The document discusses a new challenge called the Multichannel Scheduling Cost (MSC) that arises in multichannel networks due to the inability of the control channel to schedule simultaneous transmissions, resulting in data channels lying idle. To address this, a Cyclic Scheduling Algorithm (CSA) is proposed that employs one control channel and 4 data channels using a proactive channel reservation scheme. The scheme reserves data channels while they are still busy transmitting to reduce idle times. Simulation results show the CSA scheme improves bandwidth utilization by limiting the effects of the MSC to the first scheduling cycle.
DESIGN OF A COMPACT CIRCULAR MICROSTRIP PATCH ANTENNA FOR WLAN APPLICATIONS pijans
This paper presents the design of a compact circular microstrip patch antenna for WLAN applications which covers the band 5.15 to 5.825 GHz. The antenna is designed using 1.4mm thick FR-4 (lossy)substrate with relative permittivity 4.4 and a microstrip line feed is used. The radius of the circular patch is chosen as 7.62mm. To reduce the size and enhance the performance of the proposed antenna, a circular slot is loaded on circular patch and a square slot is etched on the ground plane of dimension 30mm×30mm. Design of the antenna is carried out using CST Microsoft Studio Sonimulation Software. The proposed antenna resonates at 5.5 GHz with a wider bandwidth of 702 MHz and it provides low return loss of -31.58 dB, good gain of 3.23 dB and directivity of 4.28 dBi and high efficiency of around 79% against the resonance frequency. The geometry of the proposed circular antenna with reduced size and its various performance parameters such as return loss, bandwidth, VSWR, gain, directivity, efficiency and radiation pattern plots are presented and discussed.
COMPARATIVE PERFORMANCE ASSESSMENT OF VBLAST ENCODED 8×8 MIMO MC-CDMA WIRELES...pijans
The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system
for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM)
schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system
employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN channel
and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study
demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2-
rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance
utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission
Effect of Interleaved FEC Code on Wavelet Based MC-CDMA System with Alamouti ...IJCSEIT Journal
In this paper, the impact of Forward Error Correction (FEC) code namely Trellis code with interleaver on
the performance of wavelet based MC-CDMA wireless communication system with the implementation of
Alamouti antenna diversity scheme has been investigated in terms of Bit Error Rate (BER) as a function of
Signal-to-Noise Ratio (SNR) per bit. Simulation of the system under proposed study has been done in M-ary
modulation schemes (MPSK, MQAM and DPSK) over AWGN and Rayleigh fading channel incorporating
Walsh Hadamard code as orthogonal spreading code to discriminate the message signal for individual
user. It is observed via computer simulation that the performance of the interleaved coded based proposed
system outperforms than that of the uncoded system in all modulation schemes over Rayleigh fading
channel.
A Cross Layer Based Scalable Channel Slot Re-Utilization Technique for Wirele...csandit
Due to tremendous growth of the wireless based application services are increasing the demand
for wireless communication techniques that use bandwidth more effectively. Channel slot reutilization
in multi-radio wireless mesh networks is a very challenging problem. WMNs have
been adopted as back haul to connect various networks such as Wi-Fi (802.11), WI-MAX
(802.16e) etc. to the internet. The slot re-utilization technique proposed so far suffer due to high
collision due to improper channel slot usage approximation error. To overcome this here the
author propose the cross layer optimization technique by designing a device classification
based channel slot re-utilization routing strategy which considers the channel slot and node
information from various layers and use some of these parameters to approximate the risk
involve in channel slot re-utilization in order to improve the QoS of the network. The simulation
and analytical results show the effectiveness of our proposed approach in term of channel slot
re-utilization efficiency and thus helps in reducing latency for data transmission and reduce
channel slot collision.
Some of the key driving forces behind the transition from the UMTS based cellular system to the Long Term Evolution Advanced (LTE-A) are to improve the mean and the cell-edge throughput, improve the user fairness, and improve the quality of service (QoS) satisfaction for all users. In the latter system, relays appear as one of the most prominent enabler for improving the cell-edge user experience while increasing the system’s fairness.
In this white paper, we present the basics of relay deployments in LTE-A networks. Moreover, we analyze resource allocation problem for Relay Nodes (RN) deployments and present some of the solutions for improvement in system resource usage and QoS satisfaction. Afterwards, we introduce the capabilities of NOMOR’s LTE-A system level simulator and evaluate the performance of LTE-A relay systems under the described solutions.
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]
ABSTRACT : Performance enhancement of smart antennas versus their complexity for commercial wireless
applications. The goal of the study presented in this paper is to investigate the performance improvement
attainable using relatively simple smart antenna techniques when applied to the third-generation W-CDMA air
interface. Methods to achieve this goal include fixed multi beam architectures with different beam selection
algorithms (maximum power criterion, combined beams) or adaptive solutions driven by relatively simple direction
finding algorithms. After comparing these methods against each other for several representative scenarios, some
issues related to the sensitivity of these methods are also studied, (e.g., robustness to environment, mismatches
originating from implementation limitations, etc.). Results indicate that overall, conventional beam forming
seems to be the best choice in terms of balancing the performance and complexity requirements, in particular
when the problem with interfering high-bit-rate W-CDMA 3g users is considered.
Heterogeneous LTE Networks and Inter-Cell Interference Coordination - Dec 201...Eiko Seidel
This document discusses heterogeneous LTE networks and inter-cell interference coordination (ICIC). It begins by explaining that initial LTE networks consisted of homogeneous macro cell deployments but that heterogeneous networks using smaller pico and femto cells are now being implemented to improve capacity and coverage. This introduces new interference challenges. The document then outlines various ICIC methods like frequency reuse and power control techniques that can help mitigate interference. It provides simulation results showing the benefits of heterogeneous networks and techniques like range expansion.
DESIGN OF A COMPACT CIRCULAR MICROSTRIP PATCH ANTENNA FOR WLAN APPLICATIONS pijans
This paper presents the design of a compact circular microstrip patch antenna for WLAN applications which covers the band 5.15 to 5.825 GHz. The antenna is designed using 1.4mm thick FR-4 (lossy)substrate with relative permittivity 4.4 and a microstrip line feed is used. The radius of the circular patch is chosen as 7.62mm. To reduce the size and enhance the performance of the proposed antenna, a circular slot is loaded on circular patch and a square slot is etched on the ground plane of dimension 30mm×30mm. Design of the antenna is carried out using CST Microsoft Studio Sonimulation Software. The proposed antenna resonates at 5.5 GHz with a wider bandwidth of 702 MHz and it provides low return loss of -31.58 dB, good gain of 3.23 dB and directivity of 4.28 dBi and high efficiency of around 79% against the resonance frequency. The geometry of the proposed circular antenna with reduced size and its various performance parameters such as return loss, bandwidth, VSWR, gain, directivity, efficiency and radiation pattern plots are presented and discussed.
COMPARATIVE PERFORMANCE ASSESSMENT OF VBLAST ENCODED 8×8 MIMO MC-CDMA WIRELES...pijans
The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system
for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM)
schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system
employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN channel
and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study
demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2-
rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance
utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission
Effect of Interleaved FEC Code on Wavelet Based MC-CDMA System with Alamouti ...IJCSEIT Journal
In this paper, the impact of Forward Error Correction (FEC) code namely Trellis code with interleaver on
the performance of wavelet based MC-CDMA wireless communication system with the implementation of
Alamouti antenna diversity scheme has been investigated in terms of Bit Error Rate (BER) as a function of
Signal-to-Noise Ratio (SNR) per bit. Simulation of the system under proposed study has been done in M-ary
modulation schemes (MPSK, MQAM and DPSK) over AWGN and Rayleigh fading channel incorporating
Walsh Hadamard code as orthogonal spreading code to discriminate the message signal for individual
user. It is observed via computer simulation that the performance of the interleaved coded based proposed
system outperforms than that of the uncoded system in all modulation schemes over Rayleigh fading
channel.
A Cross Layer Based Scalable Channel Slot Re-Utilization Technique for Wirele...csandit
Due to tremendous growth of the wireless based application services are increasing the demand
for wireless communication techniques that use bandwidth more effectively. Channel slot reutilization
in multi-radio wireless mesh networks is a very challenging problem. WMNs have
been adopted as back haul to connect various networks such as Wi-Fi (802.11), WI-MAX
(802.16e) etc. to the internet. The slot re-utilization technique proposed so far suffer due to high
collision due to improper channel slot usage approximation error. To overcome this here the
author propose the cross layer optimization technique by designing a device classification
based channel slot re-utilization routing strategy which considers the channel slot and node
information from various layers and use some of these parameters to approximate the risk
involve in channel slot re-utilization in order to improve the QoS of the network. The simulation
and analytical results show the effectiveness of our proposed approach in term of channel slot
re-utilization efficiency and thus helps in reducing latency for data transmission and reduce
channel slot collision.
Some of the key driving forces behind the transition from the UMTS based cellular system to the Long Term Evolution Advanced (LTE-A) are to improve the mean and the cell-edge throughput, improve the user fairness, and improve the quality of service (QoS) satisfaction for all users. In the latter system, relays appear as one of the most prominent enabler for improving the cell-edge user experience while increasing the system’s fairness.
In this white paper, we present the basics of relay deployments in LTE-A networks. Moreover, we analyze resource allocation problem for Relay Nodes (RN) deployments and present some of the solutions for improvement in system resource usage and QoS satisfaction. Afterwards, we introduce the capabilities of NOMOR’s LTE-A system level simulator and evaluate the performance of LTE-A relay systems under the described solutions.
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]
ABSTRACT : Performance enhancement of smart antennas versus their complexity for commercial wireless
applications. The goal of the study presented in this paper is to investigate the performance improvement
attainable using relatively simple smart antenna techniques when applied to the third-generation W-CDMA air
interface. Methods to achieve this goal include fixed multi beam architectures with different beam selection
algorithms (maximum power criterion, combined beams) or adaptive solutions driven by relatively simple direction
finding algorithms. After comparing these methods against each other for several representative scenarios, some
issues related to the sensitivity of these methods are also studied, (e.g., robustness to environment, mismatches
originating from implementation limitations, etc.). Results indicate that overall, conventional beam forming
seems to be the best choice in terms of balancing the performance and complexity requirements, in particular
when the problem with interfering high-bit-rate W-CDMA 3g users is considered.
Heterogeneous LTE Networks and Inter-Cell Interference Coordination - Dec 201...Eiko Seidel
This document discusses heterogeneous LTE networks and inter-cell interference coordination (ICIC). It begins by explaining that initial LTE networks consisted of homogeneous macro cell deployments but that heterogeneous networks using smaller pico and femto cells are now being implemented to improve capacity and coverage. This introduces new interference challenges. The document then outlines various ICIC methods like frequency reuse and power control techniques that can help mitigate interference. It provides simulation results showing the benefits of heterogeneous networks and techniques like range expansion.
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.
