This paper discusses the distributed coordination function (DCF) access mechanism which is a carrier sense multiple access with collision avoidance (CSMA/CA) scheme. Simulation projects for different DCF performance parameters have been built using the OPNET network simulator. The projects are mainly basic service set (BSS) topology simulated under different parameter values (data rate, fragmentation, RTS/CTS, number of nodes, and load condition). Simulation results show when the DCF access mechanism is better under what load condition, and how to choose the best fragmentation threshold and other access-mechanism specific parameters according to the network conditions. Simulation results were validated against a theoretically calculated maximum throughput (the simulation maximum throughput was about 70% of the theoretically calculated maximum throughput).
Daly Analysis for WiMax under balanced and unbalanced traffic conditions in f...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
A DDRESSING T HE M ULTICHANNEL S ELECTION , S CHEDULING A ND C OORDINATION...pijans
We discuss a new multichannel coordination and sche
duling challenge called the Multichannel Scheduling
Cost (MSC). It is caused by the inability of the co
ntrol channel to schedule simultaneous transmission
s
resulting in data channels lying idle and their ban
dwidth underutilized. As a result, wasted bandwidth
increases as the number of data channels increases.
To address this challenge, a cyclic scheduling
Algorithm (CSA) is proposed. It employs one dedicat
ed signaling channel and 4 data channels. It is
premised on a proactive channel reservation scheme
which reduces the idleness of channels. The scheme
ensures that data channels are reserved while they
are still busy. The data channels are reserved whil
e
their remaining transmission duration is equal to t
he virtual carrier sensing duration. This gives the
next
pair sufficient time to reserve the current data ch
annel before it becomes available, limiting the MSC
to the
first cycle. The simulation results show a performa
nce benefit of the CSA scheme in addressing the eff
ects
of the MSC
A bi scheduler algorithm for frame aggregation in ieee 802.11 nijwmn
IEEE 802.11n mainly aims to provide high throughput, reliability and good security over its other previous
standards. The performance of 802.11n is very effective on the saturated traffic through the use of frame
aggregation. But this frame aggregation will not effectively function in all scenarios. The main objective of
this paper is to improve the throughput of the wireless LAN through effective frame aggregation using
scheduler mechanism. The Bi-Scheduler algorithm proposed in this article aims to segregate frames based
on their access categories. The outer scheduler separates delay sensitive applications from the incoming
burst of multi-part data and also decides whether to apply Aggregated - MAC Service Data Unit (AMSDU)
aggregation technique or to send the data without any aggregation. The inner scheduler schedules
the remaining (delay-insensitive, background and best-effort) packets using Aggregated-MAC Protocol
Data unit (A-MPDU) aggregation technique.
PERFORMANCE EVALUATION OF MC-CDMA SYSTEM OVER RAYLEIGH FADING CHANNELIJCSES Journal
Multi Carrier Code Division Multiple Access (MC-CDMA) is a well known technique for high speed
wireless data transmission .Two advanced technology was included in the MC-CDMA structure, such as
orthogonal frequency division multiplex (OFDM) and the code division multiple access (CDMA),so that it
benefits from the robustness of OFDM against multipath environment and from the capability of multiuser
multiplexing services that is achieved via (CDMA) system. MC-CDMA is a multicarrier spread spectrum
system which is classified as the candidate scheme for future mobile radio systems. In this paper MCCDMA
system, with Rayleigh fading channel and 16QAM array modulation, was simulated to investigate
the effects of different parameters on the system performance, such as processing gain; number of paths;
number of users; interleaving; and coding ratio.MC-CDMA performances can be considerably improved
by proper selection of these parameters. As expected, results show that MC-CDMA has a better performance over CDMA system.
An Implementation and Analysis of RTS/CTS Mechanism for Data Transfer in Wire...iosrjce
In this paper, the implementation and analysis of RTS/CTS mechanism for data transfer in wireless
network is being studied. The Request-To-Send (RTS) and Clear-To-Send (CTS) mechanism is widely used in
wireless networks to avoid collisions due to hidden nodes by reserving the channel for transmitting data from
source to destination. The collisions caused by the hidden nodes reduce the network throughput and efficiency.
In RTS/CTS mechanism, RTS/CTS packets set the timer for the neighboring nodes so that these nodes defer their
transmission for the entire data packet transmission period. But there may be the case when the intended
transmission completes before the expiration of this timer, so a kind of delay has been developed. To reduce this
delay, the proposed methodology in this paper provides RTR (Ready-To-Receive) packets along with RTS/CTS
packets. The receiving node sends RTR packets to notify all the neighboring nodes that the intended
communication has finished. The results show that this method improves the data transfer rate resulting in
higher throughput and network efficiency and the system will be more efficient. This will reflect in the overall
information transfer time.
Hierarchical Genetic Algorithm For Dynamic Channel Units Allocation in TD-CDM...ijwmn
Hierarchical Genetic Algorithms (HGA) as a tool for search and optimizing methodology have now reached a mature stage. The minimum resource facility to carry user traffic, termed a channel unit (CU), is composed of a one time-slot and one code in the TD-CDMA/TDD system. The control of the number of CUs depends on the traffic load solves varied and asymmetrical traffic problems in the 3G system. In a cellular network, the call arrival rate, call duration and the communication overhead between the base stations and the control center are vague and uncertain, regardless of whether the criteria of concern are nonlinear, constrained, discrete or NP hard. In this paper, the HGA is used to tackle the neural network (NN) topology as well as the fuzzy logic controller for the dynamic CU allocation scheme in wireless cellular networks. Therefore, we propose a new efficient HGA CUs Allocation (HGACA) in cellular networks. It aims to efficiently satisfy the diverse quality-of-service (QoS) requirements of multimedia traffic. The results show our algorithm has a lower blocking rate, lower dropping rate, less update overhead, and shorter channel-acquisition delay than previous methods
Daly Analysis for WiMax under balanced and unbalanced traffic conditions in f...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
A DDRESSING T HE M ULTICHANNEL S ELECTION , S CHEDULING A ND C OORDINATION...pijans
We discuss a new multichannel coordination and sche
duling challenge called the Multichannel Scheduling
Cost (MSC). It is caused by the inability of the co
ntrol channel to schedule simultaneous transmission
s
resulting in data channels lying idle and their ban
dwidth underutilized. As a result, wasted bandwidth
increases as the number of data channels increases.
To address this challenge, a cyclic scheduling
Algorithm (CSA) is proposed. It employs one dedicat
ed signaling channel and 4 data channels. It is
premised on a proactive channel reservation scheme
which reduces the idleness of channels. The scheme
ensures that data channels are reserved while they
are still busy. The data channels are reserved whil
e
their remaining transmission duration is equal to t
he virtual carrier sensing duration. This gives the
next
pair sufficient time to reserve the current data ch
annel before it becomes available, limiting the MSC
to the
first cycle. The simulation results show a performa
nce benefit of the CSA scheme in addressing the eff
ects
of the MSC
A bi scheduler algorithm for frame aggregation in ieee 802.11 nijwmn
IEEE 802.11n mainly aims to provide high throughput, reliability and good security over its other previous
standards. The performance of 802.11n is very effective on the saturated traffic through the use of frame
aggregation. But this frame aggregation will not effectively function in all scenarios. The main objective of
this paper is to improve the throughput of the wireless LAN through effective frame aggregation using
scheduler mechanism. The Bi-Scheduler algorithm proposed in this article aims to segregate frames based
on their access categories. The outer scheduler separates delay sensitive applications from the incoming
burst of multi-part data and also decides whether to apply Aggregated - MAC Service Data Unit (AMSDU)
aggregation technique or to send the data without any aggregation. The inner scheduler schedules
the remaining (delay-insensitive, background and best-effort) packets using Aggregated-MAC Protocol
Data unit (A-MPDU) aggregation technique.
PERFORMANCE EVALUATION OF MC-CDMA SYSTEM OVER RAYLEIGH FADING CHANNELIJCSES Journal
Multi Carrier Code Division Multiple Access (MC-CDMA) is a well known technique for high speed
wireless data transmission .Two advanced technology was included in the MC-CDMA structure, such as
orthogonal frequency division multiplex (OFDM) and the code division multiple access (CDMA),so that it
benefits from the robustness of OFDM against multipath environment and from the capability of multiuser
multiplexing services that is achieved via (CDMA) system. MC-CDMA is a multicarrier spread spectrum
system which is classified as the candidate scheme for future mobile radio systems. In this paper MCCDMA
system, with Rayleigh fading channel and 16QAM array modulation, was simulated to investigate
the effects of different parameters on the system performance, such as processing gain; number of paths;
number of users; interleaving; and coding ratio.MC-CDMA performances can be considerably improved
by proper selection of these parameters. As expected, results show that MC-CDMA has a better performance over CDMA system.
An Implementation and Analysis of RTS/CTS Mechanism for Data Transfer in Wire...iosrjce
In this paper, the implementation and analysis of RTS/CTS mechanism for data transfer in wireless
network is being studied. The Request-To-Send (RTS) and Clear-To-Send (CTS) mechanism is widely used in
wireless networks to avoid collisions due to hidden nodes by reserving the channel for transmitting data from
source to destination. The collisions caused by the hidden nodes reduce the network throughput and efficiency.
In RTS/CTS mechanism, RTS/CTS packets set the timer for the neighboring nodes so that these nodes defer their
transmission for the entire data packet transmission period. But there may be the case when the intended
transmission completes before the expiration of this timer, so a kind of delay has been developed. To reduce this
delay, the proposed methodology in this paper provides RTR (Ready-To-Receive) packets along with RTS/CTS
packets. The receiving node sends RTR packets to notify all the neighboring nodes that the intended
communication has finished. The results show that this method improves the data transfer rate resulting in
higher throughput and network efficiency and the system will be more efficient. This will reflect in the overall
information transfer time.
