- The document discusses scheduling and radio resource allocation in LTE networks. It focuses on the radio resource manager (RRM) element in LTE that performs admission control and packet scheduling.
- Several scheduling algorithms are proposed for both uplink and downlink directions, including proportional fair, EXP-PF, round robin, max-min fair, and algorithms that aim to maximize throughput or support quality of service requirements.
- The paper provides an overview of these scheduling algorithms, evaluates their performance, and offers criticism on how to best allocate radio resources in LTE networks.
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.
Macro with pico cells (hetnets) system behaviour using well known scheduling ...ijwmn
This paper demonstrates the concept of using Heterogeneous networks (HetNets) to improve Long Term Evolution (LTE) system by introducing the LTE Advance (LTE-A). The type of HetNets that has been chosen for this study is Macro with Pico cells. Comparing the system performance with and without Pico cells has clearly illustrated using three well-known scheduling algorithms (Proportional Fair PF, Maximum Largest Weighted Delay First MLWDF and Exponential/Proportional Fair EXP/PF). The system is judged based on throughput, Packet Loss Ratio PLR, delay and fairness.. A simulation platform called LTE-Sim has been used to collect the data and produce the paper’s outcomes and graphs. The results prove that adding Pico cells enhances the overall system performance. From the simulation outcomes, the overall system performance is as follows: throughput is duplicated or tripled based on the number of users, the PLR is almost quartered, the delay is nearly reduced ten times (PF case) and changed to be a half (MLWDF/EXP cases), and the fairness stays closer to value of 1. It is considered an efficient and cost effective way to increase the throughput, coverage and reduce the latency.
Long-Term Evolution (LTE), an emerging and promising fourth generation mobile technology, is expected
to offer ubiquitous broadband access to the mobile subscribers. In this paper, the performance of Frame
Level Scheduler (FLS), Exponential (EXP) rule, Logarithmic (LOG) rule and Maximum-Largest Weighted
Delay First (M-LWDF) packet scheduling algorithms has been studied in the downlink 3GPP LTE cellular
network. To this aim, a single cell with interference scenario has been considered. The performance
evaluation is made by varying the number of UEs ranging from 10 to 50 (Case 1) and user speed in the
range of [3, 120] km/h (Case 2). Results show that while the number of UEs and user speed increases, the
performance of the considered scheduling schemes degrades and in both case FLS outperforms other three
schemes in terms of several performance indexes such as average throughput, packet loss ratio (PLR),
packet delay and fairness index.
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.
Macro with pico cells (hetnets) system behaviour using well known scheduling ...ijwmn
This paper demonstrates the concept of using Heterogeneous networks (HetNets) to improve Long Term Evolution (LTE) system by introducing the LTE Advance (LTE-A). The type of HetNets that has been chosen for this study is Macro with Pico cells. Comparing the system performance with and without Pico cells has clearly illustrated using three well-known scheduling algorithms (Proportional Fair PF, Maximum Largest Weighted Delay First MLWDF and Exponential/Proportional Fair EXP/PF). The system is judged based on throughput, Packet Loss Ratio PLR, delay and fairness.. A simulation platform called LTE-Sim has been used to collect the data and produce the paper’s outcomes and graphs. The results prove that adding Pico cells enhances the overall system performance. From the simulation outcomes, the overall system performance is as follows: throughput is duplicated or tripled based on the number of users, the PLR is almost quartered, the delay is nearly reduced ten times (PF case) and changed to be a half (MLWDF/EXP cases), and the fairness stays closer to value of 1. It is considered an efficient and cost effective way to increase the throughput, coverage and reduce the latency.
Long-Term Evolution (LTE), an emerging and promising fourth generation mobile technology, is expected
to offer ubiquitous broadband access to the mobile subscribers. In this paper, the performance of Frame
Level Scheduler (FLS), Exponential (EXP) rule, Logarithmic (LOG) rule and Maximum-Largest Weighted
Delay First (M-LWDF) packet scheduling algorithms has been studied in the downlink 3GPP LTE cellular
network. To this aim, a single cell with interference scenario has been considered. The performance
evaluation is made by varying the number of UEs ranging from 10 to 50 (Case 1) and user speed in the
range of [3, 120] km/h (Case 2). Results show that while the number of UEs and user speed increases, the
performance of the considered scheduling schemes degrades and in both case FLS outperforms other three
schemes in terms of several performance indexes such as average throughput, packet loss ratio (PLR),
packet delay and fairness index.
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.
Two-level scheduling scheme for integrated 4G-WLAN network IJECEIAES
In this paper, a novel scheduling scheme for the Fourth Generation (4G)-Wireless Local Area Network (WLAN) network is proposed to ensure that end to end traffic transaction is provisioned seamlessly. The scheduling scheme is divided into two stages; in stage one, traffic is separated into Actual Time Traffic (ATT) and Non-Actual-Time Traffic (NATT), while in stage two, complex queuing strategy is performed. In stage one, Class-Based Queuing (CBQ) and Deficit Round Robin(DRR) are used for NATT and ATT applications, respectively to separate and forward traffic themselves according to source requirements. Whereas in the stage, two Control Priority Queuing (CPQ) is used to assign each class the appropriate priority level. Evaluation of the performance of the integrated network was done according to several metrics such as end-to-end delay, jitter, packet loss, and network’s throughput. Results demonstrate major improvements for AT services with minor degradation on NAT applications after implementing the new scheduling scheme.
Multi-layer heterogeneous network layout including small cell base stations are considered to be the key to further enhancements of the spectral efficiency achieved in mobile communication networks. It has been recognized that inter-cell interference has become the limiting factor when trying to achieve not only high average user satisfaction, but a high degree of satisfaction for as many users as possible. Therefore, inter-cell interference coordination (ICIC) lies in the focus of researchers defining next generation mobile communication standards, such as LTE-A.
Building upon [1], this paper provides an overview over the background calling for ICIC in heterogeneous LTE-A networks. It outlines techniques standardized in Rel. 10 of LTE-A, discusses them showing their benefits and limitations by means of system-level simulations and motivates the importance of self optimizing network (SON) procedures for ICIC in LTE-A.
PERFORMANCE ANALYSIS AND COMPARISON OF IMPROVED DSR WITH DSR, AODV AND DSDV R...ijp2p
Mobile Ad-hoc networks are categorized by multi-hop wireless connectivity and numbers of nodes are connecting each other through wireless network. It includes several routing protocols specifically designed for ad-hoc routing. The most widely used ad hoc routing protocols are Ad-hoc On Demand Distance Vector (AODV), Destination Sequence Distance Vector (DSDV), and Dynamic Source Routing (DSR). In this paper, we present an analysis of DSR protocol and propose our algorithm to improve the performance of DSR protocol by using small delay applied on last route ACK path when an original route fails in Mobile Ad Hoc networks. Past researchers the MANET have focused on simulation study by varying network parameters, such as network size, number of nodes. The simulation results shows that the M-DSR protocol
having some excellent performance Metrics then other protocols. We have taken different performance parameters over the comparison of Modified -DSR with other three protocols in mobility as well as Nonmobility scenario up to 300 nodes in MANETs using NS2 simulator. To achieve this goal DSR is modified by using modified algorithm technique in order to load balancing, to avoid congestion and lower packet
delivery.
Our area of interest for the paper is the improvement of performance of DSR routing protocol by
changing in algorithm and this Improved DSR protocol should compare with remaining protocols
taken in this research paper.
2. In this paper we made changesin traditional DSR protocol and generation of new improved DSR the
different performance parameters and compare with AODV/DSR/DSDV protocols in mobility and
non- mobility scenarios nodes up to 300.
3. We can plot the graphs throughput, End to end Delay, Packet delivery Ratio, Dropping Ratio, and
average energy consumption on Mobility and Non-Mobility scenario by using Network Simulator
version 2.34 for Modified DSR protocols. M-DSR, DSDV perform well when Mobility is low.
PERFORMANCE COMPARISON AND ANALYSIS OF PROACTIVE, REACTIVE AND HYBRID ROUTING...ijwmn
Wireless Sensor networks are a challenging task due to the lack of resources in the network as well as the frequent changes in network topology. Various routing protocols are designed basically to establish correct and efficient paths between source and destination. In the recent years, several routing protocols
have been proposed in literature and many of them studied through extensive simulation at different network characteristics. In this paper, we compare the performance of three most common routing protocols of wireless sensor networks i.e. AODV, DSDV and ZRP. These protocols have been simulated
using NS2 Package. This study investigates the routing protocols corresponding to packet delivery ratio, packet loss ratio, average throughput, dropped packets and end-to-end delay. Hence, evaluation and comparison between routing protocols is required because performance of any routing protocol can be changed with various parameters such as speed of nodes, pause times and number of nodes.
Improving Performance of TCP in Wireless Environment using TCP-PIDES Editor
Improving the performance of the transmission
control protocol (TCP) in wireless environment has been an
active research area. Main reason behind performance
degradation of TCP is not having ability to detect actual reason
of packet losses in wireless environment. In this paper, we are
providing a simulation results for TCP-P (TCP-Performance).
TCP-P is intelligent protocol in wireless environment which
is able to distinguish actual reasons for packet losses and
applies an appropriate solution to packet loss.
TCP-P deals with main three issues, Congestion in
network, Disconnection in network and random packet losses.
TCP-P consists of Congestion avoidance algorithm and
Disconnection detection algorithm with some changes in TCP
header part. If congestion is occurring in network then
congestion avoidance algorithm is applied. In congestion
avoidance algorithm, TCP-P calculates number of sending
packets and receiving acknowledgements and accordingly set
a sending buffer value, so that it can prevent system from
happening congestion. In disconnection detection algorithm,
TCP-P senses medium continuously to detect a happening
disconnection in network. TCP-P modifies header of TCP
packet so that loss packet can itself notify sender that it is
lost.This paper describes the design of TCP-P, and presents
results from experiments using the NS-2 network simulator.
Results from simulations show that TCP-P is 4% more
efficient than TCP-Tahoe, 5% more efficient than TCP-Vegas,
7% more efficient than TCP-Sack and equally efficient in
performance as of TCP-Reno and TCP-New Reno. But we can
say TCP-P is more efficient than TCP-Reno and TCP-New
Reno since it is able to solve more issues of TCP in wireless
environment.
Mobile Ad hoc Networks (MANETs) are characterized by open structure, lack of standard infrastructure
and un-accessibility to the trusted servers. The performance of various MANET routing protocols is
significantly affected due to frequently changing network topology, confined network resources and
security of data packets. In this paper, a simulation based performance comparison of one of the most
commonly used on-demand application oriented routing protocols, AODV (Ad hoc on-demand Distance
Vector) and its optimized versions R-AODV (Reverse AODV) and PHR-AODV (Path hopping based
Reverse AODV) has been presented. Basically the paper evaluates these protocols based on a wide set of
performance metrics by varying both the number of nodes and the nodes maximum speed. A NS-2 based
simulation study shows that, as compared to AODV and PHR-AODV, R-AODV enhances the packet
delivery fraction by 15-20% and reduces the latency approximately by 50%. R-AODV requires lesser node
energy for data transmission.
