is evaluated by system level simulation. Our simulation results illustrate an increased handover success rate and reduced radio link failures.
Efficient Utilization of Bandwidth in Location Aided RoutingIOSR Journals
Abstract : Earlier work on routing MANETs developed several routing protocols, which finds available route from source to destination without taking into the consideration of Band width availability for data transfer, and they frequently fails to discover stable routes between source and destination. As a result of that there is a large numbers of discarding of data packets as well as overloading of packets as the consequences of that large wastage of band width. EUBLAR (Efficient Utilization of band width in Location Aided Routing) protocol is introduced in this proposed work, which is capable of calculating the available band width of all the intermediate nodes between source and destination. In this proposed protocol find the minimum available band width of all the intermediate nodes between source and destination and then according to that band width sends the data packets over that path. The EUBLAR can effectively utilized the wastage of band width and every single band width can be used for data transfer can be used over entirely configured network. In this way we can increase the quality of service of the Ad- hoc network in terms of bandwidth. Keywords: Ad Hoc Networks, Global Positioning System, Maximum & Minimum slopes, Minimum available Bandwidth, Time to Live
A Summative Comparison of Blind Channel Estimation Techniques for Orthogonal ...IJECEIAES
The OFDM technique i.e. Orthogonal frequency division multiplexing has become prominent in wireless communication since its instruction in 1950’s due to its feature of combating the multipath fading and other losses. In an OFDM system, a large number of orthogonal, overlapping, narrow band subchannels or subcarriers, transmitted in parallel, divide the available transmission bandwidth. The separation of the subcarriers is theoretically optimal such that there is a very compact spectral utilization. This paper reviewed the possible approaches for blind channel estimation in the light of the improved performance in terms of speed of convergence and complexity. There were various researches which adopted the ways for channel estimation for Blind, Semi Blind and trained channel estimators and detectors. Various ways of channel estimation such as Subspace, iteration based, LMSE or MSE based (using statistical methods), SDR, Maximum likelihood approach, cyclostationarity, Redundancy and Cyclic prefix based. The paper reviewed all the above approaches in order to summarize the outcomes of approaches aimed at optimum performance for channel estimation in OFDM systems.
A JOINT TIMING OFFSET AND CHANNEL ESTIMATION USING FRACTIONAL FOURIER TRANSFO...IJCNCJournal
This paper deals with symbol timing offset and channel estimation in OFDM (orthogonal frequency
division multiplexing) system in fast varying channel. Symbol timing offset (STO) estimation is a major task
in OFDM. Most of existing methods for estimating STO used cyclic prefix or training sequences. In this
paper, we consider a new system for STO estimation using constant amplitude zero autocorrelation
(CAZAC) sequences as pilot sequences in conjunction with fractional Fourier transform (FRFT). After STO
estimation is done, timing compensation is made. Thereafter, channel is estimated to well recover the
original transmitted signal. This method gives good results in terms of MSE in comparison with other
known techniques, it estimated well the channel and it is important for fast varying channel. MATLAB
Monte-Carlo simulations are used to evaluate the performance of the proposed estimator.
Web object size satisfying mean waitingIJCNCJournal
This paper addresses web object size which is one of important performance measures and affects to
service time in multiple access environment. Since packets arrive according to Poission distribution and
web service time has arbitrary distribution, M/G/1 model can be used to describe the behavior of the web
server system. In the time division multiplexing (TDM), we can use M/D/1 with vacations model, because
service time is constant and server may have a vacation. We derive the mean web object size satisfying the
constraint such that mean waiting time by round-robin scheduling in multiple access environment is equal
to the mean queueing delay of M/D/1 with vacations model in TDM and M/H2/1 model, respectively.
Performance evaluation shows that the mean web object size increases as the link utilization increases at
the given maximum segment size (MSS), but converges on the lower bound when the number of embedded
objects included in a web page is beyond the threshold. Our results can be applied to the economic design
and maintenance of web service.
Visualize network anomaly detection by using k means clustering algorithmIJCNCJournal
With the ever increasing amount of new attacks in today’s world the amount of data will keep increasing,
and because of the base-rate fallacy the amount of false alarms will also increase. Another problem with
detection of attacks is that they usually isn’t detected until after the attack has taken place, this makes
defending against attacks hard and can easily lead to disclosure of sensitive information.
In this paper we choose K-means algorithm with the Kdd Cup 1999 network data set to evaluate the
performance of an unsupervised learning method for anomaly detection. The results of the evaluation
showed that a high detection rate can be achieve while maintaining a low false alarm rate .This paper
presents the result of using k-means clustering by applying Cluster 3.0 tool and visualized this result by
using TreeView visualization tool .
A MANET is an autonomous collection of mobile users that communicate over relatively bandwidth constrained wireless links. When designing mobile ad hoc networks, several interesting and difficult problems arise because of the shared nature of the wireless medium, limited transmission power (range) of wireless devices, node mobility, and battery limitations. This paper aims at providing a new schema to improve Dynamic Source Routing (DSR) Protocol. The aim
behind the proposed enhancement is to find the best route in acceptable time limit without having broadcast storm. Moreover, O-DSR enables network not only to overcome congestion but also maximize the lifetime of mobile nodes. Some simulations results show that the Route Request (RREQ) and the Control Packet Overhead decrease by 15% when O-DSR is used, consequently. Also the global energy consumption in O-DSR is lower until to 60 % , which leads to a long lifetime of the network.
ANALYSIS AND STUDY OF MATHEMATICAL MODELS FOR RWA PROBLEM IN OPTICAL NETWORKSIJEEE
Blocking probability has been one of the key performance to solve Routing and Wavelength Assignment problem (RWA) indexes in the design of wavelength-routed all-optical WDM networks. To evaluate blocking probability different analytical model are introduced.
Implementing packet broadcasting algorithm of mimo based mobile ad hoc networ...IJNSA Journal
With the rapid growth of wireless communication infras,,tructure over the recent few years, new
challenges has been posed on the system and analysis on wireless adhoc networking. Implementation of
MIMO communication in such type of network is enhancing the packet transmission capabilities. There
are different techniques for cooperative transmission and broadcasting packet in MIMO equipped
Mobile Adhoc Network. We have employed a model network in the OPNET environment and propose a
new scheduling algorithm based on investigating the different broadcasting algorithm. The new
broadcasting algorithm improves the packet transmission rate of the network based on energy
performance of the network and minimizes the BER for different transmission mode which is illustrated
in this paper. The simulations are done in MATLAB and OPNET environment and the simulated result
for the packet transmission rate are collected and shown in the tabular form. Also simulate the network
for generating a comparative statement for each mobile node. And performance analysis is also done for
the model network. The main focus is to minimize BER and improve information efficiency of the
network.
A Cluster-Based Routing Protocol and Fault Detection for Wireless Sensor NetworkIJCNCJournal
In Wireless Sensors Networks (WSN) based application, a large number of sensor devices must be deployed. Energy efficiency and network lifetime are the two most challenging issues in WSN. As a consequence, the main goal is to reduce the overall energy consumption using clustering protocols which have to ensure reliability and connectivity in large-scale WSN. This work presents a new clustering and routing algorithm based on the properties of the sensor networks. The main goal of this work is to extend the network lifetime via charge equilibration in the WSN. According to many errors with sensing devices and to have greater data accuracy, we use a quorum mechanism. The proposed algorithms are evaluated widely and the results are compared with related works. The experimental results show that the proposed algorithm provides an effective improvement in terms of energy consumption, data accuracy and network lifetime.
Design and analysis of routing protocol for cognitive radio ad hoc networks i...IJECEIAES
Multi-hop routing protocol in cognitive radio mobile ad hoc networks (CRMANETs) is a critical issue. Furthermore, the routing metric used in multi-hop CRMANETs should reflect the bands availability, the links quality, the PU activities and quality of service (QoS) requirements of SUs. For the best of our knowledge, many of researchers investigated the performance of the different routing protocols in a homogeneous environment only. In this paper, we propose a heterogeneous cognitive radio routing protocol (HCR) operates in heterogeneous environment (i.e. the route from source to destination utilize the licensed and unlicensed spectrum bands). The proposed routing protocol is carefully developed to make a tradeoff between the channel diversity of the routing path along with the CRMANETs throughput. Using simulations, we discuss the performance of the proposed HCR routing protocol and compare it with the AODV routing protocol using a discrete-event simulation which we developed using JAVA platform.
PERFORMANCE ANALYSIS IN CELLULAR NETWORKS CONSIDERING THE QOS BY RETRIAL QUEU...IJCNCJournal
In this article, a retrial queueing model will be considered with persevering customers for wireless cellular
networks which can be frequently applied in the Fractional Guard Channel (FGC) policies, including
Limited FGC (LFGC), Uniform FGC (UFGC), Limited Average FGC (LAFGC) and Quasi Uniform FGC
(QUFGC). In this model, the examination on the retrial phenomena permits the analyses of important
effectiveness measures pertained to the standard of services undergone by users with the probability that a
fresh call first arrives the system and find all busy channels at the time, the probability that a fresh call
arrives the system from the orbit and find all busy channels at the time and the probability that a handover
call arrives the system and find all busy channels at the time. Comparison between four types of the FGC
policy can befound to evaluate the performance of the system.
Design and implementation of new routingIJCNCJournal
Energy consumption is a key element in the Wireless Sensor Networks (WSNs) design. Indeed, sensor nodes are really constrained by energy supply. Hence, how to improve the network lifetime is a crucial and challenging task. Several techniques are available at different levels of the OSI model to maximize the WSN lifetime and especially at the network layer which uses routing strategies to maintain the routes in the network and guarantee reliable communication. In this paper we intend to propose a new protocol called
Combined Energy and Distance Metrics Dynamic Routing Protocol (CEDM-DR). Our new approach considers not only the distance between wireless sensors but also the energy of node acting as a router in order to find the optimal path and achieve a dynamic and adaptive routing.
The performance metrics exploited for the evaluation of our protocol are average energy consumed, network lifetime and packets lost. By comparing our proposed routing strategy to protocol widely used in WSN namely Ad hoc On demand Distance Vector(AODV), simulation results show that CEDM-DR strategy might effectively balance the sensor power consumption and permits accordingly to enhance the network
lifetime. As well, this new protocol yields a noticeable energy saving compared to its counterpart.
An Efficient and Stable Routing Algorithm in Mobile Ad Hoc NetworkIJCNCJournal
Mobile Ad hoc Network (MANET) is mainly designed to set up communication among devices in infrastructure-less wireless communication network. Routing in this kind of communication network is highly affected by its restricted characteristics such as frequent topological changes and limited battery power. Several research works have been carried out to improve routing performance in MANET. However, the overall performance enhancement in terms of packet delivery, delay and control message overhead is still not come into the wrapping up. In order to overcome the addressed issues, an Efficient and Stable-AODV (EFST-AODV) routing scheme has been proposed which is an improvement over AODV to establish a better quality route between source and destination. In this method, we have modified the route request and route reply phase. During the route request phase, cost metric of a route is calculated on the basis of parameters such as residual energy, delay and distance. In a route reply phase, average residual energy and average delay of overall path is calculated and the data forwarding decision is taken at the source node accordingly. Simulation outcomes reveal that the proposed approach gives better results in terms of packet delivery ratio, delay, throughput, normalized routing load and control message overhead as compared to AODV.
A Novel Path Tracing Scheme In All-Optical Networks Using Benes NetworkCSCJournals
A novel path tracing scheme is described in this paper which is known as Prime number encoding scheme using Benes network. In this scheme every data packet consist a label which is default 1 and every node consist of a prime number tag, as this data packet pass through the network label will be multiplied with the tag of the node. Prime number multiplication is done with encoder. At the receiver end factorization is done which gives the information of travelled path. In this scheme optical cross connects (OXC) is replaced with the Benes network which gives the better result than OXC. System having Benes network gives less attenuation than OXC and complexity of the system also decreases.