Peak to Average Power Ratio Reduction in Mc Cdma System by Using Pulse Shapin...IOSR Journals
Abstract: One of the drawback of multicarrier code division multiple access (MC CDMA) is the high peak to
average power ratio (PAPR). In this paper A novel scheme based on pulse shaping described for PAPR
reduction. Here three different pulse shaping filters (Raised cosine, Sinc power pulse and Nyqist pulse) are
described for PAPR reduction in MC CDMA system. The method is based on the proper selection of the pulses
for shaping the different sub carriers of the MC CDMA modulation scheme. It is shown by computer simulation
that the scheme achieves the significant improvement in PAPR reduction in MC CDMA system. Its
implementation complexity is much low in comparison to the previous published methods. Thus pulse shaping
technique can be used not only to shape the spectrum of the transmitted signal but also to reduce its PAPR. In
computer simulation It is observed that by using nyquist pulse near about 6.8 db PAPR is obtained. Which is
considerable PAPR reduction than a PAPR value of Original MC CDMA signal
Keywords: MC CDMA, PAPR, PULSE SHAPING, BPSK
Index modulation is one of the promising techniques for future communications systems due to many improvement over the classical orthogonal frequency division multiplexing systems such as single RF chain, increased throughput for the same modulation order, achieved tradeoff between the efficiencies of the power and the spectral, and elimination of inter-channel interference. Many forms of index modulation researches exist where symbols are conveyed in antennas, subcarriers, time slots, and the space-time matrix. Spatial modulation is one member of index modulation family where symbols are conveyed in activating transmit/receive antennas. In this paper, a modification to a standard multiple input single output scheme by integrating spatial modulation using simplified mathematical procedure is achieved. In the transmitter side, data and activation symbols are distributed simultaneously using mathematical module and floor functions. At the receiver, a simplified maximum likelihood detector is used to obtain transmitted pair of symbols. To verify this, MATLAB simulink is used to simulate a downlink system where spatial modulation is applied to a base station. Results for different transmit antenna number and modulation order are obtained in the form of bit error rate versus signal to noise ratio.
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.
This document summarizes LTE uplink transport channel processing and physical layer procedures. It discusses:
1. Uplink transport channel processing including channel coding and modulation for uplink shared channels and uplink control information.
2. Physical layer procedures including uplink reference signals, random access channels, HARQ, channel quality indicator feedback, and scheduling.
3. Specific topics covered include SC-FDMA modulation for the uplink, uplink reference signal structure, PUCCH formats for control information, and coding schemes for different control information types.
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.
IRJET- BER Reduction of Distributed Spatial Modulation in Cooperative Relay N...IRJET Journal
This document summarizes a research paper on reducing bit error rate (BER) of distributed spatial modulation in cooperative relay networks for cellular systems. The key points are:
1) Distributed spatial modulation (DSM) is proposed to overcome limitations of spatial modulation for mobile terminals by using multiple cooperative relays to form a virtual antenna array.
2) In DSM, source information is broadcast to relays and one relay is selected to forward the information to the destination, reducing transmit power.
3) A DSM-OFDM protocol is proposed where only one relay transmits per OFDM subcarrier while others transmit zero power.
4) Simulation results show the proposed DSM-OFDM scheme achieves
BER Performance Improvement for 4 X 4 MIMO Single Carrier FDMA System Using M...IRJET Journal
This document describes a system that aims to improve the bit error rate (BER) performance of 4x4 MIMO single-carrier frequency-division multiple access (SC-FDMA) uplink transmission. It investigates using minimum mean square error (MMSE) equalization at the receiver to better detect MIMO data over Rayleigh fading channels. Simulation results using MATLAB show that the proposed MMSE detection scheme decreases BER as signal-to-noise ratio increases for 16-QAM modulation. The BER performance is also compared to orthogonal frequency-division multiple access (OFDMA) MIMO systems, showing improved results for SC-FDMA.
Routing in Cognitive Radio Networks - A SurveyIJERA Editor
Cognitive Radio Networks (CRNs) have been emerged as a revolutionary solution to migrate the spectrum
scarcity problem in wireless networks. Due to increasing demand for additional spectrum resources, CRNs have
been receiving significant research to solve issues related with spectrum underutilization. This technology
brings efficient spectrum usage and effective interference avoidance, and also brings new challenges to routing
in multi-hop Cognitive Radio Networks. In CRN, unlicensed users or secondary users are able to use
underutilized licensed channels, but they have to leave the channel if any interference is caused to the primary or
licensed users. So CR technology allows sharing of licensed spectrum band in opportunistic and non-interfering
manner. Different routing protocols have been proposed recently based on different design goals under different
assumptions.
Simulation of LTE-TDD in the HAPS channel IJECEIAES
LTE stands for Long Term Evolution. This technology enhances the data rate and capacity using a new radio interface and an optimized core network. This progress was done to satisfy standards defined for the fourth generation of cellular communications in ITU. LTE has two types of transmission: Frequency Division Duplex (FDD) and Time Division Duplex (TDD). Nowadays, LTE-TDD rapidly Grows and takes place of old fixed cellular communications, like WiMAX. Another upcoming technology in the communication industry is High Amplitude Platform Stations (HAPS). Studying the capability of HAPS as a base station for LTE-TDD is the main purpose of this paper. Simulations have done using HAPS channel and compared to Stanford University Interim (SUI) standard channels for different scenarios. Results were compared to achieve a conclusion on HAPS implementation for LTE-TDD based on BER and data throughput.
This document summarizes adaptive resource allocation techniques for wireless MIMO-OFDMA systems used for multimedia multicasting. It discusses different multicast scheduling approaches, including single-rate and multi-rate transmissions. For single-rate, a fixed default rate, worst user's rate, or group average throughput can be used. For multi-rate, information can be split into multiple streams or subgroups can be formed based on channel quality. The document also provides an overview of the multicast resource allocation block in an OFDMA system, which determines subcarrier allocation and transmit power based on channel state information feedback to optimize throughput or power.
Improving thrpoughput and energy efficiency by pctar protocol in wirelessIaetsd Iaetsd
The document discusses a proposed Prioritized Congestion and Traffic Aware Routing (PCTAR) protocol for wireless sensor networks. PCTAR aims to improve throughput and energy efficiency. It does so by dynamically discovering routing zones using hybrid potential fields that consider both depth (distance to sink) and queue length, as well as data priority. Simulation results showed PCTAR improved overall throughput by 70% compared to the TADR protocol. PCTAR is suitable for applications in healthcare monitoring and military domains by prioritizing data delivery and reducing congestion.
Analysis of MAC protocol for Cognitive Radio Wireless Sensor Network (CR-WSN)IRJET Journal
This document analyzes MAC protocols for cognitive radio wireless sensor networks (CR-WSNs). It begins with an introduction to cognitive radio and how combining it with wireless sensor networks can yield new networking capabilities. It then discusses various MAC protocol layers and focuses on the COGMAC protocol. COGMAC is a decentralized cognitive MAC protocol based on the multichannel preamble reservation scheme. The document outlines COGMAC's advantages over conventional MAC protocols and introduces an upgraded version called COGMAC+. COGMAC+ uses adaptive energy detection and random backoff schemes to improve performance. Finally, the document summarizes that cognitive radio can improve spectrum utilization and quality in sensor networks by exploiting multiple channel availability and overcoming issues from dense deployments.
ADAPTIVE HANDOVER HYSTERESIS AND CALL ADMISSION CONTROL FOR MOBILE RELAY NODESIJCNCJournal
The aim of equipping a wireless network with a mobile relay node is to support broadband wireless communications for vehicular users and their devices. The high mobility of vehicular users, possibly at a very high velocity in the area in which two cells overlap, could cause the network to suffer from a reduced handover success rate and, hence, increased radio link failure. The combined impact of these problems is service interruptions to vehicular users. Thus, the handover schemes are crucial in solving these problems. In this work, we first present the adaptive handover hysteresis scheme for the wireless network with mobile relay nodes in the high-speed train scenario. Specifically, our proposed adaptive hysteresis scheme is based on the velocity of the train. Second, the handover call dropping probability is reduced by introducing a modified call admission control scheme to support radio resource reservation for handover calls that prioritizes handover calls of mobile relay over the other calls. The proposed solution in which adaptive parameter is combined with call admission control is evaluated by system level simulation. Our simulation results illustrate an increased handover success rate and reduced radio link failures.
This document summarizes a research paper that proposes a distributed polar transmission system for frequency selective fading channels in a MIMO-OFDM relay communication system. The system uses polar coding at the source and relay nodes to provide higher reliability than conventional decode-and-forward or amplify-and-forward relay schemes. The system divides the polarizing relay channels into a down-polarizing system and an up-polarizing system. Analysis of the bit error rate performance indicates that the polar system can increase symmetric capacity under low-complexity successive interference cancellation decoding by exploiting channel polarization with OFDM symbol combining and splitting over frequency selective fading channels.
The document surveys 17 literature sources on multi-carrier modulation techniques like OFDM and MC-CDMA. Several sources propose using wavelet transforms instead of Fourier transforms to improve bandwidth efficiency and reduce interference for MC-CDMA systems. Simulation results from the literature show that wavelet packet based MC-CDMA can outperform FFT based MC-CDMA in terms of lower bit error rates, especially in frequency selective fading channels. The rationale given is that wavelet transforms eliminate the need for cyclic prefixes, thereby improving spectral efficiency over traditional MC-CDMA schemes.
The document discusses various literature on OFDM and MC-CDMA techniques. It summarizes 17 research papers on topics like using wavelet packets instead of Fourier transform in MC-CDMA to improve bandwidth efficiency and reduce interference. It also discusses using techniques like DWT, Radon transform, and antenna diversity with MC-CDMA and comparing the BER performance of different approaches in various channel conditions like AWGN, Rayleigh fading and frequency selective fading channels. The rationale given is that replacing Fourier transform with wavelet packets in MC-CDMA can eliminate the need for cyclic prefix and improve spectral efficiency.
The three-way need for higher data rates, good quality of service and ubiquity in a converged all IP
communication cloud drives research in wireless communication. Wireless access networks are envisaged
candidates of the next generation wireless networks. The various access networks will be integrated with
other technologies including the wired backbone. The major issues in an all IP and converged networks
are: quality of service, seamless handover and network capacity. Emerging research seeks to address these
open research issues; for example the implementation of multi-channel and multi radio MAC protocols in
WMN. In this paper we analyze and evaluate the effectiveness of multi-channel and multi radio techniques
in WMN. The shortcomings of these schemes are highlighted and possible solutions are suggested. The
signalling delay metric is used for evaluation purposes. The focus is on the performance of the control
channel identified as the critical performance metric of multi-channel MAC protocols.
DYNAMIC CURATIVE MECHANISM FOR GEOGRAPHIC ROUTING IN WIRELESS MULTIMEDIA SENS...csandit
Maintaining network stability and extending network lifetime to cope with breaking links and topology changes remain nowadays a unsolved issues in Wireless Multimedia Sensor Networks (WMSNs), which aim to ensure flow delivery while guaranteeing QoS requirements, particularly, during data transmission phase. Therefore, in this paper, we jointly consider multipath transmission, load balancing and fault tolerance, to enhance the reliability of transmitted data. We propose a Dynamic Curative Mechanism for Geographic Routing in WMSNs. Theoricals results and those obtained from simulation study demonstrate the validity and efficiency of our proposed mechanism, and indicate that it is highly advised for multimedia transmission and network stability
Simulation based Evaluation of a Simple Channel Distribution Scheme for MANETsIOSR Journals
This document presents a proposed multi-channel distribution scheme for mobile ad hoc networks (MANETs) and evaluates it through simulation. The proposed scheme assigns channels to nodes based on their node IDs to avoid control overhead from time synchronization. While neighboring nodes on the same channel is possible, the probability is low given random node distribution. The proposed scheme is compared to a single-channel scheme in ns-2 simulations. Results show the proposed technique has better performance.