Hierarchical Genetic Algorithm For Dynamic Channel Units Allocation in TD-CDM...ijwmn
Hierarchical Genetic Algorithms (HGA) as a tool for search and optimizing methodology have now reached a mature stage. The minimum resource facility to carry user traffic, termed a channel unit (CU), is composed of a one time-slot and one code in the TD-CDMA/TDD system. The control of the number of CUs depends on the traffic load solves varied and asymmetrical traffic problems in the 3G system. In a cellular network, the call arrival rate, call duration and the communication overhead between the base stations and the control center are vague and uncertain, regardless of whether the criteria of concern are nonlinear, constrained, discrete or NP hard. In this paper, the HGA is used to tackle the neural network (NN) topology as well as the fuzzy logic controller for the dynamic CU allocation scheme in wireless cellular networks. Therefore, we propose a new efficient HGA CUs Allocation (HGACA) in cellular networks. It aims to efficiently satisfy the diverse quality-of-service (QoS) requirements of multimedia traffic. The results show our algorithm has a lower blocking rate, lower dropping rate, less update overhead, and shorter channel-acquisition delay than previous methods
COMPARATIVE PERFORMANCE ASSESSMENT OF VBLAST ENCODED 8×8 MIMO MC-CDMA WIRELES...pijans
The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system
for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM)
schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system
employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN channel
and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study
demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2-
rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance
utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission
In Wireless Sensor Network (WSN), QoS (Quality of Service) in sensor application plays a very important
role. QoS based routing is required to ensure the best use of nodes in WSN. In this paper, a comparative
study of QoS based routing in Media Access Control (MAC) protocols are presented based on the traits to
solve problems like prioritization, timeliness, reliability etc. The study mainly focuses on some priority
based QoS protocols used in WSN and a comparison among them. The study reveals that among the five
mentioned protocols; QMAC, PRIMA, DB-MAC, RAP, GTS; PRIMA shows the best performance in the
category of Packet Prioritization, Scheduling Scheme, Queue Type, Energy Awareness and QoS.
WARM WELCOME FROM HCL VELACHERY…….
HCL Learning is part of HCL Info Systems Ltd, India’s Premier information enabling company with an annual turnover of 15000 crores Leveraging on the 34 years of industry experience of HCL, with an objective to develop quality IT professionals to meet this ever expanding requirement of Hardware Networking and Software professionals for the IT sector, HCL has launched HCL Career Development Centre.
For any clarification,
contact Person
Mr.Senthilvel.S
9382207007
HCL Velachery -42
S URVEY OF L TE D OWNLINK S CHEDULERS A LGORITHMS IN O PEN A CCESS S IM...ijwmn
he LTE/LTE-A has become a catchphrase for research
and lot of research are being conducted and
carried out in LTE in various issues by various peo
ple. New tools are developed and introduced in the
market to interpret the results of the new algorith
ms proposed by various people. Some tools are open
access which are free to use but some tools are pro
duced by the companies which are not open access. I
n
this paper some of the open access simulation tools
like LTE-Sim and NS-3 are analyzed and LTE downlin
k
scheduler algorithms are simulated using those tool
s. In LTE systems, the downlink scheduler is an
important component for radio resource management;
hence in the context of LTE simulation, a study
between the downlink scheduler models between the s
imulators are performed.
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.
LTE QOS DYNAMIC RESOURCE BLOCK ALLOCATION WITH POWER SOURCE LIMITATION AND QU...IJCNCJournal
3GPP has defined the long term evolution (LTE) for 3G radio access in order to maintain the future
competitiveness for 3G technology, the system provides the capability of supporting a mixture of services
with different quality of service (QoS) requirements. This paper proposes a new cross-layer scheduling
algorithm to satisfy better QoS parameters for real time applications. The proposed algorithm takes care of
allocating resource blocks (RBs) with different modulation and coding schemes (MCS) according to target
bit error rate (BER), user equipment supportable MCS, queue stability constraints and available transmit
power constraints. The proposed algorithm has been valued, compared with an earlier allocation algorithm
in terms of service rate and packet delay and showed better performance regards the real time
applications.
Analysis of Packet Loss Rate in Wireless Sensor Network using LEACH ProtocolIJTET Journal
Abstract: Wireless sensor network (WSN) is used to collect and send various kinds of messages to a base station (BS). Wireless sensor nodes are deployed randomly and densely in a target region, especially where the physical environment is very harsh that the macro-sensor counterparts cannot be deployed. Low Energy Adaptive Clustering Hierarchical (LEACH) Routing protocol builds a process where it reduces the Packet Loss Rate from 100 % to 55% .Simulations are carried out using NS2 simulator.
Some of the key driving forces behind the transition from the UMTS based cellular system to the Long Term Evolution Advanced (LTE-A) are to improve the mean and the cell-edge throughput, improve the user fairness, and improve the quality of service (QoS) satisfaction for all users. In the latter system, relays appear as one of the most prominent enabler for improving the cell-edge user experience while increasing the system’s fairness.
In this white paper, we present the basics of relay deployments in LTE-A networks. Moreover, we analyze resource allocation problem for Relay Nodes (RN) deployments and present some of the solutions for improvement in system resource usage and QoS satisfaction. Afterwards, we introduce the capabilities of NOMOR’s LTE-A system level simulator and evaluate the performance of LTE-A relay systems under the described solutions.
The 3GPP Long Term Evolution Advanced (LTE-A) standard specifies a set of pioneer features such as relay nodes and carrier aggregation. At the same time, the Software Defined Networks (SDN) have become an emerging technology which provides centralized control and programmability to modern networks. In the current communication environment, cloud computing could combine the advantages of both technologies in order to create a novel cloud assisted Software Defined LTEA architecture with relay nodes. Moreover, due to the increased requirements of modern services, the optimal resource allocation is a necessity. In such a context, this paper describes a QoS aware cross carrier scheduler for downlink flows, aiming at the optimization of system resources allocation. The proposed scheduler is evaluated against the PF, MLWDF, EXP/PF, EXP RULE, LOG RULE, FLS and FLSA schedulers in a cloud assisted Software Defined LTE-A topology with relay nodes. Simulation results show that the proposed scheduler improves the real time services performance while at the same time maintains an acceptable performance for best effort flows.
Distributed differential beamforming and power allocation for cooperative com...IJECEIAES
Many coherent cooperative diversity techniques for wireless relay networks have recently been suggested to improve the overall system performance in terms of the achievable data rate or bit error rate (BER) with low decoding complexity and delay. However, these techniques require channel state information (CSI) at the transmitter side, at the receiver side, or at both sides. Therefore, due to the overhead associated with estimating CSI, distributed differential space-time coding techniques have been suggested to overcome this overhead by detecting the information symbols without requiring any (CSI) at any transmitting or receiving antenna. However, the latter techniques suffer from low performance in terms of BER as well as high latency and decoding complexity. In this paper, a distributed differential beamforming technique with power allocation is proposed to overcome all drawbacks associated with the later techniques without needing CSI at any antenna and to be used for cooperative communication networks. We prove through our simulation results which is based on error probability that the proposed technique outperforms the conventional technique with comparably low decoding complexity and latency.
Efficient and Fair Bandwidth Allocation AQM Scheme for Wireless NetworksCSCJournals
Heterogeneous Wireless Networks are considered nowadays as one of the potential areas in research and development. The traffic management’s schemes that have been used at the fusion points between the different wireless networks are classical and conventional. This paper is focused on developing a novel scheme to overcome the problem of traffic congestion in the fusion point router interconnected the heterogeneous wireless networks. The paper proposed an EF-AQM algorithm which provides an efficient and fair allocation of bandwidth among different established flows. Finally, the proposed scheme developed, tested and validated through a set of experiments to demonstrate the relative merits and capabilities of a proposed scheme
ON DEMAND CHANNEL ASSIGNMENT METHOD FOR CHANNEL DIVERSITY (ODCAM)ijwmn
The IEEE 802.11s Wireless Mesh Networks (WMN) is a new multi-hop technology increasing the coverage
of IEEE 802.11 Wireless Network and providing Internet access. In order to increase the mesh network
capacity, the WMN has evolved from single-radio single-channel architecture to Multi-Channel Multi-
Radios (MC-MR) architecture. In MC-MR the main challenge of the WMN is the channel assignment. In
this article, we propose a new channel assignment method based on channel diversity. This new method
named ODCAM (On Demand channel Assignment Method for channel diversity ) defines a channel
diversity mechanism used to select a new channel along the path between the source and the destination.
The best path between the source and the destination is provided by the HWMP (Hybrid Wireless Mesh
Protocol) protocol using MWCETT (Modified Weighted Cumulative Expected Transmission Time) an
extension of the WCETT metric. The simulation results show the ODCAM performance compared with an
hybrid approach.
COMPARATIVE PERFORMANCE ASSESSMENT OF VBLAST ENCODED 8×8 MIMO MC-CDMA WIRELES...pijans
The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system
for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM)
schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system
employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN channel
and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study
demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2-
rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance
utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission
In Wireless Sensor Network (WSN), QoS (Quality of Service) in sensor application plays a very important
role. QoS based routing is required to ensure the best use of nodes in WSN. In this paper, a comparative
study of QoS based routing in Media Access Control (MAC) protocols are presented based on the traits to
solve problems like prioritization, timeliness, reliability etc. The study mainly focuses on some priority
based QoS protocols used in WSN and a comparison among them. The study reveals that among the five
mentioned protocols; QMAC, PRIMA, DB-MAC, RAP, GTS; PRIMA shows the best performance in the
category of Packet Prioritization, Scheduling Scheme, Queue Type, Energy Awareness and QoS.
WARM WELCOME FROM HCL VELACHERY…….
HCL Learning is part of HCL Info Systems Ltd, India’s Premier information enabling company with an annual turnover of 15000 crores Leveraging on the 34 years of industry experience of HCL, with an objective to develop quality IT professionals to meet this ever expanding requirement of Hardware Networking and Software professionals for the IT sector, HCL has launched HCL Career Development Centre.
For any clarification,
contact Person
Mr.Senthilvel.S
9382207007
HCL Velachery -42
S URVEY OF L TE D OWNLINK S CHEDULERS A LGORITHMS IN O PEN A CCESS S IM...ijwmn
he LTE/LTE-A has become a catchphrase for research
and lot of research are being conducted and
carried out in LTE in various issues by various peo
ple. New tools are developed and introduced in the
market to interpret the results of the new algorith
ms proposed by various people. Some tools are open
access which are free to use but some tools are pro
duced by the companies which are not open access. I
n
this paper some of the open access simulation tools
like LTE-Sim and NS-3 are analyzed and LTE downlin
k
scheduler algorithms are simulated using those tool
s. In LTE systems, the downlink scheduler is an
important component for radio resource management;
hence in the context of LTE simulation, a study
between the downlink scheduler models between the s
imulators are performed.
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.
