International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Performance of Wideband Mobile Channel with Perfect Synchronism BPSK vs QPSK ...Editor Jacotech
Direct-sequence code-division multiple access (DS-CDMA) is
currently the subject of much research as it is a promising
multiple access capability for third and fourth generations
mobile communication systems. The synchronous DS-CDMA
system is well known for eliminating the effects of multiple
access interference (MAI) which limits the capacity and
degrades the BER performance of the system. In this paper,
we investigate the bit error rate (BER) performance of a
synchronous DS-CDMA system over a wideband mobile
radio channel. The BER performance is affected by the
difference in path length ΔL and the number of arriving
signals N. Furthermore, the effect of these parameters is
examined on the synchronous DS-CDMA system for different
users’ number as well as different processing gain Gp. In this
environment and under the above conditions the performances
of the BPSK (Binary Phase Shift Keying) and the QPSK
(Quadrature Phase Shift Keying) modulations are compared.
The promising simulation results showed the possibility of
applying this system to the wideband mobile radio channel.
ACHIEVING ENHANCED THROUGHPUT IN MOBILE ADHOC NETWORK USING COLLISION AWARE M...ijasuc
Since wireless medium is high demand resource the design of an efficient medium access protocol is
important for Mobile Adhoc Networks. As MAC is the base layer in the protocol stack a performance gain
in this layer will have significant improvement in the overall performance of the network. Since the current
IEEE 802.11 MAC standard is not adaptive to the network scenario its performance is poor in terms of
throughput, fairness and delay. Although several alternatives to the existing standard is proposed many of
them are not satisfactorily address the key issues of keeping the simplicity of the protocol and avoiding the
overhead on the nodes on duty in emergency situations where usually adhoc networks are applied. In this
paper we propose an adaptive, collision aware MAC protocol for wireless adhoc networks, termed the
Collision Based Contention (CBC) protocol, in which depends on the current collision level on the shared
medium contending nodes dynamically decides its Backoff value to avoid a blind random waiting before
access to the medium. The CBC scheme outperforms the BEB scheme employed in the IEEE 802.11 MAC
standard and other competing proposals.
An approach to control inter cellular interference using load matrix in multi...eSAT Journals
Abstract
This paper deals with reduction of inter cellular interference in Multi-carrier communication systems. In the past, Load Matrix(LM) is proposed to allocate power to different users in a network based upon Signal to noise plus interference ratio (SNIR) so as to reduce inter cellular interference and is observed for single carrier systems. In Multi carrier systems the SNIR is affected distinctly in each carrier thus a single SNIR for power allocation is not optimal. In this paper, to obtain the optimization of power allocation in Multi-Carrier system, Load Matrix coding with bifurcated SNIR (LM-BFSNIR) is proposed. Using this approach it is observed that inter cellular interference is reduced better when compared to a single carrier system evaluated over a 3GPP-LTE standard.
Keywords−Power allocation, Inter cellular interference, Multi-Carrier mobile Communication system.
WARM WELCOME FROM HCL VELACHERY…….
HCL Learning is part of HCL Info Systems Ltd, India’s Premier information enabling company with an annual turnover of 15000 crores Leveraging on the 34 years of industry experience of HCL, with an objective to develop quality IT professionals to meet this ever expanding requirement of Hardware Networking and Software professionals for the IT sector, HCL has launched HCL Career Development Centre.
For any clarification,
contact Person
Mr.Senthilvel.S
9382207007
HCL Velachery -42
Wimax technology has reshaped the framework of broadband wireless internet
service. It provides the internet service to unconnected or detached areas such as east South
Africa, rural areas of America and Asia region. Full duplex helpers employed with one of
the relay stations selection and indexing method that is Randomized Distributed Space Time
are used to expand the coverage area of primary Wimax station. The basic problem was
identified at cell edge due to weather conditions (rain, fog), insertion of destruction because
of multiple paths in the same communication channel and due to interference created by
other users in that communication. It is impractical task for the receiver station to decode
the transmitted signal successfully at the cell edges, which increases the high packet loss and
retransmissions. But Wimax is a outstanding technology which is used for improving the
quality of internet service and also it offers various services like Voice over Internet
Protocol, Video conferencing and Multimedia broadcast etc where a little delay in packet
transmission can cause a big loss in the communication. Even setup and initialization of
another Wimax station nearer to each other is not a good alternate, where any mobile
station can easily handover to another base station if it gets a strong signal from other one.
But in rural areas, for few numbers of customers, installation of base station nearer to each
other is costlier task. In this review article, we present a scheme using R-DSTC technique to
choose and select helpers (relay nodes) randomly to expand the coverage area and help to
mobile station as a helper to provide secure communication with base station. In this work,
we use full duplex helpers for better utilization of bandwidth.
A Survey of Various Routing and Channel Assignment Strategies for MR-MC WMNsijsrd.com
One fundamental problem of WMNs with a limited number of radio interfaces and orthogonal channels is that the performance degrades significantly as the network size grows. This results from increased interference between nodes and diminished spatial reuse over the network. A WMN node needs to share a common channel with each of its neighbours in the communication range, requiring it to set up a virtual link. Moreover, to reduce network interference, a node should minimize the number of neighbours that it shares a common channel with. The objective of a channel assignment strategy is to ensure efficient utilization of the available channels (e.g., by minimizing interference) while maximizing connectivity in the network. However, since these two requirements are conflicting with each other, the goal is to achieve a balance between these two. The major constraints which need to be satisfied by a channel assignment scheme include fixed number of channels in the network, limited number of radios in mesh nodes, common channel between two communicating nodes, and limited channel capacity. Also, a channel assignment scheme should take the amount of traffic load supported by each mesh node into consideration.
The Neighborhood Broadcast Problem in Wireless Ad Hoc Sensor Networksgraphhoc
to all neighbors of a network node v under the assumption that v does not participate due to
being corrupted or damaged. We present practical network protocol that can be used completely
reactive. It is parameterized with a positive integer k ∈ N and it is proven to guarantee delivery for
k ≥ 2d−1, if node v is d-locally connected, which means that the set of nodes with distance between
1 and d to v induces a connected subgraph of the communication graph. It is also shown that the
number of participating nodes is optimal under the restriction to 1-hop neighborhood information.
The protocol is also analyzed in simulations that demonstrate very high success rates for very low
values of k.