MULTI-CLUSTER MULTI-CHANNEL SCHEDULING (MMS) ALGORITHM FOR MAXIMUM DATA COLLE...IJCNCJournal
Interference during data transmission can cause performance degradation like packet collisions in Wireless Sensor Networks (WSNs). While multi-channels available in IEEE 802.15.4 protocol standard WSN technology can be exploited to reduce interference, allocating channel and channel switching
algorithms can have a major impact on the performance of multi-channel communication. This paper presents an improved Fuzzy Logic based Cluster Formation and Cluster Head (CH) Selection algorithm with enhanced network lifetime for multi-cluster topology. The Multi-Cluster Multi-Channel Scheduling
(MMS) algorithm proposed in this paper improves the data collection by minimizing the maximum interference and collision. The presented work has developed Cluster formation and cluster head (CH) selection algorithm and Interference-free data communication by proper channel scheduled. The extensive
simulation and experimental outcomes prove that the proposed algorithm not only provides an interference-free transmission but also provides delay minimization and longevity of the network lifetime, which makes the presented algorithm suitable for energy-constrained wireless sensor networks.
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.
Peak to Average Power Ratio Reduction in Mc Cdma System by Using Pulse Shapin...IOSR Journals
Abstract: One of the drawback of multicarrier code division multiple access (MC CDMA) is the high peak to
average power ratio (PAPR). In this paper A novel scheme based on pulse shaping described for PAPR
reduction. Here three different pulse shaping filters (Raised cosine, Sinc power pulse and Nyqist pulse) are
described for PAPR reduction in MC CDMA system. The method is based on the proper selection of the pulses
for shaping the different sub carriers of the MC CDMA modulation scheme. It is shown by computer simulation
that the scheme achieves the significant improvement in PAPR reduction in MC CDMA system. Its
implementation complexity is much low in comparison to the previous published methods. Thus pulse shaping
technique can be used not only to shape the spectrum of the transmitted signal but also to reduce its PAPR. In
computer simulation It is observed that by using nyquist pulse near about 6.8 db PAPR is obtained. Which is
considerable PAPR reduction than a PAPR value of Original MC CDMA signal
Keywords: MC CDMA, PAPR, PULSE SHAPING, BPSK
Index modulation is one of the promising techniques for future communications systems due to many improvement over the classical orthogonal frequency division multiplexing systems such as single RF chain, increased throughput for the same modulation order, achieved tradeoff between the efficiencies of the power and the spectral, and elimination of inter-channel interference. Many forms of index modulation researches exist where symbols are conveyed in antennas, subcarriers, time slots, and the space-time matrix. Spatial modulation is one member of index modulation family where symbols are conveyed in activating transmit/receive antennas. In this paper, a modification to a standard multiple input single output scheme by integrating spatial modulation using simplified mathematical procedure is achieved. In the transmitter side, data and activation symbols are distributed simultaneously using mathematical module and floor functions. At the receiver, a simplified maximum likelihood detector is used to obtain transmitted pair of symbols. To verify this, MATLAB simulink is used to simulate a downlink system where spatial modulation is applied to a base station. Results for different transmit antenna number and modulation order are obtained in the form of bit error rate versus signal to noise ratio.
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.
This document summarizes LTE uplink transport channel processing and physical layer procedures. It discusses:
1. Uplink transport channel processing including channel coding and modulation for uplink shared channels and uplink control information.
2. Physical layer procedures including uplink reference signals, random access channels, HARQ, channel quality indicator feedback, and scheduling.
3. Specific topics covered include SC-FDMA modulation for the uplink, uplink reference signal structure, PUCCH formats for control information, and coding schemes for different control information types.
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.
IRJET- BER Reduction of Distributed Spatial Modulation in Cooperative Relay N...IRJET Journal
This document summarizes a research paper on reducing bit error rate (BER) of distributed spatial modulation in cooperative relay networks for cellular systems. The key points are:
1) Distributed spatial modulation (DSM) is proposed to overcome limitations of spatial modulation for mobile terminals by using multiple cooperative relays to form a virtual antenna array.
2) In DSM, source information is broadcast to relays and one relay is selected to forward the information to the destination, reducing transmit power.
3) A DSM-OFDM protocol is proposed where only one relay transmits per OFDM subcarrier while others transmit zero power.
4) Simulation results show the proposed DSM-OFDM scheme achieves
BER Performance Improvement for 4 X 4 MIMO Single Carrier FDMA System Using M...IRJET Journal
This document describes a system that aims to improve the bit error rate (BER) performance of 4x4 MIMO single-carrier frequency-division multiple access (SC-FDMA) uplink transmission. It investigates using minimum mean square error (MMSE) equalization at the receiver to better detect MIMO data over Rayleigh fading channels. Simulation results using MATLAB show that the proposed MMSE detection scheme decreases BER as signal-to-noise ratio increases for 16-QAM modulation. The BER performance is also compared to orthogonal frequency-division multiple access (OFDMA) MIMO systems, showing improved results for SC-FDMA.
Routing in Cognitive Radio Networks - A SurveyIJERA Editor
Cognitive Radio Networks (CRNs) have been emerged as a revolutionary solution to migrate the spectrum
scarcity problem in wireless networks. Due to increasing demand for additional spectrum resources, CRNs have
been receiving significant research to solve issues related with spectrum underutilization. This technology
brings efficient spectrum usage and effective interference avoidance, and also brings new challenges to routing
in multi-hop Cognitive Radio Networks. In CRN, unlicensed users or secondary users are able to use
underutilized licensed channels, but they have to leave the channel if any interference is caused to the primary or
licensed users. So CR technology allows sharing of licensed spectrum band in opportunistic and non-interfering
manner. Different routing protocols have been proposed recently based on different design goals under different
assumptions.
Simulation of LTE-TDD in the HAPS channel IJECEIAES
LTE stands for Long Term Evolution. This technology enhances the data rate and capacity using a new radio interface and an optimized core network. This progress was done to satisfy standards defined for the fourth generation of cellular communications in ITU. LTE has two types of transmission: Frequency Division Duplex (FDD) and Time Division Duplex (TDD). Nowadays, LTE-TDD rapidly Grows and takes place of old fixed cellular communications, like WiMAX. Another upcoming technology in the communication industry is High Amplitude Platform Stations (HAPS). Studying the capability of HAPS as a base station for LTE-TDD is the main purpose of this paper. Simulations have done using HAPS channel and compared to Stanford University Interim (SUI) standard channels for different scenarios. Results were compared to achieve a conclusion on HAPS implementation for LTE-TDD based on BER and data throughput.
This document summarizes adaptive resource allocation techniques for wireless MIMO-OFDMA systems used for multimedia multicasting. It discusses different multicast scheduling approaches, including single-rate and multi-rate transmissions. For single-rate, a fixed default rate, worst user's rate, or group average throughput can be used. For multi-rate, information can be split into multiple streams or subgroups can be formed based on channel quality. The document also provides an overview of the multicast resource allocation block in an OFDMA system, which determines subcarrier allocation and transmit power based on channel state information feedback to optimize throughput or power.
Improving thrpoughput and energy efficiency by pctar protocol in wirelessIaetsd Iaetsd
The document discusses a proposed Prioritized Congestion and Traffic Aware Routing (PCTAR) protocol for wireless sensor networks. PCTAR aims to improve throughput and energy efficiency. It does so by dynamically discovering routing zones using hybrid potential fields that consider both depth (distance to sink) and queue length, as well as data priority. Simulation results showed PCTAR improved overall throughput by 70% compared to the TADR protocol. PCTAR is suitable for applications in healthcare monitoring and military domains by prioritizing data delivery and reducing congestion.
Analysis of MAC protocol for Cognitive Radio Wireless Sensor Network (CR-WSN)IRJET Journal
This document analyzes MAC protocols for cognitive radio wireless sensor networks (CR-WSNs). It begins with an introduction to cognitive radio and how combining it with wireless sensor networks can yield new networking capabilities. It then discusses various MAC protocol layers and focuses on the COGMAC protocol. COGMAC is a decentralized cognitive MAC protocol based on the multichannel preamble reservation scheme. The document outlines COGMAC's advantages over conventional MAC protocols and introduces an upgraded version called COGMAC+. COGMAC+ uses adaptive energy detection and random backoff schemes to improve performance. Finally, the document summarizes that cognitive radio can improve spectrum utilization and quality in sensor networks by exploiting multiple channel availability and overcoming issues from dense deployments.
ADAPTIVE HANDOVER HYSTERESIS AND CALL ADMISSION CONTROL FOR MOBILE RELAY NODESIJCNCJournal
The aim of equipping a wireless network with a mobile relay node is to support broadband wireless communications for vehicular users and their devices. The high mobility of vehicular users, possibly at a very high velocity in the area in which two cells overlap, could cause the network to suffer from a reduced handover success rate and, hence, increased radio link failure. The combined impact of these problems is service interruptions to vehicular users. Thus, the handover schemes are crucial in solving these problems. In this work, we first present the adaptive handover hysteresis scheme for the wireless network with mobile relay nodes in the high-speed train scenario. Specifically, our proposed adaptive hysteresis scheme is based on the velocity of the train. Second, the handover call dropping probability is reduced by introducing a modified call admission control scheme to support radio resource reservation for handover calls that prioritizes handover calls of mobile relay over the other calls. The proposed solution in which adaptive parameter is combined with call admission control is evaluated by system level simulation. Our simulation results illustrate an increased handover success rate and reduced radio link failures.
This document summarizes a research paper that proposes a distributed polar transmission system for frequency selective fading channels in a MIMO-OFDM relay communication system. The system uses polar coding at the source and relay nodes to provide higher reliability than conventional decode-and-forward or amplify-and-forward relay schemes. The system divides the polarizing relay channels into a down-polarizing system and an up-polarizing system. Analysis of the bit error rate performance indicates that the polar system can increase symmetric capacity under low-complexity successive interference cancellation decoding by exploiting channel polarization with OFDM symbol combining and splitting over frequency selective fading channels.
The document surveys 17 literature sources on multi-carrier modulation techniques like OFDM and MC-CDMA. Several sources propose using wavelet transforms instead of Fourier transforms to improve bandwidth efficiency and reduce interference for MC-CDMA systems. Simulation results from the literature show that wavelet packet based MC-CDMA can outperform FFT based MC-CDMA in terms of lower bit error rates, especially in frequency selective fading channels. The rationale given is that wavelet transforms eliminate the need for cyclic prefixes, thereby improving spectral efficiency over traditional MC-CDMA schemes.