LTE QOS DYNAMIC RESOURCE BLOCK ALLOCATION WITH POWER SOURCE LIMITATION AND QU...IJCNCJournal
3GPP has defined the long term evolution (LTE) for 3G radio access in order to maintain the future
competitiveness for 3G technology, the system provides the capability of supporting a mixture of services
with different quality of service (QoS) requirements. This paper proposes a new cross-layer scheduling
algorithm to satisfy better QoS parameters for real time applications. The proposed algorithm takes care of
allocating resource blocks (RBs) with different modulation and coding schemes (MCS) according to target
bit error rate (BER), user equipment supportable MCS, queue stability constraints and available transmit
power constraints. The proposed algorithm has been valued, compared with an earlier allocation algorithm
in terms of service rate and packet delay and showed better performance regards the real time
applications.
Analysis of Packet Loss Rate in Wireless Sensor Network using LEACH ProtocolIJTET Journal
Abstract: Wireless sensor network (WSN) is used to collect and send various kinds of messages to a base station (BS). Wireless sensor nodes are deployed randomly and densely in a target region, especially where the physical environment is very harsh that the macro-sensor counterparts cannot be deployed. Low Energy Adaptive Clustering Hierarchical (LEACH) Routing protocol builds a process where it reduces the Packet Loss Rate from 100 % to 55% .Simulations are carried out using NS2 simulator.
Some of the key driving forces behind the transition from the UMTS based cellular system to the Long Term Evolution Advanced (LTE-A) are to improve the mean and the cell-edge throughput, improve the user fairness, and improve the quality of service (QoS) satisfaction for all users. In the latter system, relays appear as one of the most prominent enabler for improving the cell-edge user experience while increasing the system’s fairness.
In this white paper, we present the basics of relay deployments in LTE-A networks. Moreover, we analyze resource allocation problem for Relay Nodes (RN) deployments and present some of the solutions for improvement in system resource usage and QoS satisfaction. Afterwards, we introduce the capabilities of NOMOR’s LTE-A system level simulator and evaluate the performance of LTE-A relay systems under the described solutions.
The 3GPP Long Term Evolution Advanced (LTE-A) standard specifies a set of pioneer features such as relay nodes and carrier aggregation. At the same time, the Software Defined Networks (SDN) have become an emerging technology which provides centralized control and programmability to modern networks. In the current communication environment, cloud computing could combine the advantages of both technologies in order to create a novel cloud assisted Software Defined LTEA architecture with relay nodes. Moreover, due to the increased requirements of modern services, the optimal resource allocation is a necessity. In such a context, this paper describes a QoS aware cross carrier scheduler for downlink flows, aiming at the optimization of system resources allocation. The proposed scheduler is evaluated against the PF, MLWDF, EXP/PF, EXP RULE, LOG RULE, FLS and FLSA schedulers in a cloud assisted Software Defined LTE-A topology with relay nodes. Simulation results show that the proposed scheduler improves the real time services performance while at the same time maintains an acceptable performance for best effort flows.
Distributed differential beamforming and power allocation for cooperative com...IJECEIAES
Many coherent cooperative diversity techniques for wireless relay networks have recently been suggested to improve the overall system performance in terms of the achievable data rate or bit error rate (BER) with low decoding complexity and delay. However, these techniques require channel state information (CSI) at the transmitter side, at the receiver side, or at both sides. Therefore, due to the overhead associated with estimating CSI, distributed differential space-time coding techniques have been suggested to overcome this overhead by detecting the information symbols without requiring any (CSI) at any transmitting or receiving antenna. However, the latter techniques suffer from low performance in terms of BER as well as high latency and decoding complexity. In this paper, a distributed differential beamforming technique with power allocation is proposed to overcome all drawbacks associated with the later techniques without needing CSI at any antenna and to be used for cooperative communication networks. We prove through our simulation results which is based on error probability that the proposed technique outperforms the conventional technique with comparably low decoding complexity and latency.
Efficient and Fair Bandwidth Allocation AQM Scheme for Wireless NetworksCSCJournals
Heterogeneous Wireless Networks are considered nowadays as one of the potential areas in research and development. The traffic management’s schemes that have been used at the fusion points between the different wireless networks are classical and conventional. This paper is focused on developing a novel scheme to overcome the problem of traffic congestion in the fusion point router interconnected the heterogeneous wireless networks. The paper proposed an EF-AQM algorithm which provides an efficient and fair allocation of bandwidth among different established flows. Finally, the proposed scheme developed, tested and validated through a set of experiments to demonstrate the relative merits and capabilities of a proposed scheme
ON DEMAND CHANNEL ASSIGNMENT METHOD FOR CHANNEL DIVERSITY (ODCAM)ijwmn
The IEEE 802.11s Wireless Mesh Networks (WMN) is a new multi-hop technology increasing the coverage
of IEEE 802.11 Wireless Network and providing Internet access. In order to increase the mesh network
capacity, the WMN has evolved from single-radio single-channel architecture to Multi-Channel Multi-
Radios (MC-MR) architecture. In MC-MR the main challenge of the WMN is the channel assignment. In
this article, we propose a new channel assignment method based on channel diversity. This new method
named ODCAM (On Demand channel Assignment Method for channel diversity ) defines a channel
diversity mechanism used to select a new channel along the path between the source and the destination.
The best path between the source and the destination is provided by the HWMP (Hybrid Wireless Mesh
Protocol) protocol using MWCETT (Modified Weighted Cumulative Expected Transmission Time) an
extension of the WCETT metric. The simulation results show the ODCAM performance compared with an
hybrid approach.
ACHIEVING ENHANCED THROUGHPUT IN MOBILE ADHOC NETWORK USING COLLISION AWARE M...ijasuc
Since wireless medium is high demand resource the design of an efficient medium access protocol is
important for Mobile Adhoc Networks. As MAC is the base layer in the protocol stack a performance gain
in this layer will have significant improvement in the overall performance of the network. Since the current
IEEE 802.11 MAC standard is not adaptive to the network scenario its performance is poor in terms of
throughput, fairness and delay. Although several alternatives to the existing standard is proposed many of
them are not satisfactorily address the key issues of keeping the simplicity of the protocol and avoiding the
overhead on the nodes on duty in emergency situations where usually adhoc networks are applied. In this
paper we propose an adaptive, collision aware MAC protocol for wireless adhoc networks, termed the
Collision Based Contention (CBC) protocol, in which depends on the current collision level on the shared
medium contending nodes dynamically decides its Backoff value to avoid a blind random waiting before
access to the medium. The CBC scheme outperforms the BEB scheme employed in the IEEE 802.11 MAC
standard and other competing proposals.
A NOVEL SLOTTED ALLOCATION MECHANISM TO PROVIDE QOS FOR EDCF PROTOCOLIAEME Publication
The IEEE 802.11e EDCF mechanism cannot guarantee the QOS of high-priority traffic as the bandwidth consumption of the low-priority traffic increases. Also, in the presence of high priority traffic dampen link utilization of low priority traffic. To overcome these problems, we propose the Novel mechanism in our research that extends IEEE 802.11e EDCF by introducing a Super Slot and Virtual Collision. Compared to EDCF, our proposed approach has EDCF has two advantages: (a) Higher priority traffic achieves Quality of service regardless of the amount of low priority traffic, and (b) Low priority traffic obtains a higher throughput in the presence of same amount of high priority traffic.
Quadrant Based DIR in CWin Adaptation Mechanism for Multihop Wireless NetworkIJCI JOURNAL
In Multihop Wireless Networks, traffic forwarding capability of each node varies according to its level of contention. Each node can yield its channel access opportunity to its neighbouring nodes, so that all the nodes can evenly share the channel and have similar forwarding capability. In this manner the wireless channel is utilized effectively, which is achieved using Contention Window Adaptation Mechanism (CWAM). This mechanism achieves a higher end-to-end throughout but consumes the network power to a higher level. So, a newly proposed algorithm Quadrant- Based Directional Routing Protocol (Q-DIR) is implemented as a cross-layer with CWAM, to reduce the total network power consumption through limited flooding and also reduce the routing overheads, which eventually increases overall network throughput. This algorithm limits the broadcast region to a quadrant where the source node and the destination nodes are located. Implementation of the algorithm is done in Linux based NS-2 simulator
An Accurate Performance Analysis of Hybrid Efficient and Reliable MAC Protoco...IJECEIAES
Vehicular Ad Hoc Networks (VANETs) is a technology supporting two types of applications, safety and service applications with higher and lower priorities respectively. Thereby, Medium Access Control (MAC) protocol is designed to provide reliable and efficient data broadcasting based on prioritization. Different from the IEEE 1609.4 (legacy), HER-MAC protocol is a new multi-channel MAC proposed for VANETs, offering remarkable performance with regards to safety applications transmission. This paper focuses on the analysis of packet delivery ratio of the HER-MAC protocol under non-saturated conditions. 1-D and 2-D Markov chains have been developed for safety and non-safety applications respectively, to evaluate mathematically the performance of HER-MAC protocol. The presented work has taken into account the freezing of the backoff timer for both applications and the backoff stages along with short retry limit for non-safety applications in order to meet the IEEE 802.11p specifications. It highlights that taking these elements into consideration are important in modeling the system, to provide an accurate estimation of the channel access, and guarantees that no packet is served indefinitely. More precise results of the system packet delivery ratio have been yield. The probability of successful transmission and collisions were derived and used to compute the packet delivery ratio. The simulation results validate the analytical results of our models and indicate that the performance of our models outperformed the existing models in terms of the packet delivery ratio under different number of vehicles and contention window.