Heterogeneous LTE Networks and Inter-Cell Interference Coordination - Dec 201...Eiko Seidel
Initial deployments of LTE networks are based on so-called homogeneous networks consisting of base stations providing basic coverage, called macro base stations. The concept of heterogeneous networks has recently attracted considerable attention to optimize performance particularly for unequal user or traffic distribution. Here, the layer of planned high-power macro eNBs is overlaid with layers of lower-power pico or femto eNBs that are deployed in a less well planed or even entirely uncoordinated manner. Such deployments can achieve significantly improved overall capacity and cell-edge performance and are often seen as the second phase in LTE network deployment.
This paper discusses the concept of heterogeneous networks as compared to homogeneous networks. It demonstrates the need for inter-cell interference coordination (ICIC) and outlines some ICIC methods that are feasible with release 8 /9 of the LTE standard. System-level simulation results illustrate the benefits of the various features discussed in the following.
Implementing True Zero Cycle Branching in Scalar and Superscalar Pipelined Pr...IDES Editor
In this paper, we have proposed a novel architectural
technique which can be used to boost performance of modern
day processors. It is especially useful in certain code constructs
like small loops and try-catch blocks. The technique is aimed
at improving performance by reducing the number of
instructions that need to enter the pipeline itself. We also
demonstrate its working in a scalar pipelined soft-core
processor developed by us. Lastly, we present how a superscalar
microprocessor can take advantage of this technique and
increase its performance.
Rm literature survey_on_scheduling_and_resource_allocation_for_ieee_80211ax_p...RESHAN FARAZ
IEEE 8021.11 is the standard defined for WLAN(Wireless Local Area Network). It first
came into the picture in 1997 which offer a speed of 2Mbit/s. After that we have different
versions, 802.11b having speed 11Mbit/s, 802.11a/g having 54 Mbit/s, 802.11n having 600
Mbit/s, and even above Gbit/s rates in the latest 802.11ac. These speeds can be achieved
by means of different modulation and coding scheme, wider channel and adaptation of
Multiple Input Multiple Output (MIMO) technologies[7]. The 802.11ax will provide outstanding average throughput in the dense environment. Many clients connect with the
Access Point (AP) simultaneously using the Orthogonal frequency-division multiple access
(OFDMA) where AP divides the entire frequency band into multiple subsets of orthogonal
sub carrier called as Resource Unit (RU),These RUs are assigned to different user to transit
in parallel which make 802.11ax different from all other versions of 802.11 so we need some
scheduling and resource allocation mechanism to utilize the features of 802.11ax. Before
going to scheduling and resource allocation, let us discuss some features of 802.11ax
NETWORK PERFORMANCE EVALUATION WITH REAL TIME APPLICATION ENSURING QUALITY OF...ijngnjournal
The quality of service is a need in recent computer network developments. The present paper evaluates some characteristics in a proposed network topology such as dropped packets and bandwidth use, using two traffic sources, firstly a VoIP source over an UDP agent, then a CBR traffic source over an UDP agent as well as the previous one. Two possible configurations are proposed, implementing both of them in the Network Simulator, and implementing in one of them differentiated services to compare the results. Statistics results are shown, in both cases showing the accumulative dropped packet number and the throughput in the link, obtaining a reducer number of dropped packets in the stage with differentiated services, and an improvement in the bandwidth use.
THE FUTURE DIRECTIONS IN EVOLVING WI-FI: TECHNOLOGIES, APPLICATIONS AND SERVICESijngnjournal
New research directions will lead to fundamental changes in the design of future WiFi networks. However, with an explosion of wireless mobile applications and services, there are still some challenges on the spectrum crisis and high energy consumption. Wireless system designers have been facing the continuously increasing demand for high data rates and spectrum sharing required by new wireless applications and therefore have started research on future WiFi wireless technologies that are expected to be deployed beyond 2020. In this article we propose WiFi key technologies and there prospective: WiFi CERTIFIEDTM ac and Wi Fi CERTIFIED passpointTM . Also represent super WiFi such as WiGig solution, White Fi, HetNets and Cognitive Fi. Future applications and services facing these potential technologies are also
discussed.
Transferring quantum information through theijngnjournal
Transmission of information in the form of qubits much faster than the speed of light is the important
aspects of quantum information theory. Quantum information processing exploits the quantum nature of
information that needs to be stored, encoded, transmit, receive and decode the information in the form of
qubits. Bosonic channels appear to be very attractive for the physical implementation of quantum
communication. This paper does the study of quantum channels and how best it can be implemented with
the existing infrastructure that is the classical communication. Multiple access to the quantum network is
the requirement where multiple users want to transmit their quantum information simultaneously without
interfering with each others.
BOTTLENECK DETECTION ALGORITHM TO ENHANCE LIFETIME OF WSNijngnjournal
In recent years, a wireless sensor network is gaining much more importance due to its immense
contribution in numerous applications. Deployment of sensor nodes that would reduce computation,
minimize cost and gaining high degree of network connectivity is an challenging task. Random deployment
of sensor nodes causes the wireless sensor networks to face topological weaknesses such as communication
bottlenecks, network partitions and sensing holes. These problems lead to uneven energy utilization,
reduction in reliability of network and reduction in network lifetime. Bottleneck detection algorithm is
proposed to identify bottleneck and minimal bottleneck zones in network. Additional sensor node
deployment strategy is used in bottleneck detection algorithm to extend network lifetime. Random
additional sensor node deployment and Targeted additional sensor node deployment are proposed to
enhance network lifetime. Deployment strategies are compared with respect to network parameters such as
throughput, packet delivery fraction and network lifetime.
Survey of uncertainty handling in cloud service discovery and compositionijngnjournal
With the spread of services related to cloud environment, it is tiresome and time consuming for users to look for the appropriate service that meet with their needs. Therefore, finding a valid and reliable service is essential. However, in case a single cloud service cannot fulfil every user requirements, a composition of cloud services is needed. In addition, the need to treat uncertainty in cloud service discovery and composition induces a lot of concerns in order to minimize the risk. Risk includes some sort of either loss or damage which is possible to be received by a target (i.e., the environment, cloud providers or customers). In this paper, we will focus on the uncertainty application for cloud service discovery and composition. A set of existing approaches in literature are reviewed and categorized according to the risk modeling
Network parameters impact on dynamic transmission power control in vehicular ...ijngnjournal
the throughput of the wireless vehicular network and decrease the delay of the message communication
between vehicular nodes on the highway. Whenever an event occurs on the highway, the reliability
of the communication in the vehicular network becomes so vital so that event created messages should
reach to all the moving network nodes. It becomes necessary that there should be no interference from
outside of the network and all the neighbor nodes should lie in the transmission range of the
reference vehicular node. Transmission range is directly proportional to the transmission power the
moving node. If the transmission power will be high, the interference increases that can cause higher
delay in message reception at receiver end, hence the performance of the network decreased. In this
paper, it is analyzed that how transmission power can be controlled by considering other different
parameter of the network such as; density, distance between moving nodes, different types of messages
dissemination with their priority, selection of an antenna also affects on the transmission power. The
dynamic control of transmission power in VANET serves also for the optimization of the resources
where it needs, can be decreased and increased depending on the circumstances of the network.
Different applications and events of different types also cause changes in transmission power to enhance
the reachability. The analysis in this paper is comprised of density, distance with single hop and multi
hop message broadcasting based dynamic transmission power control as well as antenna selection and
applications based. Some summarized tables are produced according to the respective parameters of
the vehicular network. At the end some valuable observations are made and discussed in detail. This
paper concludes with a grand summary of all the protocols discussed in it.
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.
Two-level scheduling scheme for integrated 4G-WLAN network IJECEIAES
In this paper, a novel scheduling scheme for the Fourth Generation (4G)-Wireless Local Area Network (WLAN) network is proposed to ensure that end to end traffic transaction is provisioned seamlessly. The scheduling scheme is divided into two stages; in stage one, traffic is separated into Actual Time Traffic (ATT) and Non-Actual-Time Traffic (NATT), while in stage two, complex queuing strategy is performed. In stage one, Class-Based Queuing (CBQ) and Deficit Round Robin(DRR) are used for NATT and ATT applications, respectively to separate and forward traffic themselves according to source requirements. Whereas in the stage, two Control Priority Queuing (CPQ) is used to assign each class the appropriate priority level. Evaluation of the performance of the integrated network was done according to several metrics such as end-to-end delay, jitter, packet loss, and network’s throughput. Results demonstrate major improvements for AT services with minor degradation on NAT applications after implementing the new scheduling scheme.
Multi-layer heterogeneous network layout including small cell base stations are considered to be the key to further enhancements of the spectral efficiency achieved in mobile communication networks. It has been recognized that inter-cell interference has become the limiting factor when trying to achieve not only high average user satisfaction, but a high degree of satisfaction for as many users as possible. Therefore, inter-cell interference coordination (ICIC) lies in the focus of researchers defining next generation mobile communication standards, such as LTE-A.
Building upon [1], this paper provides an overview over the background calling for ICIC in heterogeneous LTE-A networks. It outlines techniques standardized in Rel. 10 of LTE-A, discusses them showing their benefits and limitations by means of system-level simulations and motivates the importance of self optimizing network (SON) procedures for ICIC in LTE-A.
PERFORMANCE ANALYSIS AND COMPARISON OF IMPROVED DSR WITH DSR, AODV AND DSDV R...ijp2p
Mobile Ad-hoc networks are categorized by multi-hop wireless connectivity and numbers of nodes are connecting each other through wireless network. It includes several routing protocols specifically designed for ad-hoc routing. The most widely used ad hoc routing protocols are Ad-hoc On Demand Distance Vector (AODV), Destination Sequence Distance Vector (DSDV), and Dynamic Source Routing (DSR). In this paper, we present an analysis of DSR protocol and propose our algorithm to improve the performance of DSR protocol by using small delay applied on last route ACK path when an original route fails in Mobile Ad Hoc networks. Past researchers the MANET have focused on simulation study by varying network parameters, such as network size, number of nodes. The simulation results shows that the M-DSR protocol
having some excellent performance Metrics then other protocols. We have taken different performance parameters over the comparison of Modified -DSR with other three protocols in mobility as well as Nonmobility scenario up to 300 nodes in MANETs using NS2 simulator. To achieve this goal DSR is modified by using modified algorithm technique in order to load balancing, to avoid congestion and lower packet
delivery.
Our area of interest for the paper is the improvement of performance of DSR routing protocol by
changing in algorithm and this Improved DSR protocol should compare with remaining protocols
taken in this research paper.