The document discusses various literature on OFDM and MC-CDMA techniques. It summarizes 17 research papers on topics like using wavelet packets instead of Fourier transform in MC-CDMA to improve bandwidth efficiency and reduce interference. It also discusses using techniques like DWT, Radon transform, and antenna diversity with MC-CDMA and comparing the BER performance of different approaches in various channel conditions like AWGN, Rayleigh fading and frequency selective fading channels. The rationale given is that replacing Fourier transform with wavelet packets in MC-CDMA can eliminate the need for cyclic prefix and improve spectral efficiency.
The three-way need for higher data rates, good quality of service and ubiquity in a converged all IP
communication cloud drives research in wireless communication. Wireless access networks are envisaged
candidates of the next generation wireless networks. The various access networks will be integrated with
other technologies including the wired backbone. The major issues in an all IP and converged networks
are: quality of service, seamless handover and network capacity. Emerging research seeks to address these
open research issues; for example the implementation of multi-channel and multi radio MAC protocols in
WMN. In this paper we analyze and evaluate the effectiveness of multi-channel and multi radio techniques
in WMN. The shortcomings of these schemes are highlighted and possible solutions are suggested. The
signalling delay metric is used for evaluation purposes. The focus is on the performance of the control
channel identified as the critical performance metric of multi-channel MAC protocols.
DYNAMIC CURATIVE MECHANISM FOR GEOGRAPHIC ROUTING IN WIRELESS MULTIMEDIA SENS...csandit
Maintaining network stability and extending network lifetime to cope with breaking links and topology changes remain nowadays a unsolved issues in Wireless Multimedia Sensor Networks (WMSNs), which aim to ensure flow delivery while guaranteeing QoS requirements, particularly, during data transmission phase. Therefore, in this paper, we jointly consider multipath transmission, load balancing and fault tolerance, to enhance the reliability of transmitted data. We propose a Dynamic Curative Mechanism for Geographic Routing in WMSNs. Theoricals results and those obtained from simulation study demonstrate the validity and efficiency of our proposed mechanism, and indicate that it is highly advised for multimedia transmission and network stability
Simulation based Evaluation of a Simple Channel Distribution Scheme for MANETsIOSR Journals
This document presents a proposed multi-channel distribution scheme for mobile ad hoc networks (MANETs) and evaluates it through simulation. The proposed scheme assigns channels to nodes based on their node IDs to avoid control overhead from time synchronization. While neighboring nodes on the same channel is possible, the probability is low given random node distribution. The proposed scheme is compared to a single-channel scheme in ns-2 simulations. Results show the proposed technique has better performance.
MULTI-CLUSTER MULTI-CHANNEL SCHEDULING (MMS) ALGORITHM FOR MAXIMUM DATA COLLE...IJCNCJournal
Interference during data transmission can cause performance degradation like packet collisions in Wireless Sensor Networks (WSNs). While multi-channels available in IEEE 802.15.4 protocol standard WSN technology can be exploited to reduce interference, allocating channel and channel switching
algorithms can have a major impact on the performance of multi-channel communication. This paper presents an improved Fuzzy Logic based Cluster Formation and Cluster Head (CH) Selection algorithm with enhanced network lifetime for multi-cluster topology. The Multi-Cluster Multi-Channel Scheduling
(MMS) algorithm proposed in this paper improves the data collection by minimizing the maximum interference and collision. The presented work has developed Cluster formation and cluster head (CH) selection algorithm and Interference-free data communication by proper channel scheduled. The extensive
simulation and experimental outcomes prove that the proposed algorithm not only provides an interference-free transmission but also provides delay minimization and longevity of the network lifetime, which makes the presented algorithm suitable for energy-constrained wireless sensor networks.
INVESTIGATING THE EFFECTS OF THE COMMON CONTROL CHANNEL CHALLENGE IN MULTICHA...IJNSA Journal
Multichannel MAC protocols have become a design choice of wireless access networks as they increase the achievable throughput. However, the implementation of a common control channel has been a challenge. The common control channel challenge has not been investigated in opportunistic networks where the availability of medium is temporary and unpredictable. The uncertainty of the availability of the channel coupled with the common control channel challenge makes this area an interesting research topic. Unfortunately, this challenge requires further investigation in Cognitive Radio Ad Hoc Networks (CRAHN), a promising next generation technology. The challenge makes an interesting study in CRAHN given the opportunistic access and use of channels. Given a hypothetical spectrum hole of any size coupled with the implementation of a control channel in a multi-channel environment, how much of good put can be realized and be effectively utilized for data transmission. We investigate the common control channel challenge in CRAHN through network simulations. The opportunistic nature of CRAHNs in the presence of the common control channel challenge is investigated. The simulation results show that the combination of the control channel challenge and the size of the spectrum hole degrade gracefully the network. Furthermore, the size of the spectrum hole has a bearing on good put. The results show that a big hole improves performance. Unfortunately, the opportunistic attribute of CRAHNs does not guarantee desirable spectrum holes.
Investigating the effects of the common control channel challenge in multicha...IJNSA Journal
Multichannel MAC protocols have become a design choice of wireless access networks as they increase the
achievable throughput. However, the implementation of a common control channel has been a challenge.
The common control channel challenge has not been investigated in opportunistic networks where the
availability of medium is temporary and unpredictable. The uncertainty of the availability of the channel
coupled with the common control channel challenge makes this area an interesting research topic.
Unfortunately, this challenge requires further investigation in Cognitive Radio Ad Hoc Networks
(CRAHN), a promising next generation technology. The challenge makes an interesting study in CRAHN
given the opportunistic access and use of channels. Given a hypothetical spectrum hole of any size coupled
with the implementation of a control channel in a multi-channel environment, how much of good put can be
realized and be effectively utilized for data transmission. We investigate the common control channel
challenge in CRAHN through network simulations. The opportunistic nature of CRAHNs in the presence of
the common control channel challenge is investigated. The simulation results show that the combination of
the control channel challenge and the size of the spectrum hole degrade gracefully the network.
Furthermore, the size of the spectrum hole has a bearing on good put. The results show that a big hole
improves performance. Unfortunately, the opportunistic attribute of CRAHNs does not guarantee desirable
spectrum holes.
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.
PERFORMANCE ANALYSIS OF CHANNEL ACCESS MODEL FOR MAC IN RANDOMLY DISTRIBUTED ...IJCNCJournal
Medium Access control (MAC) is one of the fundamental problems in wireless sensor networks. The performance of wireless sensor network depends on it. The main objective of a medium access control method is to provide high throughput, minimize the delay, and conservers the energy consumption by avoiding the collisions. In this paper, a general model for MAC protocol to reduce the delay, maximize throughput and conserve the energy consumption in channel accessing in high density randomly distributed wireless sensor network is presented. The proposed model is simulated using MATLAB. The simulation results show that the average delay for sensors with sufficient memory is lower than sensors without
memory. Further, the throughput of the channel access method with memory is better than without memory.
Analysis of Rate Based Congestion Control Algorithms in Wireless TechnologiesIOSR Journals
The document analyzes various rate-based congestion control algorithms for wireless technologies. It finds that TCP Vegas performs better than other TCP variants in terms of delivery fraction and delay. However, TCP Vegas has a consistent window size. Congestion avoidance is more effective at resolving congestion and has higher throughput than slow start. Cross-layer congestion control requires significant power and memory. The document then analyzes the performance of AIMD, TFRC, and TCP congestion control protocols via simulation. It finds that GAIMD performs better than TFRC in terms of throughput, while TFRC is better than GAIMD in terms of smoothness.
MACHINE LEARNING BASED FRAME SIZE OPTIMIZATION IN WLAN DOWNLINK MU-MIMO CHANN...IJCNCJournal
This document summarizes a research paper that proposes a machine learning approach to optimize frame size in wireless local area networks (WLANs) using multi-user multiple-input multiple-output (MU-MIMO) transmission. The approach aims to maximize throughput while minimizing transmission delay. It collects data on frame sizes and system throughput under different conditions. A neural network is trained on this data to model throughput as a function of frame size. Gradient information from the neural network is then used to adaptively adjust the frame size to optimize throughput with minimum delay. The effectiveness of this adaptive, machine learning approach is evaluated under various traffic patterns, channel conditions, and number of stations.
Machine Learning based Frame Size Optimization in WLAN Downlink MU-MIMO Chann...IJCNCJournal
The key enhancement in the medium access control (MAC) layer is frame aggregation introduced by the IEEE 802.11n/ac standard to accommodate the growing traffic demand in the WLAN by allowing multiple packets aggregated per transmission. Frame aggregation efficiently reduces control overhead in the MAC layer, such as the MAC header and thus it helps to enhance transmission efficiency and throughput performance of WLAN. However, heterogeneous traffic demand among streams in the WLAN downlink MU-MIMO channel creates a challenge to efficiently utilize the benefits of frame aggregation. Transmission efficiency is also compromised during frame size setting determination because when a frame size is larger, the impact of the overhead frame can be lower, but they are also more vulnerable to transmission errors. Thus, this trade-off between maximizing frame size and minimizing overhead frames should be addressed by employing an adaptive frame aggregation technique to derive the optimal frame size that would maximize the throughput in WLAN downlink MU-MIMO channel. Moreover, when frame aggregation approach is employed, more frames must wait before transmission in a buffer which causes a delay in the performance of WLAN. Thus, analysing the trade-off between maximizing throughput and minimizing delay is a critical issue that should also be addressed to enhance the performance of WLAN. However, the majority of the existing adaptive aggregation algorithms in the WLAN downlink MU-MIMO channel are focused to maximize the throughput or minimize the delay. The main contribution of this paper is to propose a machine learning-based frame size optimization algorithm by extending our earlier approach in considering the cost of delay to maximize the system throughput of WLAN. The effectiveness of the proposed scheme is evaluated over the FIFO Baseline Approach and earlier conventional approaches under the effects of various traffic patterns, channel conditions, and the number of STAs.
Elastic hybrid MAC protocol for wireless sensor networks IJECEIAES
This document summarizes an article that proposes an elastic hybrid medium access control (MAC) protocol for wireless sensor networks. The protocol aims to improve performance for diverse quality of service requirements by dynamically adapting between contention-based CSMA/CA and scheduled TDMA transmission schemes depending on traffic conditions. It allows nodes to transmit using CSMA/CA for low traffic, reserves more slots for TDMA scheduling as traffic increases, and provides an emergency contention-free period at the start of frames for urgent data. Simulation results showed improved performance over typical protocols in terms of queue delay, packet delivery ratio, and frame drops. The proposed elastic hybrid approach aims to balance efficiencies across various QoS metrics by flexibly distributing the transmission strategies in response
The document proposes a multi-channel MAC protocol called MMDQS-MAC for wireless sensor networks. It aims to improve network performance by selecting the best channel for each sensor node and supporting dynamic channel assignment. MMDQS-MAC is designed to decrease collision probability, interference, and improve throughput, energy efficiency, packet delivery ratio, and end-to-end delay. It analyzes the performance of MMDQS-MAC through mathematical modeling and simulation.
Multihop Multi-Channel Distributed QOS Scheduling MAC Scheme for Wireless Sen...IOSR Journals
This document proposes a Multihop Multi-Channel Distributed QoS Scheduling MAC scheme (MMDQS-MAC) to improve the performance of wireless sensor networks. MMDQS-MAC supports dynamic channel assignment where each sensor node is equipped with a directional antenna. It aims to decrease collisions and interference, improve overall network performance, and is suitable for low traffic networks. Simulation results show that MMDQS-MAC improves aggregate throughput, transmission success rate, packet delivery ratio, energy efficiency, and end-to-end delay.