Mobile Primary User in Cognitive Radio State of the Arts and Recent Advancesjosephjonse
The processing of primary user mobility with static or mobile secondary user in the context of cognitive radio (CR) has recently been the subject of several studies and discussions all over the world. These studies are seeking to broaden the horizons of CR implementation beyond the formalism described in the diverse existing standards. The mobility of primary users is likely to reduce the overall performance of the Cognitive Radio Network (CRN) and affects the different phases of the cognitive cycle. Said mobility alters the network’s topology, the channel’s availability, and affects spectrum sensing. This makes any endeavor aiming to implement CR technology complicated. This paper is devoted to the analysis and discussion of the scientific literature that has addressed the issue of the primary user’s mobility.
Analysing Mobile Random Early Detection for Congestion Control in Mobile Ad-h...IJECEIAES
This research paper suggests and analyse a technique for congestion control in mobile ad hoc networks. The technique is based on a new hybrid approach that uses clustering and queuing techniques. In clustering, in general cluster head transfers the data, following a queuing method based on a RED (Random Early Detection), the mobile environment makes it Mobile RED (or MRED), It majorly depends upon mobility of nodes and mobile environments leads to unpredictable queue size. To simulate this technique, the Network Simulator 2 (or NS2) is used for various scenarios. The simulated results are compared with NRED (Neighbourhood Random Early Detection) queuing technique of congestion control. It has been observed that the results are improved using MRED comparatively.
Routing in Cognitive Radio Networks - A SurveyIJERA Editor
Cognitive Radio Networks (CRNs) have been emerged as a revolutionary solution to migrate the spectrum
scarcity problem in wireless networks. Due to increasing demand for additional spectrum resources, CRNs have
been receiving significant research to solve issues related with spectrum underutilization. This technology
brings efficient spectrum usage and effective interference avoidance, and also brings new challenges to routing
in multi-hop Cognitive Radio Networks. In CRN, unlicensed users or secondary users are able to use
underutilized licensed channels, but they have to leave the channel if any interference is caused to the primary or
licensed users. So CR technology allows sharing of licensed spectrum band in opportunistic and non-interfering
manner. Different routing protocols have been proposed recently based on different design goals under different
assumptions.
ADAPTIVE HANDOVER HYSTERESIS AND CALL ADMISSION CONTROL FOR MOBILE RELAY NODESIJCNCJournal
The aim of equipping a wireless network with a mobile relay node is to support broadband wireless communications for vehicular users and their devices. The high mobility of vehicular users, possibly at a very high velocity in the area in which two cells overlap, could cause the network to suffer from a reduced handover success rate and, hence, increased radio link failure. The combined impact of these problems is service interruptions to vehicular users. Thus, the handover schemes are crucial in solving these problems. In this work, we first present the adaptive handover hysteresis scheme for the wireless network with mobile relay nodes in the high-speed train scenario. Specifically, our proposed adaptive hysteresis scheme is based on the velocity of the train. Second, the handover call dropping probability is reduced by introducing a modified call admission control scheme to support radio resource reservation for handover calls that prioritizes handover calls of mobile relay over the other calls. The proposed solution in which adaptive parameter is combined with call admission control is evaluated by system level simulation. Our simulation results illustrate an increased handover success rate and reduced radio link failures.
Efficient Utilization of Bandwidth in Location Aided RoutingIOSR Journals
Abstract : Earlier work on routing MANETs developed several routing protocols, which finds available route from source to destination without taking into the consideration of Band width availability for data transfer, and they frequently fails to discover stable routes between source and destination. As a result of that there is a large numbers of discarding of data packets as well as overloading of packets as the consequences of that large wastage of band width. EUBLAR (Efficient Utilization of band width in Location Aided Routing) protocol is introduced in this proposed work, which is capable of calculating the available band width of all the intermediate nodes between source and destination. In this proposed protocol find the minimum available band width of all the intermediate nodes between source and destination and then according to that band width sends the data packets over that path. The EUBLAR can effectively utilized the wastage of band width and every single band width can be used for data transfer can be used over entirely configured network. In this way we can increase the quality of service of the Ad- hoc network in terms of bandwidth. Keywords: Ad Hoc Networks, Global Positioning System, Maximum & Minimum slopes, Minimum available Bandwidth, Time to Live
A Summative Comparison of Blind Channel Estimation Techniques for Orthogonal ...IJECEIAES
The OFDM technique i.e. Orthogonal frequency division multiplexing has become prominent in wireless communication since its instruction in 1950’s due to its feature of combating the multipath fading and other losses. In an OFDM system, a large number of orthogonal, overlapping, narrow band subchannels or subcarriers, transmitted in parallel, divide the available transmission bandwidth. The separation of the subcarriers is theoretically optimal such that there is a very compact spectral utilization. This paper reviewed the possible approaches for blind channel estimation in the light of the improved performance in terms of speed of convergence and complexity. There were various researches which adopted the ways for channel estimation for Blind, Semi Blind and trained channel estimators and detectors. Various ways of channel estimation such as Subspace, iteration based, LMSE or MSE based (using statistical methods), SDR, Maximum likelihood approach, cyclostationarity, Redundancy and Cyclic prefix based. The paper reviewed all the above approaches in order to summarize the outcomes of approaches aimed at optimum performance for channel estimation in OFDM systems.
A JOINT TIMING OFFSET AND CHANNEL ESTIMATION USING FRACTIONAL FOURIER TRANSFO...IJCNCJournal
This paper deals with symbol timing offset and channel estimation in OFDM (orthogonal frequency
division multiplexing) system in fast varying channel. Symbol timing offset (STO) estimation is a major task
in OFDM. Most of existing methods for estimating STO used cyclic prefix or training sequences. In this
paper, we consider a new system for STO estimation using constant amplitude zero autocorrelation
(CAZAC) sequences as pilot sequences in conjunction with fractional Fourier transform (FRFT). After STO
estimation is done, timing compensation is made. Thereafter, channel is estimated to well recover the
original transmitted signal. This method gives good results in terms of MSE in comparison with other
known techniques, it estimated well the channel and it is important for fast varying channel. MATLAB
Monte-Carlo simulations are used to evaluate the performance of the proposed estimator.
Web object size satisfying mean waitingIJCNCJournal
This paper addresses web object size which is one of important performance measures and affects to
service time in multiple access environment. Since packets arrive according to Poission distribution and
web service time has arbitrary distribution, M/G/1 model can be used to describe the behavior of the web
server system. In the time division multiplexing (TDM), we can use M/D/1 with vacations model, because
service time is constant and server may have a vacation. We derive the mean web object size satisfying the
constraint such that mean waiting time by round-robin scheduling in multiple access environment is equal
to the mean queueing delay of M/D/1 with vacations model in TDM and M/H2/1 model, respectively.
Performance evaluation shows that the mean web object size increases as the link utilization increases at
the given maximum segment size (MSS), but converges on the lower bound when the number of embedded
objects included in a web page is beyond the threshold. Our results can be applied to the economic design
and maintenance of web service.
Visualize network anomaly detection by using k means clustering algorithmIJCNCJournal
With the ever increasing amount of new attacks in today’s world the amount of data will keep increasing,
and because of the base-rate fallacy the amount of false alarms will also increase. Another problem with
detection of attacks is that they usually isn’t detected until after the attack has taken place, this makes
defending against attacks hard and can easily lead to disclosure of sensitive information.
In this paper we choose K-means algorithm with the Kdd Cup 1999 network data set to evaluate the
performance of an unsupervised learning method for anomaly detection. The results of the evaluation
showed that a high detection rate can be achieve while maintaining a low false alarm rate .This paper
presents the result of using k-means clustering by applying Cluster 3.0 tool and visualized this result by
using TreeView visualization tool .
Hex-Cell is an interconnection network that has attractive features like the embedding capability of topological structures; such as; bus, ring, tree and mesh topologies. In this paper, we present two algorithms for embedding bus and ring topologies onto Hex-Cell interconnection network. We use three metrics to evaluate our proposed algorithms: dilation, congestion, and expansion. Our evaluation results
show that the congestion of our two proposed algorithms is equal to one; and the dilation is equal to 2d-1 for the first algorithm and 1 for the second.
A novel signature based traffic classification engine to reduce false alarms ...IJCNCJournal
Pattern matching plays a significant role in ascertaining network attacks and the foremost prerequisite for a trusted intrusion detection system (IDS) is accurate pattern matching. During the pattern matching process packets are scanned against a pre-defined rule sets. After getting scanned, the packets are marked as alert or benign by the detection system. Sometimes the detection system generates false alarms i.e., good traffic being identified as bad traffic. The ratio of generating the false positives varies from the performance of the detection engines used to scan incoming packets. Intrusion detection systems use to deploy algorithmic procedures to reduce false positives though producing a good number of false alarms. As the necessities, we have been working on the optimization of the algorithms and procedures so that false positives can be reduced to a great extent. As an effort we have proposed a signature-based traffic classification technique that can categorize the incoming packets based on the traffic characteristics and behaviour which would eventually reduce the rate of false alarms
PERFORMANCE OF TCP CONGESTION CONTROL IN UAV NETWORKS OF VARIOUS RADIO PROPAG...IJCNCJournal
Unmanned aerial vehicles (UAVs) have recently become popular for both recreational and commercial use
and UAV networks have thus started to attract the attention of researchers in area of the computer
communication and networking. One important topic in UAV networks is congestion control because
congestion causes packet losses and delays which result in the waste of all types of network resources such
as bandwidth and power. Although there are studies on the performance of TCP congestion control in
wireless networks, they focus on terrestrial networks of two dimensions in general. In this paper we study
the performance of TCP congestion control in three dimensional UAV networks. In particular, we
investigate how TCP congestion control performs in such type of network using various radio propagation
models. Our data on the average flow throughput, packet delay, and packet loss rate in UAV networks
show that TCP congestion control improves the network performance of UAV networks in general, but it
faces challenges when the link losses become severe. Our study thus shows that investigation on new
congestion control schemes is stilled needed for the emerging UAV networks.
COMPARATIVE ANALYSIS OF DIFFERENT ENCRYPTION TECHNIQUES IN MOBILE AD HOC NETW...IJCNCJournal
In this paper a detailed analysis of Data Encryption Standard (DES), Triple DES (3DES) and Advanced
Encryption Standard (AES) symmetric encryption algorithms in MANET was done using the Network
Simulator 2 (NS-2) in terms of energy consumption, data transfer time, End-to-End delay time and
throughput with varying data sizes. Two simulation models were adopted: the first simulates the network
performance assuming the availability of the common key, and the second simulates the network
performance including the use of the Diffie-Hellman Key Exchange (DHKE) protocol in the key
management phase. The obtained simulation results showed the superiority of AES over DES by 65%, 70%
and 83% in term of the energy consumption, data transfer time, and network throughput respectively. On
the other hand, the results showed that AES is better than 3DES by approximately 90% for all of the
performance metrics. Based on these results the AES was the recommended encryption scheme.
Clock synchronization estimation of non deterministic delays in wireless mess...IJCNCJournal
Clock synchronization is significantly essential as they require universal time on WSN nodes for time measurement, event ordering and coordinated actions, and power management. This paper gives an insight of solving the problem of the non-deterministic delays that exist in the wireless message delivery. Sensor nodes consisting of Arduino Mega and 2.4 GHz nRF24L01+ radio modules are used, and based on the estimation of non-deterministic delays a clock synchronization protocol for WSN is proposed. The results obtained are quiet promising compared to the existing synchronization protocols for WSNs.
Clustering problems are considered amongst the prominent challenges in statistics and computational science. Clustering of nodes in wireless sensor networks which is used to prolong the life-time of networks is one of the difficult tasks of clustering procedure. In order to perform nodes’ clustering, a number of nodes are determined as cluster heads and other ones are joined to one of these heads, based on different criteria e.g. Euclidean distance. So far, different approaches have been proposed for this process, where swarm and evolutionary algorithms contribute in this regard. In this study, a novel algorithm is proposed based on Artificial Fish Swarm Algorithm (AFSA) for clustering procedure. In the proposed method, the
performance of the standard AFSA is improved by increasing balance between local and global searches.