Review Paper on 802.11ax Scheduling and Resource Allocationijtsrd
Nowadays a fast remote Internet association is a need as opposed to a luxury. IEEE 802.11ax could be a revolution to present an improvement over this age of 802.11. 802.11ax has been accepted to convey next generation Wireless Local Area Network WLAN techniques. 802.11ax using multiple techniques as using modulation 1024 Quadrature Amplitude Modulation QAM , Orthogonal Frequency Division Multiple Access OFDMA , robust high efficiency signaling for better operation at a significantly lower Received Signal Strength Indication RSSI , Target Wakeup Time TWT where the station can request to wake up at any time in the future and more. 802.11ax achieves multiple benefits as enabling a more than 35 speed burst, reduce overhead and latency, and more. This paper gives a review of the IEEE 802.11ax resource allocation scheduling in both 1 Downlink DL data transfer 2 Uplink UL data transfer. Ibrahim Masri | Erdal Erdal | Atilla Ergüzen "Review Paper on 802.11ax Scheduling and Resource Allocation" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-1 , December 2020, URL: https://www.ijtsrd.com/papers/ijtsrd38162.pdf Paper URL : https://www.ijtsrd.com/engineering/computer-engineering/38162/review-paper-on-80211ax-scheduling-and-resource-allocation/ibrahim-masri
we find out various power aware and data packet rate control with-collision-avoidance (CSMA/CA)-based ad hoc wireless network communication. And identifies that CSMA
Quality of Service for Video Streaming using EDCA in MANETijsrd.com
Mobile Ad-hoc network(MANET) is a collection of wireless terminals that are able to dynamically form a temporary network. To establish such a network no fixed infrastructure is required. Here, it is the responsibility of network nodes to forward each other's packets and thus these nodes also act as routers. In such a network resources are limited and also topology changes dynamically. So providing Quality of service(QoS) is also necessary. QoS is more important for real time applications for example Video Streaming. IEEE 802.11e network standard supports QoS through EDCA technique. This technique does not fulfill the requirements of QoS. So, in this project modified EDCA technique is proposed to enhance QoS for Video Streaming application. This technique is implemented in NS2 and compared with traditional EDCA.
Dcf learn and performance analysis of 802.11 b wireless networkIJCNCJournal
Though WLAN wireless network has been widely deployed as the main split-flow deployment of the
communication network, little study emphasizes its performance as WLAN protocols were only designed for
the public communicating conveniently with each other. Actually that too much wireless access points
assembling together will cause self-interference to the whole WLAN network. This paper investigates the
distributed coordination function (DCF) learn and the performance study of 802.11b networks. Firstly, our
study illustrates the performance of its MAC layer and its fairness issues related to DCF. Next we propose
the details which should be paid attention to in deploying network services. Then, performance analyses
are evaluated by simulation and real test for a dense wireless network. Our main goal is to give proposals
to network operators how to design a WLAN network more standardized and orderly.
ENERGY EFFICIENT MULTICAST ROUTING IN MANET ijac journal
In this paper, we have presented the Modified Multicasting through Time Reservation using Adaptive
Control for Excellent Energy efficiency (MMC-TRACE). It is a real time multicasting architecture for
Mobile Ad-Hoc networks to make their work an energy efficient one .MMC-TRACE is a cross layer design
where the network layer and medium access control layer functionality are done in a single integrated
layer design. The basic design of the architecture is to establish and maintain an active multicast tree
surrounded by a passive mesh within a mobile ad hoc network. Energy efficiency is maximized by enabling
the particular node from sleep to awake mode while the remaining nodes of the same path are maintained
at sleep mode. Energy efficiency too achieved by eliminating most of the redundant data receptions across
nodes. The performance of MMC-TRACE are evaluated with the help of ns-2 simulations and comparisons
are made with its predecessor such as MC-TRACE. The results show that the MMC-TRACE provides
superior energy efficiency, competitive QoS performance and bandwidth efficiency.
Effect of Interleaved FEC Code on Wavelet Based MC-CDMA System with Alamouti ...IJCSEIT Journal
In this paper, the impact of Forward Error Correction (FEC) code namely Trellis code with interleaver on
the performance of wavelet based MC-CDMA wireless communication system with the implementation of
Alamouti antenna diversity scheme has been investigated in terms of Bit Error Rate (BER) as a function of
Signal-to-Noise Ratio (SNR) per bit. Simulation of the system under proposed study has been done in M-ary
modulation schemes (MPSK, MQAM and DPSK) over AWGN and Rayleigh fading channel incorporating
Walsh Hadamard code as orthogonal spreading code to discriminate the message signal for individual
user. It is observed via computer simulation that the performance of the interleaved coded based proposed
system outperforms than that of the uncoded system in all modulation schemes over Rayleigh fading
channel.
A Survey on Cross Layer Routing Protocol with Quality of ServiceIJSRD
Wireless is playing the wide role in today’s industrial application. Central idea of this paper is to enhance quality of service (QoS) for multimedia transmission over ad-hoc network. This paper describes the operational of different QoS routing protocols, their properties and various parameters advantages and disadvantages. Also describes the use of QoS in Cross layer routing protocol. Finally, it concludes by study of all these cross layer QoS routing protocols.
QOS CATEGORIES ACTIVENESS-AWARE ADAPTIVE EDCA ALGORITHM FOR DENSE IOT NETWORKSIJCNCJournal
IEEE 802.11 networks have a great role to play in supporting and deploying of the Internet of Things (IoT). The realization of IoT depends on the ability of the network to handle a massive number of stations and transmissions and to support Quality of Service (QoS). IEEE 802.11 networks enable the QoS by applying the Enhanced Distributed Channel Access (EDCA) with static parameters regardless of existing network capacity or which Access Category (AC) of QoS is already active. Our objective in this paper is to improve the efficiency of the uplink access in 802.11 networks; therefore we proposed an algorithm called QoS Categories Activeness-Aware Adaptive EDCA Algorithm (QCAAAE) which adapts Contention Window (CW) size, and Arbitration Inter-Frame Space Number (AIFSN) values depending on the number of associated Stations (STAs) and considering the presence of each AC. For different traffic scenarios, the simulation results confirm the outperformance of the proposed algorithm in terms of throughput (increased on average 23%) and retransmission attempts rate (decreased on average 47%) considering acceptable delay for sensitive delay services.
A Cross Layer Based Scalable Channel Slot Re-Utilization Technique for Wirele...csandit
Due to tremendous growth of the wireless based application services are increasing the demand
for wireless communication techniques that use bandwidth more effectively. Channel slot reutilization
in multi-radio wireless mesh networks is a very challenging problem. WMNs have
been adopted as back haul to connect various networks such as Wi-Fi (802.11), WI-MAX
(802.16e) etc. to the internet. The slot re-utilization technique proposed so far suffer due to high
collision due to improper channel slot usage approximation error. To overcome this here the
author propose the cross layer optimization technique by designing a device classification
based channel slot re-utilization routing strategy which considers the channel slot and node
information from various layers and use some of these parameters to approximate the risk
involve in channel slot re-utilization in order to improve the QoS of the network. The simulation
and analytical results show the effectiveness of our proposed approach in term of channel slot
re-utilization efficiency and thus helps in reducing latency for data transmission and reduce
channel slot collision.
A CROSS-LAYER BASED SCALABLE CHANNEL SLOT RE-UTILIZATION TECHNIQUE FOR WIRELE...cscpconf
Due to tremendous growth of the wireless based application services are increasing the demand for wireless communication techniques that use bandwidth more effectively. Channel slot reutilization in multi-radio wireless mesh networks is a very challenging problem. WMNs have been adopted as back haul to connect various networks such as Wi-Fi (802.11), WI-MAX (802.16e) etc. to the internet. The slot re-utilization technique proposed so far suffer due to high collision due to improper channel slot usage approximation error. To overcome this here the author propose the cross layer optimization technique by designing a device classification based channel slot re-utilization routing strategy which considers the channel slot and node information from various layers and use some of these parameters to approximate the risk involve in channel slot re-utilization in order to improve the QoS of the network. The simulation and analytical results show the effectiveness of our proposed approach in term of channel slot re-utilization efficiency and thus helps in reducing latency for data transmission and reduce
channel slot collision.
Long-Term Advancement Progressed (LTE-ADV) is the advancement of the long-term evolution,
which created via 3GPP. LTE-ADV aims to offer a transmission bandwidth of (100) MHz by using Carrier
Aggregation (CA) to aggregate LTE-ADV carriers. To increase the data capacity of the system and
resource allocation converts a very good tool. LTE-Advanced multiple Component Carriers (CCs) becomes
a difficult optimization problem. In the paper proposes a new scheduling algorithm and compares with a
different scheduling traditional algorithms that are proportional fair and round robin in the CA, in order to
find the best scheduler that provides high-quality throughput and improves fairness. It also evaluates
mapping model types are Mutual Information Effective SINR Mapping (MIESM) and Exponential Effective
SINR Mapping (EESM). The results show that the throughput in the proposed algorithm with MIESM
outperforms from others mapping and scheduling.
Similar to Performance analysis and evaluation of IEEE 802.11 distributed coordination function using OPNET (20)
Square transposition: an approach to the transposition process in block cipherjournalBEEI
The transposition process is needed in cryptography to create a diffusion effect on data encryption standard (DES) and advanced encryption standard (AES) algorithms as standard information security algorithms by the National Institute of Standards and Technology. The problem with DES and AES algorithms is that their transposition index values form patterns and do not form random values. This condition will certainly make it easier for a cryptanalyst to look for a relationship between ciphertexts because some processes are predictable. This research designs a transposition algorithm called square transposition. Each process uses square 8 × 8 as a place to insert and retrieve 64-bits. The determination of the pairing of the input scheme and the retrieval scheme that have unequal flow is an important factor in producing a good transposition. The square transposition can generate random and non-pattern indices so that transposition can be done better than DES and AES.
Hyper-parameter optimization of convolutional neural network based on particl...journalBEEI
Deep neural networks have accomplished enormous progress in tackling many problems. More specifically, convolutional neural network (CNN) is a category of deep networks that have been a dominant technique in computer vision tasks. Despite that these deep neural networks are highly effective; the ideal structure is still an issue that needs a lot of investigation. Deep Convolutional Neural Network model is usually designed manually by trials and repeated tests which enormously constrain its application. Many hyper-parameters of the CNN can affect the model performance. These parameters are depth of the network, numbers of convolutional layers, and numbers of kernels with their sizes. Therefore, it may be a huge challenge to design an appropriate CNN model that uses optimized hyper-parameters and reduces the reliance on manual involvement and domain expertise. In this paper, a design architecture method for CNNs is proposed by utilization of particle swarm optimization (PSO) algorithm to learn the optimal CNN hyper-parameters values. In the experiment, we used Modified National Institute of Standards and Technology (MNIST) database of handwritten digit recognition. The experiments showed that our proposed approach can find an architecture that is competitive to the state-of-the-art models with a testing error of 0.87%.