PERFORMANCE ANALYSIS OF WIRELESS MESH NETWORK USING ADAPTIVE INFORMANT FACTOR...IJCSES Journal
Wireless mesh network (WMN) has become an important leading technology which provides several types of useful applications such as community network, broadband home network and internet access, etc. The rise in the size of users in WMN has created a degradation of efficiency in a network especially in dense areas due to the clumsy channel allocation and hence creating many challenges for enhancing the users experience, network quality and throughput. Therefore in this paper, we proposed OCA based AIF model that can access the channel information and then it process to improve the RF channel association. The proposed OCA-AIF will function for each period when some interference is detected via AIF and we further extend this analysis by taking in to consideration the influence of interference to provide a high quality indicator in network. The analysis of result shows the optimization by our proposed approach which increases as per the increment of relay nodes (RNs).
A CROSS-LAYER BASED SCALABLE CHANNEL SLOT RE-UTILIZATION TECHNIQUE FOR WIRELE...cscpconf
Due to tremendous growth of the wireless based application services are increasing the demand for wireless communication techniques that use bandwidth more effectively. Channel slot reutilization in multi-radio wireless mesh networks is a very challenging problem. WMNs have been adopted as back haul to connect various networks such as Wi-Fi (802.11), WI-MAX (802.16e) etc. to the internet. The slot re-utilization technique proposed so far suffer due to high collision due to improper channel slot usage approximation error. To overcome this here the author propose the cross layer optimization technique by designing a device classification based channel slot re-utilization routing strategy which considers the channel slot and node information from various layers and use some of these parameters to approximate the risk involve in channel slot re-utilization in order to improve the QoS of the network. The simulation and analytical results show the effectiveness of our proposed approach in term of channel slot re-utilization efficiency and thus helps in reducing latency for data transmission and reduce
channel slot collision.
Channel Aware Mac Protocol for Maximizing Throughput and FairnessIJORCS
The proper channel utilization and the queue length aware routing protocol is a challenging task in MANET. To overcome this drawback we are extending the previous work by improving the MAC protocol to maximize the Throughput and Fairness. In this work we are estimating the channel condition and Contention for a channel aware packet scheduling and the queue length is also calculated for the routing protocol which is aware of the queue length. The channel is scheduled based on the channel condition and the routing is carried out by considering the queue length. This queue length will provide a measurement of traffic load at the mobile node itself. Depending upon this load the node with the lesser load will be selected for the routing; this will effectively balance the load and improve the throughput of the ad hoc network.
ENERGY EFFICIENT MULTICAST ROUTING IN MANET ijac journal
In this paper, we have presented the Modified Multicasting through Time Reservation using Adaptive
Control for Excellent Energy efficiency (MMC-TRACE). It is a real time multicasting architecture for
Mobile Ad-Hoc networks to make their work an energy efficient one .MMC-TRACE is a cross layer design
where the network layer and medium access control layer functionality are done in a single integrated
layer design. The basic design of the architecture is to establish and maintain an active multicast tree
surrounded by a passive mesh within a mobile ad hoc network. Energy efficiency is maximized by enabling
the particular node from sleep to awake mode while the remaining nodes of the same path are maintained
at sleep mode. Energy efficiency too achieved by eliminating most of the redundant data receptions across
nodes. The performance of MMC-TRACE are evaluated with the help of ns-2 simulations and comparisons
are made with its predecessor such as MC-TRACE. The results show that the MMC-TRACE provides
superior energy efficiency, competitive QoS performance and bandwidth efficiency.
The document describes an opportunistic packet scheduling and media access control (OSMA) protocol for wireless LANs and multi-hop ad hoc networks. The OSMA protocol aims to alleviate the head-of-line blocking problem and exploit multiuser diversity by allowing a node to schedule transmissions to receivers with good channel conditions. The key mechanisms of OSMA are multicast RTS frames containing a list of candidate receivers, and priority-based CTS frames where the receiver with the best channel and highest priority replies first to avoid collisions. Simulation results show the OSMA protocol can significantly improve network throughput while maintaining fairness between links.
IRJET- Reliable Transmission of Packets using Multiple ChannelsIRJET Journal
This document summarizes research on reliable transmission of packets using multiple channels. It discusses how the presence of time-varying channels and reconfiguration delays reduces network stability and optimal policies. Frame-based dynamic control and myopic policies are proposed to provide throughput-optimal network control despite delays. Simulation results show memory in channels can be exploited to improve stability region and throughput compared to memoryless channels. The work aims to stabilize networks using scheduling policies and Markov decision processes to achieve higher throughput with reduced delays.
Similar to Addressing the Multichannel Selection, Scheduling and Coordination Cost (20)
Performance Evaluation of Vehicular Ad Hoc Network (Vanet) Using Clustering A...pijans
Vehicular ad hoc networks (VANETS) have actually attracted a lot of attention over the last few years as
being used to improve road safety. In this paper, cluster based technique has been introduced in VANET.
As VANET is a new form of MANET, so with this cluster based technique in VANET, several handoff
problems have been removed, which were actually difficult to remove in MANET. For this traffic
infrastructure cluster based routing has been used, with two routing protocols i.e. AODV and AODV+. The
network simulator NS2 has been used for removing unpredictable movements that may arise in the network.
An Optimized Mechanism for Adaptive and Dynamic Policy Based Handover in Clus...pijans
On-going revolution in ever-improving wireless communication enforces the necessity of a self configuring,
rapidly deployable and infrastructure less network. MANET is such an autonomous wireless network that
meets the requirements. At the same time MANET’s random behavior and absence of any central
intelligence to gather unambiguous knowledge about user contexts complexes QoS maintenance and
hampers proper utilization of network resources resulting into unnecessary handovers. In past, few policy
driven handover approaches have been proposed for MANET but none of them explores a comprehensive
policy design. Therefore in this paper we propose an adaptive and optimized policy based handover
mechanism which is based on explicitly designed policies like load balancing, service discovery and next
hop selection .Efficient procedures for these policies are also explored .This work predicts the high time of
handover need on the basis of application specific needs of individual freely roaming mobile nodes,
avoiding unnecessary handovers and provides efficient handover procedure with optimized resource
consumption, reduced latency and interruption time.
An Efficient Routing Protocol for Mobile Ad Hoc Network for Secured Communica...pijans
Security and reliable communication is challenging task in mobile Ad Hoc network. Through mobility of network device compromised with attack and loss of data. For the prevention of attack and reliable communication, various authors proposed a method of secured routing protocol such as SAODV and SBRP (secured backup routing protocol). The process of these methods work along with route discovery and route maintains, discovery and route maintained needed more power consumption for that process. The power of devices is decrease during such process and network lifetimes expire. In this paper, we modified the secured stateless protocol for secured routing and minimized the utilization of power during path discovering and establishment. For the authentication of group node used group signature technique and sleep mode threshold concept for power minimization. Our proposed technique is simulated in ns-2 and compare to other routing protocol gives a better performance in comparison to energy consumption and throughput of network.
As-Puma : Anycast Semantics In Parking Using Metaheuristic Approachpijans
The number of vehicle used in the world are increasing day by day resulting in the obvious problem of
parking of these vehicle’s in residential and vocational areas. We perceive the problem of vehicles parking
in vocational establishments / malls. Today majority of parking systems are manual parking systems where
in, on the spot, parking of the vehicle is done and a parking slip is generated and handed over to customer.
This is cumbersome technique wherein various parking attendants in the parking areas manually keeps on
informing the Parking inspector on how many free parking slots available so that only that many number of
parking slips/tickets are generated as the number of free parking slots. We address the problem of parking
in Delay Tolerant Network (DTN) by proposing metaheuristic driven approach of Ant Colony optimization
(ACO) technique with anycast semantics models . Here we propose the parking architecture to solve the
problem of parking especially in commercial areas with their design diagrams . In this architecture we
apply the delivery model to deliver the packet correctly to the intended receiver. Using this we can book
various parking’s through remote areas so that the customer can get the information about availability of
various parking’s inside an area and the parking fare for each category of the automobile. Using this
architecture the customer can get the prior knowledge about various vacant parking slots inside a parking
area and he can book the corresponding parking from his location.
A Survey of Enhanced Routing Protocols for Manetspijans
Mobile Ad Hoc Networks (MANETs) form a class of dynamic multi-hop networks consisting of a set of
mobile nodes that intercommunicate on shared wireless channels. MANETs are self-organizing and selfconfiguring multi-hop wireless networks, where the network structure changes dynamically due to the node
mobility. There exists no fixed topology due to the mobility of nodes, interference, multipath propagation
and path loss. Hence efficient dynamic routing protocols are required for these networks to function
properly. Many routing protocols have been developed to accomplish this task. In this paper we survey
various new routing protocols that have been developed as extensions or advanced versions of previously
existing routing protocols for MANETs such as DSR, AODV, OLSR etc.
Black Hole Attack Prevention Using Random Dispersive Routing for Mobile Adhoc...pijans
Mobile Adhoc Networks is a wireless network and it has become an important technology in current years
in which security has become an important problem. Black hole Attack is one of the promising and severe
security attacks in mobile ad hoc networks which block the communication of secret data during packet
delivery. Black hole attack directly attacks the node’s data traffic on the path and with intent drops, alters
or delays the data traffic passing through that node. In other type of black hole attack which misleadingly
replies for the route request which comes from the node which initiates the route discovery process that it
has as much as necessary routes to the destination even it does not have path to the destination. This paper
deals with prevention of black hole attacks using Shamir’s secret sharing and Random Multipath Routing
Algorithm
Performance Analysis of Mtpr Routing Protocol in Power Deficient Nodepijans
Power conservation in Mobile Ad hoc Network (MANET) is a major challenge even today for researchers.
To conserve it various power aware routing protocols have been proposed. These protocols do not take into
consideration the residual power left in nodes. To find the impact of the same a simulator was designed in
MATLAB-7.01. The routing protocol used in our simulation is Minimum Total Power Routing (MTPR) and
different performance metrics such as path optimality, throughput and hop count were recorded in
presence and absence of power scarce node. The result shows significant impact of power scarce node on
MANET performance.
Path Duration Analysis in Vehicular Ad Hoc Networkpijans
In Vehicular Ad hoc Networks (VANETs) the mobility of the nodes is the main concern. This mobility of
nodes makes the route unstable and unreliable for the information exchange and communication between
two nodes in the network. To enhance the performance and throughput of the VANETs, routes between
nodes must be reliable and stable. In this paper, we study the significance of path duration and link
duration in Vehicular Ad hoc Networks (VANETs). Because of this mobility, connectivity graphs changes
very frequently and it affects the performance of VANETs. Therefore, path duration can be used to predict
the behaviour of the mobile nodes in the network. Estimation of the path duration in VANETs can be a key
factor to improve the performance of the routing protocol. Estimation of path duration is a challenging task
to perform as it depends on many parameters including node density, transmission range, numbers of hops,
and velocity of nodes. This paper will provide a comprehensive study for estimating the path duration in
VANETs.