Furthermore, a new mechanism has been added to the base algorithm for improving convergence speed in
clustering problems. Performance of the proposed technique is compared to a number of state-of-the-art
techniques in this field and the outcomes indicate the supremacy of the proposed technique.
3GPP has introduced LTE Femtocells to manipulate the traffic for indoor users and to minimize
the charge on the Macro cells. A key mechanism in the LTE traffic handling is the packet
scheduler which is in charge of allocating resources to active flows in both the frequency and
time dimension. So several scheduling algorithms need to be analyzed for femtocells networks.
In this paper we introduce a performance analysis of three distinct scheduling algorithms of
mixed type of traffic flows in LTE femtocells networks. The particularly study is evaluated in
terms of throughput, packet loss ratio, fairness index and spectral efficiency.
PERFORMANCE ANALYSIS OF RESOURCE SCHEDULING IN LTE FEMTOCELLS NETWORKScscpconf
3GPP has introduced LTE Femtocells to manipulate the traffic for indoor users and to minimize the charge on the Macro cells. A key mechanism in the LTE traffic handling is the packet
scheduler which is in charge of allocating resources to active flows in both the frequency and time dimension. So several scheduling algorithms need to be analyzed for femtocells networks. In this paper we introduce a performance analysis of three distinct scheduling algorithms of mixed type of traffic flows in LTE femtocells networks. The particularly study is evaluated in terms of throughput, packet loss ratio, fairness index and spectral efficiency.
Macro with pico cells (hetnets) system behaviour using well known scheduling ...ijwmn
This paper demonstrates the concept of using Heterogeneous networks (HetNets) to improve Long Term Evolution (LTE) system by introducing the LTE Advance (LTE-A). The type of HetNets that has been chosen for this study is Macro with Pico cells. Comparing the system performance with and without Pico cells has clearly illustrated using three well-known scheduling algorithms (Proportional Fair PF, Maximum Largest Weighted Delay First MLWDF and Exponential/Proportional Fair EXP/PF). The system is judged based on throughput, Packet Loss Ratio PLR, delay and fairness.. A simulation platform called LTE-Sim has been used to collect the data and produce the paper’s outcomes and graphs. The results prove that adding Pico cells enhances the overall system performance. From the simulation outcomes, the overall system performance is as follows: throughput is duplicated or tripled based on the number of users, the PLR is almost quartered, the delay is nearly reduced ten times (PF case) and changed to be a half (MLWDF/EXP cases), and the fairness stays closer to value of 1. It is considered an efficient and cost effective way to increase the throughput, coverage and reduce the latency.
Optimize the Network Coding Paths to Enhance the Coding Protection in Wireles...IJCNCJournal
Efficient protection techniques for multimedia data transfer over Wireless Sensor Network (WSN) are very essential issues. In noisy Wireless Multimedia Sensor Networks (WMSN) Quality of Service (QoS) is a challenging task due to bandwidth and limited energy, and unpredictable channel conditions. Therefore, Forward Error Correction (FEC), a class of channel coding has been widely used in WSN. Nevertheless, the bulky size of multimedia data makes it more difficult to be transported over the noisy multi-hop wireless network. Moreover, the efficiency of FEC drops as the number of hops increases. In this paper, an optimized protection technique based on network coding and rateless code has been proposed to enhance the throughput and reduce overhead during data transfer in WMSN. The performance of NCP-OPR is enhanced via Optimal Network Path Model (ONPM) where the best available paths are optimally selected using Particle Swarm Optimization (PSO). In conjunction with the proposed protection scheme, the proposed ONPM is intended for limited power WSN by optimally distributing the power usage among the network paths so that the throughput can be improved.
Optimize the Network Coding Paths to Enhance the Coding Protection in Wireles...IJCNCJournal
Efficient protection techniques for multimedia data transfer over Wireless Sensor Network (WSN) are very essential issues. In noisy Wireless Multimedia Sensor Networks (WMSN) Quality of Service (QoS) is a challenging task due to bandwidth and limited energy, and unpredictable channel conditions. Therefore, Forward Error Correction (FEC), a class of channel coding has been widely used in WSN. Nevertheless, the bulky size of multimedia data makes it more difficult to be transported over the noisy multi-hop wireless network. Moreover, the efficiency of FEC drops as the number of hops increases. In this paper, an optimized protection technique based on network coding and rateless code has been proposed to enhance the throughput and reduce overhead during data transfer in WMSN. The performance of NCP-OPR is enhanced via Optimal Network Path Model (ONPM) where the best available paths are optimally selected using Particle Swarm Optimization (PSO). In conjunction with the proposed protection scheme, the proposed ONPM is intended for limited power WSN by optimally distributing the power usage among the network paths so that the throughput can be improved.
Survey on scheduling and radio resources allocation in lteijngnjournal
This paper focuses on an essential task of the enhanced NodeB eNodeB element in LTE architecture, the
Radio Resource Manager RRM, which aims to accept or reject requests for connection to the network
based on some constraints and ensuring optimal distribution of radio resources between Users Equipments
UEs. Its main functionalities include Admission Control AC and Packet Scheduling PS.
This paper will center mainly on the PS part of the RRM task, which performs the radio resource
allocation in both uplink and downlink directions. Several approaches and algorithms have been proposed
in the literature to address this need (allocate resources efficiently), the diversity and multitude of
algorithms is related to the factors considered for the optimal management of radio resource, specifically,
the traffic type and the QoS (Quality of Service) requested by the UE.
In this article, an art’s state of the radio resource allocation strategies and a detailed study of several
scheduling algorithms proposed for LTE (uplink and downlink) are made. Therefore, we offer our
evaluation and criticism.
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QOS ROUTING AND PERFORMANCE EVALUATION FOR MOBILE AD HOC NETWORKS USING OLSR ...ijasuc
Mobile Ad-Hoc network is a collection of mobile nodes in communication without using infrastructure.
As the real-time applications used in today’s wireless network grow, we need some schemes to provide
more suitable service for them. We know that most of actual schemes do not perform well on traffic which
is not strictly CBR. Therefore, in this paper we have studied the impact, respectively, of mobility models
and the density of nodes on the performances (End-to-End Delay, Throughput and Packet Delivery ratio)
of routing protocol (Optimized Link State Routing) OLSR by using in the first a real-time VBR (MPEG-4)
and secondly the Constant Bit Rate (CBR) traffic. Finally we compare the performance on both cases.
Experimentally, we considered the three mobility models as follows Random Waypoint, Random
Direction and Mobgen Steady State. The experimental results illustrate that the behavior of OLSR change
according to the model and the used traffics.
Congestion Control in Manets Using Hybrid Routing ProtocolIOSR Journals
Abstract : As the network size increases the probability of congestion occurrence at nodes increases. This is because of the event driven nature of ad hoc networks that leads to unpredictable network load. As a result congestion may occur at the nodes which receive more data than that can be forwarded and cause packet losses. In this paper we propose a hybrid scheme that attempts to avoid packet loss due to congestion as well as reduce end to end delay in delivering data packets by combining two protocols- Destination sequenced distance vector routing (DSDV), which is a table driven or proactive protocol and Improved Ad-hoc on demand vector routing (IAODV) which is an on-demand or reactive protocol that reduces packet loss due to congestion. The strategy adopted is use DSDV for path selection and if congestion occurs than switch over to IAODV. The routing performance of this model is then compared with IAODV and DSDV in terms of end to end delay, throughput and packet delivery fraction. Keywords- DSDV, Hybrid protocol, AODV, IAODV, MANET
B ENCHMARKING OF C ELL T HROUGHPUT U SING P ROPORTIONAL F AIR S CHEDULE...ijwmn
The proportional fair (PF) scheduling algorithm com
promises between cell throughput and fairness. Many
research findings have been published by various re
searchers about PF algorithm based on mathematical
model and simulations. In this paper we have taken
the practical route to analyse the algorithm based
on
three types of subscription. In this benchmarking s
tudy, the user subscriptions are differentiated as
Gold,
Silver and Bronze schemes and they are provisioned
with certain throughputs. Apart from subscriptions
plans, the channel condition also plays a major rol
e in determining the throughput. So in order to ens
ure
fairness among different subscriptions even in the
bad channel conditions and to deliver the provision
ed
throughputs certain priorities are attached with th
e subscriptions. As per the subscription plans Gold
subscribers are assigned with 50% of the speed offe
red by the network as maximum based on CAT3 speed
(100 Mbps in DL and 50 Mbps in UL), Silver is assig
ned with 25% of the max speed and Bronze is
assigned with 12% of the max speed. The priorities
assigned to subscribers determines the fairness in
the
unfavourable channel conditions - Bronze (high), Si
lver and Gold (medium). In this paper, an
benchmarking tests have been performed with all of
three types of subscribers for nearly two hours in
the
live single cell network without any heterogeneous
cells influencing it. Furthermore, the results are
compared with the simulation results.
ANALYSIS OF LINK STATE RESOURCE RESERVATION PROTOCOL FOR CONGESTION MANAGEMEN...ijgca
With the wide spread of WiFi hotspots, concentrated traffic workload on Smart Web (SW) can slow down the network performance. This paper presents a congestion management strategy considering real time activities in today’s smart web. With the SW context, cooperative packet recovery using resource reservation procedure for TCP flows was adapted for mitigating packet losses. This is to maintain data consistency between various access points of smart web hotspot. Using a real world scenario, it was confirmed that generic TCP cannot handle traffic congestion in a SW hotspot network. With TCP in scalable workload environments, continuous packet drops at the event of congestion remains obvious. This is unacceptable for mission critical domains. An enhanced Link State Resource Reservation Protocol (LSRSVP) which serves as dynamic feedback mechanism in smart web hotspots is presented. The contextual behaviour was contrasted with the generic TCP model. For the LS-RSVP, a simulation experiment for TCP connection between servers at the remote core layer and the access layer was carried out while using selected benchmark metrics. From the results, under realistic workloads, a steady-state throughput response was achieved by TCP LS-RSVP to about 3650Bits/secs compared with generic TCP plots in a previous study. Considering network service availability, this was found to be dependent on fault-tolerance of the hotspot network. From study, a high peak threshold of 0.009 (i.e. 90%) was observed. This shows fairly acceptable service availability behaviour compared with the existing TCP schemes. For packet drop effects, an analysis on the network behaviour with respect to the LS-RSVP yielded a drop response of about 0.000106 bits/sec which is much lower compared with the case with generic TCP with over 0.38 bits/sec. The latency profile of average FTP download response was found to be 0.030secs, but with that of FTP upload response, this yielded about 0.028 sec. The results from the study demonstrate efficiency and optimality for realistic loads in Smart web contexts.
Analysis of Link State Resource Reservation Protocol for Congestion Managemen...ijgca
With the wide spread of WiFi hotspots, concentrated traffic workload on Smart Web (SW) can slow down
the network performance. This paper presents a congestion management strategy considering real time
activities in today’s smart web. With the SW context, cooperative packet recovery using resource
reservation procedure for TCP flows was adapted for mitigating packet losses. This is to maintain data
consistency between various access points of smart web hotspot. Using a real world scenario, it was
confirmed that generic TCP cannot handle traffic congestion in a SW hotspot network. With TCP in
scalable workload environments, continuous packet drops at the event of congestion remains obvious. This
is unacceptable for mission critical domains. An enhanced Link State Resource Reservation Protocol (LSRSVP)
which serves as dynamic feedback mechanism in smart web hotspots is presented. The contextual
behaviour was contrasted with the generic TCP model. For the LS-RSVP, a simulation experiment for TCP
connection between servers at the remote core layer and the access layer was carried out while using
selected benchmark metrics. From the results, under realistic workloads, a steady-state throughput
response was achieved by TCP LS-RSVP to about 3650Bits/secs compared with generic TCP plots in a
previous study. Considering network service availability, this was found to be dependent on fault-tolerance
of the hotspot network. From study, a high peak threshold of 0.009 (i.e. 90%) was observed. This shows
fairly acceptable service availability behaviour compared with the existing TCP schemes. For packet drop
effects, an analysis on the network behaviour with respect to the LS-RSVP yielded a drop response of about
0.000106 bits/sec which is much lower compared with the case with generic TCP with over 0.38 bits/sec.