Supervised machine learning based liver disease prediction approach with LASS...journalBEEI
In this contemporary era, the uses of machine learning techniques are increasing rapidly in the field of medical science for detecting various diseases such as liver disease (LD). Around the globe, a large number of people die because of this deadly disease. By diagnosing the disease in a primary stage, early treatment can be helpful to cure the patient. In this research paper, a method is proposed to diagnose the LD using supervised machine learning classification algorithms, namely logistic regression, decision tree, random forest, AdaBoost, KNN, linear discriminant analysis, gradient boosting and support vector machine (SVM). We also deployed a least absolute shrinkage and selection operator (LASSO) feature selection technique on our taken dataset to suggest the most highly correlated attributes of LD. The predictions with 10 fold cross-validation (CV) made by the algorithms are tested in terms of accuracy, sensitivity, precision and f1-score values to forecast the disease. It is observed that the decision tree algorithm has the best performance score where accuracy, precision, sensitivity and f1-score values are 94.295%, 92%, 99% and 96% respectively with the inclusion of LASSO. Furthermore, a comparison with recent studies is shown to prove the significance of the proposed system.
A secure and energy saving protocol for wireless sensor networksjournalBEEI
The research domain for wireless sensor networks (WSN) has been extensively conducted due to innovative technologies and research directions that have come up addressing the usability of WSN under various schemes. This domain permits dependable tracking of a diversity of environments for both military and civil applications. The key management mechanism is a primary protocol for keeping the privacy and confidentiality of the data transmitted among different sensor nodes in WSNs. Since node's size is small; they are intrinsically limited by inadequate resources such as battery life-time and memory capacity. The proposed secure and energy saving protocol (SESP) for wireless sensor networks) has a significant impact on the overall network life-time and energy dissipation. To encrypt sent messsages, the SESP uses the public-key cryptography’s concept. It depends on sensor nodes' identities (IDs) to prevent the messages repeated; making security goals- authentication, confidentiality, integrity, availability, and freshness to be achieved. Finally, simulation results show that the proposed approach produced better energy consumption and network life-time compared to LEACH protocol; sensors are dead after 900 rounds in the proposed SESP protocol. While, in the low-energy adaptive clustering hierarchy (LEACH) scheme, the sensors are dead after 750 rounds.
Plant leaf identification system using convolutional neural networkjournalBEEI
This paper proposes a leaf identification system using convolutional neural network (CNN). This proposed system can identify five types of local Malaysia leaf which were acacia, papaya, cherry, mango and rambutan. By using CNN from deep learning, the network is trained from the database that acquired from leaf images captured by mobile phone for image classification. ResNet-50 was the architecture has been used for neural networks image classification and training the network for leaf identification. The recognition of photographs leaves requested several numbers of steps, starting with image pre-processing, feature extraction, plant identification, matching and testing, and finally extracting the results achieved in MATLAB. Testing sets of the system consists of 3 types of images which were white background, and noise added and random background images. Finally, interfaces for the leaf identification system have developed as the end software product using MATLAB app designer. As a result, the accuracy achieved for each training sets on five leaf classes are recorded above 98%, thus recognition process was successfully implemented.
Customized moodle-based learning management system for socially disadvantaged...journalBEEI
This study aims to develop Moodle-based LMS with customized learning content and modified user interface to facilitate pedagogical processes during covid-19 pandemic and investigate how teachers of socially disadvantaged schools perceived usability and technology acceptance. Co-design process was conducted with two activities: 1) need assessment phase using an online survey and interview session with the teachers and 2) the development phase of the LMS. The system was evaluated by 30 teachers from socially disadvantaged schools for relevance to their distance learning activities. We employed computer software usability questionnaire (CSUQ) to measure perceived usability and the technology acceptance model (TAM) with insertion of 3 original variables (i.e., perceived usefulness, perceived ease of use, and intention to use) and 5 external variables (i.e., attitude toward the system, perceived interaction, self-efficacy, user interface design, and course design). The average CSUQ rating exceeded 5.0 of 7 point-scale, indicated that teachers agreed that the information quality, interaction quality, and user interface quality were clear and easy to understand. TAM results concluded that the LMS design was judged to be usable, interactive, and well-developed. Teachers reported an effective user interface that allows effective teaching operations and lead to the system adoption in immediate time.
Understanding the role of individual learner in adaptive and personalized e-l...journalBEEI
Dynamic learning environment has emerged as a powerful platform in a modern e-learning system. The learning situation that constantly changing has forced the learning platform to adapt and personalize its learning resources for students. Evidence suggested that adaptation and personalization of e-learning systems (APLS) can be achieved by utilizing learner modeling, domain modeling, and instructional modeling. In the literature of APLS, questions have been raised about the role of individual characteristics that are relevant for adaptation. With several options, a new problem has been raised where the attributes of students in APLS often overlap and are not related between studies. Therefore, this study proposed a list of learner model attributes in dynamic learning to support adaptation and personalization. The study was conducted by exploring concepts from the literature selected based on the best criteria. Then, we described the results of important concepts in student modeling and provided definitions and examples of data values that researchers have used. Besides, we also discussed the implementation of the selected learner model in providing adaptation in dynamic learning.
Prototype mobile contactless transaction system in traditional markets to sup...journalBEEI
One way to prevent and reduce the spread of the covid-19 pandemic is through physical distancing program. This research aims to develop a prototype contactless transaction system using digital payment mechanisms and QR code technology that will be applied in traditional markets. The method used in the development of electronic market systems is a prototype approach. The application of QR code and digital payments are used as a solution to minimize money exchange contacts that are common in traditional markets. The results showed that the system built was able to accelerate and facilitate the buying and selling transaction process in traditional market environment. Alpha testing shows that all functional systems are running well. Meanwhile, beta testing shows that the user can very well accept the system that was built. The results of the study also show acceptance of the usefulness of the system being built, as well as the optimism of its users to be able to take advantage of this system both technologically and functionally, so its can be a part of the digital transformation of the traditional market to the electronic market and has become one of the solutions in reducing the spread of the current covid-19 pandemic.
Wireless HART stack using multiprocessor technique with laxity algorithmjournalBEEI
The use of a real-time operating system is required for the demarcation of industrial wireless sensor network (IWSN) stacks (RTOS). In the industrial world, a vast number of sensors are utilised to gather various types of data. The data gathered by the sensors cannot be prioritised ahead of time. Because all of the information is equally essential. As a result, a protocol stack is employed to guarantee that data is acquired and processed fairly. In IWSN, the protocol stack is implemented using RTOS. The data collected from IWSN sensor nodes is processed using non-preemptive scheduling and the protocol stack, and then sent in parallel to the IWSN's central controller. The real-time operating system (RTOS) is a process that occurs between hardware and software. Packets must be sent at a certain time. It's possible that some packets may collide during transmission. We're going to undertake this project to get around this collision. As a prototype, this project is divided into two parts. The first uses RTOS and the LPC2148 as a master node, while the second serves as a standard data collection node to which sensors are attached. Any controller may be used in the second part, depending on the situation. Wireless HART allows two nodes to communicate with each other.
Implementation of double-layer loaded on octagon microstrip yagi antennajournalBEEI
A double-layer loaded on the octagon microstrip yagi antenna (OMYA) at 5.8 GHz industrial, scientific and medical (ISM) Band is investigated in this paper. The double-layer consist of two double positive (DPS) substrates. The OMYA is overlaid with a double-layer configuration were simulated, fabricated and measured. A good agreement was observed between the computed and measured results of the gain for this antenna. According to comparison results, it shows that 2.5 dB improvement of the OMYA gain can be obtained by applying the double-layer on the top of the OMYA. Meanwhile, the bandwidth of the measured OMYA with the double-layer is 14.6%. It indicates that the double-layer can be used to increase the OMYA performance in term of gain and bandwidth.
The calculation of the field of an antenna located near the human headjournalBEEI
In this work, a numerical calculation was carried out in one of the universal programs for automatic electro-dynamic design. The calculation is aimed at obtaining numerical values for specific absorbed power (SAR). It is the SAR value that can be used to determine the effect of the antenna of a wireless device on biological objects; the dipole parameters will be selected for GSM1800. Investigation of the influence of distance to a cell phone on radiation shows that absorbed in the head of a person the effect of electromagnetic radiation on the brain decreases by three times this is a very important result the SAR value has decreased by almost three times it is acceptable results.
Exact secure outage probability performance of uplinkdownlink multiple access...journalBEEI
In this paper, we study uplink-downlink non-orthogonal multiple access (NOMA) systems by considering the secure performance at the physical layer. In the considered system model, the base station acts a relay to allow two users at the left side communicate with two users at the right side. By considering imperfect channel state information (CSI), the secure performance need be studied since an eavesdropper wants to overhear signals processed at the downlink. To provide secure performance metric, we derive exact expressions of secrecy outage probability (SOP) and and evaluating the impacts of main parameters on SOP metric. The important finding is that we can achieve the higher secrecy performance at high signal to noise ratio (SNR). Moreover, the numerical results demonstrate that the SOP tends to a constant at high SNR. Finally, our results show that the power allocation factors, target rates are main factors affecting to the secrecy performance of considered uplink-downlink NOMA systems.
Design of a dual-band antenna for energy harvesting applicationjournalBEEI
This report presents an investigation on how to improve the current dual-band antenna to enhance the better result of the antenna parameters for energy harvesting application. Besides that, to develop a new design and validate the antenna frequencies that will operate at 2.4 GHz and 5.4 GHz. At 5.4 GHz, more data can be transmitted compare to 2.4 GHz. However, 2.4 GHz has long distance of radiation, so it can be used when far away from the antenna module compare to 5 GHz that has short distance in radiation. The development of this project includes the scope of designing and testing of antenna using computer simulation technology (CST) 2018 software and vector network analyzer (VNA) equipment. In the process of designing, fundamental parameters of antenna are being measured and validated, in purpose to identify the better antenna performance.
Transforming data-centric eXtensible markup language into relational database...journalBEEI
eXtensible markup language (XML) appeared internationally as the format for data representation over the web. Yet, most organizations are still utilising relational databases as their database solutions. As such, it is crucial to provide seamless integration via effective transformation between these database infrastructures. In this paper, we propose XML-REG to bridge these two technologies based on node-based and path-based approaches. The node-based approach is good to annotate each positional node uniquely, while the path-based approach provides summarised path information to join the nodes. On top of that, a new range labelling is also proposed to annotate nodes uniquely by ensuring the structural relationships are maintained between nodes. If a new node is to be added to the document, re-labelling is not required as the new label will be assigned to the node via the new proposed labelling scheme. Experimental evaluations indicated that the performance of XML-REG exceeded XMap, XRecursive, XAncestor and Mini-XML concerning storing time, query retrieval time and scalability. This research produces a core framework for XML to relational databases (RDB) mapping, which could be adopted in various industries.