KEYWORD
In order enhance the network efficiency of Mobile ad hoc Networks (MANETs), an Power Unbiased Cooperative Media Access Control(PUC-MAC) protocol in MANETs was planned during this paper. It adopted the most effective partnership choice statement to select the cooperative node with higher channel condition, higher passing rate and additional balanced power consumption. Simulation results showed that PUC-MAC outperforms EC-MAC,Cooperative MAC (CoopMAC) and IEEE 802.11 Distributed Coordination perform (DCF) in terms of the packet release quantitative relation, network outturn and network lifespan beneath 2 distinct channel noise levels, particularly beneath the worst channel condition.
Performance of Wideband Mobile Channel with Perfect Synchronism BPSK vs QPSK ...Editor Jacotech
Direct-sequence code-division multiple access (DS-CDMA) is
currently the subject of much research as it is a promising
multiple access capability for third and fourth generations
mobile communication systems. The synchronous DS-CDMA
system is well known for eliminating the effects of multiple
access interference (MAI) which limits the capacity and
degrades the BER performance of the system. In this paper,
we investigate the bit error rate (BER) performance of a
synchronous DS-CDMA system over a wideband mobile
radio channel. The BER performance is affected by the
difference in path length ΔL and the number of arriving
signals N. Furthermore, the effect of these parameters is
examined on the synchronous DS-CDMA system for different
users’ number as well as different processing gain Gp. In this
environment and under the above conditions the performances
of the BPSK (Binary Phase Shift Keying) and the QPSK
(Quadrature Phase Shift Keying) modulations are compared.
The promising simulation results showed the possibility of
applying this system to the wideband mobile radio channel.
ACHIEVING ENHANCED THROUGHPUT IN MOBILE ADHOC NETWORK USING COLLISION AWARE M...ijasuc
Since wireless medium is high demand resource the design of an efficient medium access protocol is
important for Mobile Adhoc Networks. As MAC is the base layer in the protocol stack a performance gain
in this layer will have significant improvement in the overall performance of the network. Since the current
IEEE 802.11 MAC standard is not adaptive to the network scenario its performance is poor in terms of
throughput, fairness and delay. Although several alternatives to the existing standard is proposed many of
them are not satisfactorily address the key issues of keeping the simplicity of the protocol and avoiding the
overhead on the nodes on duty in emergency situations where usually adhoc networks are applied. In this
paper we propose an adaptive, collision aware MAC protocol for wireless adhoc networks, termed the
Collision Based Contention (CBC) protocol, in which depends on the current collision level on the shared
medium contending nodes dynamically decides its Backoff value to avoid a blind random waiting before
access to the medium. The CBC scheme outperforms the BEB scheme employed in the IEEE 802.11 MAC
standard and other competing proposals.
An approach to control inter cellular interference using load matrix in multi...eSAT Journals
Abstract
This paper deals with reduction of inter cellular interference in Multi-carrier communication systems. In the past, Load Matrix(LM) is proposed to allocate power to different users in a network based upon Signal to noise plus interference ratio (SNIR) so as to reduce inter cellular interference and is observed for single carrier systems. In Multi carrier systems the SNIR is affected distinctly in each carrier thus a single SNIR for power allocation is not optimal. In this paper, to obtain the optimization of power allocation in Multi-Carrier system, Load Matrix coding with bifurcated SNIR (LM-BFSNIR) is proposed. Using this approach it is observed that inter cellular interference is reduced better when compared to a single carrier system evaluated over a 3GPP-LTE standard.
Keywords−Power allocation, Inter cellular interference, Multi-Carrier mobile Communication system.
WARM WELCOME FROM HCL VELACHERY…….
HCL Learning is part of HCL Info Systems Ltd, India’s Premier information enabling company with an annual turnover of 15000 crores Leveraging on the 34 years of industry experience of HCL, with an objective to develop quality IT professionals to meet this ever expanding requirement of Hardware Networking and Software professionals for the IT sector, HCL has launched HCL Career Development Centre.
For any clarification,
contact Person
Mr.Senthilvel.S
9382207007
HCL Velachery -42
Wimax technology has reshaped the framework of broadband wireless internet
service. It provides the internet service to unconnected or detached areas such as east South
Africa, rural areas of America and Asia region. Full duplex helpers employed with one of
the relay stations selection and indexing method that is Randomized Distributed Space Time
are used to expand the coverage area of primary Wimax station. The basic problem was
identified at cell edge due to weather conditions (rain, fog), insertion of destruction because
of multiple paths in the same communication channel and due to interference created by
other users in that communication. It is impractical task for the receiver station to decode
the transmitted signal successfully at the cell edges, which increases the high packet loss and
retransmissions. But Wimax is a outstanding technology which is used for improving the
quality of internet service and also it offers various services like Voice over Internet
Protocol, Video conferencing and Multimedia broadcast etc where a little delay in packet
transmission can cause a big loss in the communication. Even setup and initialization of
another Wimax station nearer to each other is not a good alternate, where any mobile
station can easily handover to another base station if it gets a strong signal from other one.
But in rural areas, for few numbers of customers, installation of base station nearer to each
other is costlier task. In this review article, we present a scheme using R-DSTC technique to
choose and select helpers (relay nodes) randomly to expand the coverage area and help to
mobile station as a helper to provide secure communication with base station. In this work,
we use full duplex helpers for better utilization of bandwidth.
A Survey of Various Routing and Channel Assignment Strategies for MR-MC WMNsijsrd.com
One fundamental problem of WMNs with a limited number of radio interfaces and orthogonal channels is that the performance degrades significantly as the network size grows. This results from increased interference between nodes and diminished spatial reuse over the network. A WMN node needs to share a common channel with each of its neighbours in the communication range, requiring it to set up a virtual link. Moreover, to reduce network interference, a node should minimize the number of neighbours that it shares a common channel with. The objective of a channel assignment strategy is to ensure efficient utilization of the available channels (e.g., by minimizing interference) while maximizing connectivity in the network. However, since these two requirements are conflicting with each other, the goal is to achieve a balance between these two. The major constraints which need to be satisfied by a channel assignment scheme include fixed number of channels in the network, limited number of radios in mesh nodes, common channel between two communicating nodes, and limited channel capacity. Also, a channel assignment scheme should take the amount of traffic load supported by each mesh node into consideration.