Study of Various Schemes for Link Recovery in Wireless Mesh Networkpijans
As there is a growing need for the cost effective and highly dynamic large-bandwidth networks over large
coverage area , the Wireless Mesh Network provide first step towards effective communication. A Wireless
Mesh Network is one of the most advanced wireless network used for communication. During their
operating period , the wireless mesh network may suffer from frequent link failure which results in poor
performance of network. Link failure detection plays crucial role in performance of WMN. The proposed
paper presents the review of various techniques used for detection of link failure and the techniques used
for recovery of wireless mesh network.
A Survey on Security Issues to Detect Wormhole Attack in Wireless Sensor Networkpijans
Sensor nodes, when deployed to form Wireless sensor network operating under control of central authority
i.e. Base station are capable of exhibiting interesting applications due to their ability to be deployed
ubiquitously in hostile & pervasive environments. But due to same reason security is becoming a major
concern for these networks. Wireless sensor networks are vulnerable against various types of external and
internal attacks being limited by computation resources, smaller memory capacity, limited battery life,
processing power & lack of tamper resistant packaging. This survey paper is an attempt to analyze threats
to Wireless sensor networks and to report various research efforts in studying variety of routing attacks
which target the network layer. Particularly devastating attack is Wormhole attack- a Denial of Service
attack, where attackers create a low-latency link between two points in the network. With focus on survey of
existing methods of detecting Wormhole attacks, researchers are in process to identify and demarcate the
key research challenges for detection of Wormhole attacks in network layer.
This document is Intended for the purpose of Enabling the power of social media to Empower Ridesharing.
this entails the creation of an ad-ridesharing Initiative with a view to tackling real-world problems such as
traffic congestion and the ever-increasing fuel prices. The main objectives include creating applications,
both web and mobile based, to seamlessly integrate the app’s functionality into and everyday user’s
routine.
Performance Analysis of Improved Autonomous Power Control Mac Protocol (IAPCM...pijans
Power Control in Mobile Ad Hoc networks is a critical issue, since nodes are powered by batteries.The
main idea of power control schemes is to use different power levels for RTS/CTS and DATA/ACK. These
schemes may degrade network throughput and reduce energy efficiency of the network. In this paper we
have evaluated the performance of Improved Autonomous Power Control MAC Protocol (IAPCMP),that
allows nodes to dynamically adjust power levels for transmission of DATA/ACK according to the distance
between the transmitter and its neighbors.In IAPCMP power level for transmission of RTS/CTS is also
adjustable. This also used maximum power level for transmitting DATA/ACK periodically to make
neighboring nodes aware about ongoing transmission. The performance of IAPCMP is evaluated through
the metrics namely, packet delivery ratio and rate of energy efficiency.The simulation results show
significant improvement in protocol.
A Survey of Using Directional Antennas in Ad Hoc Networkspijans
In this paper, we present a comprehensive overview on Ad hoc networking by directional antennas. Use of
Directional antennas can largely reduce the interference, increase the spatial reuse and due to their longer
range we can have routes with fewer hop for two distant nodes. However the main problem of using
directional antennas in Ad hoc networks is due to the dynamic nature of the network. Neighbour discovery,
maintenance the track of moving neighbours, exploitation of the benefit of long range and directional MAC
protocols are the most challenging issues. We present three Directional MAC protocols and two
combinational protocols and system which give solutions to MAC and Neighbour discovery and compare
the throughput of them with 802.11 with omnidirectional antennas.
Wireless Evolution: IEEE 802.11N, 802.11AC, and 802.11AX Performance Comparisonpijans
The widespread adoption of IEEE 802.11 WLANs is attributed to their inherent mobility, flexibility, and
cost-effectiveness. Within the IEEE 802 working group, a dedicated task group is diligently advancing
WLAN technologies, particularly tailored for dense network scenarios. Amidst these advancements, the
802.11ac protocols have emerged as a preferred choice, delivering superior data transfer rates compared
to the preceding 802.11n standard. Significantly, the sixth-generation wireless protocol, IEEE 802.11ax,
has been introduced, showcasing enhanced performance capabilities that outpace its fifth-generation
predecessor, 802.11ac.In this pioneering investigation, we engage in an in-depth simulation-based scrutiny
of prominentWLAN protocols—namely, IEEE 802.11n, IEEE 802.11ac, and the cutting-edge IEEE
802.11ax. Our exhaustive analyses traverse a spectrum of critical metrics, encompassing throughput,
coverage, spectral efficiency, Tx/Rx gain, and Tx/Rx power.In a single-user and SISO scenario, both
802.11ac and 802.11ax outperform 802.11n. Significantly, 802.11ax surpasses the previous 802.11n/ac
standards, highlighting substantial advancements in wireless performance.
Performance Improvement of Multiple Connections in AODV with the Concern of N...pijans
Mobile Ad-hoc Networks (MANETS) consists of a collection of mobile nodes without having a central
coordination. In MANET, node mobility and dynamic topology play an important role in the performance.
MANET provide a solution for network connection at anywhere and at any time. The major features of
MANET are quick set up, self organization and self maintenance. Routing is a major challenge in MANET
due to it’s dynamic topology and high mobility. Several routing algorithms have been developed for
routing. This paper studies the AODV protocol and how AODV is performed under multiple connections in
the network. Several issues have been identified. The bandwidth is recognized as the prominent factor
reducing the performance of the network. This paper gives an improvement of normal AODV for
simultaneous multiple connections under the consideration of bandwidth of node.
An Efficient Call Admission Control Scheme for Handling Handoffs in Wireless ...pijans
Personal Communication Network (PCN) is an emerging wireless network that promises many new
services for the telecommunication industry. The proliferation of demands for extending wireless services
to integrated services, which supports the transmission of data and multimedia information, has resulted in
the need for broadband wireless systems that are able to provide service capabilities similar to those of
wire line networks. The ATM cell - relay paradigm is one possible approach to provide broadband wireless
transmission with PCN’s using the ATM switching networks for interconnection of PCN cells. As traffic in
these mobile cellular networks increases, Handoffs will become an increasingly important issue. As cell
sizes shrink to accommodate an increasingly large demand of services, newer more efficient handoff
schemes need to be used. 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.
Design and Implementation of Low-Cost Electric Vehicles (EVs) Supercharger: A...pijans
This article presents a probabilistic modeling method utilizing smart meter data and an innovative agentbased simulator for electric vehicles (EVs). The aim is to assess the effects of different cost-driven EV charging strategies on the power distribution network (PDN). We investigate the effects of a 40% EV adoption on three parts of Frederiksberg's low voltage distribution network (LVDN), a densely urbanized municipality in Denmark. Our findings indicate that cable and transformer overloading especially pose a challenge. However, the impact of EVs varies significantly between each LVDN area and charging scenario. Across scenarios and LVDNs, the share of cables facing congestion ranges between 5% and 60%. It is also revealed that time-of-use (ToU)-based and single-day cost-minimized charging could be beneficial for LVDNs with moderate EV adoption rates. In contrast, multiple-day optimization will likely lead to severe congestion, as such strategies concentrate demand on a single day that would otherwise be distributed over several days, thus raising concerns about how to prevent it. The broader implications of our research suggest that, despite initial worries primarily centered on congestion due to unregulated charging during peak hours, a transition to cost-based smart charging, propelled by an increasing awareness of time-dependent electricity prices, may lead to a significant rise in charging synchronization, bringing about undesirable consequences for the power distribution network (PDN).
Design and Implementation of Low-Cost Electric Vehicles (EVs) Supercharger: A...pijans
This article presents a probabilistic modeling method utilizing smart meter data and an innovative agentbased simulator for electric vehicles (EVs). The aim is to assess the effects of different cost-driven EV
charging strategies on the power distribution network (PDN). We investigate the effects of a 40% EV
adoption on three parts of Frederiksberg's low voltage distribution network (LVDN), a densely urbanized
municipality in Denmark. Our findings indicate that cable and transformer overloading especially pose a
challenge. However, the impact of EVs varies significantly between each LVDN area and charging
scenario. Across scenarios and LVDNs, the share of cables facing congestion ranges between 5% and
60%. It is also revealed that time-of-use (ToU)-based and single-day cost-minimized charging could be
beneficial for LVDNs with moderate EV adoption rates. In contrast, multiple-day optimization will likely
lead to severe congestion, as such strategies concentrate demand on a single day that would otherwise be
distributed over several days, thus raising concerns about how to prevent it. The broader implications of
our research suggest that, despite initial worries primarily centered on congestion due to unregulated
charging during peak hours, a transition to cost-based smart charging, propelled by an increasing
awareness of time-dependent electricity prices, may lead to a significant rise in charging synchronization,
bringing about undesirable consequences for the power distribution network (PDN).
Multilayer Perceptron Guided Key Generation through Mutation with Recursive R...pijans
In this paper, a multilayer perceptron guided key generation for encryption/decryption (MLPKG) has been
proposed through recursive replacement using mutated character code generation for wireless
communication of data/information. Multilayer perceptron transmitting systems at both ends accept an
identical input vector, generate an output bit and the network are trained based on the output bit which is
used to form a protected variable length secret-key. For each session, different hidden layer of multilayer
neural network is selected randomly and weights or hidden units of this selected hidden layer help to form
a secret session key. The plain text is encrypted using mutated character code table. Intermediate cipher
text is yet again encrypted through recursive replacement technique to from next intermediate encrypted
text which is again encrypted to form the final cipher text through chaining , cascaded xoring of multilayer
perceptron generated session key. If size of the final block of intermediate cipher text is less than the size of
the key then this block is kept unaltered. Receiver will use identical multilayer perceptron generated
session key for performing deciphering process for getting the recursive replacement encrypted cipher text
and then mutated character code table is used for decoding. Parametric tests have been done and results
are compared in terms of Chi-Square test, response time in transmission with some existing classical
techniques, which shows comparable results for the proposed technique.
Performance Analysis of Mobile Adhoc Network Routing Protocols Over Tcppijans
In order to reduce the communication cost and time we are looking forward for successful implementation
of an infrastructure less network like Mobile Ad Hoc Network in all arena of wireless mobile
communication. But still it is a challenge to decide a most appropriate routing protocol for MANET. In
MANET there is no fixed topology due to the mobility of nodes, interference, multipath propagation and
path loss. Since MANET does not use fixed infrastructure rather it always have to find suitable router and
routing path for each communication, existing established routing protocol is not suitable for MANET to
function properly. Different Routing protocols have been proposed to meet the challenges with MANETs.
This paper evaluates the performances of four MANET routing protocols which are DSDV, AODV, DSR
and TORA over TCP, a Transport Layer Protocol. The performance metrics which are considered in this
paper are packet delivery fractions, normalized routing overload, end to end delay and throughput. DSDV
is a proactive protocol and the others are reactive protocols.