2. In this paper we made changesin traditional DSR protocol and generation of new improved DSR the
different performance parameters and compare with AODV/DSR/DSDV protocols in mobility and
non- mobility scenarios nodes up to 300.
3. We can plot the graphs throughput, End to end Delay, Packet delivery Ratio, Dropping Ratio, and
average energy consumption on Mobility and Non-Mobility scenario by using Network Simulator
version 2.34 for Modified DSR protocols. M-DSR, DSDV perform well when Mobility is low.
PERFORMANCE COMPARISON AND ANALYSIS OF PROACTIVE, REACTIVE AND HYBRID ROUTING...ijwmn
Wireless Sensor networks are a challenging task due to the lack of resources in the network as well as the frequent changes in network topology. Various routing protocols are designed basically to establish correct and efficient paths between source and destination. In the recent years, several routing protocols
have been proposed in literature and many of them studied through extensive simulation at different network characteristics. In this paper, we compare the performance of three most common routing protocols of wireless sensor networks i.e. AODV, DSDV and ZRP. These protocols have been simulated
using NS2 Package. This study investigates the routing protocols corresponding to packet delivery ratio, packet loss ratio, average throughput, dropped packets and end-to-end delay. Hence, evaluation and comparison between routing protocols is required because performance of any routing protocol can be changed with various parameters such as speed of nodes, pause times and number of nodes.
Improving Performance of TCP in Wireless Environment using TCP-PIDES Editor
Improving the performance of the transmission
control protocol (TCP) in wireless environment has been an
active research area. Main reason behind performance
degradation of TCP is not having ability to detect actual reason
of packet losses in wireless environment. In this paper, we are
providing a simulation results for TCP-P (TCP-Performance).
TCP-P is intelligent protocol in wireless environment which
is able to distinguish actual reasons for packet losses and
applies an appropriate solution to packet loss.
TCP-P deals with main three issues, Congestion in
network, Disconnection in network and random packet losses.
TCP-P consists of Congestion avoidance algorithm and
Disconnection detection algorithm with some changes in TCP
header part. If congestion is occurring in network then
congestion avoidance algorithm is applied. In congestion
avoidance algorithm, TCP-P calculates number of sending
packets and receiving acknowledgements and accordingly set
a sending buffer value, so that it can prevent system from
happening congestion. In disconnection detection algorithm,
TCP-P senses medium continuously to detect a happening
disconnection in network. TCP-P modifies header of TCP
packet so that loss packet can itself notify sender that it is
lost.This paper describes the design of TCP-P, and presents
results from experiments using the NS-2 network simulator.
Results from simulations show that TCP-P is 4% more
efficient than TCP-Tahoe, 5% more efficient than TCP-Vegas,
7% more efficient than TCP-Sack and equally efficient in
performance as of TCP-Reno and TCP-New Reno. But we can
say TCP-P is more efficient than TCP-Reno and TCP-New
Reno since it is able to solve more issues of TCP in wireless
environment.
Mobile Ad hoc Networks (MANETs) are characterized by open structure, lack of standard infrastructure
and un-accessibility to the trusted servers. The performance of various MANET routing protocols is
significantly affected due to frequently changing network topology, confined network resources and
security of data packets. In this paper, a simulation based performance comparison of one of the most
commonly used on-demand application oriented routing protocols, AODV (Ad hoc on-demand Distance
Vector) and its optimized versions R-AODV (Reverse AODV) and PHR-AODV (Path hopping based
Reverse AODV) has been presented. Basically the paper evaluates these protocols based on a wide set of
performance metrics by varying both the number of nodes and the nodes maximum speed. A NS-2 based
simulation study shows that, as compared to AODV and PHR-AODV, R-AODV enhances the packet
delivery fraction by 15-20% and reduces the latency approximately by 50%. R-AODV requires lesser node
energy for data transmission.
Heterogeneous LTE Networks and Inter-Cell Interference Coordination - Dec 201...Eiko Seidel
Initial deployments of LTE networks are based on so-called homogeneous networks consisting of base stations providing basic coverage, called macro base stations. The concept of heterogeneous networks has recently attracted considerable attention to optimize performance particularly for unequal user or traffic distribution. Here, the layer of planned high-power macro eNBs is overlaid with layers of lower-power pico or femto eNBs that are deployed in a less well planed or even entirely uncoordinated manner. Such deployments can achieve significantly improved overall capacity and cell-edge performance and are often seen as the second phase in LTE network deployment.
This paper discusses the concept of heterogeneous networks as compared to homogeneous networks. It demonstrates the need for inter-cell interference coordination (ICIC) and outlines some ICIC methods that are feasible with release 8 /9 of the LTE standard. System-level simulation results illustrate the benefits of the various features discussed in the following.
Implementing True Zero Cycle Branching in Scalar and Superscalar Pipelined Pr...IDES Editor
In this paper, we have proposed a novel architectural
technique which can be used to boost performance of modern
day processors. It is especially useful in certain code constructs
like small loops and try-catch blocks. The technique is aimed
at improving performance by reducing the number of
instructions that need to enter the pipeline itself. We also
demonstrate its working in a scalar pipelined soft-core
processor developed by us. Lastly, we present how a superscalar
microprocessor can take advantage of this technique and
increase its performance.
Rm literature survey_on_scheduling_and_resource_allocation_for_ieee_80211ax_p...RESHAN FARAZ
IEEE 8021.11 is the standard defined for WLAN(Wireless Local Area Network). It first
came into the picture in 1997 which offer a speed of 2Mbit/s. After that we have different
versions, 802.11b having speed 11Mbit/s, 802.11a/g having 54 Mbit/s, 802.11n having 600
Mbit/s, and even above Gbit/s rates in the latest 802.11ac. These speeds can be achieved
by means of different modulation and coding scheme, wider channel and adaptation of
Multiple Input Multiple Output (MIMO) technologies[7]. The 802.11ax will provide outstanding average throughput in the dense environment. Many clients connect with the
Access Point (AP) simultaneously using the Orthogonal frequency-division multiple access
(OFDMA) where AP divides the entire frequency band into multiple subsets of orthogonal
sub carrier called as Resource Unit (RU),These RUs are assigned to different user to transit
in parallel which make 802.11ax different from all other versions of 802.11 so we need some
scheduling and resource allocation mechanism to utilize the features of 802.11ax. Before
going to scheduling and resource allocation, let us discuss some features of 802.11ax
NETWORK PERFORMANCE EVALUATION WITH REAL TIME APPLICATION ENSURING QUALITY OF...ijngnjournal
The quality of service is a need in recent computer network developments. The present paper evaluates some characteristics in a proposed network topology such as dropped packets and bandwidth use, using two traffic sources, firstly a VoIP source over an UDP agent, then a CBR traffic source over an UDP agent as well as the previous one. Two possible configurations are proposed, implementing both of them in the Network Simulator, and implementing in one of them differentiated services to compare the results. Statistics results are shown, in both cases showing the accumulative dropped packet number and the throughput in the link, obtaining a reducer number of dropped packets in the stage with differentiated services, and an improvement in the bandwidth use.
THE FUTURE DIRECTIONS IN EVOLVING WI-FI: TECHNOLOGIES, APPLICATIONS AND SERVICESijngnjournal
New research directions will lead to fundamental changes in the design of future WiFi networks. However, with an explosion of wireless mobile applications and services, there are still some challenges on the spectrum crisis and high energy consumption. Wireless system designers have been facing the continuously increasing demand for high data rates and spectrum sharing required by new wireless applications and therefore have started research on future WiFi wireless technologies that are expected to be deployed beyond 2020. In this article we propose WiFi key technologies and there prospective: WiFi CERTIFIEDTM ac and Wi Fi CERTIFIED passpointTM . Also represent super WiFi such as WiGig solution, White Fi, HetNets and Cognitive Fi. Future applications and services facing these potential technologies are also
discussed.
Transferring quantum information through theijngnjournal
Transmission of information in the form of qubits much faster than the speed of light is the important
aspects of quantum information theory. Quantum information processing exploits the quantum nature of
information that needs to be stored, encoded, transmit, receive and decode the information in the form of
qubits. Bosonic channels appear to be very attractive for the physical implementation of quantum
communication. This paper does the study of quantum channels and how best it can be implemented with
the existing infrastructure that is the classical communication. Multiple access to the quantum network is
the requirement where multiple users want to transmit their quantum information simultaneously without
interfering with each others.
BOTTLENECK DETECTION ALGORITHM TO ENHANCE LIFETIME OF WSNijngnjournal
In recent years, a wireless sensor network is gaining much more importance due to its immense
contribution in numerous applications. Deployment of sensor nodes that would reduce computation,
minimize cost and gaining high degree of network connectivity is an challenging task. Random deployment
of sensor nodes causes the wireless sensor networks to face topological weaknesses such as communication
bottlenecks, network partitions and sensing holes. These problems lead to uneven energy utilization,
reduction in reliability of network and reduction in network lifetime. Bottleneck detection algorithm is
proposed to identify bottleneck and minimal bottleneck zones in network. Additional sensor node
deployment strategy is used in bottleneck detection algorithm to extend network lifetime. Random
additional sensor node deployment and Targeted additional sensor node deployment are proposed to
enhance network lifetime. Deployment strategies are compared with respect to network parameters such as
throughput, packet delivery fraction and network lifetime.
Survey of uncertainty handling in cloud service discovery and compositionijngnjournal
With the spread of services related to cloud environment, it is tiresome and time consuming for users to look for the appropriate service that meet with their needs. Therefore, finding a valid and reliable service is essential. However, in case a single cloud service cannot fulfil every user requirements, a composition of cloud services is needed. In addition, the need to treat uncertainty in cloud service discovery and composition induces a lot of concerns in order to minimize the risk. Risk includes some sort of either loss or damage which is possible to be received by a target (i.e., the environment, cloud providers or customers). In this paper, we will focus on the uncertainty application for cloud service discovery and composition. A set of existing approaches in literature are reviewed and categorized according to the risk modeling
Network parameters impact on dynamic transmission power control in vehicular ...ijngnjournal
the throughput of the wireless vehicular network and decrease the delay of the message communication
between vehicular nodes on the highway. Whenever an event occurs on the highway, the reliability
of the communication in the vehicular network becomes so vital so that event created messages should
reach to all the moving network nodes. It becomes necessary that there should be no interference from
outside of the network and all the neighbor nodes should lie in the transmission range of the
reference vehicular node. Transmission range is directly proportional to the transmission power the
moving node. If the transmission power will be high, the interference increases that can cause higher
delay in message reception at receiver end, hence the performance of the network decreased. In this
paper, it is analyzed that how transmission power can be controlled by considering other different
parameter of the network such as; density, distance between moving nodes, different types of messages
dissemination with their priority, selection of an antenna also affects on the transmission power. The
dynamic control of transmission power in VANET serves also for the optimization of the resources
where it needs, can be decreased and increased depending on the circumstances of the network.