The latency profile of average FTP download response was found to be 0.030secs, but with that of FTP
upload response, this yielded about 0.028 sec. The results from the study demonstrate efficiency and
optimality for realistic loads in Smart web contexts.
Vehicle Ad Hoc Networks (VANETs) have become a viable technology to improve traffic flow and safety on the roads. Due to its effectiveness and scalability, the Wingsuit Search-based Optimised Link State Routing Protocol (WS-OLSR) is frequently used for data distribution in VANETs. However, the selection of MultiPoint Relays (MPRs) plays a pivotal role in WS-OLSR's performance. This paper presents an improved MPR selection algorithm tailored to WS-OLSR, designed to enhance the overall routing efficiency and reduce overhead. The analysis found that the current OLSR protocol has problems such as redundancy of HELLO and TC message packets or failure to update routing information in time, so a WS-OLSR routing protocol based on improved-MPR selection algorithm was proposed. Firstly, factors such as node mobility and link changes are comprehensively considered to reflect network topology changes, and the broadcast cycle of node HELLO messages is controlled through topology changes. Secondly, a new MPR selection algorithm is proposed, considering link stability issues and nodes. Finally, evaluate its effectiveness in terms of packet delivery ratio, end-to-end delay, and control message overhead. Simulation results demonstrate the superior performance of our improved MR selection algorithm when compared to traditional approaches.
A Novel Medium Access Control Strategy for Heterogeneous Traffic in Wireless ...IJCNCJournal
So far, Wireless Body Area Networks (WBANs) have played a pivotal role in driving the development of intelligent healthcare systems with broad applicability across various domains. Each WBAN consists of one or more types of sensors that can be embedded in clothing, attached directly to the body, or even implanted beneath an individual's skin. These sensors typically serve asingle application. However, the traffic generated by each sensor may have distinct requirements. This diversity necessitates a dual approach: tailored treatment based on the specific needs of each traffic typeand the fulfillment of application requirements, such asreliability and timeliness. Never the less, the presence of energy constraints and the unreliable nature of wireless communications make QoS provisioning under such networks a non-trivial task. In this context, the current paper introduces a novel Medium AccessControl (MAC) strategy for the regular traffic applications of WBANs, designed to significantly enhance efficiency when compared to the established MAC protocols IEEE 802.15.4 and IEEE 802.15.6, with a particular focus on improving reliability, timeliness, and energy efficiency.
May_2024 Top 10 Read Articles in Computer Networks & Communications.pdfIJCNCJournal
The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications. The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new collaborations in these areas.
A Topology Control Algorithm Taking into Account Energy and Quality of Transm...IJCNCJournal
The efficient use of energy in wireless sensor networks is critical for extending node lifetime. The network topology is one of the factors that have a significant impact on the energy usage at the nodes and the quality of transmission (QoT) in the network. We propose a topology control algorithm for software-defined wireless sensor networks (SDWSNs) in this paper. Our method is to formulate topology control algorithm as a nonlinear programming (NP) problem with the objective to optimizing two metrics, maximum communication range, and desired degree. This NP problem is solved at the SDWSN controller by employing the genetic algorithm (GA) to determine the best topology. The simulation results show that the proposed algorithm outperforms the MaxPower algorithm in terms of average node degree and energy expansion ratio.
Multi-Server user Authentication Scheme for Privacy Preservation with Fuzzy C...IJCNCJournal
The integration of artificial intelligence technology with a scalable Internet of Things (IoT) platform facilitates diverse smart communication services, allowing remote users to access services from anywhere at any time. The multi-server environment within IoT introduces a flexible security service model, enabling users to interact with any server through a single registration. To ensure secure and privacy preservation services for resources, an authentication scheme is essential. Zhao et al. recently introduced a user authentication scheme for the multi-server environment, utilizing passwords and smart cards, claiming resilience against well-known attacks. This paper conducts cryptanalysis on Zhao et al.'s scheme, focusing on denial of service and privacy attacks, revealing a lack of user-friendliness. Subsequently, we propose a new multi-server user authentication scheme for privacy preservation with fuzzy commitment over the IoT environment, addressing the shortcomings of Zhao et al.'s scheme. Formal security verification of the proposed scheme is conducted using the ProVerif simulation tool. Through both formal and informal security analyses, we demonstrate that the proposed scheme is resilient against various known attacks and those identified in Zhao et al.'s scheme.
Advanced Privacy Scheme to Improve Road Safety in Smart Transportation SystemsIJCNCJournal
In -Vehicle Ad-Hoc Network (VANET), vehicles continuously transmit and receive spatiotemporal data with neighboring vehicles, thereby establishing a comprehensive 360-degree traffic awareness system. Vehicular Network safety applications facilitate the transmission of messages between vehicles that are near each other, at regular intervals, enhancing drivers' contextual understanding of the driving environment and significantly improving traffic safety. Privacy schemes in VANETs are vital to safeguard vehicles’ identities and their associated owners or drivers. Privacy schemes prevent unauthorized parties from linking the vehicle's communications to a specific real-world identity by employing techniques such as pseudonyms, randomization, or cryptographic protocols. Nevertheless, these communications frequently contain important vehicle information that malevolent groups could use to Monitor the vehicle over a long period. The acquisition of this shared data has the potential to facilitate the reconstruction of vehicle trajectories, thereby posing a potential risk to the privacy of the driver. Addressing the critical challenge of developing effective and scalable privacy-preserving protocols for communication in vehicle networks is of the highest priority. These protocols aim to reduce the transmission of confidential data while ensuring the required level of communication. This paper aims to propose an Advanced Privacy Vehicle Scheme (APV) that periodically changes pseudonyms to protect vehicle identities and improve privacy. The APV scheme utilizes a concept called the silent period, which involves changing the pseudonym of a vehicle periodically based on the tracking of neighboring vehicles. The pseudonym is a temporary identifier that vehicles use to communicate with each other in a VANET. By changing the pseudonym regularly, the APV scheme makes it difficult for unauthorized entities to link a vehicle's communications to its real-world identity. The proposed APV is compared to the SLOW, RSP, CAPS, and CPN techniques. The data indicates that the efficiency of APV is a better improvement in privacy metrics. It is evident that the AVP offers enhanced safety for vehicles during transportation in the smart city.
April 2024 - Top 10 Read Articles in Computer Networks & CommunicationsIJCNCJournal
The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications. The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new collaborations in these areas.
DEF: Deep Ensemble Neural Network Classifier for Android Malware DetectionIJCNCJournal
Malware is one of the threats to security of computer networks and information systems. Since malware instances are available sufficiently, there is increased interest among researchers on usage of Artificial Intelligence (AI). Of late AI-enabled methods such as machine learning (ML) and deep learning paved way for solving many real-world problems. As it is a learning-based approach, accumulated training samples help in improving thequality of training and thus leveraging malware detection accuracy. Existing deep learning methods are focusing on learning-based malware detection systems. However, there is need for improving the state of the art through ensemble approach. Towards this end, in this paper we proposed a framework known as Deep Ensemble Framework (DEF) for automatic malware detection. The framework obtains features from training samples. From given malware instance a grayscale image is generated. There is another process to extract the opcode sequences. Convolutional Neural Network (CNN) and Long Short Term Memory (LSTM) techniques are used to obtain grayscale image and opcode sequence respectively. Afterwards, a stacking ensemble is employed in order to achieve efficient malware detection and classification. Malware samples collected fromthe Internet sources and Microsoft are used for theempirical study. An algorithm known as Ensemble Learning for Automatic Malware Detection (EL-AML) is proposed to realize our framework. Another algorithm named Pre-Process is proposed to assist the EL-AML algorithm for obtaining intermediate features required by CNN and LSTM.Empirical study reveals that our framework outperforms many existing methods in terms of speed-up and accuracy.
High Performance NMF Based Intrusion Detection System for Big Data IOT TrafficIJCNCJournal
With the emergence of smart devices and the Internet of Things (IoT), millions of users connected to the network produce massive network traffic datasets. These vast datasets of network traffic, Big Data are challenging to store, deal with and analyse using a single computer. In this paper we developed parallel implementation using a High Performance Computer (HPC) for the Non-Negative Matrix Factorization technique as an engine for an Intrusion Detection System (HPC-NMF-IDS). The large IoT traffic datasets of order of millions samples are distributed evenly on all the computing cores for both storage and speedup purpose. The distribution of computing tasks involved in the Matrix Factorization takes into account the reduction of the communication cost between the computing cores. The experiments we conducted on the proposed HPC-IDS-NMF give better results than the traditional ML-based intrusion detection systems. We could train the HPC model with datasets of one million samples in only 31 seconds instead of the 40 minutes using one processor), that is a speed up of 87 times. Moreover, we have got an excellent detection accuracy rate of 98% for KDD dataset.
A Novel Medium Access Control Strategy for Heterogeneous Traffic in Wireless ...IJCNCJournal
So far, Wireless Body Area Networks (WBANs) have played a pivotal role in driving the development of intelligent healthcare systems with broad applicability across various domains. Each WBAN consists of one or more types of sensors that can be embedded in clothing, attached directly to the body, or even implanted beneath an individual's skin. These sensors typically serve asingle application. However, the traffic generated by each sensor may have distinct requirements. This diversity necessitates a dual approach: tailored treatment based on the specific needs of each traffic typeand the fulfillment of application requirements, such asreliability and timeliness. Never the less, the presence of energy constraints and the unreliable nature of wireless communications make QoS provisioning under such networks a non-trivial task. In this context, the current paper introduces a novel Medium AccessControl (MAC) strategy for the regular traffic applications of WBANs, designed to significantly enhance efficiency when compared to the established MAC protocols IEEE 802.15.4 and IEEE 802.15.6, with a particular focus on improving reliability, timeliness, and energy efficiency.
A Topology Control Algorithm Taking into Account Energy and Quality of Transm...IJCNCJournal
The efficient use of energy in wireless sensor networks is critical for extending node lifetime. The network topology is one of the factors that have a significant impact on the energy usage at the nodes and the quality of transmission (QoT) in the network. We propose a topology control algorithm for software-defined wireless sensor networks (SDWSNs) in this paper. Our method is to formulate topology control algorithm as a nonlinear programming (NP) problem with the objective to optimizing two metrics, maximum communication range, and desired degree. This NP problem is solved at the SDWSN controller by employing the genetic algorithm (GA) to determine the best topology. The simulation results show that the proposed algorithm outperforms the MaxPower algorithm in terms of average node degree and energy expansion ratio.
Multi-Server user Authentication Scheme for Privacy Preservation with Fuzzy C...IJCNCJournal
The integration of artificial intelligence technology with a scalable Internet of Things (IoT) platform facilitates diverse smart communication services, allowing remote users to access services from anywhere at any time. The multi-server environment within IoT introduces a flexible security service model, enabling users to interact with any server through a single registration. To ensure secure and privacy preservation services for resources, an authentication scheme is essential. Zhao et al. recently introduced a user authentication scheme for the multi-server environment, utilizing passwords and smart cards, claiming resilience against well-known attacks. This paper conducts cryptanalysis on Zhao et al.'s scheme, focusing on denial of service and privacy attacks, revealing a lack of user-friendliness. Subsequently, we propose a new multi-server user authentication scheme for privacy preservation with fuzzy commitment over the IoT environment, addressing the shortcomings of Zhao et al.'s scheme. Formal security verification of the proposed scheme is conducted using the ProVerif simulation tool. Through both formal and informal security analyses, we demonstrate that the proposed scheme is resilient against various known attacks and those identified in Zhao et al.'s scheme.