Low power architecture of logic gates using adiabatic techniquesnooriasukmaningtyas
The growing significance of portable systems to limit power consumption in ultra-large-scale-integration chips of very high density, has recently led to rapid and inventive progresses in low-power design. The most effective technique is adiabatic logic circuit design in energy-efficient hardware. This paper presents two adiabatic approaches for the design of low power circuits, modified positive feedback adiabatic logic (modified PFAL) and the other is direct current diode based positive feedback adiabatic logic (DC-DB PFAL). Logic gates are the preliminary components in any digital circuit design. By improving the performance of basic gates, one can improvise the whole system performance. In this paper proposed circuit design of the low power architecture of OR/NOR, AND/NAND, and XOR/XNOR gates are presented using the said approaches and their results are analyzed for powerdissipation, delay, power-delay-product and rise time and compared with the other adiabatic techniques along with the conventional complementary metal oxide semiconductor (CMOS) designs reported in the literature. It has been found that the designs with DC-DB PFAL technique outperform with the percentage improvement of 65% for NOR gate and 7% for NAND gate and 34% for XNOR gate over the modified PFAL techniques at 10 MHz respectively.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODELgerogepatton
As digital technology becomes more deeply embedded in power systems, protecting the communication
networks of Smart Grids (SG) has emerged as a critical concern. Distributed Network Protocol 3 (DNP3)
represents a multi-tiered application layer protocol extensively utilized in Supervisory Control and Data
Acquisition (SCADA)-based smart grids to facilitate real-time data gathering and control functionalities.
Robust Intrusion Detection Systems (IDS) are necessary for early threat detection and mitigation because
of the interconnection of these networks, which makes them vulnerable to a variety of cyberattacks. To
solve this issue, this paper develops a hybrid Deep Learning (DL) model specifically designed for intrusion
detection in smart grids. The proposed approach is a combination of the Convolutional Neural Network
(CNN) and the Long-Short-Term Memory algorithms (LSTM). We employed a recent intrusion detection
dataset (DNP3), which focuses on unauthorized commands and Denial of Service (DoS) cyberattacks, to
train and test our model. The results of our experiments show that our CNN-LSTM method is much better
at finding smart grid intrusions than other deep learning algorithms used for classification. In addition,
our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
accuracy rate of 99.50%.
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
Harnessing WebAssembly for Real-time Stateless Streaming PipelinesChristina Lin
Traditionally, dealing with real-time data pipelines has involved significant overhead, even for straightforward tasks like data transformation or masking. However, in this talk, we’ll venture into the dynamic realm of WebAssembly (WASM) and discover how it can revolutionize the creation of stateless streaming pipelines within a Kafka (Redpanda) broker. These pipelines are adept at managing low-latency, high-data-volume scenarios.
ACEP Magazine edition 4th launched on 05.06.2024Rahul
This document provides information about the third edition of the magazine "Sthapatya" published by the Association of Civil Engineers (Practicing) Aurangabad. It includes messages from current and past presidents of ACEP, memories and photos from past ACEP events, information on life time achievement awards given by ACEP, and a technical article on concrete maintenance, repairs and strengthening. The document highlights activities of ACEP and provides a technical educational article for members.
Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
This paper describes a speed control device for generating electrical energy on an electricity network based on the doubly fed induction generator (DFIG) used for wind power conversion systems. At first, a double-fed induction generator model was constructed. A control law is formulated to govern the flow of energy between the stator of a DFIG and the energy network using three types of controllers: proportional integral (PI), sliding mode controller (SMC) and second order sliding mode controller (SOSMC). Their different results in terms of power reference tracking, reaction to unexpected speed fluctuations, sensitivity to perturbations, and resilience against machine parameter alterations are compared. MATLAB/Simulink was used to conduct the simulations for the preceding study. Multiple simulations have shown very satisfying results, and the investigations demonstrate the efficacy and power-enhancing capabilities of the suggested control system.
We have compiled the most important slides from each speaker's presentation. This year’s compilation, available for free, captures the key insights and contributions shared during the DfMAy 2024 conference.
Addressing the Multichannel Selection, Scheduling and Coordination Cost
1. International Journal on AdHoc Networking Systems ( IJANS) Vol. 5, No. 2, April 2015
DOI : 10.5121/ijans.2015.5201 1
ADDRESSING THE MULTICHANNEL
SELECTION, SCHEDULING AND
COORDINATION COST
Mthulisi Velempini1
and Mqhele E. Dlodlo2
1
University of Limpopo , South Africa
2
University of Cape Town , South Africa
Abstract
We discuss a new multichannel coordination and scheduling challenge called the Multichannel Scheduling
Cost (MSC). It is caused by the inability of the control channel to schedule simultaneous transmissions
resulting in data channels lying idle and their bandwidth underutilized. As a result, wasted bandwidth
increases as the number of data channels increases. To address this challenge, a cyclic scheduling
Algorithm (CSA) is proposed. It employs one dedicated signaling channel and 4 data channels. It is
premised on a proactive channel reservation scheme which reduces the idleness of channels. The scheme
ensures that data channels are reserved while they are still busy. The data channels are reserved while
their remaining transmission duration is equal to the virtual carrier sensing duration. This gives the next
pair sufficient time to reserve the current data channel before it becomes available, limiting the MSC to the
first cycle. The simulation results show a performance benefit of the CSA scheme in addressing the effects
of the MSC.
Keywords: Bandwidth Utilization; Connectivity; Control channel; Multichannel Scheduling Cost
1.0 Introduction
The implementation of multichannel MAC protocols in Wireless Mesh Networks (WMN) has
generated some encouraging results, which increases network capacity and throughput. However,
there are still outstanding challenges which degrade the capacity of multichannel networks. For
example, the channel assignment, selection and coordination strategies result in the creation of a
new multichannel degradation challenge we call the Multichannel Scheduling Cost (MSC). MSC
wastes the capacity of data channels during the reservation phase. Data channels remain idle for
long durations waiting for their turns to be reserved, resulting in the underutilization of their
capacity. The amount of wasted bandwidth increases linearly as the number of data channels
increases. Furthermore, the MSC challenge is recurring and repetitive. To address this challenge,
we propose a proactive data channel reservation scheme which addresses the MSC and improves
the utilization of data channels. The scheme reduces the idle durations of data channels while
improving their capacity.
Data channels are reserved in phases. The first channel to be reserved in the first cycle suffers the
least degradation caused by the MSC, while the last data channel suffers the worst degradation.
The adverse effect of the MSC increases as the number of data channels increases. The MSC is a
scheduling challenge is addressed in this paper through the implementation of a proactive
scheduling scheme which limits the MSC to the first cycle, thereby improving the performance of
multichannel MAC protocols.
2. International Journal on AdHoc Networking Systems ( IJANS) Vol. 5, No. 2, April 2015
2
The MSC interference challenge affects the multichannel MAC protocols which implement
control channel coordination schemes. Besides the perceived performance benefits of the control
channel schemes, they give rise to the MSC. We characterize and demonstrate the impact of the
MSC on network performance. A proposed MSC solution is presented and evaluated through
network simulations. The results show an improvement in the performance of the network.
The scheme is implemented in a backhaul of static mesh routers equipped with intelligence. The
word intelligence in this context means the ability of the network to acquire knowledge of the
network status, to facilitate distributed decision-making, to aid data channel reservation. The
number of channels was not changed in the simulation environment.
The paper is structured as follows: The next Section justifies the implementation of a common
signaling channel. Section 3 discusses related work. The system model is discussed and analyzed
in Section 4 and 5 respectively. The simulation environment is presented in Section 6 and the
results are analyzed in Section 7. Section 8 summarizes the paper.
2.0 Motivation
Multichannel MAC schemes implementing a common control channel have been designed. The
protocols show a significant improvement in network performance and they offer reasonable
capacity. However, their implementations have given rise to a new multichannel scheduling cost.
The MSC has not been addressed in literature. It is a challenge which degrades network
performance.
The use of multi-channels avail more bandwidth which is a requirement of the next generation
networks however, channel selection, access and coordination remains a challenge. Channel
coordination challenges result in the degradation of bandwidth. This challenge is evident in MSC
in which a number of channels remain idle while they wait for the active channel to finish its
transmission. Furthermore, channels are accessed in turns, one at a time successively leading to
repetitive cycles of bandwidth wastage. A scheduling algorithm which reduces either the idle
duration of channels or which addresses these idle slots is required. In this paper, an algorithm
which restricts the idleness of channel to the first cycle and eliminates them in the successive
cycles is presented
3.0 Related Work
Multichannel MAC protocols which employ a single transceiver and a control channel, which is
reserved for signaling, are examined. The impact of the MSC on network performance is
highlighted. The emphasis is on the MSC challenge and how it degrades the capacity of
multichannel MAC protocols.
The scheme in [1] employs a temporary control channel called the quiescent channel. The
protocol makes use of a dedicated busy tone channel to coordinate data channels access to
prevent data collision. The busy tone channel wastes bandwidth, though it does not give rise to
the MSC challenge it requires optimization.
The second algorithm proposed in [1] which divides a communication session into control and
data windows is subjected to the effects of the MSC. The MSC is experienced during the control
window. Given that the control window precedes any communication, the effects of the MSC are
recurring. Lastly, during the data window there is no manifestation of the MSC. All the channels
are utilized during the data window.
3. International Journal on AdHoc Networking Systems ( IJANS) Vol. 5, No. 2, April 2015
3
The protocol utilizes only one channel during the control window sessions. The data channels lie
idle and their bandwidth is wasted. It allows more than one pair of nodes to reserve one data
channel thereby worsening the effects of the MSC when nodes take turns to transmit on the
reserved data channels.
In [2], a window based scheme is proposed. Data channels are reserved during ATIM window
through the default channel. One data channel can be reserved by many nodes, which later
contend to access it during the data window. The scheme is similar to the one described above
however, the implementation of the virtual carrier sensing (VCS) results in the worst case of the
MSC which is repetitive both during the ATIM and the data windows. The two forms of MSC are
experienced degrading the network performance significantly.
A window based scheme which implements a temporary control channel is also proposed in [3].
The protocol consists of a contention reservation interval (CRI) and the contention free interval
(CFI). Terminals contend for data channels during the CRI and then defer their transmissions
until the start of the CFI. The deferment of transmission and the reservation of channels during
the CRI give rise to the MSC challenge.
The protocol proposed in [4] implements the concept of home channels instead of a control
channel. The implementation of the home channels addresses the MSC at the cost of partitioning
the network and lack of reach.
In [5], a single transceiver Multichannel MAC protocol which implements contention and data
windows is proposed. A three way channel reservation handshake is implemented with an
additional control packet called the Multichannel CTS Recognition (MCTS-R). The increasing
control packets worsen the effects of the MSC. Furthermore, the data channels are not used
during the control window and they are reserved in phases sequentially resulting in the
manifestation of the MSC challenge.
The Group Allocation Multi hop Multiple Access (GAMMA) proposed in [6] implements
multiple transmission channels. Each transmitter has a unique channel which reduces the effects
of the MSC. The process of realigning data slots, the management of group membership,
registration and de-registration procedures however, worsens the MSC.
The protocol proposed in [7] introduces the idea of distributed information sharing to ensure that
communicating pairs do not make independent decisions. The proposed protocol does implement
a dedicated control channel however; it is optimized to solve the terminal deafness problem and
collisions in the data channels. The protocol introduces up to six control packets which worsens
the impact of the MSC which is repetitive.
In [8] a Distributed Queue Dual Channel (DQDC) scheme is proposed. The DQDC scheme
introduces 4 control packets which increases the idle durations of the data channels which in turn
worsens the impact of the MSC challenge.