Different applications and events of different types also cause changes in transmission power to enhance
the reachability. The analysis in this paper is comprised of density, distance with single hop and multi
hop message broadcasting based dynamic transmission power control as well as antenna selection and
applications based. Some summarized tables are produced according to the respective parameters of
the vehicular network. At the end some valuable observations are made and discussed in detail. This
paper concludes with a grand summary of all the protocols discussed in it.
Online social networks (OSNs) contain data about users, their relations, interests and daily activities and
the great value of this data results in ever growing popularity of OSNs. There are two types of OSNs data,
semantic and topological. Both can be used to support decision making processes in many applications
such as in information diffusion, viral marketing and epidemiology. Online Social network analysis (OSNA)
research is used to maximize the benefits gained from OSNs’ data. This paper provides a comprehensive
study of OSNs and OSNA to provide analysts with the knowledge needed to analyse OSNs. OSNs’
internetworking was found to increase the wealth of the analysed data by depending on more than one OSN
as the source of the analysed data.
Paper proposes a generic model of OSNs’ internetworking system that an analyst can rely on. Two
different data sources in OSNs were identified in our efforts to provide a thorough study of OSNs, which
are the OSN User data and the OSN platform data. Additionally, we propose a classification of the OSN
User data according to its analysis models for different data types to shed some light into the current used
OSNA methodologies. We also highlight the different metrics and parameters that analysts can use to
evaluate semantic or topologic OSN user data. Further, we present a classification of the other data types
and OSN platform data that can be used to compare the capabilities of different OSNs whether separate or
in a OSNs’ internetworking system. To increase analysts’ awareness about the available tools they can use,
we overview some of the currently publically available OSNs’ datasets and simulation tools and identify
whether they are capable of being used in semantic, topological OSNA, or both. The overview identifies
that only few datasets includes both data types (semantic and topological) and there are few analysis tools
that can perform analysis on both data types. Finally paper present a scenario that shows that an
integration of semantic and topologic data (hybrid data) in the OSNA is beneficial.
Validation study of path loss models onijngnjournal
The radio wave propagation in form of path loss model plays very significant role in planning of any
wireless communication network. Measurement of signal strength of OFDM driven WiMAX technology at
2.6 GHz band is taken in Suburban Town of India. The results are analyzed and compared with Empirical
path loss models such as Hata-Okumura, Modified Hata and COST-231Hata. COST-231 model shows
highest path loss for suburban environment. These analyzed results establish that COST-231 model is
suitable for suburban environment also. Threshold RSSI estimates cell coverage probability in the area.
This paper is about the implementation of performance monitoring and resource availability solution in transport stratum of Next Generation Network (NGN) over Enhanced Telecom Operations Map (eTOM) framework. Continuous monitoring of performance is done to ensure consistent Quality of Service (QoS) to the users. Monitoring of network parameters such as delay, delay variation, path unavailability, packet loss ratio is done in the transport stratum of next generation network architecture. Resource and Admission
Control Functions (RACF) will interact with Management functions for performance measurement of NGN transport control traffic and transport services and allocate resources to the customers whose QoS requirements are satisfied. The above functionalities are mapped into NGN business elements, defined by eTOM framework.
Cache performance analysis of virtualized router on virtual content centric n...ijngnjournal
Content-centric networking (CCN) is one of the major proposals for realizing information-centric networking. CCN routers cache forwarded data in a buffer memory called the ContentStore (CS). Virtual content-centric networking (VCCN), which enables the construction of multiple virtual networks (called VCCN slices) on a content-centric network, has been recently proposed. When multiple VCCN slices are constructed, the performance of each VCCN slice and that of the entire network are strongly affected by the CCN routers' CS allocation to VCCN router instances in VCCN slices. In this paper, we analyze the effects of CS allocation methods and content request patterns in VCCN slices on the performance of each VCCN slice and that of the entire network. Through several numerical examples, we show that when content request patterns are heterogeneous, a hybrid resource allocation method is effective in terms of both network fairness for VCCN slices and overall network performance.
Global mobility and handover management for heterogeneous network in vanetijngnjournal
Now a day’s Vehicular Ad Hoc Network (VANET) is an emerging technology. Mobility management is one
of the most challenging research issues for VANETs to support variety of intelligent transportation system
(ITS) applications. VANETs are getting importance for inter-vehicle communication, because they allow
the communication among vehicles without any infrastructure, configuration effort, and without the high
costs of cellular networks. Besides local data exchange, vehicular applications may be used to accessing
Internet services. The access is provided by Internet gateways located on the site of roadside. However, the
Internet integration requires a respective mobility support of the vehicular ad hoc network. In this paper
we will study about the network mobility approach in vehicular ad hoc network; the model will describe the
movement of vehicles from one network to other network. The proposed handover scheme reduces the
handover latency, packet loss signaling overhead.
AN ARCHITECTURAL FRAMEWORK FOR DELIVERING SIP-AS MULTIMEDIA SERVICES BASED ON...ijngnjournal
This paper proposes a new scalable service-oriented architecture based on Open Service Gateway Initiative (OSGI) technology. A key part of this architecture is its SIP application as a service (SIP-AS). It relies on IMS core network supported by multi agents components implemented using Java Agent DEvelopment (JADE) platform. As a proof of concept, a real testbed/prototype has been developed to validate our approach. The validation process consisted of two phases: (i) configuration of the JADE/OSGi SIP-AS architecture to provide a televoting service and (ii) characterization and analysis of jitter, packet loss, load capacity and CPU utilization of the implemented architecture. Results demonstrate that this televoting service scales up and out enabling the elasticity of the architecture on the processing of concurrent calls and dynamic load balancing.
On the equality of the grundy numbers of a graphijngnjournal
Our work becomes integrated into the general problem of the stability of the network ad hoc. Some, works attacked(affected) this problem. Among these works, we find the modelling of the network ad hoc in the form of a graph. Thus the problem of stability of the network ad hoc which corresponds to a problem of allocation of frequency amounts to a problem of allocation of colors in the vertex of graph. we present use a parameter of coloring " the number of Grundy”. The Grundy number of a graph G, denoted by Γ(G), is the largest k such that G has a greedy k-coloring, that is a coloring with colours obtained by applying the greedy algorithm according to some ordering of the vertices of G. In this paper, we study the Grundy number of the lexicographic, Cartesian and direct products of two graphs in terms of the Grundy numbers of these graphs.
MECC scheduling algorithm in vehicular environment for uplink transmission in...IJECEIAES
Single Carrier Frequency Division Multiple Access (SC-FDMA) is chosen because of the lower peak-to-average power ratio (PAPR) value in uplink transmission. However, the contiguity constraint is one of the major constraint presents in uplink packet scheduling, where all RBs allocated to a single UE must be contiguous in the frequency-domain within each time slot to maintain its single carrier. This paper proposed an uplink-scheduling algorithm namely the Maximum Expansion with Contiguity Constraints (MECC) algorithm, which supports both the RT and NRT services. The MECC algorithm is deployed in two stages. In the first stage, the RBs are allocated fairly among the UEs. The second stage allocates the RBs with the highest metric value and expands the allocation on both sides of the matrix, M with respect to the contiguity constraint. The performance of the MECC algorithm was observed in terms of throughput, fairness, delay, and Packet Loss Ratio (PLR) for VoIP, video and best effort flows. The MECC scheduling algorithm is compared to other algorithms namely the Round Robin (RR), Channel-Dependent First Maximum Expansion (CD-FME), and Proportional Fairness First Maximum Expansion (PF-FME). From here, it can be concluded that the MECC algorithm shows the best results among other algorithms by delivering the highest throughput which is up to 81.29% and 90.04% than CD-FME and RR scheduler for RT and NRT traffic respectively, having low PLR and delay which is up to 93.92% and 56.22% of improvement than CD-FME for the RT traffic flow. The MECC also has a satisfactory level of fairness for the cell-edge users in a vehicular environment of LTE network.
3GPP has introduced LTE Femtocells to manipulate the traffic for indoor users and to minimize
the charge on the Macro cells. A key mechanism in the LTE traffic handling is the packet
scheduler which is in charge of allocating resources to active flows in both the frequency and
time dimension. So several scheduling algorithms need to be analyzed for femtocells networks.
In this paper we introduce a performance analysis of three distinct scheduling algorithms of
mixed type of traffic flows in LTE femtocells networks. The particularly study is evaluated in
terms of throughput, packet loss ratio, fairness index and spectral efficiency.
PERFORMANCE ANALYSIS OF RESOURCE SCHEDULING IN LTE FEMTOCELLS NETWORKScscpconf
3GPP has introduced LTE Femtocells to manipulate the traffic for indoor users and to minimize the charge on the Macro cells. A key mechanism in the LTE traffic handling is the packet
scheduler which is in charge of allocating resources to active flows in both the frequency and time dimension. So several scheduling algorithms need to be analyzed for femtocells networks. In this paper we introduce a performance analysis of three distinct scheduling algorithms of mixed type of traffic flows in LTE femtocells networks. The particularly study is evaluated in terms of throughput, packet loss ratio, fairness index and spectral efficiency.
LTE Cellular Networks Packet Scheduling Algorithms in Downlink and Uplink Tra...ijwmn
This survey paper provides a detailed explanation of Long Term Evolution (LTE) cellular network’s packet scheduling algorithms in both downlink and uplink directions. It starts by explaining the difference between Orthogonal Frequency Division Multiple Access (OFDMA) that is used in downlink transmission, and Single Carrier – Frequency Division Multiple Access (SC-FDMA) is used in uplink. Then, it explains the difference between the LTE scheduling process in the donwlink and uplink through explaining the interaction between users and the scheduler. Then, it explains the most commonly used downlink and uplink scheduling algorithms through analyzing their formulas, characteristics, most suitable conditions for them to work in, and the main differences among them. This explanation covers the Max Carrier-toInterference (C/I), Round Robin (RR), Proportional Fair (PF), Earliest Deadline First (EDF), Modified EDF-PF, Modified-Largest Weighted Delay First (M-LWDF), Exponential Proportional Fairness (EXPPF), Token Queues Mechanism, Packet Loss Ratio (PLR), Quality Guaranteed (QG), Opportunistic Packet Loss Fair (OPLF), Low Complexity (LC), LC-Delay, PF-Delay, Maximum Throughput (MT), First Maximum Expansion (FME), and Adaptive Resource Allocation Based Packet Scheduling (ARABPS). Lastly, it provides some concluding remarks.
Duplexing mode, ARB and modulation approaches parameters affection on LTE upl...IJECEIAES
The next generation of radio technologies designed to increase the capacity and speed of mobile networks. LTE is the first technology designed explicitly for the Next Generation Network NGN and is set to become the de-facto NGN mobile access network standard. It takes advantage of the NGN's capabilities to provide an always-on mobile data experience comparable to wired networks. In this paper LTE uplink waveforms displayed with various duplexing mode, Allocated Resources Blocks ARB, Modulation types and total information per frame, QPSK and 16 QAM used as modulation techniques and tested under AWGN and Rayleigh channels, similarity and interference of the generated waveforms tested using auto-correlation and cross-correlation respectively.