Advanced Privacy Scheme to Improve Road Safety in Smart Transportation SystemsIJCNCJournal
In -Vehicle Ad-Hoc Network (VANET), vehicles continuously transmit and receive spatiotemporal data with neighboring vehicles, thereby establishing a comprehensive 360-degree traffic awareness system. Vehicular Network safety applications facilitate the transmission of messages between vehicles that are near each other, at regular intervals, enhancing drivers' contextual understanding of the driving environment and significantly improving traffic safety. Privacy schemes in VANETs are vital to safeguard vehicles’ identities and their associated owners or drivers. Privacy schemes prevent unauthorized parties from linking the vehicle's communications to a specific real-world identity by employing techniques such as pseudonyms, randomization, or cryptographic protocols. Nevertheless, these communications frequently contain important vehicle information that malevolent groups could use to Monitor the vehicle over a long period. The acquisition of this shared data has the potential to facilitate the reconstruction of vehicle trajectories, thereby posing a potential risk to the privacy of the driver. Addressing the critical challenge of developing effective and scalable privacy-preserving protocols for communication in vehicle networks is of the highest priority. These protocols aim to reduce the transmission of confidential data while ensuring the required level of communication. This paper aims to propose an Advanced Privacy Vehicle Scheme (APV) that periodically changes pseudonyms to protect vehicle identities and improve privacy. The APV scheme utilizes a concept called the silent period, which involves changing the pseudonym of a vehicle periodically based on the tracking of neighboring vehicles. The pseudonym is a temporary identifier that vehicles use to communicate with each other in a VANET. By changing the pseudonym regularly, the APV scheme makes it difficult for unauthorized entities to link a vehicle's communications to its real-world identity. The proposed APV is compared to the SLOW, RSP, CAPS, and CPN techniques. The data indicates that the efficiency of APV is a better improvement in privacy metrics. It is evident that the AVP offers enhanced safety for vehicles during transportation in the smart city.
DEF: Deep Ensemble Neural Network Classifier for Android Malware DetectionIJCNCJournal
Malware is one of the threats to security of computer networks and information systems. Since malware instances are available sufficiently, there is increased interest among researchers on usage of Artificial Intelligence (AI). Of late AI-enabled methods such as machine learning (ML) and deep learning paved way for solving many real-world problems. As it is a learning-based approach, accumulated training samples help in improving thequality of training and thus leveraging malware detection accuracy. Existing deep learning methods are focusing on learning-based malware detection systems. However, there is need for improving the state of the art through ensemble approach. Towards this end, in this paper we proposed a framework known as Deep Ensemble Framework (DEF) for automatic malware detection. The framework obtains features from training samples. From given malware instance a grayscale image is generated. There is another process to extract the opcode sequences. Convolutional Neural Network (CNN) and Long Short Term Memory (LSTM) techniques are used to obtain grayscale image and opcode sequence respectively. Afterwards, a stacking ensemble is employed in order to achieve efficient malware detection and classification. Malware samples collected fromthe Internet sources and Microsoft are used for theempirical study. An algorithm known as Ensemble Learning for Automatic Malware Detection (EL-AML) is proposed to realize our framework. Another algorithm named Pre-Process is proposed to assist the EL-AML algorithm for obtaining intermediate features required by CNN and LSTM.Empirical study reveals that our framework outperforms many existing methods in terms of speed-up and accuracy.
High Performance NMF based Intrusion Detection System for Big Data IoT TrafficIJCNCJournal
With the emergence of smart devices and the Internet of Things (IoT), millions of users connected to the network produce massive network traffic datasets. These vast datasets of network traffic, Big Data are challenging to store, deal with and analyse using a single computer. In this paper we developed parallel implementation using a High Performance Computer (HPC) for the Non-Negative Matrix Factorization technique as an engine for an Intrusion Detection System (HPC-NMF-IDS). The large IoT traffic datasets of order of millions samples are distributed evenly on all the computing cores for both storage and speedup purpose. The distribution of computing tasks involved in the Matrix Factorization takes into account the reduction of the communication cost between the computing cores. The experiments we conducted on the proposed HPC-IDS-NMF give better results than the traditional ML-based intrusion detection systems. We could train the HPC model with datasets of one million samples in only 31 seconds instead of the 40 minutes using one processor), that is a speed up of 87 times. Moreover, we have got an excellent detection accuracy rate of 98% for KDD dataset.
IoT Guardian: A Novel Feature Discovery and Cooperative Game Theory Empowered...IJCNCJournal
Cyber intrusion attacks increasingly target the Internet of Things (IoT) ecosystem, exploiting vulnerable devices and networks. Malicious activities must be identified early to minimize damage and mitigate threats. Using actual benign and attack traffic from the CICIoT2023 dataset, this WORK aims to evaluate and benchmark machine-learning techniques for IoT intrusion detection. There are four main phases to the system. First, the CICIoT2023 dataset is refined to remove irrelevant features and clean up missing and duplicate data. The second phase employs statistical models and artificial intelligence to discover novel features. The most significant features are then selected in the third phase based on cooperative game theory. Using the original CICIoT2023 dataset and a dataset containing only novel features, we train and evaluate a variety of machine learning classifiers. On the original dataset, Random Forest achieved the highest accuracy of 99%. Still, with novel features, Random Forest's performance dropped only slightly (96%) while other models achieved significantly lower accuracy. As a whole, the work contributes substantial contributions to tailored feature engineering, feature selection, and rigorous benchmarking of IoT intrusion detection techniques. IoT networks and devices face continuously evolving threats, making it necessary to develop robust intrusion detection systems.
Enhancing Traffic Routing Inside a Network through IoT Technology & Network C...IJCNCJournal
IoT networking uses real items as stationary or mobile nodes. Mobile nodes complicate networking. Internet of Things (IoT) networks have a lot of control overhead messages because devices are mobile. These signals are generated by the constant flow of control data as such device identity, geographical positioning, node mobility, device configuration, and others. Network clustering is a popular overhead communication management method. Many cluster-based routing methods have been developed to address system restrictions. Node clustering based on the Internet of Things (IoT) protocol, may be used to cluster all network nodes according to predefined criteria. Each cluster will have a Smart Designated Node. SDN cluster management is efficient. Many intelligent nodes remain in the network. The network design spreads these signals. This paper presents an intelligent and responsive routing approach for clustered nodes in IoT networks. An existing method builds a new sub-area clustered topology. The Nodes Clustering Based on the Internet of Things (NCIoT) method improves message transmission between any two nodes. This will facilitate the secure and reliable interchange of healthcare data between professionals and patients. NCIoT is a system that organizes nodes in the Internet of Things (IoT) by grouping them together based on their proximity. It also picks SDN routes for these nodes. This approach involves selecting one option from a range of choices and preparing for likely outcomes problem addressing limitations on activities is a primary focus during the review process. Predictive inquiry employs the process of analyzing data to forecast and anticipate future events. This document provides an explanation of compact units. The Predictive Inquiry Small Packets (PISP) improved its backup system and partnered with SDN to establish a routing information table for each intelligent node, resulting in higher routing performance. Both principal and secondary roads are available for use. The simulation findings indicate that NCIoT algorithms outperform CBR protocols. Enhancements lead to a substantial 78% boost in network performance. In addition, the end-to-end latency dropped by 12.5%. The PISP methodology produces 5.9% more inquiry packets compared to alternative approaches. The algorithms are constructed and evaluated against academic ones.
IoT Guardian: A Novel Feature Discovery and Cooperative Game Theory Empowered...IJCNCJournal
Cyber intrusion attacks increasingly target the Internet of Things (IoT) ecosystem, exploiting vulnerable devices and networks. Malicious activities must be identified early to minimize damage and mitigate threats. Using actual benign and attack traffic from the CICIoT2023 dataset, this WORK aims to evaluate and benchmark machine-learning techniques for IoT intrusion detection. There are four main phases to the system. First, the CICIoT2023 dataset is refined to remove irrelevant features and clean up missing and duplicate data. The second phase employs statistical models and artificial intelligence to discover novel features. The most significant features are then selected in the third phase based on cooperative game theory. Using the original CICIoT2023 dataset and a dataset containing only novel features, we train and evaluate a variety of machine learning classifiers. On the original dataset, Random Forest achieved the highest accuracy of 99%. Still, with novel features, Random Forest's performance dropped only slightly (96%) while other models achieved significantly lower accuracy. As a whole, the work contributes substantial contributions to tailored feature engineering, feature selection, and rigorous benchmarking of IoT intrusion detection techniques. IoT networks and devices face continuously evolving threats, making it necessary to develop robust intrusion detection systems.
** Connect, Collaborate, And Innovate: IJCNC - Where Networking Futures Take ...IJCNCJournal
The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications. The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new collaborations in these areas.
Enhancing Traffic Routing Inside a Network through IoT Technology & Network C...IJCNCJournal
IoT networking uses real items as stationary or mobile nodes. Mobile nodes complicate networking. Internet of Things (IoT) networks have a lot of control overhead messages because devices are mobile. These signals are generated by the constant flow of control data as such device identity, geographical positioning, node mobility, device configuration, and others. Network clustering is a popular overhead communication management method. Many cluster-based routing methods have been developed to address system restrictions. Node clustering based on the Internet of Things (IoT) protocol, may be used to cluster all network nodes according to predefined criteria. Each cluster will have a Smart Designated Node. SDN cluster management is efficient. Many intelligent nodes remain in the network. The network design spreads these signals. This paper presents an intelligent and responsive routing approach for clustered nodes in IoT networks. An existing method builds a new sub-area clustered topology. The Nodes Clustering Based on the Internet of Things (NCIoT) method improves message transmission between any two nodes. This will facilitate the secure and reliable interchange of healthcare data between professionals and patients. NCIoT is a system that organizes nodes in the Internet of Things (IoT) by grouping them together based on their proximity. It also picks SDN routes for these nodes. This approach involves selecting one option from a range of choices and preparing for likely outcomes problem addressing limitations on activities is a primary focus during the review process. Predictive inquiry employs the process of analyzing data to forecast and anticipate future events. This document provides an explanation of compact units. The Predictive Inquiry Small Packets (PISP) improved its backup system and partnered with SDN to establish a routing information table for each intelligent node, resulting in higher routing performance. Both principal and secondary roads are available for use. The simulation findings indicate that NCIoT algorithms outperform CBR protocols. Enhancements lead to a substantial 78% boost in network performance. In addition, the end-to-end latency dropped by 12.5%. The PISP methodology produces 5.9% more inquiry packets compared to alternative approaches. The algorithms are constructed and evaluated against academic ones.
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
UiPath Test Automation using UiPath Test Suite series, part 3DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 3. In this session, we will cover desktop automation along with UI automation.
Topics covered:
UI automation Introduction,
UI automation Sample
Desktop automation flow
Pradeep Chinnala, Senior Consultant Automation Developer @WonderBotz and UiPath MVP
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Connector Corner: Automate dynamic content and events by pushing a buttonDianaGray10
Here is something new! In our next Connector Corner webinar, we will demonstrate how you can use a single workflow to:
Create a campaign using Mailchimp with merge tags/fields
Send an interactive Slack channel message (using buttons)
Have the message received by managers and peers along with a test email for review
But there’s more:
In a second workflow supporting the same use case, you’ll see:
Your campaign sent to target colleagues for approval
If the “Approve” button is clicked, a Jira/Zendesk ticket is created for the marketing design team
But—if the “Reject” button is pushed, colleagues will be alerted via Slack message
Join us to learn more about this new, human-in-the-loop capability, brought to you by Integration Service connectors.
And...
Speakers:
Akshay Agnihotri, Product Manager
Charlie Greenberg, Host
Slack (or Teams) Automation for Bonterra Impact Management (fka Social Soluti...Jeffrey Haguewood
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
We believe integration and automation are essential to user experience and the promise of efficient work through technology. Automation is the critical ingredient to realizing that full vision. We develop integration products and services for Bonterra Case Management software to support the deployment of automations for a variety of use cases.