The Neighborhood Broadcast Problem in Wireless Ad Hoc Sensor Networksgraphhoc
to all neighbors of a network node v under the assumption that v does not participate due to
being corrupted or damaged. We present practical network protocol that can be used completely
reactive. It is parameterized with a positive integer k ∈ N and it is proven to guarantee delivery for
k ≥ 2d−1, if node v is d-locally connected, which means that the set of nodes with distance between
1 and d to v induces a connected subgraph of the communication graph. It is also shown that the
number of participating nodes is optimal under the restriction to 1-hop neighborhood information.
The protocol is also analyzed in simulations that demonstrate very high success rates for very low
values of k.
KEYWORD
In order enhance the network efficiency of Mobile ad hoc Networks (MANETs), an Power Unbiased Cooperative Media Access Control(PUC-MAC) protocol in MANETs was planned during this paper. It adopted the most effective partnership choice statement to select the cooperative node with higher channel condition, higher passing rate and additional balanced power consumption. Simulation results showed that PUC-MAC outperforms EC-MAC,Cooperative MAC (CoopMAC) and IEEE 802.11 Distributed Coordination perform (DCF) in terms of the packet release quantitative relation, network outturn and network lifespan beneath 2 distinct channel noise levels, particularly beneath the worst channel condition.
With the increase of usage of wireless networks for purposes where the nodes are either stationary or minimally mobile, focus is also on increasing the network capacity of wireless networks. One such way is to use non-overlapping multiple channels provided by 802.11 by using multiple interfaces per node. Multiple non overlapped channels exist in the 2.4 GHz and 5 GHz spectrum. Under this scenario, several challenges need to be addressed before all the available channels can be fully utilized.
Control Channel Dilemma (CCD) is still an open problem for Cognitive Radio Network (CRN). In this
article, we investigate and present a novel solution of Distributed Coordination in CRN to mitigate the
necessity for a common control channel. This scheme is based on the fact that a group of nearby nodes
almost detects the same frequency spectrum. That will allow every group of close nodes to choose a node
called coordinator, which in its turn chooses a reliable control channel for the group, then the reaming
nodes become slaves. Furthermore, the nodes that belong to two or more groups have an important role in
maintaining the network connectivity since they act as bridges to relay data between different groups. The
proposed approach carries potentials to provide robust operation under network dynamics conditions.
Finally, several simulation experiments are presented to validate the proposed approach.
Hexagonal based Clustering for Reducing Rebroadcasts in Mobile Ad Hoc NetworksIJTET Journal
Abstract— In mobile ad hoc networks multihop routing is performed in order to communicate the packets from the source to destination. The nodes within these networks are dynamic due which frequent path change occurs which can cause frequent link breakages and induces route discoveries. These route discoveries can introduce overhead in terms of contention, collision and rebroadcasts which are non-negligible. Here, the paper discusses a hexagonal based clustering for reducing rebroadcasts thus maximizing the lifetime of the networks and providing coverage area thus reducing the end – end delays.
Multi-Hop Routing Cooperative Communication for Improving Throughput in IEEE ...IJERA Editor
In this paper, we propose cooperative communication scheme using multiple relays to improve the throughput of IEEE 802.11x wireless LAN. The proposed scheme performs cooperative communication with a terminal supporting a high data rate in order to solve the problem that a total network throughput is greatly reduced when a terminal supporting a low data rate occupies a channel. Also, the multi-hop routing is performed to optimize the performance of cooperative communication. According to the simulation results, the proposed cooperative communication scheme improves the reduction rate of the throughput even if the number of terminals supporting a low data rate increases in the entire network
Quadrant Based DIR in CWin Adaptation Mechanism for Multihop Wireless NetworkIJCI JOURNAL
In Multihop Wireless Networks, traffic forwarding capability of each node varies according to its level of contention. Each node can yield its channel access opportunity to its neighbouring nodes, so that all the nodes can evenly share the channel and have similar forwarding capability. In this manner the wireless channel is utilized effectively, which is achieved using Contention Window Adaptation Mechanism (CWAM). This mechanism achieves a higher end-to-end throughout but consumes the network power to a higher level. So, a newly proposed algorithm Quadrant- Based Directional Routing Protocol (Q-DIR) is implemented as a cross-layer with CWAM, to reduce the total network power consumption through limited flooding and also reduce the routing overheads, which eventually increases overall network throughput. This algorithm limits the broadcast region to a quadrant where the source node and the destination nodes are located. Implementation of the algorithm is done in Linux based NS-2 simulator
PERFORMANCE EVALUATION OF MC-CDMA SYSTEM OVER RAYLEIGH FADING CHANNELIJCSES Journal
Multi Carrier Code Division Multiple Access (MC-CDMA) is a well known technique for high speed
wireless data transmission .Two advanced technology was included in the MC-CDMA structure, such as
orthogonal frequency division multiplex (OFDM) and the code division multiple access (CDMA),so that it
benefits from the robustness of OFDM against multipath environment and from the capability of multiuser
multiplexing services that is achieved via (CDMA) system. MC-CDMA is a multicarrier spread spectrum
system which is classified as the candidate scheme for future mobile radio systems. In this paper MCCDMA
system, with Rayleigh fading channel and 16QAM array modulation, was simulated to investigate
the effects of different parameters on the system performance, such as processing gain; number of paths;
number of users; interleaving; and coding ratio.MC-CDMA performances can be considerably improved
by proper selection of these parameters. As expected, results show that MC-CDMA has a better performance over CDMA system.
COOPERATIVE COMMUNICATIONS COMBINATION DIVERSITY TECHNIQUES AND OPTIMAL POWER...ijaceeejournal
The main task of this article is to focus on the performance of cooperative MIMO relaying in terms of data rate and Power. Furthermore, compare these performances when using Maximum Ratio Combining (MRC) and equal gain combining (EGC).The average SNR improvement of MRC is typically about 5 dB better than with EGC and direct link.The preciseness of the derived closed form expression of optimum power allocation of the DF-based relaying system is demonstrated by simulation results.
Improved Algorithm for Throughput Maximization in MC-CDMAVLSICS Design
The Multi-Carrier Code Division Multiple Access (MC-CDMA) is becoming a very significant downlink multiple access technique for high-rate data transmission in the fourth generation wireless communication systems. By means of efficient resource allocation higher data rate i.e. throughput can be achieved. This paper evaluates the performance of group (subchannel) allocation criteria employed in downlink transmission, which results in throughput maximization. Proposed algorithm gives the modified technique of sub channel allocation in the downlink transmission of MC-CDMA systems. Simulation are carried out for all the three combining schemes, results shows that for the given power and BER proposed algorithm comparatively gives far better results .