QOS-B ASED P ERFORMANCE E VALUATION OF C HANNEL -A WARE /QOS-A WARE S CHEDULI...csandit
Long Term Evolution (LTE) is defined by the Third G
eneration Partnership Project (3GPP)
standards as Release 8/9. The LTE supports at max 2
0 MHz channel bandwidth for a carrier.
The number of LTE users and their applications are
increasing, which increases the demand on
the system BW. A new feature of the LTE-Advanced (L
TE-A) which is defined in the 3GPP
standards as Release 10/11 is called Carrier Aggreg
ation (CA), this feature allows the network
to aggregate more carriers in-order to provide a hi
gher bandwidth. Carrier Aggregation has
three main cases: Intra-band contiguous, Intra-band
non-contiguous, Inter-band contiguous.
The main contribution of this paper was in implemen
ting the Intra-band contiguous case by
modifying the LTE-Sim-5, then evaluating the Qualit
y of Service (QoS) performance of the
Modified Largest Weighted Delay First (MLWDF), the
Exponential Rule (Exp-Rule), and the
Logarithmic Rule (Log-Rule) scheduling algorithms
Exponential MLWDF (EXP-MLWDF) Downlink Scheduling Algorithm Evaluated in LTE ...IJECEIAES
Nowadays, with the advent of smartphones, most of people started to make voice and video conference calls continuously even in a high mobility scenario, the bandwidth requirements have increased considerably, which can cause network congestion phenomena. To avoid network congestion problems and to support high mobility scenario, 3GPP has developed a new cellular standard based packet switching, termed LTE (Long Term Evolution). The purpose of this paper is to evaluate the performance of the new proposed algorithm, named Exponential Modified Largest Weighted Delay First „EXP-MLWDF‟, for high mobility scenario and with the presence of a large number of active users, in comparison with the wellknown algorithms such as a proportional fair algorithm (PF), Exponential Proportional Fairness (EXP/PF), Logarithm Rule (LOG-Rule), Exponential Rule (EXP-Rule) and Modified Largest Weighted Delay First (MLWDF). The performance evaluation is conducted in terms of system throughput, delay and PLR. Finally, it will be concluded that the proposed scheduler satisfies the quality of service (QoS) requirements of the real-time traffic in terms of packet loss ratio (PLR), average throughput and packet delay. Because of the traffic evolution, some key issues related to scheduling strategies that will be considered in the future requirements are discussed in this article.
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.
An Approach to Improve the Quality of Service in OFDMA Relay Networks via Re-...iosrjce
With the next-generation cellular networks making a transition toward smaller cells, two-hop
orthogonal frequency-division multiple access (OFDMA) relay networks have become a dominant, mandatory
component in the 4G standards (WiMAX802.16j, 3GPP LTE-Adv.). Here we are using the multicasting strategy
Given the growing importance of multimedia broadcast and multicast services (MBMS) in 4G networks, the
latter forms the focus of this project. The main aim of this project is to improve the performance of the OFDMA
based relay networks. The OFDMA transmission Scheme is a widely accepted scheme for improving the quality
and speed of communication over the 4G cellular network. There are two different models designed for OFDMA
relay networks .Distributed (DP) and Contiguous (CP) permutations. We are checking the performance of two
algorithms The linear programming algorithm and the greedy algorithm by using two models of OFDMA for
multicast scheduling and after performance evaluation we select the best model and the algorithm for
transmission. We further improve the throughput via retransmission of lost packets during data transfer over the
specified network. We can detect the packet loss by packet synchronization technique and a request will be sent
by the destination for re-sending the lost packets which is called as Re-Transmission.[1]
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.
Trend-Based Networking Driven by Big Data Telemetry for Sdn and Traditional N...ijngnjournal
Organizations face a challenge of accurately analyzing network data and providing automated action based on the observed trend. This trend-based analytics is beneficial to minimize the downtime and improve the performance of the network services, but organizations use different network management tools to understand and visualize the network traffic with limited abilities to dynamically optimize the network. This research focuses on the development of an intelligent system that leverages big data
telemetry analysis in Platform for Network Data Analytics (PNDA) to enable comprehensive trendbased networking decisions. The results include a graphical user interface (GUI) done via a web application for effortless management of all subsystems, and the system and application developed in
this research demonstrate the true potential for a scalable system capable of effectively benchmarking the network to set the expected behavior for comparison and trend analysis. Moreover, this research provides a proof of concept of how trend analysis results are actioned in both a traditional network and a software-defined network (SDN) to achieve dynamic, automated load balancing.
TREND-BASED NETWORKING DRIVEN BY BIG DATA TELEMETRY FOR SDN AND TRADITIONAL N...ijngnjournal
Organizations face a challenge of accurately analyzing network data and providing automated action
based on the observed trend. This trend-based analytics is beneficial to minimize the downtime and
improve the performance of the network services, but organizations use different network management
tools to understand and visualize the network traffic with limited abilities to dynamically optimize the
network. This research focuses on the development of an intelligent system that leverages big data
telemetry analysis in Platform for Network Data Analytics (PNDA) to enable comprehensive trendbased networking decisions. The results include a graphical user interface (GUI) done via a web
application for effortless management of all subsystems, and the system and application developed in
this research demonstrate the true potential for a scalable system capable of effectively benchmarking
the network to set the expected behavior for comparison and trend analysis. Moreover, this research
provides a proof of concept of how trend analysis results are actioned in both a traditional network and
a software-defined network (SDN) to achieve dynamic, automated load balancing.
PERFORMANCE PREDICTION OF 5G: THE NEXT GENERATION OF MOBILE COMMUNICATIONijngnjournal
The 5G standard is a mobile communication of the 5th generation, which presupposes an increase of the information exchange speed up to 10 Gbit/s. It is 30 times quicker than the speed of 4G network. It is a new stage in the development of technologies connecting society. This standard will provide an unlimited access to the network for individual users and devices. When developing the 5G standard, the advanced opportunities of LTE and HSPA, as well as other technologies of a radio access focused on the solution of specific objectives are considered. The main advantage of the mass introduction of the 5G communication development represents the so-called Internet of Things (IoT). There the devices and not people will be the main consumers of traffic. The functional requirements of5G networks, their speed, and its traffic parameters for HD video services and massifs of M2M-devices are analyzed in the paper. They will have been the most demandedones by 2020.
PERFORMANCE EVALUATION OF VERTICAL HARD HANDOVERS IN CELLULAR MOBILE SYSTEMSijngnjournal
With the rapid increase of new and diverse cellular mobile services, the overlapping of cells has become typical in the majority of the coverage area of the network. Vertical handovers occur between two layers of cells when a user is switched from one layer to the other. In this paper we investigate the influence of network parameters on vertical hard handover performance in a cell environment. The work considers two layers of cells: a layer of macrocells and a layer of microcells. Handover requests enter the macrocell from neighbor macrocells and from microcells that belong to a different layer. Using Markov chain analysis and simulation we calculate network performance parameters such as mean queue delay, handover dropping probability and channel utilization. We also compare the handover performance for the macrocell and macrocell traffic separately. Our results show the influence of total channels, maximum queue size and handover request arrival rate on handover performance. They also show that when the traffic from each layer is treated with equal priority in the system, the performance of each layer is comparable.
PERFORMANCE EVALUATION OF VERTICAL HARD HANDOVERS IN CELLULAR MOBILE SYSTEMSijngnjournal
With the rapid increase of new and diverse cellular mobile services, the overlapping of cells has become typical in the majority of the coverage area of the network. Vertical handovers occur between two layers of cells when a user is switched from one layer to the other. In this paper we investigate the influence of network parameters on vertical hard handover performance in a cell environment. The work considers two layers of cells: a layer of macrocells and a layer of microcells. Handover requests enter the macrocell from neighbor macrocells and from microcells that belong to a different layer. Using Markov chain analysis and simulation we calculate network performance parameters such as mean queue delay, handover dropping probability and channel utilization. We also compare the handover performance for the macrocell and macrocell traffic separately. Our results show the influence of total channels, maximum queue size and handover request arrival rate on handover performance. They also show that when the traffic from each layer is treated with equal priority in the system, the performance of each layer is comparable.
COMPARISON OF RADIO PROPAGATION MODELS FOR LONG TERM EVOLUTION (LTE) NETWORKijngnjournal
This paper concerns about the radio propagation models used for the upcoming 4th Generation (4G) of cellular networks known as Long Term Evolution (LTE). The radio wave propagation model or path loss model plays a very significant role in planning of any wireless communication systems. In this paper, a comparison is made between different proposed radio propagation models that would be used for LTE, like Stanford University Interim (SUI) model, Okumura model, Hata COST 231 model, COST Walfisch-Ikegami & Ericsson 9999 model. The comparison is made using different terrains e.g. urban, suburban and rural area.SUI model shows the lowest path lost in all the terrains while COST 231 Hata model illustrates highest path loss in urban area and COST Walfisch-Ikegami model has highest path loss for suburban and rural environments.
IMPLEMENTATION AND COMPARISION OF DATA LINK QUALITY SCHEME ON ODMRP AND ADMR ...ijngnjournal
An ad hoc network is a collection of wireless mobile nodes dynamically forming a temporary network without the use of any fixed network infrastructure or centralized administration. In order to enable communication within the network, a routing protocol is needed to discover routes between nodes. The primary goal of ad hoc network routing protocols is to establish routes between node pairs so that messages may be delivered reliably and in a timely manner. The objective of any routing protocol is to have packet delivered with least possible cost in terms of receiving power, transmission power, battery energy consumption and distance. All these factors basically effect the establishment of link between the mobile nodes and liability and stability of these links. In this paper, we implement a data link quality scheme on two protocols ODMRP and ADMR and compare them on the bases link quality and link stability.
The Performance of a Cylindrical Microstrip Printed Antenna for TM10 Mode as...ijngnjournal
A temperature is one of the parameters that have a great effect on the performance of microstrip antennas for TM10 mode at 2.4 GHz frequency range. The effect of temperature on a resonance frequency, input impedance, voltage standing wave ratio, and return loss on the performance of a cylindrical microstrip printed antenna is studied in this paper. The effect of temperature on electric and magnetic fields are also studied. Three different substrate materials RT/duroid-5880 PTFE, K-6098 Teflon/Glass, and Epsilam-10 ceramic-filled Teflon are used for verifying the new model.