Key performance requirement of future next wireless networks (6G)journalBEEI
Given the massive potentials of 5G communication networks and their foreseeable evolution, what should there be in 6G that is not in 5G or its long-term evolution? 6G communication networks are estimated to integrate the terrestrial, aerial, and maritime communications into a forceful network which would be faster, more reliable, and can support a massive number of devices with ultra-low latency requirements. This article presents a complete overview of potential 6G communication networks. The major contribution of this study is to present a broad overview of key performance indicators (KPIs) of 6G networks that cover the latest manufacturing progress in the environment of the principal areas of research application, and challenges.
Noise resistance territorial intensity-based optical flow using inverse confi...journalBEEI
This paper presents the use of the inverse confidential technique on bilateral function with the territorial intensity-based optical flow to prove the effectiveness in noise resistance environment. In general, the image’s motion vector is coded by the technique called optical flow where the sequences of the image are used to determine the motion vector. But, the accuracy rate of the motion vector is reduced when the source of image sequences is interfered by noises. This work proved that the inverse confidential technique on bilateral function can increase the percentage of accuracy in the motion vector determination by the territorial intensity-based optical flow under the noisy environment. We performed the testing with several kinds of non-Gaussian noises at several patterns of standard image sequences by analyzing the result of the motion vector in a form of the error vector magnitude (EVM) and compared it with several noise resistance techniques in territorial intensity-based optical flow method.
Modeling climate phenomenon with software grids analysis and display system i...journalBEEI
This study aims to model climate change based on rainfall, air temperature, pressure, humidity and wind with grADS software and create a global warming module. This research uses 3D model, define, design, and develop. The results of the modeling of the five climate elements consist of the annual average temperature in Indonesia in 2009-2015 which is between 29oC to 30.1oC, the horizontal distribution of the annual average pressure in Indonesia in 2009-2018 is between 800 mBar to 1000 mBar, the horizontal distribution the average annual humidity in Indonesia in 2009 and 2011 ranged between 27-57, in 2012-2015, 2017 and 2018 it ranged between 30-60, during the East Monsoon, the wind circulation moved from northern Indonesia to the southern region Indonesia. During the west monsoon, the wind circulation moves from the southern part of Indonesia to the northern part of Indonesia. The global warming module for SMA/MA produced is feasible to use, this is in accordance with the value given by the validate of 69 which is in the appropriate category and the response of teachers and students through a 91% questionnaire.
An approach of re-organizing input dataset to enhance the quality of emotion ...journalBEEI
The purpose of this paper is to propose an approach of re-organizing input data to recognize emotion based on short signal segments and increase the quality of emotional recognition using physiological signals. MIT's long physiological signal set was divided into two new datasets, with shorter and overlapped segments. Three different classification methods (support vector machine, random forest, and multilayer perceptron) were implemented to identify eight emotional states based on statistical features of each segment in these two datasets. By re-organizing the input dataset, the quality of recognition results was enhanced. The random forest shows the best classification result among three implemented classification methods, with an accuracy of 97.72% for eight emotional states, on the overlapped dataset. This approach shows that, by re-organizing the input dataset, the high accuracy of recognition results can be achieved without the use of EEG and ECG signals.
Parking detection system using background subtraction and HSV color segmentationjournalBEEI
Manual system vehicle parking makes finding vacant parking lots difficult, so it has to check directly to the vacant space. If many people do parking, then the time needed for it is very much or requires many people to handle it. This research develops a real-time parking system to detect parking. The system is designed using the HSV color segmentation method in determining the background image. In addition, the detection process uses the background subtraction method. Applying these two methods requires image preprocessing using several methods such as grayscaling, blurring (low-pass filter). In addition, it is followed by a thresholding and filtering process to get the best image in the detection process. In the process, there is a determination of the ROI to determine the focus area of the object identified as empty parking. The parking detection process produces the best average accuracy of 95.76%. The minimum threshold value of 255 pixels is 0.4. This value is the best value from 33 test data in several criteria, such as the time of capture, composition and color of the vehicle, the shape of the shadow of the object’s environment, and the intensity of light. This parking detection system can be implemented in real-time to determine the position of an empty place.
Quality of service performances of video and voice transmission in universal ...journalBEEI
The universal mobile telecommunications system (UMTS) has distinct benefits in that it supports a wide range of quality of service (QoS) criteria that users require in order to fulfill their requirements. The transmission of video and audio in real-time applications places a high demand on the cellular network, therefore QoS is a major problem in these applications. The ability to provide QoS in the UMTS backbone network necessitates an active QoS mechanism in order to maintain the necessary level of convenience on UMTS networks. For UMTS networks, investigation models for end-to-end QoS, total transmitted and received data, packet loss, and throughput providing techniques are run and assessed and the simulation results are examined. According to the results, appropriate QoS adaption allows for specific voice and video transmission. Finally, by analyzing existing QoS parameters, the QoS performance of 4G/UMTS networks may be improved.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
Contact with Dawood Bhai Just call on +92322-6382012 and we'll help you. We'll solve all your problems within 12 to 24 hours and with 101% guarantee and with astrology systematic. If you want to take any personal or professional advice then also you can call us on +92322-6382012 , ONLINE LOVE PROBLEM & Other all types of Daily Life Problem's.Then CALL or WHATSAPP us on +92322-6382012 and Get all these problems solutions here by Amil Baba DAWOOD BANGALI
#vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore#blackmagicformarriage #aamilbaba #kalajadu #kalailam #taweez #wazifaexpert #jadumantar #vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore #blackmagicforlove #blackmagicformarriage #aamilbaba #kalajadu #kalailam #taweez #wazifaexpert #jadumantar #vashikaranspecialist #astrologer #palmistry #amliyaat #taweez #manpasandshadi #horoscope #spiritual #lovelife #lovespell #marriagespell#aamilbabainpakistan #amilbabainkarachi #powerfullblackmagicspell #kalajadumantarspecialist #realamilbaba #AmilbabainPakistan #astrologerincanada #astrologerindubai #lovespellsmaster #kalajaduspecialist #lovespellsthatwork #aamilbabainlahore #Amilbabainuk #amilbabainspain #amilbabaindubai #Amilbabainnorway #amilbabainkrachi #amilbabainlahore #amilbabaingujranwalan #amilbabainislamabad
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Water Industry Process Automation and Control Monthly - May 2024.pdf
Performance analysis and evaluation of IEEE 802.11 distributed coordination function using OPNET
1. Bulletin of Electrical Engineering and Informatics
Vol. 9, No. 6, December 2020, pp. 2595~2600
ISSN: 2302-9285, DOI: 10.11591/eei.v9i6.2477 2595
Journal homepage: http://beei.org
Performance analysis and evaluation of IEEE 802.11 distributed
coordination function using OPNET
Zaynab Mahir Abdel-Ameer1
, Abdul Kareem A. Najem Alaloosy2
, Khattab M. Ali Alheeti3
1
College of Engineering, Computer Engineering Department, AL-Nahrain University Baghdad, Iraq
2
College of Computer, Computer Networking Systems Department, University of Anbar, Iraq
3
College of Computer and Information Technology, Computer Networking Systems Department,
University of Anbar, Iraq
Article Info ABSTRACT
Article history:
Received Mar 1, 2020
Revised May 14, 2020
Accepted Jun 1, 2020
This paper discusses the distributed coordination function (DCF) access
mechanism which is a carrier sense multiple access with collision avoidance
(CSMA/CA) scheme. Simulation projects for different DCF performance
parameters have been built using the OPNET network simulator.
The projects are mainly basic service set (BSS) topology simulated under
different parameter values (data rate, fragmentation, RTS/CTS, number of
nodes, and load condition). Simulation results show when the DCF access
mechanism is better under what load condition, and how to choose the best
fragmentation threshold and other access-mechanism specific parameters
according to the network conditions. Simulation results were validated
against a theoretically calculated maximum throughput (the simulation
maximum throughput was about 70% of the theoretically calculated
maximum throughput).
Keywords:
Collision avoidance
DCF
Fragmentation
OPNET
Throughput
This is an open access article under the CC BY-SA license.
Corresponding Author:
Khattab M. Ali Alheeti,
Department of Computer Networking Systems,
University of Anbar,
Iraq, Anbar- Ramadi, P.O Box (55431 Baghdad, 55 Ramadi).
Email: co.khattab.alheeti@uoanbar.edu.iq
1. INTRODUCTION
Wireless LAN (WLAN) is an adaptable system of data communication applied as an expansion to
a wired LAN in a building or campus. Wireless LANs transport and collect data over the air, reducing
the requirement for connections of wired. Thus, WLANs integrate data connectivity with user mobility [1, 2].
Group of study 802.11 was molded under Project 802 of IEEE to prompt an international standard for
WLANs [3, 4]. The major method to access the medium is named distributed coordination function (DCF) in
the 802.11 protocol [5]. It is a random-access method based on (CSMA/CA) protocol. The DCF provides
best-effort delivery of data inside a BSS during contention periods. DCF must be implemented in all STAs
and can be used in Infrastructure and ad-hoc modes [6, 7]. The MAC layer software also combines
a voluntary access scheme named the point coordination function (PCF). Both access schemes are exclusive
alternately and work in various time frames identified as the contention period (CP) and contention-free
period (CFP) [1]. The DCF defines two methods to use for transmission of a packet [8]. Two-way
handshaking is a default method performance named the fundamental access method. This mechanism
is described by the current communication of an affirmative acknowledgment by the destination station, upon
the effective reception of a packet conveyed by the sender station. Clear transmission of an ACK is necessary
since, in the wireless middle, a transmitter cannot define if a packet is effectively obtained by listening to its
particular transmission [5]. When two nodes can communicate with another station but cannot communicate
2. ISSN: 2302-9285
Bulletin of Electr Eng & Inf, Vol. 9, No. 6, December 2020: 2595 – 2600
2596
with each other because of physical or spatial constraints, this situation known as the hidden node problem in
wireless networks. The occurrence of hidden nodes may cause degradation performance of the network. It
also produces wrong in medium access because the location of the station may indicate a greater privilege of
transmission. The basis of the difficulty is that a station applies interference as it misses to sense the presence
of transmission from the alternative station and thus believes that the medium is available and accessible for
transmission. Carrier sense multiple access with collision detection (CSMA/CD) method, which is exploited
in Ethernet networks, mitigates this problem by noticing medium collisions. CSMA/CA method attempt to
avert collisions using methods like DCF [9, 10].