This video focuses on the notifications, alerts, and approval requests using Slack for Bonterra Impact Management. The solutions covered in this webinar can also be deployed for Microsoft Teams.
Interested in deploying notification automations for Bonterra Impact Management? Contact us at sales@sidekicksolutionsllc.com to discuss next steps.
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
Dynamic bandwidth allocation scheme in lr pon with performance modelling and analysis
1. International Journal of Computer Networks & Communications (IJCNC) Vol.6, No.2, March 2014
DOI : 10.5121/ijcnc.2014.6201 01
DYNAMIC BANDWIDTH ALLOCATION SCHEME IN
LR-PON WITH PERFORMANCE MODELLING AND
ANALYSIS
Tony Tsang1
1
Department of Computer Science and Computer Engineering,
La Trobe University, Melbourne, Australia
ABSTRACT
We consider models of telecommunication systems that incorporate probability, dense real-time and data.
We present a new formal abstraction method for computing minimum and maximum reachability
probabilities for such models. Our approach uses strictly local formal abstract steps to reduce both the size
of abstract specifications generated and the complexity of operations needed, in comparison to previous
approaches of this kind. A selection of large case studies are implemented the techniques and evaluate,
which include some infinite-state probabilistic real time models, demonstrating improvements over existing
tools in several cases. The capacity of metro and access networks are extended the reach and split ratio of
the conventional Long - Reach Passive Optical Networks (LR-PONs). The efficient solutions of LR-PONs
are appeared in feeder distances around 100km and high split ratios up to 1000-way . Among many
existing approaches, one of the most effective options to improve network performance in LR-PONs are the
multi-thread based dynamic bandwidth allocation (DBA) scheme where several bandwidth allocation
processes are performed in parallel is considered. Without proper intercommunication between the
overlapped threads, multi-thread DBA may lose efficiency and even perform worse than the conventional
single thread algorithm. Real Time Probabilistic Systems are used to evaluate a typical PON systems
performance. This approach is more convenient, flexible, and lower cost than the former simulation method,
which do not need develop special hardware and software tools. Moreover, how changes in performance
depend on changes in the particular modes can be easily analysis by supplying ranges for parameter values.
The proposed algorithm with traditional DBA is compared, and shows its advantage on average packet
delay. The key parameters of the algorithm are analysed and optimized, such as initiating and tuning
multiple threads, inter -thread scheduling, and fairness among users. The algorithms advantage in
numerical results are decreased the average packet delay and improve network throughput under varying
offered loads.
KEYWORDS
Long- reach Passive Optical Networks; Dynamic Bandwidth Allocation; Real Time Probabilistic Systems;
Performance Analysis;
1. INTRODUCTION
Formal Modelling is a highly successful approach to the performance analysis of complex
infinite-state systems. The basic idea is to construct a sequence of increasingly precise
abstractions of the system to be verified, with each abstraction typically over-approximating its
behaviour. Through a process of refinement which terminates once the abstraction is precise
enough to verify the desired property of the system under analysis, construct the successive
abstractions. Formal techniques have also been used to verify probabilistic systems, including
those with real-time characteristics and continuous variables. Frequently, though, the high
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complexity of both the abstractions involved and the operations needed to construct and refine,
which hinder the practical implementations of these techniques.
In this article, the performance analysis of systems is targeted, whose behaviour incorporates both
probabilistic and real-time aspects, and which include the manipulation of (potentially infinite)
data variables. Real Time Probabilistic Systems (RTPS) are modelled, whose semantics are
defined as infinite-state Markov decision processes (MDPs) [1]. A formal abstraction procedure is
introduced for computing minimum and maximum reachability probabilities in RTPS. This
provides outer bounds on reachability probabilities (i.e., a lower bound on the minimum
probability or an upper bound on the maximum). In addition, the inner bounds and based on a
stepwise concretization of adversaries of this abstract MDP are computed, yielding upper and
lower bounds on minimum and maximum probabilities, respectively. Untimed models used
concretization. The key difference in our work is kept the abstraction small by using local
refinement and simplification operations, so as reducing the need for expensive operations such as
Craig interpolation.
The formal abstraction loop repeated to attempt constructing a concrete adversary of the RTPS.
Based on the exploration of the part of the state space, which is the current abstract adversary can
be concretized. In each exploration step, an inconsistency is encountered, in which case we derive
a formal operation and restart. Otherwise, the constructed adversary is numerically solved, giving
inner bounds on the desired probability values. The difference between upper and lower bounds is
smaller than a specified threshold is terminated the formal abstraction loop. The formal
abstraction approach are implemented; deploy it on various large case studies, and compare to the
probabilistic verification tools PRISM [2], are illustrated to improve performance in many cases.
Real Time Probabilistic Systems enable to verify and containing both real-time behaviour and
infinite data variables, which this tool can be handle.
The high bandwidth of high-capacity communication systems (e.g., optical fibre) are bring closer
to the remote end users with affordable costs, the long-reach passive optical network (PON) was
introduced and studied over the past few years. The LR-PON are developed coinciding with the
momentum in the integration of metro and access networks, as well as the integration of wire line
and wireless networks. The hierarchical architecture of the telecommunication network are
simplified and can significantly reduce both capital expenditure (CapEx) and operational
expenditure (OpEx) by lowering the total number of active sites, such as points of presence
(PoPs) and local exchanges (LXs). Three parts are consisted in a typical PON: the optical line
terminal (OLT) at the telecom central office (CO), optical network units (ONUs) located at end
users’ premises and remote nodes (RNs) in between, as shown in Figure 1. To provide high
bandwidth to a large number of users in an LR-BAN, hybrid architecture should be deployed,
exploiting both time-division multiplexing (TDM), where a single wavelength channel is shared
among multiple users and wavelength-division multiplexing (WDM), which supports multiple
wavelengths to increase capacity.
However, the traditional PONs are relatively small span and inflexible topology of restrict a
Broadband Access Networks from reaching remote users. Extend the coverage of PONs in both
directions are do the research. In the network direction, the long-reach PON (LR-PON) [3] it is no
longer a passive structure has been proposed to extend the coverage from 20 to 100 km by
exploiting advanced technologies such as reflective semiconductor optical amplifiers (R-SOAs)
and burst-mode receivers. Instead of copying the traditional ``tree-and-branch’’ topology in
PONs, researchers are also investigating a ``ring-and-spur'' topology for LR-PONs [3], as shown
in Figure 2, where a PON segment consists of the OLT and a set of ONUs operating on a
wavelength set; each PON segment exhibits a logical tree topology; several such PON segments
coexist; and the OLT and ONUs are connected through a fibre ring, and RNs are deployed on the
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ring. Although, additional RNs are introduced increasing the overall complexity of the network,
an advantage of this design is that the metro synchronous optical network / digital hierarchy
(SONET/SDH) ring networks with fibre can be reused already deployed by substituting the RN
equipment and thus achieve great savings in CapEx. This ring-and-spur topology can not only
cover a larger area than the traditional tree topology, but also provide the broadband access
networks two-dimensional coverage for failure protection, which is very important today as strict
quality of service (QoS) may be specified in a user’s service level agreement (SLA). The
introduction of the paper has been explained the nature of the problem, previous work, purpose,
and the contribution of the paper. The contents of each section may be provided to understand
easily about the paper.
Figure 1. PON Architecture
Figure 2. Ring and Spur LR-PON
The PON standards have adopted Time-division multiple access (TDMA), Ethernet PON
(EPON) and Gigabit PON (GPON), to share the optical capacity among subscribers by assigning
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different timeslots for each user. Centralized dynamic bandwidth allocation (DBA), in which the
OLT at the CO arbitrates time-division access to the shared upstream channel. The round-trip
time (RTT) are depended on performance of centralized allocation, since it imposes a delay on the
OLT-ONUs bandwidth allocation control loop. This delay is not as significant in traditional PONs
as it is in LR-PONs, where the reach extension may cause the RTT to grow from todays 200 µs
(20 km reach) to 1 ms (100 km reach). The performance of centralized DBA is ultimately
degraded with this is increased.
multi-thread polling and inter-thread scheduling are reviewed and analysed, which is a recently
proposed bandwidth allocation algorithm for LR-PONs, and traditional interleaved polling is
compared. Unexpectedly, the overall packet delay performance of the latter is found better than
the recently proposed multi-thread polling scheme. Our investigation highlights how multi-thread
polling looks compelling for LR-PONs compared to single thread polling only when the latter is
assumed to be scheduled offline. The offline scheduling is used a single thread leaves a long idle
period that the multi-thread scheme utilizes by creating additional threads. However, while
traditional inter-thread polling is a single-thread scheme, online scheduling is exploited with
extremely small idle times. The demonstration of key results are that inter-thread polling with
online scheduling better reduces the overall packet delay in addition to better utilizing the
upstream channel. In the paper, some inaccuracies are pointed out in the multi-thread algorithm,
and suggest some modifications.
The rest of the paper is organized as follows. In Section II we give a brief introduction to Real
Time Probabilistic Systems. Next, we review PRISM Probabilistic Model Checker in Section III,
explaining how its performance analysis is highly affected by extending the network span. In
Section IV, we review multi-thread polling and discuss the different aspects of its algorithm,
highlighting its major differences from enhanced inter-thread scheduling. Section V presents
illustrative numerical results, and Section VI concludes the study.
2. REAL TIME PROBABILISTIC SYSTEMS
The definition of real time probabilistic system is reviewed in this section, both nondeterministic
and stochastic behaviour are exhibited in the modelling framework for real-time systems. The
extending classical timed automata with discrete probability distributions over edges derive the
formalism. First, standard notation is introduced for clocks and zones of timed automata, and then
we proceed to the definition of probabilistic timed automata [4, 5, 6]. At the end of this section,
Probabilistic Timed Computation Tree Logic (PTCTL) is introduced as a probabilistic timed
temporal logic for the specification of properties of probabilistic timed automata.
2.1. Clocks and Zones
Let X is a finite set of variables called clocks which take values from the time domain 0≥ℜ
(non-negative reals). A function 0:v ≥→ ℜX is referred to as a clock valuation. The set of all
clock valuations is denoted by 0≥ℜX
. For any 0v ≥∈ℜX
and 0t ≥∈ℜ , we use v + t to denote the
clock valuation defined as (v + t)(x) = v(x) + t for all x∈X . We use v[X := 0] to denote the
clock valuation obtained from v by resetting all of the clocks in X ⊆ X to 0, and leaving the
values of all other clocks unchanged; formally, v[X := 0](x) = 0n if x ∈ X and v[X := 0](x) = v(x)
otherwise.
The set of zones ofX , written Zones (X ), is defined inductively by the syntax:
ς :: = x ≤ d | c ≤ x | x + c ≤ y + d | ¬ς | ς ∨ ς
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Where x, y ∈ X and c, d ∈ N. As usual, ς1 ∧ ς2 = ¬(¬ς1 ∨ ¬ς2) and strict constraints can be
written using negation, for example x > 2 = ¬(x ≤ 2) .
The clock valuation v satisfies the zone ς, written v ς> , if and only if ς resolves to true after
substituting each clock v ς> with the corresponding clock value v(x) from v . Intuitively, the
semantics of a zone is the set of clock valuations (subset of 0≥ℜX
) which satisfy the zone. Note
that more than one zone may represent the same set of clock valuations (for example, (x ≤ 2) ∧ (y
≤ 1) ∧ (x ≤ y + 2) and (x ≤ 2) ∧ (y ≤ 1) ∧ (x ≤ y + 3)). We hence forth consider only canonical
zones, which are zones for which the constraints are as tight as possible. For any valid zone
Zonesς ∈ X , there exists a 3
(O X∣ ∣) algorithm to compute the (unique) canonical zone of ς .