EFFICIENT UTILIZATION OF CHANNELS USING DYNAMIC GUARD CHANNEL ALLOCATION WITH...cscpconf
User mobility in wireless data networks is increasing because of technological advances and the
desire for voice and multimedia applications. These applications, however, require fast handoffs
between base stations to maintain the quality of the connections. In this paper, the authors
describe the use of novel and efficient data structure which dynamically allocates guard channel
for handoffs and introduces the concept of channel borrowing strategy. The proposed scheme
allocates the guard channels for handoff requests dynamically, based on the traffic load for
certain time period. A new originating call in the cell coverage area also uses these guard
channels if they are unused. Our basic idea is to allow Guard channels to be shared between new calls and handoff calls. This approach maximizes the channel utilization. The simulation results prove that the channel borrowing scheme improves the overall throughput.
ISSUES AND CHALLENGES IN BROADCAST STORM SUPPRESSION ALGORITHMS OF VEHICULAR ...ieijjournal
Vehicular Ad-Hoc Networks (VANETs) are the networks of vehicles which are characterized with high mobility and dynamic changing topology. Most of the communication interchanges in VANETs take place in broadcasting mode, which is supposed to be the simplest way to disseminate (spread) emergency
messages all over the vehicular network. This broadcasting technique assures the optimal delivery of emergency messages all over the VANET. However, it also results in unwanted flooding of messages which causes severe contention and collisions in VANETs leading to Broadcast Storm Problem (BSP) and in turn affects the overall performance of VANETs. A Multitude of research work have proposed Broadcast Storm
Suppression Algorithms (BSSA) to control this Broadcast Storm. These mechanisms tried to control BSP by either reducing the number of rebroadcasting/ relaying nodes or by identifying the best relay node. The suppression mechanisms help to overcome BSP to certain extent, still there is need to still reduce the number of rebroadcasting nodes in existing mechanisms and also to identify the best possible rebroadcasting node.
With the increase of usage of wireless networks for purposes where the nodes are either stationary or minimally mobile, focus is also on increasing the network capacity of wireless networks. One such way is to use non-overlapping multiple channels provided by 802.11 by using multiple interfaces per node. Multiple non overlapped channels exist in the 2.4 GHz and 5 GHz spectrum. Under this scenario, several challenges need to be addressed before all the available channels can be fully utilized.
Control Channel Dilemma (CCD) is still an open problem for Cognitive Radio Network (CRN). In this
article, we investigate and present a novel solution of Distributed Coordination in CRN to mitigate the
necessity for a common control channel. This scheme is based on the fact that a group of nearby nodes
almost detects the same frequency spectrum. That will allow every group of close nodes to choose a node
called coordinator, which in its turn chooses a reliable control channel for the group, then the reaming
nodes become slaves. Furthermore, the nodes that belong to two or more groups have an important role in
maintaining the network connectivity since they act as bridges to relay data between different groups. The
proposed approach carries potentials to provide robust operation under network dynamics conditions.
Finally, several simulation experiments are presented to validate the proposed approach.
Hexagonal based Clustering for Reducing Rebroadcasts in Mobile Ad Hoc NetworksIJTET Journal
Abstract— In mobile ad hoc networks multihop routing is performed in order to communicate the packets from the source to destination. The nodes within these networks are dynamic due which frequent path change occurs which can cause frequent link breakages and induces route discoveries. These route discoveries can introduce overhead in terms of contention, collision and rebroadcasts which are non-negligible. Here, the paper discusses a hexagonal based clustering for reducing rebroadcasts thus maximizing the lifetime of the networks and providing coverage area thus reducing the end – end delays.
Multi-Hop Routing Cooperative Communication for Improving Throughput in IEEE ...IJERA Editor
In this paper, we propose cooperative communication scheme using multiple relays to improve the throughput of IEEE 802.11x wireless LAN. The proposed scheme performs cooperative communication with a terminal supporting a high data rate in order to solve the problem that a total network throughput is greatly reduced when a terminal supporting a low data rate occupies a channel. Also, the multi-hop routing is performed to optimize the performance of cooperative communication. According to the simulation results, the proposed cooperative communication scheme improves the reduction rate of the throughput even if the number of terminals supporting a low data rate increases in the entire network
Quadrant Based DIR in CWin Adaptation Mechanism for Multihop Wireless NetworkIJCI JOURNAL
In Multihop Wireless Networks, traffic forwarding capability of each node varies according to its level of contention. Each node can yield its channel access opportunity to its neighbouring nodes, so that all the nodes can evenly share the channel and have similar forwarding capability. In this manner the wireless channel is utilized effectively, which is achieved using Contention Window Adaptation Mechanism (CWAM). This mechanism achieves a higher end-to-end throughout but consumes the network power to a higher level. So, a newly proposed algorithm Quadrant- Based Directional Routing Protocol (Q-DIR) is implemented as a cross-layer with CWAM, to reduce the total network power consumption through limited flooding and also reduce the routing overheads, which eventually increases overall network throughput. This algorithm limits the broadcast region to a quadrant where the source node and the destination nodes are located. Implementation of the algorithm is done in Linux based NS-2 simulator
PERFORMANCE EVALUATION OF MC-CDMA SYSTEM OVER RAYLEIGH FADING CHANNELIJCSES Journal
Multi Carrier Code Division Multiple Access (MC-CDMA) is a well known technique for high speed
wireless data transmission .Two advanced technology was included in the MC-CDMA structure, such as
orthogonal frequency division multiplex (OFDM) and the code division multiple access (CDMA),so that it
benefits from the robustness of OFDM against multipath environment and from the capability of multiuser
multiplexing services that is achieved via (CDMA) system. MC-CDMA is a multicarrier spread spectrum
system which is classified as the candidate scheme for future mobile radio systems. In this paper MCCDMA
system, with Rayleigh fading channel and 16QAM array modulation, was simulated to investigate
the effects of different parameters on the system performance, such as processing gain; number of paths;
number of users; interleaving; and coding ratio.MC-CDMA performances can be considerably improved
by proper selection of these parameters. As expected, results show that MC-CDMA has a better performance over CDMA system.