Optimization of Quality of Service Parameters for Dynamic Channel Allocation ...ijngnjournal
As the spectrum for wireless transmission gets crowded due to the increase in the users and applications, the efficient use of the spectrum is a major challenge in today’s world. A major affecting factor is the inefficient usage of the frequency bands. Interference in the neighboring cells affects the reuse of the frequency bands. In this paper, some of the quality of service parameters such as residual bandwidth, number of users, duration of calls, frequency of calls and priority are considered. This paper presents work based on the optimization of dynamic channel allocation using genetic algorithm (GA). This attempts to allocate the channel to users such that overall congestion in the network is minimized by reusing already allocated frequencies. The working of Genetic Algorithm which is used in the optimization procedure is also explained. The optimized channel is then compared with a non-optimized channel to check the efficiency of the genetic algorithm.
PURGING OF UNTRUSTWORTHY RECOMMENDATIONS FROM A GRIDijngnjournal
In grid computing, trust has massive significance. There is lot of research to propose various models in providing trusted resource sharing mechanisms. The trust is a belief or perception that various researchers have tried to correlate with some computational model. Trust on any entity can be direct or indirect. Direct trust is the impact of either first impression over the entity or acquired during some direct interaction. Indirect trust is the trust may be due to either reputation gained or recommendations received from various recommenders of a particular domain in a grid or any other domain outside that grid or outside that grid itself. Unfortunately, malicious indirect trust leads to the misuse of valuable resources of the grid. This paper proposes the mechanism of identifying and purging the untrustworthy recommendations in the grid environment. Through the obtained results, we show the way of purging of untrustworthy entities.
A SURVEY ON DYNAMIC SPECTRUM ACCESS TECHNIQUES FOR COGNITIVE RADIOijngnjournal
Cognitive radio (CR) is a new paradigm that utilizes the available spectrum band. The key characteristic of CR system is to sense the electromagnetic environment to adapt their operation and dynamically vary its radio operating parameters. The technique of dynamically accessing the unused spectrum band is known as Dynamic Spectrum Access (DSA). The dynamic spectrum access technology helps to minimize unused spectrum bands. In this paper, main functions of Cognitive Radio (CR) i.e. spectrum sensing, spectrum management, spectrum mobility and spectrum sharing are discussed. Then DSA models are discussed along with different methods of DSA such as Command and Control, Exclusive-Use, Shared Use of Primary Licensed User and Commons method. Game-theoretic approach using Bertrand game model, Markovian Queuing Model for spectrum allocation in centralized architecture and Fuzzy logic based method are also discussed and result are shown.
HYBRID LS-LMMSE CHANNEL ESTIMATION Technique for LTE Downlink Systemsijngnjournal
In this paper, we propose to improve the performance of the channel estimation for LTE Downlink systems under the effect of the channel length. As LTE Downlink system is a MIMO-OFDMA based system, a cyclic prefix (CP) is inserted at the beginning of each transmitted OFDM symbol in order to mitigate both intercarrier interference (ICI) and inter-symbol interference (ISI). The inserted CP is usually equal to or longer than the channel length. However, the cyclic prefix can be shorter because of some unforeseen channel behaviour. Previous works have shown that in the case where the cyclic prefix is equal to or longer than the channel length, LMMSE performs better than LSE but at the cost of computational complexity .In the other case, LMMSE performs also better than LS only for low SNR values. However, LS shows better performance for LTE Downlink systems for high SNR values. Therefore, we propose a hybrid LS-LMMSE channel estimation technique robust to the channel length effect. MATLAB Monte –Carlo simulations areused to evaluate the performance of the proposed estimator in terms of Mean Square Error (MSE) and Bit Error Rate (BER) for 2x2 LTE Downlink systems.
SERVICES AS PARAMETER TO PROVIDE BEST QOS : AN ANALYSIS OVER WIMAXijngnjournal
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more suitable for Next Generation Networks (NGN). Ethernet packet processor design can be configured for use with multiple projects targeted to a FPGA device the system is designed to support 1/10/20/40/100 Gigabit links with a speed and performance advantage. VHDL has been used to implement and simulated the required functions in FPGA
ESTIMATION AND COMPENSATION OF INTER CARRIER INTERFERENCE IN WIMAX PHYSICAL L...ijngnjournal
WiMAX is Wireless Interoperability for Microwave Access has emerged as a promising solution for transmission of higher data rates for fixed and mobile applications. IEEE 802.16d and e are the standards proposed by WiMAX group for fixed and mobile. As the wireless channel have so many limitation Such as Multipath, Doppler spread, Delay spread and Line Of Sight (LOS)/Non Line Of Sight (NLOS) components. To attain higher data rates the Multi Carrier System with Multiple Input and Multiple Output (MIMO) is incorporated in the WiMAX. The Orthogonal Frequency Division Multiplexing (OFDM) is a multi carrier technique used with the WiMAX systems. In OFDM the available spectrum is split into numerous narrow band channels of dissimilar frequencies to achieve high data rate in a multi path fading environment. And all these sub carriers are considered to be orthogonal to each other. As the number of sub carriers is increased there is no guarantee of sustained orthogonality, i.e. at some point the carriers are not
independent to each other, and hence where the orthogonality can be loosed which leads to interference and also owing to the synchronization between transmitter and receiver local oscillator, it causes interference known as Inter Carrier Interference (ICI). The systems uses MIMO-OFDM will suffer with the effects of ICI and Carrier Frequency Offset (CFO) “ε”. However these affect the power leakage in the midst of sub carriers, consequently degrading the system performance. In this paper a new approach is proposed in order to reduce the ICI caused in WiMAX and improve the system performance. In this scheme at the transmitter side the modulated data and a few predefined pilot symbols are mapped onto the non
neighboring sub carriers with weighting coefficients of +1 and -1. With the aid of pilot symbols the frequency offset is exactly estimated by using Maximum Likelihood Estimation (MLE) and hence can be minimized. At demodulation stage the received signals are linearly combined along with their weighted
coefficients and pilot symbols, called as Pilot Aided Self Cancellation Method (PASCS). And also to realize the various wireless environments the simulations are carried out on Stanford University Interim (SUI) channels. The simulation results shows that by incorporating this method into WiMAX systems it performs better when the Line Of Sight (LOS) component is present in the transmission and also it improves the Bit Error Rate (BER) and Carrier to Interference Ratio (CIR). The CIR can be improved 20 dB. In this paper the effectiveness of PASCS scheme is compared with the Self Cancellation Method (SCM). It provides accurate estimation of frequency offset and when residual CFO is less significant the ICI can be diminished successfully.
OPTIMUM EFFICIENT MOBILITY MANAGEMENT SCHEME FOR IPv6 ijngnjournal
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better than that of MIPv6 and HMIPv6.
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Also we illustrated what are control channels DCCH and the other one as understanding the whole system. Moreover, the standards have been covered as well as implemented the whole transmit and receive chain plus the generation of DPCH, DPCCH channel. we had tested the performance against the AWGN noise.
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4. Demo
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Survey on scheduling and radio resources allocation in lte
1. International Journal of Next-Generation Networks (IJNGN) Vol.6, No.1, March 2014
DOI : 10.5121/ijngn.2014.6102 17
Survey On Scheduling And Radio Resources
Allocation In Lte
Fayssal Bendaoud#1
, Marwen Abdennebi*2
, Fedoua Didi#3
#
Laboratory of Telecommunication Tlemcen (LTT)
*Laboratory of Processing and Transmission of Information (L2TI)
ABSTRACT
This paper focuses on an essential task of the enhanced NodeB eNodeB element in LTE architecture, the
Radio Resource Manager RRM, which aims to accept or reject requests for connection to the network
based on some constraints and ensuring optimal distribution of radio resources between Users Equipments
UEs. Its main functionalities include Admission Control AC and Packet Scheduling PS.
This paper will center mainly on the PS part of the RRM task, which performs the radio resource
allocation in both uplink and downlink directions. Several approaches and algorithms have been proposed
in the literature to address this need (allocate resources efficiently), the diversity and multitude of
algorithms is related to the factors considered for the optimal management of radio resource, specifically,
the traffic type and the QoS (Quality of Service) requested by the UE.
In this article, an art’s state of the radio resource allocation strategies and a detailed study of several
scheduling algorithms proposed for LTE (uplink and downlink) are made. Therefore, we offer our
evaluation and criticism.
KEYWORDS
Enhanced NodeB eNodeB, LTE, Radio Resource manager RRM, Admission Control AC, Packet Scheduler
PS.
1. INTRODUCTION
Long Term Evolution (LTE) or 3.9G systems is an important technology originally designed to
achieve a significant data rates (50Mbit/s in the uplink and 100Mbit/s in the downlink in a system
bandwidth 20 MHz), while allowing the minimizing of the latency and providing a flexible
deployment of the bandwidth. LTE offers several main benefits for the subscribers as well as to
the service providers. It significantly satisfies the user’s requirement by targeting the broadband
mobile applications with enhanced mobility. It is designated as the successor networks 3G. It
allows an efficient execution of internet services emerging in recent years. It uses the packet
switching process as well as 3G networks, the difference is the using of Time Division
multiplexing (TD) and Frequency Division multiplexing (FD) at the same time which is not the
case of High Speed Packet Access HSPA networks, which performs only the time division
multiplexing, this allows us to have a throughput gain (in spectral efficiency) concerning 40 %.
[1]
2. International Journal of Next-Generation Networks (IJNGN) Vol.6, No.1, March 2014
18
Orthogonal Frequency Division Multiple Access OFDMA is the multiple access method used in
the downlink direction. It combines Time Division Multiple Access TDMA and Frequency
Division Multiple Access FDMA. It is derived from OFDM multiplexing, but it allows the
multiple access of the radio resources shared among multiple users. The OFDMA technology
divides the available bandwidth into many narrow-band subcarriers and allocates a group of
subcarriers to a user based on: its requirements, current system load and system configuration,
this process helps to fight the Inter Symbol Interference ISI problem or the channel frequency-
selective, as well as, it allows for the same bandwidth a higher spectral efficiency (number of bits
transmitted per Hertz) and it has the ability to maintain high throughput even in unfavorable
environments with echoes and multipath radio waves.
For the uplink direction, Single Carrier-Frequency Division Multiple Access SC- FDMA method
is used, it is a variant of OFDMA, they have the same performance (throughput, efficiency ...
etc.), but SC- FDMA transmits sub bands sequentially to minimize the Peak -to- Average Power
Ratio PAPR (OFDMA has a huge PAPR), this is the reason of choosing SC-FDMA in the uplink
side, to deal with the limited power budget (the use of battery by the UE) to minimizing the
PAPR.
An important element of the LTE architecture is the eNodeB, which has an interesting task, the
RRM consisting mainly of two sub-tasks: the AC and the PS.
The AC sub-task is responsible for accepting and rejecting new requests, in fact, the decision to
accept or reject a request depends on the network capacity to deliver the QoS required by the
request (application) while ensuring the QoS asked by the already admitted users in the system.