This enables us to use the above syntax for zones interchangeably with semantic, set-theoretic
operations.
We require the following classical operations on zones [4, 6]. For zones ς, ς′ ∈ Zones(X) and
subset a of clocks X ⊆ X , let:
↙ς′ ς = {v | ∃ t ≥ 0.(v + t ς ∧ ∀ t′ ≤ t.(v + t′ ς ∨ ς′))}
[X := 0]ς = {v | v[X := 0] ς}
ς[X := 0] = {v[X := 0] | v ς} .
The zone↙ς′ ς contains the clock valuations that can, by letting time pass, reach a clock valuation
in ς and remain in ς′ until ς is reached. The zone [X := 0]ς contains the clock valuations which
result in a clock valuation in ς when the clocks in X are reset to 0. The zone ς[X := 0] contains the
clock valuations which are obtained from clock valuations in ς by resetting the clocks in X to 0.
2.2. Syntax and Semantics of Real Time Probabilistic Systems
We now present the formal syntax of Real Time Probabilistic Systems.
Timed Action
A tuple < α, λ, T > of timed action consisting of the type of the action α , the rate of the action λ
and temporal constraint of the action T . The kind of action is denoted the type, such as
transmission of data packets, while the rate indicates the speed at which the action occurs from
the view of an external observer. The random variables rate use to denoted specifying the duration
of the actions. The different types of probability distribution function define the actions such as
Exponential, Poisson, Constant, Geometric and Uniform distribution. Moreover, each transition is
also bounded by a temporal constraint. In this section, Real Time Probabilistic Systems briefly
introduce some basic notations and operation semantics. The syntax of Real Time Probabilistic
Systems is defined as follows:
P ::= stop | < α, λ,T > . P | P + Q | P ⊕r,T Q | P ▹ ◃L,T Q | P ▽△ P,T Q | P/L | A
The conventional stochastic process algebra operators and the additional operations are described
in the following:
6. International Journal of Computer Networks & Communications (IJCNC) Vol.6, No.2, March 2014
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• stop is an inactive process.
• < α, λ,T > . P , which stands for a prefix operator, where the type of the action is a probability
distribution function (pdf) type α , with the activity rate denoted by λ , and the temporal constraint
of component is T .
It subsequently behaves as P. Sequences of actions can be combined to build up a time constraint
for an action. The time constraint T is defined as above.
• P + Q is choice combinatory capturing the possibility of competition or selection between
different possible Activities. It represents a system which may behave either as P or as Q. All the
current actions P and Q are enabled. The first action to complete distinguishes one of the
processes. The other process of the choice is discarded. The system will then behave as the
derivative resulting from the evolution of the chosen process.
• P ⊕r,T Q denotes the probabilistic choice with the conventional generative interpretation, thus
with probability r the process behaves like P and with probability 1 − r it behaves like Q bounded
with the time constraint T .
• P ▹ ◃L,T Q is a cooperation, in which the two actions P and Q are parallel, synchronizing on all
activities whose type is in the cooperation set L of action types. The lifetime of two actions is the
time constraint T . These two actions are disabled when the time constraint expires. Any action
whose type is not in L will proceed independently. As a syntactic convenience the parallel
combinator is defined by ▹ ◃ϕ,T , where the cooperation set L is empty and the lifetime of two
actions is T .
• P ▽△ P,T Qis a unary operator which returns the set of actions that meet the temporal predicate
condition specified by T . P consists of several predicates combined with the boolean connectives:
‘And’ ,‘Or’, Exclusive-Or (EXOR)’ and ‘Not’. ▽△ And,T means both actions can occur during the
interval T . ▽△ Or,T means that one or both actions can occur during the interval T . ▽△ EXOR,T
means that one of these actions occurs; it immediately determines whether P or Q can
subsequently occur during the triggered interval T . ▽△ Not,T means that both actions do not
occur during the interval T .
• P/L is a hiding operation, where the set L of visible action types identifies those activities which
are to be considered internal or private to the component. These activities are not visible to an
external observer, nor are they accessible to other components for cooperation.
• A := P is a countable set of constants.
2.3. Probabilistic Timed Computation Tree Logic
We now describe Probabilistic Timed Computation Tree Logic (PTCTL) which can be used to
specify properties of probabilistic timed automata. This logic is a combination of two extensions
of the temporal logic CTL [7], the timed logic TCTL [8] and the probabilistic logic PCTL [9].
The logic TCTL employs a set of formula clocks, Z, disjoint from the clocks X of the
probabilistic timed automaton under study. Formula clocks are assigned values by formula clock
valuations ϕ ∈ RZ ≥0. The logic TCTL can express timing constraints and includes the reset
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quantifier z. ϕ, used to reset the formula clock z so that the formula ϕ is evaluated from a state at
which z = 0. PTCTL is obtained by enhancing TCTL with the probabilistic quantifier P∼λ[.] from
PCTL and removing the path quantifiers ∃ and ∀ .
The syntax of PTCTL is defined as follows:
ϕ ::= a | ζ | ¬ϕ | ϕ ∨ ϕ | z.ϕ | P∼λ[ϕUϕ] | P∼λ[ϕVϕ]
where a ∈ AP, ζ ∈ Zones(X ∪ Z), z ∈ Z, ∼∈ {≤, <, >, ≥} and λ ∈ [0, 1] . We use the abbreviations
⋄ϕ and 2ϕ for true Uϕ and false Vϕ respectively. In PTCTL we can express properties such as:
• with probability strictly greater than 0.96, the system delivers packet 1 within 5 time units and
does not try to send packet 2 in the meantime, which is represented by
z.P>0.96[packet2unsentU(packet1delivered ∧ (z < 5))] ;
• with probability at least 0.93, the system clock x does not exceed 3 before 8 time units elapse,
which is represented as z.P>0.93[(x ≤ 3)U(z = 8)] ;
• the system remains up after the first 60 time units have elapsed with probability greater than
0.97, represented as z.P>0.97[2(system up ∨ (z ≤ 60))] .
Next, we define the semantics of PTCTL. We write v, ϕ to denote the composite clock valuation
in obtained from 0v ≥∈ℜX
and 0≥∈ℜZ
ò . Given a state and formula clock valuation pair (l, v), ϕ ,
zone ζ and duration t , by abuse of notation we let ( , ),l v ζ>ò denote ,v ζ>ò v, and (l, v) + t
denote (l, v + t) .
3. PRISM PROBABILISTIC MODEL CHECKER
Model checking for several types of probabilistic models are provided in Prism [2]:
discrete and continuous time Markov chains and Markov decision processes, as well as a
modelling language in which to express them. The tool has been widely taken up and
used for quantitative verification in a broad spectrum of application domains, from
wireless communication protocols to quantum cryptography to systems biology.
3.1. Overview of Functionality
We begin with a brief overview of the current functionality of the prism tool. Items are
the new or improved features in version 4.0, which are described in more detail in the
remainder of the paper.
• many types of probabilistic models are modelled and constructed, now including
probabilistic timed automata; all can be augmented with costs or rewards, in the case of
PTAs yielding the model of priced probabilistic timed automata;
•a wide range of quantitative properties are the model checking, expressed in a language
that subsumes the temporal logics PCTL, CSL, LTL and PCTL*, as well as extensions
for quantitative specifications and costs/rewards;
8. International Journal of Computer Networks & Communications (IJCNC) Vol.6, No.2, March 2014
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•both symbolic (BDD-based) and explicit- state multiple are model checking engines; and
a variety of probabilistic verification techniques, such as symmetry reduction and
quantitative abstraction refinement;
•with support for statistical model checking methods are the discrete-event simulator,
including confidence-level approximation and acceptance sampling;
• Model import options, e.g. From SBML (systems biology mark-up language);
• Optimal adversary/strategy generation for nondeterministic models;
• With model editor is a GUI, simulator and graphing, or command-line tool;
• Probabilistic models and associated properties in benchmark suite.
4. MULTI-THREAD SCHEDULING SCHEME OF DYNAMIC
BANDWIDTH ALLOCATION
In this section, we briefly describe two different inter-thread scheduling algorithms
presented in [10, 11, 12] in Figure 3. The one proposed in [12] is referred to as newly
arrived plus (NA+), which aims to overcome the over granting problem in multithread
schemes. We name the reviewed algorithm (i.e., in [10] ) as subsequent requests plus
(SR+), since it is able to reduce grant delay by utilizing the information regarding the
requests received in the overlapped subsequent DBA processes. Furthermore, we
integrate the key advantages of these two existing approaches and propose an enhanced
inter-thread scheduling (EIS) algorithm in order to further improve the DBA performance.
All the notations used for the description of the algorithms are listed as follows:
M : Total number of active ONUs
N : Total number of threads
Bi,n : Actual bandwidth demand for ONUi in DBA process n
min
iB : Predefined guaranteed minimum bandwidth for ONUi
Ri,n : Bandwidth reported from ONUi in DBA process n (i.e., the buffer status of ONUi
at time ti,n )
R’i,n : OLT based on Ri,n are recalculated bandwidth request, and the associated inter-
thread scheduling schemes
Gi,n : Resulting grant to ONUi responding to Ri,n
gi,n : Actual bandwidth for data transmission between ti,n−1 and ti,n at ONUi
Ai,n : New traffic that arrived to ONUi between ti,n−1 and ti,n
Ui,n : Unused time slots occurrence during the nth DBA process at ONUi
Ci,n : A term to compensate backlogged traffic
The overall system specification becomes ONU and OLT:
OLT := ONU0 < λ1 > ONU1 < λ2 > ONU2 < λ3 > • • • •
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Figure 3. Mult-Thread DBA processes between an OLT and an ONU.
4.1. Newly Arrived Plus
Over-granting can be a serious performance issue in a typical LR-PON scenario when a
multi-thread DBA scheme is used. To overcome this problem, Newly Arrived Plus (NA+)
has been proposed in the literature [12]. The main idea of NA+ is that each thread is
mainly responsible for the bandwidth allocation for the traffic that has arrived since the
initiation of the last DBA process. In this way load is evenly distributed among the
different threads. NA+ can compensate for the backlogged traffic at a specific ONUi in
DBA process n using the information gathered from some previously completed DBA
process. A compensation mechanism for backlogged traffic is important because a DBA
allocation process may not be able to cater for all the requested bandwidth in a given
DBA process. Furthermore, EPON does not support frame fragmentation, and unused
time slots (UTS) may occur. NA+, presented in [12], also includes a compensation
mechanism for the UTS in EPONs. The effectiveness of NA+ can be clearly observed
from [12], where an over-reporting problem is eliminated by allocating bandwidth only
once. For instance, the first arrived packet (i.e., the black packet) is reported in both Ri,1
and Ri,2 , but the corresponding bandwidth granting is only performed once (i.e., in Gi,1 )
because R’i,2 excludes the bandwidth of the black packet, which has already been
granted in Gi,1. This allows improving network throughput as well as delay and jitter.