COOPERATIVE COMMUNICATIONS COMBINATION DIVERSITY TECHNIQUES AND OPTIMAL POWER...ijaceeejournal
The main task of this article is to focus on the performance of cooperative MIMO relaying in terms of data rate and Power. Furthermore, compare these performances when using Maximum Ratio Combining (MRC) and equal gain combining (EGC).The average SNR improvement of MRC is typically about 5 dB better than with EGC and direct link.The preciseness of the derived closed form expression of optimum power allocation of the DF-based relaying system is demonstrated by simulation results.
Improved Algorithm for Throughput Maximization in MC-CDMAVLSICS Design
The Multi-Carrier Code Division Multiple Access (MC-CDMA) is becoming a very significant downlink multiple access technique for high-rate data transmission in the fourth generation wireless communication systems. By means of efficient resource allocation higher data rate i.e. throughput can be achieved. This paper evaluates the performance of group (subchannel) allocation criteria employed in downlink transmission, which results in throughput maximization. Proposed algorithm gives the modified technique of sub channel allocation in the downlink transmission of MC-CDMA systems. Simulation are carried out for all the three combining schemes, results shows that for the given power and BER proposed algorithm comparatively gives far better results .
EFFICIENT UTILIZATION OF CHANNELS USING DYNAMIC GUARD CHANNEL ALLOCATION WITH...cscpconf
User mobility in wireless data networks is increasing because of technological advances and the
desire for voice and multimedia applications. These applications, however, require fast handoffs
between base stations to maintain the quality of the connections. In this paper, the authors
describe the use of novel and efficient data structure which dynamically allocates guard channel
for handoffs and introduces the concept of channel borrowing strategy. The proposed scheme
allocates the guard channels for handoff requests dynamically, based on the traffic load for
certain time period. A new originating call in the cell coverage area also uses these guard
channels if they are unused. Our basic idea is to allow Guard channels to be shared between new calls and handoff calls. This approach maximizes the channel utilization. The simulation results prove that the channel borrowing scheme improves the overall throughput.
ISSUES AND CHALLENGES IN BROADCAST STORM SUPPRESSION ALGORITHMS OF VEHICULAR ...ieijjournal
Vehicular Ad-Hoc Networks (VANETs) are the networks of vehicles which are characterized with high mobility and dynamic changing topology. Most of the communication interchanges in VANETs take place in broadcasting mode, which is supposed to be the simplest way to disseminate (spread) emergency
messages all over the vehicular network. This broadcasting technique assures the optimal delivery of emergency messages all over the VANET. However, it also results in unwanted flooding of messages which causes severe contention and collisions in VANETs leading to Broadcast Storm Problem (BSP) and in turn affects the overall performance of VANETs. A Multitude of research work have proposed Broadcast Storm
Suppression Algorithms (BSSA) to control this Broadcast Storm. These mechanisms tried to control BSP by either reducing the number of rebroadcasting/ relaying nodes or by identifying the best relay node. The suppression mechanisms help to overcome BSP to certain extent, still there is need to still reduce the number of rebroadcasting nodes in existing mechanisms and also to identify the best possible rebroadcasting node.
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Efficient Channel Assignment Schemes In 802.11 WLANIJSRD
A wireless local area network (LAN) is a flexible data communications system implemented as an extension to, or as an alternative for, a wired LAN. Wireless Local Area Networks (WLANs) are having tremendous growth & becoming increasingly popular. The planning of wireless local area network (WLAN) infrastructures that supply large buildings or areas requires the consideration of many aspects (coverage, different traffic densities, interference, cost minimization, network throughput) and therefore is a difficult task if done manually. The performance of WLAN can be greatly improved by efficient channel assignment. This paper presents a survey on efficient channel assignment algorithms in WLAN’s. The survey is concluded with various research issues open for further study.
GTSH: A New Channel Assignment Algorithm in Multi-Radio Multi-channel Wireles...IJERA Editor
One of the complexities in a wireless mesh networks is its low throughput. For this reason and due to the fact that throughput is highly reduced by increased number of nodes, it is difficult to extend such networks. Therefore, providing a high throughput in these networks is an essential goal. The main lowering cause of efficiency of such networks is interference between wireless links. A high interference leads to a reduced throughput. In this research, two channel assignment methods were presented using genetic and tabu search algorithms and their advantages and disadvantages were assessed. Finally, a new method combining the advantages of both methods was proposed. With the help of NS2 network simulator, our work was simulated and the combination results of the two methods were compared. The results were indicative of the better performance of the hybrid method and significant increase of throughput in the network.
we find out various power aware and data packet rate control with-collision-avoidance (CSMA/CA)-based ad hoc wireless network communication. And identifies that CSMA
Improvement of crankshaft MAC protocol for wireless sensor networks: a simula...IJECEIAES
Due to the dramatic growth in the use of Wireless Sensor Network (WSN) applications ranging from environment and habitat monitoring to tracking and surveillance, network research in WSN protocols has been very active in the last decade. With battery-powered sensors operating in unattended environments, energy conservation becomes the key technique for improving WSN lifetimes. WSN Medium Access Control (MAC) protocols address energy awareness and reduced duty cycles. The focus of this study is to investigate, through simulation, the effect of variations in various factors that influence the performance results of WSNs. Using MiXiM framework with OMNeT++ simulator, this simulation study proposes modifications in Crankshaft MAC protocol in order to improve its performance. The impact of duration and number of slots, degree of connectivity among the nodes, mobility speed and mobility update interval and also, the impact of sending data packets without preambles are investigated. Based on the simulation results, an improved version of the Crankshaft protocol for WSN is suggested and a comparative study of the performances of the original and improved protocol is presented. The results clearly indicate the superiority of the improved protocol over its original version.