The PS meanwhile, performs the radio resource allocation to the users already accepted by the
AC, i.e., performing the UE-RB mapping by selecting UEs who will use the channel affecting
their radios resources RBs that permit them to maximize system performance.
Several parameters can be used to evaluate the system performance such as, spectral efficiency,
delay, fairness and system throughput. The variety of parameters results on the creation of
multiple scheduling algorithm and strategies.
All these parameters can be summarized in one term, the consideration of flow’s QoS. Trying to
satisfy all these parameters is impossible, simply because the scheduling and resource allocation
is an NP-hard problem, because of this; different scheduling strategies have been developed. An
important parameter in the design of schedulers is the support for QoS. This forced the LTE
network to differentiate between the data streams and therefore can be distinguished:
Conversational class: this is the most sensitive to delay; it includes video conferencing and
telephony. It does not tolerate delays because it assumes that in the two ends of the connection is
a human.
Streaming class: similar to the previous class, but it assumes that only one person is at the end of
the connection, therefore, it is less demanding in terms of time and delays. Eg: video streaming
Interactive class: examples of this class are: web browsing, access to databases ... etc.
Unlike the previously mentioned types, data needs to be delivered in a time interval, but this type
of traffic emphasizes the rate of loss of data (Packet Error Rate).
Background class: Also known as Best Effort class, no QoS is applied; it tolerates delays, packet
loss. Examples of this class: FTP, E-mails etc. [2]
Two other parameters influence the design of scheduling algorithms in LTE uplink. The later are
imposed by the SC-FDMA access method, which are: the minimization of the transmit power (up
3. International Journal of Next-Generation Networks (IJNGN) Vol.6, No.1, March 2014
19
to maximize the lifetime of UEs batteries), as well, the RBs allocated to a single UE must be
contiguous. This makes the radio resource allocation for LTE uplink more difficult than for the
downlink.
The rest of the paper is as follows, in section 2 will be presented the mathematical modeling of
the radio resource allocation problem; in section 3, a state of art of the radio resource allocation
strategies and a detailed study of several scheduling algorithms proposed for LTE (uplink and
downlink) is made, we will present the scheduling algorithms existing in the literature and
evaluate the performance of these algorithms with some criticism in section 4, then a conclusion
and perspectives will be presented in section 5.
2. SYSTEM MODEL
In this section we start by giving the LTE architecture, and then, we will present the mathematical
formulation of the radio resource allocation problem.
2.1.LTE architecture
The general architecture of LTE mainly contains the Evolved Packet System EPS which includes:
the Evolved Packet Core EPC and the radio part of the core network.
EPC consists of a set of control elements: Mobility Management Entity MME, Home Subscriber
Server HSS, Serving Gateway and Packet-data S-GW and P-GW. The EPC is responsible for
connecting with other 3GPP and non-3GPP networks. The radio part of the network is composed
of eNodeB and UE. Figure 1.
Figure 1- LTE architecture
2.2.The mathematical formulation of the problem
Due to the limited signaling resources, sub-carriers are often allocated in groups; that’s mean,
sub-carriers are grouped into Resource Blocks RBs of 12 adjacent sub-carriers with an inter-sub-
carrier spacing of 15 kHz. One RB corresponds to 0.5 ms (one time slot) in the time domain, and
represents 6 or 7 OFDM symbols [1]. The smallest resource unit that can be allocated to a user is
a Scheduling Block (SB), which consists of two consecutive RBs, and it’s the minimal quantity of
radio resource that can be allocated to an UE, constituting a sub-frame time duration of 1 ms.
figure 2.
4. International Journal of Next-Generation Networks (IJNGN) Vol.6, No.1, March 2014
20
Figure 2- LTE frame structure
We consider an LTE system with N SB and K UEs, the minimum data rate required by the k-th
user is R Mbit/s. [1]
We define one SB as a set N OFDM symbols in time domain and N sub-carriers in frequency
domain. Due to control signals and other pilots, only N (s)of the N will be used to transmit
data of the s-th OFDM symbol, with s ∈ {1,2, … , N } and N (s) ≤ N . Assuming that
j ∈ {1,2, … , J}, J is total number of the supported MCS (Modulation and Coding Scheme), R
( )
the
associated code of MCS j, M s the constellation of the j-th MCS and T is the OFDM symbol
duration, then the achieved data rate r( )
by a single SB is:
r( )
=
R
( )
log (M )
T N
N (s) (1)
We define as CQI (Channel Quality Indicator, CQI is definite according to the modulation
scheme and channel coding) of user k on the n-th SB, the CQI of user k on the N SB (all SB) is
g = [g , , g , , … , g , ] and for all users on all SBs G = [g , g , … , g ].
Each user k sends it’s g , to the eNodeB to determine whose MSC must be selected by the n-th
SB.
Furthermore, let q , ( , ∗) ∈ {1,2, … , J} be the index of the highest-rate MCS that can be
supported by user k for the n-th SB at CQI value g , ∗, i.e.
q , , ∗ = arg max R
( )
log M g , ∗ (2)
The achievable throughput by user k on one sub-frame is:
r = ρ , b r( )
, , ∗
(3)
5. International Journal of Next-Generation Networks (IJNGN) Vol.6, No.1, March 2014
21
Where:
ρ , =1 if the n-th SB is allocated to k-th user, and ρ ′, = 0 for all k′
≠ k (one SB is assigned to
one and a single user).
b Is the MCS selected by the user k on all SBs allocated to it, b =1 means that the j-th MSC is
chosen by the user k.
Therefore, the radio resource allocation problem can be reported to the throughput maximization
for all users under the following constraints:
max r
ρ , , ,
(4)
Constraint to:
r ≥ R ∀k (5)
ρ , = 1, ρ ′, = 0 ∀ k ≠ k′ (6)
b ,
, , ∗
= 1 (7)
(4), represents the objective function that is designed to maximize the data rate. (5), means the
constraint that aims to guarantee the minimal data rate for each user. (6), is constraint assuring
that one SB is assigned to one and a single user. (7), all SBs owed to a user employ the same
MSC (it is an LTE networks constraint).
In literature, it is proven that the problem (4) is an NP-hard one, after that several authors have
proposed their algorithms aimed solving it.
3. SCHEDULING IN LTE
One of the main features in LTE systems is the multi-user scheduling because it is in charge of
satisfying the QoS of all active users.
In this section, we present an art’s state on existing scheduling algorithms for both directions
downlink and uplink. These algorithms are based on the mathematical formulations mentioned
above, try performing the efficiency radio resource allocation to the system’s users.
3.1.Downlink scheduling algorithms
The central objective of LTE scheduling is to satisfy Quality of Service QoS requirements of all
users by trying to reach an optimal trade-off between efficiency and fairness. This goal is very
challenging, especially in the presence of real-time multimedia applications, which are
characterized by strict constraints on packet delay and jitter.
The radio resource allocation algorithms, aims to improve system performance by increasing the
network spectral efficiency and fairness. It is therefore essential to find a compromise between
efficiency (rate increasing) and fairness among users. Several families and categories of algorithm
exist in literature; each family usually contains a set of algorithms that have a common
characteristics.
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3.1.1. Opportunistic algorithms
Opportunistic scheduling considers user where queues are continuously backlogged (this full
buffer setting is typically used to model elastic or best effort flows). The main objective of this
type of algorithm is to maximize the overall system throughput. Several algorithms use this
approach such as: PF (Proportional Fair), EXP-PF (Proportional Fair Exponential) and the M-
LWDF (Maximum Largest Weighted Delay First) scheduler is an opportunistic scheduler and
also a delay based one, so we will describe it later in the delay based algorithms section.
• Proportional Fair PF
It is known that the spirit of the 4G networks is the utilization of multimedia flows, which have an
important dependence with delay because they are performed in real time. Unfortunately, the PF
algorithm does not consider the packet delay and the Head of Line HoL during the resource
allocation process. [10]
On the other hand, the PF algorithm is a very appropriate scheduling option for non real-time
traffic; the purpose is to maximize the overall throughput of system by increasing the spectral
efficiency of all users together while trying to ensure fairness between users, the objective
function representing the PF algorithm is:
a =
d (t)
d
(8)
( ) : Data rate corresponding to CQI of user i.
: The maximum data rate supported by the RB.
• EXP-PF
This is an improvement of the PF algorithm that supports real-time streams (multimedia); in fact,
it prioritizes the real time flows with respect to the other ones [14][15]. The user k is designated
for scheduling according to the following relationship:
= max
( )
exp
( )
√
(10)
X =
1
N
a W (t) (11)
( ) : The HOL packet delay.
: Strictly positive parameter.
For the non elastic flows (best effort flows), the HOL packets delay is similar for all users (do not
differ a lot), the exponential term is closed to 1, and the EXP-PF perform as the PF algorithm.
3.1.2. Fair algorithms
We must know that equity or fairness does not mean equality. The main objective of this category
is to reach fairness and equity between users. Generally, these algorithms have an insufficiency in
term of spectral efficiency. Several works have treated the fairness between users like, Round
Robin, Max-Min and game theory based algorithms.
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23
• Round Robin RR
The famous RR algorithm is largely used in the radio resource allocation because of its simplicity
and low-complexity; it is dedicated to treat the fairness problem between users. So the algorithm
allocates the same amount of resource sharing the time. This strategy lack in spectral efficiency
and throughput performance, because the algorithm does not consider the reported SINR values
when performing the allocation process.
• Max-Min Fair
The algorithm allocates resources among users successively in order to increase the data rate of
each user. Once the user assigns resources required to achieve its required data rate, the algorithm
select another user for scheduling. The algorithm stops when satisfying all user or all resources
were allocated.
3.1.3. Throughput Based Algorithms
This type of algorithm tries to maximize the objective function that represents the data rate, this
approach treats the real time flows and non real-time, the resource allocation depends on the size
of the queue of each user. EXP Rule, Max -Weight are examples of this category.
• EXP Rule
Its main objective is to serves high data rate requirements; [16] it is represented by the following
relationship:
= max exp
( )
1 + √
( )
(12)
=
6
(13)
: is the maximum target delay of the i-th flow.
• Max-Weight
This algorithm use the packet delay criterion in the scheduling decision, its mathematical
formulation is:
a = ( )
( )
(14)
Where, all parameters are explained above.
3.1.4. QoS Based Algorithms
This type of algorithm focuses -on the spectral efficiency of real time or non-elastic flows (video
and VoIP), indeed, it tries to maximize the objective function that represents the data rate, this
approach treats the real time flows and for the non real-time flows, it considers that they do not
deserve any priority. The radio resource allocation process depends on the size of the queue of
each user.
3.1.5. Delay Based Algorithms
HOL and delay of packet flows are the fundamental parameters of this kind of schedulers. This
type treats the non elastic flows, when a packet exceeds its HOL, it will be removed from the
queue. M-LWDF is a delay based algorithm and in the same time an opportunistic one.