2. COORDINATION FUNCTION (802.11 DISTRIBUTED)
Traffic behavior is considered the main metric for the analysis process for any communication
system [11]. Using DCF, for STAs start to transmit they first have to sense the channel for a DIFS time [12].
If the channel is discovered active either directly or through the DIFS, then the station continues to control
the channel until it is free during this period. Although the channel is found idle during DIFS, the station still
has to generate an arbitrary back off interval before communicating. This procedure will minimize
the probability of packet collision and is a collision avoidance (CA) feature of the protocol [13].
The counter of backoff time is decreased while the channel remains inactive and now one of two
situations can happen. If the backoff timer reaches zero, the STA starts transmitting, otherwise,
if a transmission is noticed on the channel, the timer is frozen and starts to decrement, from the same
position, when the channel is sensed idle again after a DIFS. Once a transmission the destination station has
to guide a positive acknowledge indicates that the data is well caught since the station is not able to listen to
its transmission. However, it has the ability to scalable various data/ control traffic between nodes [14].
The ACK is sent after a SIFS and has priority on the channel since SIFS is the shortest IFS. This way
the channel will not be idle for any other station until ACK is received. DCF utilizes a handshaking technique
for transmission of the packet. These RTS and CTS frames carry information about the packet length to be
transferred. This information can be received by STA in the radius of communication for a sender
and a recipient and they can inform their NAV that shown in Figure 1 [15, 16].
Figure 1. RTS/CTS/data/ACK and NAV setting [15]
RTC/CTS are employed to improve the performance of communication systems [17, 18].
This technique does accurately the same while confirming for a channel. Before transmitting a data packet,
an STA directs an RTS frame to the STA destination. If the STA obtains this frame, after a SIFS it replies
with a CTS frame. To send the STA data packet, transmitting STA is allowed only. With this technique of
collisions straight to the problem of hidden terminals can be avoided since the discovery of one of RTS or
CTS frames will avoid the other STA to begin their transmission. However, these mechanisms have a lot of
important applications in the modern research area [19, 20].
3. Bulletin of Electr Eng & Inf ISSN: 2302-9285
Performance analysis and evaluation of IEEE 802.11 distributed… (Zaynab Mahir Abdel-Ameer)
2597
This four-way handshaking technique has advantages and disadvantages comparing to the basic
access method. For instance, if the CTS frame is not received the STA can repeat the whole process
in a shorter time than if the ACK frame is not received and the long data frame has to be retransmitted.
On the other hand, in the case of smaller BSSs, the amount of the collision will not be so relevant in basic
access performance comparing to the additional overheads that the RTS-CTS scheme introduces adding
inefficiency to the system [21].
3. DCF THROUGHPUT
Medium plays an important role to transfer/ receive control and data [22]. A random backoff method
is applied under rules channel access of DCF to decide WLAN station collisions. The random backoff
interval is in the unit of a Slot Time, and the arbitrary integer is extracted from an identical distribution
throughout the interval [0, CW], where CW is the size of the contention window. CW shall take a primary
value of a CW min [23]. In the state of ineffective communication, CW is improved to [2*(CW+1)-1]. If CW
successes a max of CW it shall continue at the value of a max of CW until it is reset. After an effective
acknowledged communication, the value of CW is reset to a CW min. DCF services a binary exponential
random backoff where the backoff interval Ib (i) after i ineffective efforts is [21]:
(1)
In a quietly network loaded, it would be reasonable to believe that greatest of the stations will
effectively achieve channel access after the initial backoff try (i.e., i=0), so according to (1) above.
The average backoff time would be a CW min/2=[31* 20]/2=310 µsec. Now, the maximum feasible
throughput under the DCF channel access method can be computed by (2) [21, 24]:
Throughput DCF= (MPDU size/[MPDU size + MAC header size]) * (TMPDU,
MAC/[TDIFS+ TBack off + TPOH+ TMPDU, MAC+ TSIFS+ TACK]) * Data Rate
(2)
Equation 2 can be illustrated in Figure 2 which shows occupancy times of channel in DCF with
the mode of DSSS PHY and 512 bytes size of MPDU. Replacing the values shown in Figure 2 with
(data rate=11 Mbps) and (MPDU size=512 bytes) in (2) would result in: Throughput DCF=3.423 Mbps,
when using (data rate=2 Mbps) and (MPDU size=512 bytes) in (2) would result in Throughput
DCF=637.32 Kbps, in both cases, the DCF effectiveness is about 31%. Access of DCF channel is highly
useless with packet lengths below 1500 bytes.
Figure 2. Channel occupancy times under DCF [21]
Using (2) again and putting the (MPDU size=1500 bytes) would result in Throughput DCF=6.26
Mbps, in this case, the DCF efficiency is about 57%. It is obvious that for all PHY modes. Throughput
success is greater for earlier modes of PHY because the improvidence is mostly because of DIFS/SIFS,
average time f back off, and overheads of PHY, and these parameters are stable and free for the mode of
PHY utilized. Table 1 shows the description of IEEE 802.11b PHY parameters.
4. ISSN: 2302-9285
Bulletin of Electr Eng & Inf, Vol. 9, No. 6, December 2020: 2595 – 2600
2598
Table 1. IEEE 802.11b PHY parameters
Parameter Duration (µsec) Description
Slot time 20 Slot time on the channel
SIFS 10 Short inter-frame space
PIFS 30 PIFS=SIFS + slot time
DIFS 50 DIFS=SIFS+2Xslot time
CWmin 31 X Slot time Minimum contention window size
CWmax 1023 X Slot time Maximum contention window size
Average backoff time 310* The average duration of the backoff time in a lightly
loaded network
PHY preamble 144 Duration of short and long symbols
PHY header 48 PHY related information
PHY overload (POH) 192** POH=PHY Preamble +PHY header
MAC header (31X8 bits)/(11 Mbps)=22.5 Assuming 31-byte header at 11 Mbps
ACK frame (30X8 bits)/(1 Mbps)=240 Ack frame size=30 at 1 Mbps
Beacon frame (71X8 bits)/(2 Mbps)=284 Beacon frame size=61 octets +SSID (service set ID)=
71 octets, assuming 10 bytes , SSID at 2 Mbps
Data frame (MPDUsize X 8bits)/(11 Mbps) Duration of MPDU at 11 Mbps
4. RESULTS AND DISCUSSION
The performance metrics are utilized to measure the efficiency of the proposed system.
However, before going into the details of the results the collected measures need to be defined [25] which
are throughput, delay, retransmission count, and throughput relation. In more details, the throughput metric is
the number of bits that sent from wireless LAN layers to higher layers in all nodes of WLAN of the network
is referred to as throughput. In addition, the delay metric is a referee to the amount of delay between end to
end nodes. Moreover, this metric is end - end delay of the packets achieved by the wireless LAN MACs of all
WLAN nodes in the network and sent to the higher layer is represent delay. This delay comprises delay of
access of medium at the source MAC, the response of all the fragments separately, and transport of the frames
by AP if the access point is allowed. Therefore, retransmission count is the total number for retransmissions
of TCP in the network. Inscribed when data is retransmitted from the buffer of TCP unacknowledged.
In this section, we are trying to explain the performance metrics of the proposed system as well as
these results will be discussed with the previous studies. Thus, Table 2 shows the throughput results of
the DCF project (low load scenarios). Table 3 shows the throughput results of the DCF project (heavy load
scenarios). Which (without fragmentation) gives the best throughput and (fragmentation big) gives the worst
throughput. From Tables 2 and 3 it can be noticed the following: By comparing Tables 2 and 3 it can be seen
that the scenario with a less delay is not essentially producing a better throughput. This is somehow
confusing but taking into consideration a DCF technique with RTS method enabled may produce more delay
(as the RTS/CTS frames transactions take place) but will give better performance when the collision is
avoided. Another explanation may be because that the taken values are average for the whole nodes in
the scenario. Table 3 shows very bad and unacceptable delay values that go more than 1 min. This shows that
it is not useful to apply DCF with rates of data at 2 Mbps or 11 Mbps for applications of multimedia as
the number of applied traffic packets will be more than what can be controlled. In this state, the buffer will be
full and the number of dropped packets rises.
The throughput, data rate, and the number of nodes are shown in Table 2. For this, it displays that
the throughput is monotonically increasing with the number of nodes. By examining each column of Table 2
it can be noted that the average throughput rises when nodes number goes up. This may be supported as
further nodes refer to further traffic, which in turn raises the throughput as long as the network connection
capacity has not been applied. Since Table 2 displays only the low load scenarios average throughput
(the max. throughput is about 2 Kbps), there is no big difference between the 2 Mbps results and
the corresponding 11 Mbps results. This is not true for Table 3 results which show a big difference between
the average throughput of 2 Mbps results and the corresponding 11 Mbps results (about three to six times
better). As calculated that the maximum throughput for 2 Mbps is (637.32 Kbps), and for 11 Mbps is (3.423
Mbps). In the low load case, the traffic was (2 Kbps) much below the maximum achievable throughput by
both rates; that is why there is no difference between the two rates results. While in the heavy load case
the traffic was due to the multimedia profile which can be more than 5 Mbps. In this case, the 2 Mbps rate
made a maximum throughput of about (450 Kbps) (which is quite reasonable since it is about 70% of
the maximum perfect channel theoretical throughput). The 11 Mbps rate made a maximum throughput of
about (2.33 Mbps) (which is quite reasonable since it is about 68% of the maximum perfect channel
theoretical throughput).
However, throughput delay and fragmentation are demonstrated in Table 2 and Table 3. In addition,
low load and heavy load are noticed in both Tables. The best throughput results were when fragmentation
was disabled. While most of the worst throughputs in the low load case are when fragmentation,
5. Bulletin of Electr Eng & Inf ISSN: 2302-9285
Performance analysis and evaluation of IEEE 802.11 distributed… (Zaynab Mahir Abdel-Ameer)
2599
the threshold set to big (512 bytes) as shown in Table 2. Table 3 shows the reverse; as all of the worst
throughputs in the heavy load case is when the fragmentation threshold set to small (128 bytes). This can be
validated by the fact that fragmentation is to enhance the performance when many retransmissions are taking
place. In lightly loaded network fragmentation is no more than additional overhead that degrades
the performance. This is why the (without fragmentation scenarios gave the best performance) in Tables 2
and 3. Also in the heavily loaded network when there is no or very small error rate, fragmentation is an
unwanted additional overhead especially (small fragmentation) when almost all packets are fragmented into
smaller packets thus the network is flooded with overhead. This is why all of the worst throughputs in
the heavy load case are when the fragmentation threshold set to small (128 bytes). In general,
the fragmentation threshold must be modified according to the load, rate of bit error, and nodes number of
the network. Since delay change against the fragmentation used, it can be observed that the fragmentations
raise the delay specifically the small threshold of fragmentation. And this rise in delay because of
fragmentation is much in the minor rates of data at (2 Mbps) than it is in the high rates of data at (11 Mbps).