Energy efficient and reliable communication in IEEE 802.15.6 IR UWB WBANaravind m t
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networking protocols for UAV networks usually need the help of simulations to test their protocol designs,
particularly when networks of large scales are desired in their tests. One choice that researchers need to
make in the simulation of UAV networks is the radio propagation model for the air links. In this paper we
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investigate if the choice of one particular model would have a significant impact on the simulation results
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deployment. This is aimed at solving pertinent issues such as coverage holes and cell edge problems which
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V04503123128
1. Kaushalendra Baghel et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 5( Version 1), May 2014, pp.123-128
www.ijera.com 123 | P a g e
A Client-Assisted and Distributed Channel Assignment Scheme
For Dense IEEE 802.11 WLAN
Dr. Vineeta Saxena Nigam*, Kaushalendra Baghel**
*(Department of Electronics & Communication, UIT-RGPV, Bhopal-33, India)
**(Department of Electronics & Communication, UIT-RGPV, Bhopal-33, India)
ABSTRACT
Due to huge popularity, the WLANs (Wireless Local Area Networks) have gained in recent years, especially
based on IEEE 802.11 family of standards, dense deployment of AP (Access Point) can be found in many
places. However, these dense deployments can severely affect the aggregate throughput of the network due
increased contention and interference between different APs using same channel. This often leads to decreased
overall throughput of a local wireless network, such as in a university campus or city-wide Wi-Fi network. In
this paper, a simple client-assisted and distributed channel assignment scheme has been proposed for
minimizing such adverse affects of interference in dense WLANs. Client-assisted means the resources of clients
are also used for measurements of some parameters to increase the performance of the scheme. Distributed
schemes are those schemes which can easily be used where AP belongs to different owners and administrative
domains. This scheme will be shown to have better throughput performance than other prominent distributed
schemes through simulation results.
Keywords – Channel assignment scheme, DCF-MAC, IEEE802.11, and WLAN.
I. Introduction
The WLAN has become a ubiquitous
networking technology worldwide for wireless
communication. Highly dense WLAN networks can be
found in many cities of the world. One important
characteristics of such dense WLAN is closely spaced
APs, which leads to interference among them, if they
are using same channel for transmissions with their
respective clients. This may results in limiting the value
of maximum throughput achievable.
Fortunately IEEE standard 802.11 has
specified an efficient MAC protocol, called DCF
(Distributed co-ordination function), which uses
CSMA/CA (Carrier sense multiple access/Collision
avoidance) technique. Using this technique, a station
in WLAN system transmits, only after sensing the
medium to be idle for certain DIFS (distributed inter-
frame space) amount of time. This makes it effective in
presence of other transmissions and interference.
In an infrastructure BSS (Basic Service Set),
each transmission in the network will be only via the
AP of that BSS. This means that the AP is either the
source or destination in each transmission. In case of an
infrastructure BSS (Basic Service Set) and dense
WLAN, even CSMA/CA is unable prevent the adverse
effect of increased contention. This increased
contention is a result of several APs transmitting on
same channel, when numbers of channel available are
very few to choose from (for example, 3 in case of
IEEE 802.11b). This problem is further aggravated by
the use of non-overlapping and unlicensed use of
spectrum specified in IEEE 802.11 family of standards.
This forms the basis of channel assignment
problem where a scheme is applied so that each
neighbouring AP in a dense WLAN has different
channel or atleast there is optimal channel
assignment which can maximize the throughput for
a given number of channels.
Channel assignment schemes can be
broadly classified into two categories; Centralised
[1-4] and Distributed [5-7]. Centralised schemes
are applied to centrally managed deployments,
usually seen in places such as university campuses,
offices or airports where all APs and associated
clients are managed by a central entity [8]. On the
other hand, distributed schemes are used in
uncoordinated WLANs, which operate in the
absence of a central control and are typical in
places such as residential neighborhoods or private
hotspots managed by different service providers
[8]. In distributed schemes each AP perform its own
channel assignment based on the localized
information available to it, without interacting with
neighbouring APs.
Centralized scheme’s greatest weakness is
that these techniques require information of the
whole network, which is not feasible in the
majority of the WLAN networks. Majority of
WLAN networks belong to distributed category.
Hence the main focus of this paper is to develop a
distributed channel assignment scheme.
In [5], a weighted variant of graph-
colouring problem was proposed. The weights for
each channel are set according to interference
RESEARCH ARTICLE OPEN ACCESS
2. Kaushalendra Baghel et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 5( Version 1), May 2014, pp.123-128
www.ijera.com 124 | P a g e
information reported from the client nodes to their
associated AP. A simple and effective minimum
neighbour (MINE) scheme was proposed in [6]. In the
MINE scheme, each AP only needs to choose the
channel with the minimum number of active neighbour
nodes to maximize the expected throughput. Also a
client-assisted Minimum conflict pairs (MICPA)
scheme is proposed in [7]. This scheme has identified
conflict pairs as its metric, based on which channel
assignment is done, i.e., each AP chooses channel
having minimum number of conflict pairs.
The client-assisted schemes perform better
than AP only schemes as clients are better placed,
owing to their location, to perform measurements in the
network. Hence they can also be utilized to get better
results.
In this paper, the transmission range of each
node is not assumed to be same because practically the
transmission range of each node in a network varies
according to their environment and other factors. Hence
this scheme is assumed to present better alternative to
the channel assignment problem, which will be verified
in the later segment of this paper through simulation
results.
Rest of the paper is organised as follows. In
section II, impact of interference on throughput will be
studied. Based on this study, a metric called
interference value will be proposed. Next, in section III,
the proposed channel assignment scheme will be
described. Then, in section IV extensive performance
evaluation of the scheme and comparisons with other
simple and effective schemes, namely MINE and
MICPA schemes are performed. Finally, Section V
concludes this paper.
II. Impact of High Contention on
Throughput
To effectively study the impact of high
contention on throughput performance of a dense
WLAN interference scenarios are classified into 3
categories, namely Scenario I, Scenario II and Scenario
III, as shown in fig.1. The proposed interference
scenarios are simple to identify, even in a large
network.
Before describing each scenario in detail,
several notations used needs to be introduced. In our
classification of interference scenarios two BSS are
considered, BSS1 and BSS2. Each BSS has a single
access point denoted by AP1 and AP2, respectively. The
clients in BSS1 are denoted by Cl1ᵡ. Similarly clients in
BSS2 are denoted by Cl2ᵡ. The transmission between an
APᵡ and its client Clᵪy will be denoted by TRᵪy. For
example, using fig.1 as a reference, transmission
between AP1 and Cl13 will be denoted by TR13. Nᵪ will
denote the set containing all the clients of BSSᵡ. For
example, with reference to fig. 1(b), N1 = {Cl11, Cl12,
Cl13} and N2 = {Cl21, Cl22, Cl23, Cl24}.
Fig. 1(a)
Fig. 1(b)
Fig. 1(c)
Fig.1 All three interference scenario. (a).Scenario I.
(b) Scenario II. (c) Scenario III.