The operation in Newly Arrive Plus multi-thread DBA Scheme for ONUi specified as
follows:
ONUi := < sent, λ1 > . Report(R)i,1 ▹◃L1 < get, λ1 > . OLT ;
ONUi := < poll, delayi > . Report(R)i,2 ▹◃L2 < get, λ2 > . OLT ;
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ONUi := < grantNA+, delayNA+i > . Datai ▹◃L3 < get, λ3 > . OLT ;
ONUi := < sent, delayi > . Report(R)i,3 ▹◃L4 < get, λ4 > . OLT ;
ONUi := < queue, delayi > . Datai ▹◃L5 < get, λ5 > . OLT ;
The operation in DBA Scheme for OLT specified as follows:
OLT := < sent, delay1 > . Result(G)i,1 ▹◃L1 < get, λ1 > . ONU1 ;
OLT := < sent, delay2 > . Result(G)i,2 ▹◃L2 < get, λ2 > . ONU2 ;
OLT := < sent, delay3 > . Result(G)i,3 ▹◃L3 < get, λ3 > . ONU3 ;
4.2. Subsequent Requests Plus
In Subsequent Requests Plus (SR+) [10, 11], an inter-threading mechanism is introduced
that allows bandwidth allocation even for the packets that arrived at an ONU queue after
issuing the report for the current DBA process. Therefore, this mechanism to perform
bandwidth allocation for subsequent requests can reduce packet delay noticeably in many
cases. [10] gives an example of SR+ employed in a two-thread DBA. Before calculating
the bandwidth allocation for the Ri,1, Ri,2 is also available. So some packets queuing at
the ONUi after the transmission of Ri,1 do not have to wait for the receipt of Gi,2 to be
transmitted because they have been considered in R’ i,1 before Gi,2 is issued and hence
could be transmitted as soon as Gi,1 is received. This clearly reduces the dgrant for the
light grey packet shown in Fig. 3b. It should be noted that two packets are reported in
Ri,2, but there is still a risk that not both of them can be transmitted after receiving Gi,1 ,
because the bandwidth request cannot always be satisfied. Furthermore, the over-granting
problem cannot be avoided in SR+. For instance, the black packet is considered twice in
R’ i,1.
The operation in Subsequent Requests Plus multi-thread DBA Scheme for ONUi
specified as follows:
ONUi := < sent, λ1 > . Reporti,1 ▹◃L1 < get, λ1 > .OLT ;
ONUi := < poll, delayi > . Reporti,2 ▹◃L2 < get, λ2 > .OLT ;
ONUi := < grantSR+, delaySR+i > . Datai ▹◃L3 < get, λ3 > .OLT ;
ONUi := < sent, delayi > . Reporti,3 ▹◃L4 < get, λ4 > .OLT ;
ONUi := < queue, delayi > . Datai ▹◃L5 < get, λ5 > .OLT ;
4.3. Enhanced Inter-Thread Scheduling
Our proposed enhanced inter-thread scheduling (EIS) is a hybrid scheme capturing key
ideas from both NA+ and SR+ to improve DBA performance in a multi-thread
environment. For bandwidth granting, we consider a newly arrived packet as in NA+ to
effectively eliminate the over-reporting problem, while bandwidth requested in the
subsequent DBA processes is also taken into account as in SR+ if it arrives before the
calculation of the bandwidth granted in the current DBA process. Pseudo code for the EIS
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scheme is outlined in [11]. Benefits of employing EIS can be seen clearly from [11]
where d grant of the packet with the white colour can be significantly reduced compared
to NA+ and SR+. This is because R′i,1 can correctly reflect the current bandwidth request.
The traffic reported in Ri,2 can be taken into account when issuing Gi,1 . Furthermore, by
eliminating the over-reporting for the black packet (which has been reported twice), both
packets that arrived after Ri,1 at ONUi can be transmitted after receiving Gi,1 .
Performance in a PON system is sensitive to DBA computation time, particularly in a
multi-thread environment where several threads in parallel increase the complexity. In
this regard, our proposed EIS scheme does not require any additional inter-thread
communication mechanism compared to NA+ and SR+. In other words, there is no
explicit control information that needs to be exchanged between the threads (except for
the usual report messages), so the DBA complexity grows linearly relative to a single-
thread implementation. However, due to DBA control messages in each thread, there is
still a linear increase in overhead with respect to the employed number of threads.
Consequently, it may lead to degraded performance by increasing the number of threads
beyond a certain level, as the added control messages introduced by the extra threads
could decrease the bandwidth utilization and affect the other performance measures such
as delay and jitter. As shown in the next section, in most of the evaluated cases applying
two or three threads is optimal to gain the maximum benefit depending on the specific
reach scenario as well as the employed multi-thread algorithm. The operation in
Enhanced Inter-Thread Scheduling for ONU1 specified as follows:
ONUi := < sent, λ1 > . Reporti,1 ▹◃L1 < get, λ1 > . OLT ;
ONUi := < poll, delayi > . Reporti,2 ▹◃L2 < get, λ2 > . OLT ;
ONUi := < sent, delayi > . Reporti,3 ▹◃L3 < get, λ3 > . OLT ;
ONUi := < grantEIS, delayEISi > . Datai ▹◃L4 < get, λ4 > . OLT ;
ONUi := < waitEIS, delayEISi > . Datai ▹◃L3 < get, λ5 > . OLT ;
ONUi := < queue, delayi > . Datai ▹◃L6 < get, λ6 > . OLT ;
5. PERFORMANCE EVALUATION
Several well-known benchmarks for the cyclic redundancy check problem are evaluated
on the procedure. First, parametrisable case study is used to present evidence that the
algorithm gives correct answers and then we present systematic comparisons with PRISM.
The PRISM simulation framework is extended for sampling purposes. Because we use
the same input language as PRISM, many off-the-shelf models and case studies can be
used with our approach.
5.1. Performance Result
We simulate a LR-PON with M-ONUs. Single or multiple wavelengths are used to carry
the upstream traffic, depending on the aggregated user requests. The problem are made
clear and focused on packet delay, we assume that the M-ONUs share the same upstream
channel (one upstream wavelength). If more users join the network, a new upstream
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channel can be assigned to them and the same polling scheme is implemented on the new
channel independently.
From the access side, an ONU are arrived packets from a user connected to the ONU. The
ONU buffered the packets until the ONU is allowed to transmit them to the OLT. In our
model, we consider RD to be the data rate of the access link from a user to an ONU, and
RU to be the date rate of the upstream channel from ONU to OLT. Note that, if RU < M
× RD, there are exist the bandwidth utilization problem, because the system capacity is
greater than the aggregated load from all ONUs. (The steady-state case is, but during
temporary overload situations due to burst traffic, the load may be higher than capacity.)
So, we choose M = 16 and RU and RD to be 1 Gbps and 100 Mbps, respectively.
Packets are generated in the form of Ethernet frames (64 to 1518 bytes) and they arrive at
each ONU from the end user. The property of Internet traffic is reflected, the generated
user traffic is self-similar by aggregating multiple sub-streams, each consisting of
alternating Pareto-distributed on/off periods, with a Hurst Parameter of 0.8. The buffer
size at each ONU is limited to 10 Mbytes.
The performance of our multi-thread polling algorithm are studied, the LR-PON are
simulated in two different scenarios, where ONUs is 20 km and 100 km from the OLT,
respectively. 0.5s sets in the initial interval of threads for the 100-km scenario and 0.3 s
for 20-km scenario, which represent maximum cycle duration (RTT); the tuning threshold
θ tune is set to be 5 in the simulation. The benefit of multi-thread is highlighted polling
on the average packet delay, the constraints are dropped on single-thread polling by
allowing it to ignore the fairness issue, and thereby the idle time is not counted.
From the results shown in Figure 4, high load (0.8) scenarios can observe ; delay
performance improvement is tangible in EIS compared to NA+ and SR+. The
performance can be noted in hit due to multi-threading through the increased overhead
associated with report and grant messages. For this reason, all the multi-thread schemes
perform worse when tested in the three thread case than in the two thread one. Increasing
the number of threads by more than two affects the DBA performance are introduced
extra control overhead. This performance degradation is more severe in SR+ than the
other two schemes where the over-granting problem is well treated. Besides, in NA+ and
EIS, the performance three thread cases become less obvious when the reach increases.
Because of the longer reach, the increased overhead incurred by a three thread
implementation is compensated more by the gain of introduction of one more thread than
in the two thread case. In particular for the reach of 100 km and beyond for both EIS and
NA+ three thread implementations provides better performance. High load (0.8) is true
for the statement as similar behaviour for the different schemes can be seen in the high
load situation (0.8) as well, although the absolute values for delay are larger because
higher load leads to much longer average round-trip time (RTT) per thread. EIS still
performs best, while NA+ performs the worst in the high load scenario. According to the
results shown in Figure 4, three is generally the optimal number of threads are found for
the schemes presented here in order to obtain the best delay performance except for reach
of 100 km and beyond, where a three thread implementation performs better, as explained
above, for both EIS and NA+. Furthermore, this value is also dependent on system
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characteristics (number of ONUs, line rate, buffer size, etc.) and traffic profile (load,
burstiness, etc.).
The different schemes of jitter performance are shown in Figure 5 for high (0.8) load,
respectively. EIS can saw that has the lowest jitter for three thread cases. NA+ shows
decent jitter performance but at the expense of worse delay performance, as shown earlier.
SR+ with jitter performance is very dependent on the number of threads employed. The
best performance is shown the three thread implementation at high load but it gets
significantly worse for the three thread implementation where the over-granting problem
is more intense. Apart from this observation, jitter performance for different schemes is
close at high loads.
The last set of results shown in Figure 6 is for the throughput. EIS has the highest
throughput under both low and high load conditions. As noted earlier for reach of 100 km
and beyond, a three thread implementation is the most suitable option to achieve the best
performance for the proposed EIS scheme. Here it is worth mentioning that the maximum
throughput can be slightly higher than 0.497 (Fig. 6) since the exact value for the offered
load is 0.495 under the high load scenario. Furthermore, packet loss can be minimized (or
eliminated) by employing a larger buffer at the ONUs, which may significantly degrade
the delay and jitter performance.
Figure 4. Packet Delay vs. Distance
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Figure 5. Jitter vs. Distance
Figure 6. Throughput vs. Distance
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6. CONCLUSIONS
Our approach tends to perform well, generating comparatively small abstract models using a
relatively large number of (small, local) refinement steps. When the number of formal abstract
models becomes particularly high, performance is degraded but, in our experiments, the tool still
outperformed the game-based abstraction of PRISM. This gain derives from the use of simple
operations on smaller abstractions and a reduction in the amount of numerical computation that
needs to be performed. Perhaps unsurprisingly, our approach performs better on real-time models,
than on the versions that have been discretised. We have presented a novel formal abstraction
approach for the performance analysis of probabilistic, real-time systems with potentially infinite
data variables. This approach uses local formal abstract steps, which results in more compact
abstractions than alternative abstraction refinement techniques.
The network operators have LR-PON exhibits tangible advantages in terms of cost savings and
hence have been identified as a promising candidate for future broadband access. One of the most
important challenges in LR-PON is to deal with the significant network performance degradation
because of the increased propagation delay. An efficient way to mitigate this performance
degradation has advocated multi-thread-based DBA approach. However, this article shows that
without a proper inter-communication mechanism among the overlapped bandwidth allocation
processes, the efficiency of a multi-thread DBA approach could be affected drastically. In this
regard, we concentrate on the multi-thread DBA approach, and highlight the issues arising due to
the lack of inter-thread scheduling. After making an assessment of the currently available
solutions, we have proposed a new approach named enhanced inter-thread scheduling (EIS),
which integrates key features from the existing inter-thread scheduling algorithms.
We pointed out some inaccuracies in the multi-thread allocation algorithm and suggested some
modifications to ensure that an ONU is not granted more than requested, by efficiently
distributing the excess bandwidth among heavily loaded ONUs, and also to enable enhanced
inter-thread scheduling to fully utilize a thread without disturbing the thread tuning. Simulation
results show that enhanced inter-thread polling succeeds in decreasing reporting and queuing
delays, whereas online inter-thread polling has a lower grant delay and therefore achieves a better
overall delay performance. Online inter-thread polling also achieves a higher throughput, since
multi-thread polling use more bandwidth for report messages and guard intervals.
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Authors
Tony Tsang received the BEng degree in Electronics & Electrical Engineering with First Class Honours
in U.K., in 1992. He received the Ph.D. from the La Trobe University (Australia) in 2000. He was
awarded the La Trobe University Post graduation Scholarship in 1998. He is a Lecturer at the Hong Kong
Polytechnic University. Prior to join in the Hong Kong Polytechnic University, Dr. Tsang earned several
years of teaching and researching experience in the Department of Computer Science and Computer
Engineering, La Trobe University. His research interests include mobile computing, networking, protocol
engineering and formal methods. Dr. Tsang is a member of the ACM and the IEEE.