Table 2. DCF low load scenarios average delay (msec)
Without fragmentation Fragmentation big (512 bytes) Fragmentation small (128 bytes)
No. of PCs
& data Rate
Without
RTS
RTS big RTS
small
Without
RTS
RTS big RTS
small
Without
RTS
RTS big RTS
small
2 PCs-2 Mbps 3.1 3.2 3.5 2.8 4.0 4.2 4.8 4.7 5.1
2 PCs-11 Mbps 2.0 1.9 2.3 2.1 2.2 2.8 2.2 2.2 2.7
4 PCs-2 Mbps 4.0 5.2 5.3 5.1 4.9 6.4 7.7 7.1 8.0
4 PCs-11 Mbps 2.9 2.5 3.0 2.7 2.9 3.3 4.8 4.7 5.5
8 PCs-2 Mbps 6.2 8.8 6.9 8.8 6.1 6.8 8.6 8.7 10.3
8 PCs-11 Mbps 3.2 3.2 4.0 3.4 3.9 3.9 4.6 8.6 8.3
16 PCs-2 Mbps 6.9 7.3 7.9 7.7 8.5 9.3 13.3 10.6 12.0
16 PCs-11 Mbps 3.5 4.0 6.2 4.2 4.2 4.7 6.4 6.8 7.8
Table 3. DCF heavy load scenarios average delay (sec)
Without fragmentation Fragmentation big 512 Fragmentation small 128
No. of PCs
& data Rate
Without
RTS
RTS
big
RTS
small
Without
RTS
RTS
big
RTS
small
Without
RTS
RTS big RTS
small
2 PCs-2 Mbps 92.542 80.173 90.173 78.724 87.381 112.911 106.802 113.644 87.381
2 PCs-11 Mbps 72.483 59.219 59.219 44.912 67.714 67.714 39.702 39.702 39.700
The RTS and throughput delay is illustrated in Table 2. However, it improves the implementation as
the best of the throughputs are under the small RTS column, while RTS and RTS outcomes were near to each
other. This can be confirmed as RTS is a collision avoidance mechanism for the DCF technique and also
because of the low load condition RTS small is giving the best performance. In Table 3, the RTS effect is not
clear because of the limited number of simulated scenarios in the heavy load case. Since delay change against
the RTS threshold employed as shown in Tables 2 and 3, it can be observed that RTS rises by using the delay
especially the small threshold of RTS. And this rise in delay suitable to consuming RTS is much in the minor
rates of data at 2 Mbps than it is in the high rates of data at 11Mbps. The effect of load on the behavior
is comparing the first two rows of Tables 2 and 3 show that:
‐ 11 Mbps rate is better than 2 Mbps only in the heavy load condition.
‐ Fragmentation small reduces the performance in the serious load and low rate of bit error conditions.
5. CONCLUSION
According to the results and discussion, the following conclusions can be made. First, it is not useful
to exploit DCF with rates of data at 2 Mbps or 11 Mbps for applications of multimedia as the number of
produced traffic packets will be more than what can be recovered. In this state, the buffer will be full
and dropped packets number rises exponentially. Second, DCF simulation in OPNET produces a maximum
throughput of about 70% of the maximum perfect channel theoretical throughput. This is to be considered
near to the practical maximum throughput. Third, in DCF, the heavily loaded network when there is no, or
very small error rate, fragmentation is an unwanted additional overhead especially (small fragmentation)
when almost all packets are fragmented into smaller packets thus the network is flooded with overhead.
Fourth, according to the load, the threshold of fragmentation should be modified, rate of bit error, and nodes
number, of the network. Where a small threshold of fragmentation reduces DCF performance with serious
load, and rate conditions of low bit error.
6. ISSN: 2302-9285
Bulletin of Electr Eng & Inf, Vol. 9, No. 6, December 2020: 2595 – 2600
2600
REFERENCES
[1] R. Jordan and C. T. Abdallah, “Wireless communications and networking: an overview,” in IEEE Antennas and
Propagation Magazine, vol. 44, no. 1, pp. 185-193, 2002.
[2] A. K. Salkintzis, “Interworking techniques and architectures for WLAN/3G integration toward 4G mobile data
networks,” in IEEE Wireless Communications, vol. 11, no. 3, pp. 50-61, 2004.
[3] G. Bianchi, “Performance analysis of the IEEE 802.11 distributed coordination function,” in IEEE Journal on
Selected Areas in Communications, vol. 18, no. 3, pp. 535-547, 2000.
[4] S. Banerji, “Upcoming standards in wireless local area networks,” Wireless and Mobile Technologies, vol. 1, no 1,
pp. 6-11, 2013.
[5] I. Tinnirello, G. Bianchi, and Y. Xiao, “Refinements on IEEE 802.11 distributed coordination function modeling
approaches,” in IEEE Transactions on Vehicular Technology, vol. 59, no. 3, pp. 1055-1067, 2009.
[6] R. P. de Almeida Martins, “IEEE 802.11b WLAN performance measurements and optimization,” Master Thesis,
Department of Communication Technology, Aalborg University, June 2004.
[7] N. Cranley and L. Murphy, “Handbook of research on wireless multimedia: Quality of service and solutions,”
Liam Murphy (Ed.), Information Science Reference, IGI Global, 2008,
[8] A. Balador, M. Ghasemivand, A. Movaghar, and S. Jabbehdar, “An adaptive contention window control for
improving DCF throughput and fairness,” European J. Scientific Research, vol. 45, no. 2, pp. 310-323, 2010.
[9] H-H. Choi, J-M. Moon, I-H. Lee, and H. Lee, “Carrier sense multiple access with collision resolution,” IEEE
Communications Letters, vol. 17, no. 6, pp. 1284-1290, 2013.
[10] S. Rahman, “Throughput analysis of IEEE 802.11 distributed coordination function in presence of hidden stations,”
Stanford Technical Report, Department of Electrical Engineering, Stanford University, 2003.
[11] R. Lara-Cueva and M. Simba-Herrera, “Performance evaluation for outdoor wireless scenarios based on IEEE
802.11 b/g in the presence of co-channel interference,” Bulletin of Electrical Engineering and Informatics, vol. 9,
no.1, pp. 187-197, 2020.
[12] A. Goldsmith, “Wireless communications,” Cambridge: Cambridge University Press, 2005.
[13] S. Suhane, S. Sharma, and V. Sharma, “Performance analysis of backoff algorithm in IEEE 802.11 networks,”
International Journal of Scientific & Engineering Research, vol. 2, no. 6, pp. 1-5, 2011.
[14] A. Yonis, “Influence of low power consumption on IEEE 802.15. 4 in wireless networks performance,” Bulletin of
Electrical Engineering and Informatics, vol.9, no. 1, pp. 205-211, 2020.
[15] B. Keegan and M. Davis, “An experimental analysis of the call capacity of IEEE 802.11b wireless local area
networks for VoIP telephony,” In Irish Signals and Systems Conference, Dublin, pp. 283-287, 2006.
[16] T. Shigeyasu and H. Matsuno, “Effect of adaptive RTS/CTS ON/OFF control method for mitigating transmission
overhead of IEEE 802.11DCF,” In 2010 IEEE International Conference on Broadband, Wireless Computing,
Communication and Applications, pp. 627-632, 2010.
[17] K. I. Patel and M. M. Vegad, “Effectiveness of RTS/CTS in IEEE 802.11 wireless adhoc network in light of order
dependent capture,” In 2013 IEEE Fourth International Conference on Computing, Communications and
Networking Technologies (ICCCNT), pp. 1-6, 2013.
[18] W-P. Nwadiugwu and D-S. Kim, “Novel MIMO-UWB based RTS/CTS collaboration with scalable rate prediction
for industrial WSNs,” In 2019 15th IEEE International Workshop on Factory Communication Systems (WFCS),
pp. 1-4, 2019.
[19] Z. Na, L. Ningqing, and Q. Yu, “Improved RTS-CTS algorithm to solve mobile hidden station problem in
MANET,” In Proceedings of IEEE 2011 Cross Strait Quad-Regional Radio Science and Wireless Technology
Conference, vol. 1, pp. 812-815, 2011.
[20] G. Habib and C. Bassil, “Influence of the RTS/CTS in VANET,” In 2013 IEEE 13th Mediterranean Microwave
Symposium (MMS), pp. 1-4, 2013.
[21] N. Wattanamongkhol, W. Srichavengsup, S. Nakpeerayuth, and L. Wuttisiittikulkij, “Performance analysis of
modified backoff algorithm in IEEE 802.11 networks,” In 2007 3rd IEEE/IFIP International Conference in Central
Asia on Internet, Tashkent, pp. 1-5, 2007.
[22] A. Butar-Butar, J. Leong, and M. Irwanto, “Effect of DC voltage source on the voltage and current of transmitter
and receiver coil of 2.5 kHz wireless power transfer,” Bulletin of Electrical Engineering and Informatics, vol. 9,
no. 2, pp. 484-491, 2020.
[23] R. Papa, A. Galderisi, M. C. Vigo Majello, and E. Saretta, “Smart and resilient cities. A systemic approach for
developing cross-sectoral strategies in the face of climate change,” TeMA Journal of Land Use, Mobility and
Environment, vol. 8, no. 1, pp. 19-49, 2015.
[24] A. Duda, “Understanding the performance of 802.11 networks,” In 2008 IEEE 19th International Symposium on
Personal, Indoor and Mobile Radio Communications, Cannes, vol. 8, pp. 1-6, 2008.
[25] D. Vassis, G. Kormentzas, A. Rouskas, and I. Maglogiannis, “The IEEE 802.11g standard for high data rate
WLANs,” IEEE Network, vol. 19, no. 3, pp. 21-26, 2005.