A BSS is said to be interfered by another
BSS if any of its members (AP or clients) suffers
from interference due to transmissions originating
from any member of the interfering BSS. The
proposed interference scenarios are classified from
the viewpoint that BSS1 is interfered by the BSS2
(Although BSS2 may also suffer interference due to
transmissions of BSS1). Hence, in case of Scenario
I, AP1 being in the transmission range of AP2,
directly suffers interference from AP2. In case of
3. Kaushalendra Baghel et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 5( Version 1), May 2014, pp.123-128
www.ijera.com 125 | P a g e
scenario II, only some clients of BSS1 will be in the
range of AP2. Such clients will belong to a set denoted
by Ni1. AP1 also might be in the transmission range of
some of the clients of BSS2. Set of such clients of
BSS2 will be denoted by Ni2. For example, with
reference to fig. 1(b), Ni1 = {Cl12} and Ni2 = {Cl23,
Cl24}. And finally in case of scenario III, some clients
of BSS1 are in the range of only some clients of BSS2.
For example in fig. 1(c), Cl12 and Cl14 are in the range
of Cl23. Set of such interfering clients of BSS2 in
Scenario-III will be denoted by Ni2. Remember that
number of elements of any set A will be denoted by |A|.
For example in fig. 1(a) |N1| = 4 and |N2| = 2.
In such interference scenarios, a metric called
interference value (IV) has been identified, which
approximately reflects the amount of interference a
BSS suffers from its neighbouring BSS. IV is here
defined as the number of transmissions of a BSS which
can possibly get interfered from transmissions of its
neighbouring BSS. Take for example fig 1(b), the
transmission TR23 can interfere with all four
transmissions of BSS1, as range of Cl24 encircle AP1.
Therefore the IV of TR23 is 4. Similarly with reference
to fig. 1(c), the transmission TR23 can interfere with
TR12 and TR14, hence the IV of TR23 is 2.
For Scenario I, because AP1 is in the range of
AP2, transmission without interference in BSS1 is not
possible when there is any ongoing transmission in
BSS2. Also as each transmission of BSS2 interferes
with all the transmissions of BSS1, the IV of all TR2ᵡ
will be equal to |N1|. And there are |N2| numbers of
TR2ᵡ, therefore total IV for BSS1 due to BSS2 for
Scenario-I will be given by,
IV(1,2) = |N1| x |N2| (1)
In Scenario-II, when any of the interfering
clients from the set Ni2 is transmitting, it interferes with
all transmissions of BSS1, as AP1 is in the range of all
these interfering clients. Hence IV for BSS1 due to
transmissions of all such clients of BSS2 will be equal
to |N1| x |Ni2|. Also, the clients of BSS1 belonging to the
set Ni1 suffers interference, not only from transmissions
of clients belonging to set Ni2, but also from all other
clients (N2 – Ni2) of BSS2, as all these clients from the
set Ni1 are in the range of AP2. Hence IV for BSS1 due
to all such transmission of BSS2 will be equal to (|N2| -
|Ni2|) x |Ni1|. Therefore total IV for BSS1 due to BSS2
for Scenario II will be,
IV(1,2) = |N1| x |Ni2| + |N2| x |Ni1| – |Ni1| x |Ni2| (2)
Finally, for Scenario-III, only |Ni2| number of
clients of BSS2 can interfere in the transmission of
some of the clients of BSS1. And each of such
transmission has different IV depending on number of
transmission of BSS1 they interfere with. Hence total
IV for BSS1 due to BSS2 in case of Scenario III will
be,
IV 1,2 = IVi
|Ni2|
𝑖=0
(3)
Now, having described the metric
interference value and calculating it for each of the
scenarios, it is necessary to find that how this
metric correlates to the throughput of the network
before proceeding further. It is now shown that
interference value is a good indicator of
interference experienced by each BSS due to the
transmission of other BSS using the same channel.
To validate this observation, packet-level
simulations of all the three scenarios have been
performed using NS-2. In each of the scenario two
BSS having an AP and three clients for each AP has
been taken. The IEEE 802.11b direct-sequence
spread-spectrum (DSSS) specifications have been
used in the simulations. All nodes are in saturated
condition. Each topology has been simulated for
100s. Also the Basic-access mechanism of DCF has
been used instead of RTS/CTS, as Basic-access
mechanism has been found to provide better
throughput even in presence of hidden nodes [9].
Fig.2 shows the plot between Normalised
Throughput v/s Interference Value for BSS1 for all
three scenarios.
Fig.2 Normalised Throughput vs. Interference
value
For each of the interference scenarios, it
can be seen that the throughput obtained is
somewhat inversely proportional to the interference
value. In other words, higher throughputs can be
achieved by selecting topologies that have lower
interference value. Keeping this in mind, the MIV
(Minimum Interference Value) scheme is proposed
in the next section.
III. MIV Scheme
Having defined the relationship between
Interference value and Throughput in previous
section, it is easy to predict the fact that MIV
scheme works by choosing the channel having
4. Kaushalendra Baghel et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 5( Version 1), May 2014, pp.123-128
www.ijera.com 126 | P a g e
minimum interference value, at each AP of the network
so that expected throughput is maximum. IEEE 802.11b
has specified a set of 13 channels in 2.4 GHz ISM band.
Out of these 13 overlapping channels, only 3 non-
overlapping channels are used for transmission in most
countries. IEEE 802.11a has specified a set of 12
OFDM channels in 5 GHz UNII band. Therefore for
each AP, there are 3 and 12 alternatives to choose from
in 802.11b and 802.11a, respectively.
In the MIV scheme, an AP first calculates IV
(Interference value) of each of the neighbouring
interfering BSS and adds them up to get total IV. For
example, if there are N numbers of interfering BSS,
then total IV for an APi will be,
IVi = IV(i,j) (4)
𝑁
𝑗 =0
This Total IV is calculated on each channel and
then the AP simply chooses the channel which has
minimum IV, so that its throughput can be maximized.
And if each AP in a large and dense WLAN runs this
scheme, the throughput of the whole system can be
significantly increased.
Now the main issue in the implementation of
this scheme is that how an AP calculates this metric IV.
For example, in case of Scenario-I, what is required to
calculate IV are two sets N1 and N2. And in case of
Scenario-II, sets of N1, N2, Ni1, and Ni2 are required.