8. International Journal of Next-Generation Networks (IJNGN) Vol.6, No.1, March 2014
24
• M-LWDF
M-LWDF supports multiple data flows with different QoS requirements. This algorithm is
dedicated for real time services. Its decisions are based on the HOL and packets delay values.
Unfortunately, it is not a suitable choice when performing non real time flows because packets
delay does not have a significant role [12]. The scheduling formulation is:
= max
( )
( ) (15)
[
This is substantially the same formula of the EXP-PF algorithm, except that = − log( ) ,
with
: The probability that the delay is not respected.
: Delay tolerated by user i.
3.1.6. Multiclass Algorithm
This approach considers flows classes when the treatment is different for each class RT and NRT.
This type algorithm favors real time flows compared to not real time ones, which makes it the
most suitable and more effective scheduling in LTE networks, but equity is not really considered.
3.2.Uplink Radio Resource Allocation
Unlike downlink scheduling, uplink scheduling side is much more complicated for several
reasons, first, the UE sends the data to the eNodeB and we know very well that the UE has a
limited energy source; secondly, it is very difficult to predict the number of radio resources that
the UE needs to exchange data with the base station. Depending on the objective function
considered and the traffic classes that pass over the radio channels, we have three different
categories of schedulers: those dealing with best-effort flows (best effort schedulers), whose take
into account the QoS and those optimizing the power transmission. In this section we will try to
turn on the main families of algorithms for resource allocation in LTE uplink.
3.2.1. Paradigms of matrix construction
For the LTE uplink radio resource allocation, the scheduler has in input a UE-RB association
matrix in order to give the best results that improve the system performances.
In the matrix creation process, literately speaking, there exist two major patterns or paradigms
Channel Dependent CD and Proportional Fair PF.
In the matrix creating process, the CD paradigm considers the channel state information (CSI), so,
users whom have larger CSI values will have the opportunity to allocate more resources, this
approach reaches high throughput values but suffers from starvation problem. Meanwhile, the PF
paradigm use the ratio of CSI and data rate of each user, so fairness is proportional on CSI values.
This approach achieved good throughputs and at the same time, it solves the starvation problem.
[4]
3.2.2. LTE Uplink system modeling
The uplink scheduling algorithms take in input a matrix with K rows (number of active UEs) and
M columns (number of RBs). M , is a matrix value associated to the couple ( − ).
Following the paradigm used, this value correspond to the CSI for each RB on each UE (channel
dependent), or the ratio between CSI and he data date of each user. [4][13]
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RB RB … RB
UE
UE
.
.
.
UE
Figure-3 UE-RB matrix association
As we said, the value in the matrix represents the association between UEs and RBs, thereafter,
these values will be used by the scheduler.
3.2.3. Uplink scheduling algorithms
In this sub-section, we will give an art’s state of the well known scheduling algorithms families
for the LTE uplink side.
• Legacy schedulers
This family contains the famous classical algorithm, the Round Robin algorithm; it is also called
the base scheduler’s family, the RR algorithm has been used in many old systems.
The Round Robin algorithm principle is to divide the available RBs into groups of RBs according
to
| |
| |
. Then, distribute the formed groups among available UEs.
• Best effort schedulers
The main objective of this category is to maximize the utilization of the radio resource and the
equity in the system. It doesn’t mean that this category treat only best effort flows, best effort
schedulers means it is a greedy algorithm that try to do the better that it can.
As we have already said, each algorithm has an objective function to optimize, this type of
algorithm uses the PF metric.
Several algorithms have been proposed in this family, we noted that the greedy algorithms are
very suitable for this kind of traffic.
The principle of greedy algorithm is that the RBs are grouped into RCs, with each RC containing
a set of contiguous RBs. After that each RC gets allocated to the UE having the highest metric in
the matrix, the RC and UE will be removed from the available RC list and UE schedulable list.
The algorithm aims to maximize the fairness in resource allocation among UEs.
This algorithm uses the PF paradigm and tries to maximize the following objective function
U = ln R(u)
∈
(16)
R(u) represents the data rate at instant t. The using of the logarithmic function is to have the
proportional fairness.
After that, authors in [5] have proposed three algorithms, First Maximum Expansion (FME),
Recursive Maximum Expansion (RME) and Minimum Area Difference. They belong to the same
M , M , … M ,
M , M , … M ,
.
.
.
.
.
.
…
.
.
.
M , M , … M ,
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26
category, so they use the same objective function, but they differ in the manner that the resources
were allocated.
For the FME, the algorithm starts with searching the UE having the highest metric value, once
found, it expands the allocation process in the left or in the right (it compares the value of RB in
the left with right value for the same UE and chooses the highest), until the algorithm finds no
more RB whose having highest metric for the same user selected above.
In the other hand, The RME scheduler starts similarly to FME (it searches for the couple (UE-
RB) having the highest metric value), then it expands the allocation process both in the left and
the right until there will be no more users whose maximum metrics belong to the same user.
The MAD algorithm is a search-tree based; its problem is having a higher computational
complexity.
It has been proven that RME has higher performance compared to FME in term of spectral
efficiency. So, after that, RME has been explored in [17][18], the authors proposed two variants
of RME, the Improved RME (IRME), and the Improved Tree-Based RME (ITRME).The results
show an improvement in spectral efficiency by 15%.
• QoS based algorithms
Two important elements must be taken into account by this scheduler’s family, the maximum
delay and the throughput. Also the algorithm must offer the required QoS parameters for each
user regarding to the already served users.
The Proportional Fair with Guaranteed Bit Rate (PFGBR) is a QoS based algorithm, From its
name, we identify two metrics, PF and GBR, the PF metric is used to schedule the UEs with non
GBR flows and for those with GBR flows , the algorithm changes the metric in order to
differentiate the EU (giving priorities for UEs handling GBR streams). This algorithm has two
objectives, maximizing the fairness of non GBR flows and preserves the QoS of GBR. The
objective function is as follows. [6]
( , ) =
⎩
⎪
⎨
⎪
⎧ exp α. R − R (u) .
R∗(u, c)
R(u)
u ∈ U
R∗(u, c)
R(u)
u ∈ U
(17)
R (u) : Average throughput of user u at TTI t
R∗(u, c) : Estimated throughput of user u at resource chunk c at TTI t. Resource Chunk RC is a
set of continues RBs.
This algorithm performs very well with the UEs having QoS requirement ant treats the starvation
problem of UEs handling best effort traffic.
The authors in [7] have proposed two algorithms, they use a combined utility based metric with
guaranteed bit rate and delay provisioning. The objective function used is defined as follows:
max α , . f
∈∈
(18)
α , :=1 if the RB r is allocated to the UE u.
f is defining as :
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f =
∗
∗
(19)
R : acheivable throughput.
R : minimal throughput of the i-th service class.
D : maximum dealy of i-th service class.
D : average dealy of i-th service class.
The first one, named Single Channel Scheduling Algorithm SC-SA assigns one RB to each UE at
a given TTI. In case that number of active users is lesser than the number of RBs, the algorithm
distributes the RBs proportionally between users according to . Otherwise i.e. if the number of
schedulable users is higher than the total number of available RBs, it assigns RBs to users
experiencing the poorest conditions (eg, users that the maximum delay is almost reached). The
main objective of this algorithm is to allocate resources to UEs with severe QoS constraints.
The second is called Multiple Channel Scheduling Algorithm (MC-SA). It is similar to the first
one; the main difference is the possibility to allocate more than one RB to the users that are not
meeting the throughput target. These algorithms have the same behavior in case the number of
UEs is smaller than the number of available RBs in the system. In the case where the number UE
is higher than that of available RBs, it allocates the taking into account the (19) equation.
It starts with bad conditions one; it first looks for all the RB that maximizes data rate and then
looks at the left and right of this RB to the allocation of remaining n RBs.
• Power-Optimizing schedulers
The main purpose of this class of algorithms is to minimize the transmitted signal power trying to
extend the duration activity of UE. In fact, it coincides with the objective of using SC-FDMA
method. Schedulers of this family usually have some QoS treatments, so they perform some
decisions to reduce the transmitted power till maintaining the minimal QoS requirements. This
approach was not really too addressed by researchers, therefore, few algorithms appear in the
literature. Such as [8][9]
4. DISCUSSION ET EVALUATION
The PF scheduler is often used in 3G networks, as the rate of this type of network is limited. For
beyond 3G networks, a key factor must be taken in the mind, the maximum delay of multimedia
flows that represents the type of the most important traffic in the B3G networks. Unfortunately
this factor is not considered by this algorithm, consequently, for the non-real time flows it works
fine but for the real time traffic it is not a smart choice.
Concerning EXP-PF, the parameters W (t) and a define the required QoS level by the flow.
These parameters try to give more importance to applications with a higher level of QoS. When
the exponential part of the formula is equal to one, the EXP-PF algorithm performs like the PF
algorithm. This scenario is possible if the flows have almost the same delay for different users.
The RR algorithms does not take into account the QoS, because the flow does not have same
needs (VoIP, Streaming etc.), also allocate the same amount of resources is not really fair,
because users have not necessarily the same channel conditions, nor same types of flows etc.
Beyond 3G networks, LTE specifically focuses on QoS of real time flows, so, using RR is really
not the good choice.
Trying to satisfy all users in the MMF algorithm, gives the advantage to users with low
requirements, so they will often served. In the other side, Users who require more resources are
12. International Journal of Next-Generation Networks (IJNGN) Vol.6, No.1, March 2014
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penalized. This approach does not take into account the multiuser diversity and the fact that
streams have different QoS requirements i.e. fairness does not represent equality. To summarize,
this algorithm is really not the right choice for scheduling in LTE.
As a conclusion, the radio resource allocation is feasible (several algorithms and approaches
exist), but the diversity of flows (QoS) and radio conditions affect the performance of the
algorithms. The resource allocation is an NP-hard problem, since the algorithm tries to maximize
and/or minimize several parameters simultaneously. For this reason, each approach or algorithm
tries to optimize the maximum parameters that could.
Concerning uplink side, it is much more complicated for the two SC-FDMA constraints added,
the RBs allocated to a single user must be continuous, and the signal power transmitted
constraint. Algorithms dealing with QoS are best suited and most respondents because they treat
the most important factor in LTE networks, which is the QoS flows. But also the best effort
schedulers have a good performance and there are most used because of their low complexity.
5. CONCLUSION
The Radio Resource Allocation is made in the eNB by the PS, this task is too complex, as it
requires taking into account several factors at the same time, plus it must be immediate (real
time). The objective of this paper is to present a state of the art on the radio resource allocation in
LTE. In this work, we tried to go about the existed approaches in the literature in both downlink
and uplink directions, we also mentioned some algorithms, we have shown the advantages and
disadvantages of each category and algorithms, thereafter it would be wiser to focus on one type
of traffic, trying to improve performance, and without doubt it will be the multimedia flows.
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