And finally in case of Scenario-III, only the set of
interfering nodes Ni2 with their IVs is required to
calculate total IV. For calculating these values,
addressing fields of a typical IEEE 802.11 MAC frame
(shown in Fig. 3) can be used.
Fig. 3 IEEE 802.11 MAC frame.
Therefore, the 4 address fields and “ To DS ”
and “ From DS “ fields of a MAC frame can be used for
identifying all those parameters required for calculating
IVs. For example, taking Fig. 1 as a reference, in
Scenario-I AP1 can directly sense all transmissions of
BSS2 originating from AP2. Hence AP1 can observe
MAC frames of BSS2 over a time and identify all
active clients of that BSS to get N2. Similarly in case of
Scenario-II, AP1 can observe MAC frames of BSS2 to
identify interfering clients to get Ni2. Some clients of
BSS1, which are being interfered upon by AP2, can
similarly identify total clients of BSS2 over a period of
time and report them to its access-point, i.e. AP1.
AP1 then will use this information to identify Ni1
(Set of clients of BSS1 getting affected by
interference) and N2 (Total number of clients of
BSS2). And finally in Scenario-III, similar
observation of MAC frames of BSS2 by clients of
BSS1 will help AP1 in identifying Ni2 and their
IVs.
IV. Simulation Results
This section presents performance
evaluation of the MIV scheme on the basis of the
metric Total IV (Interference Value). Simulations
have been performed using a model created using
C++ programming language. Simulation scenario
consists of a network of 100 APs, each having
random number of clients from 1 to 10. The
transmission range of each BSS is also set
randomly between 75m and 125m to account for
variable transmission range of each BSS.
Deployment density of the network will be denoted
by a metric Y (same as used in MICPA scheme
[13]), where Y is the average number of interfering
APs each node have within its transmission range.
This parameter Y will decide dimensions of the
topology of whole network of 100 APs. The
number of channels for IEEE 802.11b and IEEE
802.11a are C=3 and C=12, respectively. All results
shown are obtained using the average of 1000
independent realizations with randomly generated
initial channels and number of clients. The
performance of MIV scheme will also be compared
with other two simple and effective distributed
schemes, MINE and MICPA scheme. The results of
other schemes have also been generated in a similar
manner and using the same model as the MIV
scheme.
Performance evaluation of these 3
schemes (MINE, MICPA and MIV) has also been
performed under different levels of client spread
and different AP deployment densities. Three levels
of client spread have been used, which are low,
moderate, and high client spreads. In low client
spread, the client’s locations are normally
distributed around AP with a standard deviation of
25m. For moderate client spread, the standard
deviation is 50m. And for high client spread, the
client’s locations are uniformly distributed around
AP.
5. Kaushalendra Baghel et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 5( Version 1), May 2014, pp.123-128
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Fig.4 Total interference value for all three schemes for
high client spread
In Fig. 4, the total interference value of whole
network of 100 BSSs is plotted against the number of
iterations. The number of iterations is chosen to be 10,
because all three schemes were found to be able to
converge into their best channel assignments before 10
iterations in saturated load conditions. 0th iteration here
denotes initial random channel assignment in the
network before any scheme is applied. Also these
results have been generated for IEEE 802.11a and IEEE
802.11b with a normalized density of unity Y /C = 1 (Y
is the average number of interfering APs and C is the
number of channels) and with high client spread.
From the fig. 4, these schemes result in
significant improvement in terms of reduction in
interference value of a large and dense network. Also it
is evident from Fig. 4 that MIV scheme outperforms
both MINE scheme and MICPA scheme with a
significant reduction in interference value. Reductions
of up to 25% and 5% for interference value can be
achieved by the MIV scheme over MINE scheme and
the MICPA scheme respectively in case of IEEE
802.11b. In case of IEEE 802.11a, this reduction in
interference value by MIV scheme is even better, i.e.
75% over MINE scheme and 19% over MICPA scheme.
Also the reduction by MIV scheme over initial random
channel assignment is 55 % for IEEE 802.11b and 82%
for IEEE 802.11a. The relatively larger improvement in
the case of IEEE 802.11a was also found in case of
MICPA scheme which points to the fact as number of
channels available is greater; these two schemes
provide better performance.
Fig.5 Total interference value for all three schemes
for different client spread
Fig.6 Total interference value for all three schemes
for different deployment density
Fig. 5 shows the total interference value
for all three schemes with different levels of client
spread for IEEE 802.11a with a normalized density
of unity. These results show that as the client spread
increases, IV also increases. This is expected
because clients which are located farther away from
their APs, not only are more exposed to, but also
create more interference to other APs. Nevertheless,
MIV scheme was able to reduce interference value
by 98%, 94%, and 82% for low, moderate and high
client spread respectively. Also significant
reductions in the interference value were observed
by the MIV scheme over MICPA scheme and the
MINE scheme for all levels of client spread.
Reductions in interference value of 93%, 87%, and
75% over MINE have been observed for low,
moderate, and high client spread, respectively. Also
the reduction by MIV scheme over MICPA scheme
is observed to be 79%, 43%, and 19% for low,
moderate, and high client spread respectively.
The interference value for all three schemes with
6. Kaushalendra Baghel et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 5( Version 1), May 2014, pp.123-128
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different deployment densities for IEEE 802.11a with
high client spread is plotted in Fig.6. From the results, it
can be seen that the interference value is larger when
the deployment density is higher signifying the point
that as deployment density increases, interference
increases. In all the considered cases of deployment
densities, significant reductions in interference value of
92%, 75%, and 54% by the MIV scheme over the
MINE scheme and of 40%, 19%, and 12% over MICPA
scheme can still be observed for Y = 8, Y = 12, and Y =
16, respectively.
V. Conclusion
In this paper, the channel assignment problem
has been tackled first by classifying interference
environment of dense deployment of WLAN system
into three interference scenarios. Based on these
interference scenarios a metric, called interference
value has been identified. Then this metric was shown
to be almost inversely proportional with the throughput
obtained for all interference scenarios. Employing this
metric, the MIV scheme was proposed.
Simulation results have shown that the MIV
scheme can provide a significant reduction in
interference value of a large and dense network for both
IEEE 802.11b and IEEE 802.11a. Also in comparison
with MINE and MICPA scheme, MIV scheme performs
better for all considered cases of client spread and
deployment density. Several implementation issues of
MIV scheme was also discussed in this paper.
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