In [9] a scheme which implements a control channel and N traffic channels is presented. A node
first senses all the data channels including the control channel before it sends an RTS packet.
Both the transmitter and the receiver sense all the channels which increases the MSC. The effects
of the MSC have been worsened by an increase in the size of control packets.
In [10], an asynchronous Multichannel Coordination Protocol (AMCP) is proposed. The protocol
employs a single transceiver and a dedicated common control channel. Bandwidth is wasted when
the preferred channel of the sender is rejected by the receiver. The sender has to select randomly
the receiver’s suggested data channels and restarts the contention cycle. Furthermore, control
4. International Journal on AdHoc Networking Systems ( IJANS) Vol. 5, No. 2, April 2015
4
packets have increased in size. In addition, a new control packet, the Reserve (RES) has been
introduced. Bandwidth is further degraded as nodes attempt to reserve data channels more than
once. All these configurations contribute to the worst case of the MSC challenge.
In [11], a busy tone scheme is proposed. The scheme assumes that nodes can transmit and receive
simultaneously. A channel is divided into two sub channels, a data and a control channel. Busy
tone signals are transmitted on the control channel. The data channels are not used during data
channel reservation, which results in the MSC challenge.
In general, multichannel MAC protocols outperform single channel MAC protocols as
demonstrated in [12], [13]. The multichannel schemes have been investigated in cognitive
networks with a measure of success [14], [15]. They have also been implemented in vehicular ad
hoc networks [16], in wireless sensor networks [17], [18], [19], [20] and in general ad hoc
networks [21], [22], [23], [24], and [25]. This shows that multichannel technique is a promising
approach requiring further investigation.
4.0 System Model
In this section, we discuss the architectural design ideal for the implementation of the MSC
solution. The architecture is memory based which is equipped with nodes with sufficient network
status to facilitate the reservation of data channels.
The architecture is equipped with a network of mesh routers deployed in the ad hoc network of
mesh clients. The mesh routers are networked to facilitate communication within the network of
mesh clients. The architecture is configured such that each mesh router is within the transmission
range of the next mesh router. The mesh routers store network status information which is shared
with mesh clients to support their medium access and scheduling decisions. The proposed
architecture is depicted in Fig 1. The architecture consists of routers enclosed in blue lines. All
the Mobile nodes are assumed to be within the coverage of the network of mesh routers. The
network of support mesh routers provides a support layer to the mesh architecture.
The network support mesh routers maintain a data structure we call a Network Status Table
(NST) which is updated using overheard control packets. The network support nodes are referred
to as the Network Status Table Nodes (NSTN). The NSTNs store information on the availability
of data channels, the list of in use data channels and the duration of their unavailable – the inter-
phase time. A data channel is available when its remaining transmission time is equal to the VCS
duration of the next pair. The remaining time is determined by a hold off duration - the inter-
phase time technique which allows data channels to be reserved in a proactive manner.
5. International Journal on AdHoc Networking Systems ( IJANS) Vol. 5, No. 2, April 2015
5
Fig 1. The architecture of the proposed network support infrastructure in a hybrid mesh network
A new inter-frame space known as the inter-phase replaces the DIFS ensures cyclical
transmission of data. It is a proactive scheme which facilitates the reservation of data channels
before they finish their current transmission, effectively reducing the idleness of data channels
between the phases. The reduction of the idleness of data channels reduces the effects of the
MSC. When data channels finish their transmission in the previous phase while waiting for their
turn in the next phase to be reserved, they lie idle for long durations impacting negatively on the
efficiency of the protocol which results in MSC. Given our proactive scheme, the wait period is
reduced significantly which addresses the effects of the MSC.
A data channel is reserved when the inter-phase time has expired and nodes use the CSMA/CA to
contend for the control channel. The inter-phase replaces the DIFS implemented in IEEE 802.11
MAC and its value is stored in the NAV of nodes. It also doubles as the transmission duration of
data packets. The inter-phase time is a summation of data transmission duration plus one
switching time minus the control channel handshake [26] [27]. The inter-phase time is stored in
the NSTN as data transmission duration of the given data channel. The NSTNs maintain a
sequence of the data channels to ensure that they are reserved in a round robin basis. Furthermore,
the network status stored in tables is availed to mesh client node with insufficient knowledge of
the status of the network. The said node probes the nearest NSTN. The maintenance of the
network status tables is assigned to powerful nodes, the mesh routers. NSTN overhear control
packets, use overhead data to update their data structures. The network support nodes are
designed to equip mesh clients that cannot update their VANs after missing control packets.
Fig 2 demonstrates the functionality of the support scheme. The flow chart shows that depending
on the availability of the network, a given node can contend for the control channel, otherwise it
has to first probe the nearest NSTN for detailed network status. Three scenarios exist in which
nodes may not have adequate knowledge of the network. These are the joining, the returning and
start-up nodes.
A mesh client with insufficient network information probes the nearest NSTN before contending
for the control channel to reserves a channel. Network related data is sent to the probing node by
6. International Journal on AdHoc Networking Systems ( IJANS) Vol. 5, No. 2, April 2015
6
an NSTN. Overhearing nodes also update their tables; only if their tables are out dated. A node
which listens on the control channel is expected to be up to date; hence there is no need for it to
probe the NSTNs or to rely on probe responses.
Fig 2. The implementation of the network infrastructure in the Cyclic Scheduling Algorithm
5.0 Model Analysis
The MSC wastes bandwidth on all the data channels and it is repetitive. However, the proposed
scheme limits the MSC to the first cycle. This is achieved through the implementation of inter-
phase time scheme. The data channels are reserved when they are still busy transmitting current
data frames. The implementation of the inter-phase time ensures that data channels reservation is
done proactively when data transmission is about to end. Secondly, the Extended Inter-Frame
Space (EIFS) has been reconfigured and changed into a shorter Inter-Frame Space (IFS). In
multichannel MAC protocols, there is no need for nodes which receive erroneous packets to defer
for the EIFS duration. The EIFS worsens the MSC. The EIFS was designed to protect the ACK
packets in single channel MAC protocols. In multichannel MAC protocols, ACK packets are
transmitted on a different channel.
Fig 3 shows how the window based multichannel MAC protocols worsen the MSC. It also shows
the extent at which data channels are underutilized during the control window.
Start
Joining or Returning node or
new network
Node has knowledge of the
network
Contend for control channel
Select data channel
Switch onto data channel
Switch back to the
control channel
Transmit data packets
Next Node
Probe NSTN for network
status
Network available
Yes
No
Stop
No
Yes
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Fig 3. The poor utilization of data channels in Window based multichannel MAC protocols.
The column is marked either as a control window or data window. The rows represent the
channels and the top row represents the control channel. During the control window, the control
channel is marked “Reservation” while in the data window it is marked “Data Frame”. Data
channels are reserved through the control channel during the control window and then as a data
channel inside the data window to transmit data frames. The last two rows depict the two data
channels. They are both marked “DATA IDLE” during the control window, demonstrating the
underutilization of their capacity during the control window. It shows the extent to which the
MSC affects the performance of the network.
Fig 4 characterizes and models the MSC. It also shows how the MSC challenge degrades the
capacity of data channels. It shows the severity of the MSC and the extent at which control and
data channels are underutilized. The vertical axis denotes the number of channels marked channel
0 to 7. The horizontal axis denotes the elapsed transmission time. The control channel is assumed
to be Channel 0 while the rest are data channels. The capacity of all data channels is underutilized
between T0 and T1 while nodes are busy contending for the control channel and reserving
Channel 1. Channel 2 is reserved between epoch T1 and T2, while all other channels lie idle
except channel 1 which is currently transmitting data. In essence, Channel 1 is underutilized
between T0 and T1, Channel 2, is underutilized between T0 and T2, Channel 3 is underutilized
between T0 and T3, channel 4 between T0 and T4, channel 5 is underutilized between T0 and T5,
while channel 6 is underutilized between T0 and T6. Lastly, channel 7 underutilized between T0
and T7.
As illustrated in Figure 4, the last channel to be reserved, channel 7 in this case is subjected to the
worst effects of the MSC while the first channel (which is reserved first in phase) suffers the least
degradation due to the effects of the MSC. On the other hand the control channel lies idle
between T7 and T8. Thereafter the pattern is repeated for Data channels from T8 to T14. This
shows that the effects of the MSC are repetitive and recurring. The MSC degrades severely the
performance of the multichannel MAC protocols as illustrated in Fig 4. The illustration clearly
demonstrates the significance of this work and the magnitude of the MSC challenge. The
proposed model restricts the MSC to the first phase, there after its effects are eliminated. It is not
possible to eliminate the MSC in the first phase, due to the fact that nodes cannot be reserved in a
proactive manner in the first phase. Secondly, data transmissions cannot be scheduled to all the
available data channels concurrently. Figure 5 characterize the MSC challenge.
Control Channel
Data Channel 1
Data Channel 2
Reservation
DATA IDLE
Data Frame
DATA IDLE
Data Frame
Data Frame
DATA IDLE
Data Frame
Reservation
Data Frame
Data Frame
DATA IDLE
Control Window Control Window
Data Window Data Window
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Fig 4. The Multichannel Scheduling Cost
Fig 5 depicts the behaviour of the MSC as more data channels are added. It also shows how the
effects of the MSC increase with the increase in the number of channels. The 2nd data channel
incurs twice the degradation of the 1st data channel, while the degradation of the 3rd data channel
is thrice that of the 1st data channel. The degradation of the fourth data channel is 4 times that of
the 1st data channel. Thus, the effects of MSC increase with the increase in the number of data
channels. The total degradation of bandwidth is the summation of wasted bandwidth on all data
channels. This is a high cost which degrades severely the performance of multi-channel MAC
protocols. This cost requires an effective and efficient solution.
To calculate the wasted bandwidth due to the effects of the MSC, the following equations can be
employed:
MSC = wb + 2 x wb + 3 x wb + ....... + (n - 1) x wb + n x wb (1)
(2)
Where n is the number of data channels and wb is the amount of wasted bandwidth.
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Fig 5. The Behaviour of the MSC as the channels increase in number
6.0 Simulation Model
The proposed scheme was implemented in NS 2. The performance of the scheme was evaluated
in a multi-channel frame work developed in [10]. The EIFS was reconfigured and changed to
shorter IFS called the CIFS. The CIFS is the summation of the transmission duration of the CTS
packet and the SIFS duration. Nodes defer for CIFS instead of EIFS upon receiving erroneous
control packets. In the proposed scheme, nodes defer for SIFS after the data channel has been
reserved. The two channel switching times have been added to data packet transmission
durations.
A proactive reservation strategy which reduces the MSC by improving the utilization of the
channels is implemented. The CIFS, the data channel reservations strategy and the deferring rules
are designed to reduce idle durations of channels. They improve the utilization of channels which
improves the performance of the proposed protocol. The scalability of the scheme and its
robustness in large networks with high incidents of interference was also evaluated.
A network with 5 channels, a control channel and 4 data channels was implemented. The
channels were assumed to be orthogonal and of equal bandwidth, which was set to 2Mbs. The
number of channels was changed however; the size of the network was varied between 4 and 30
nodes to evaluate the scalability of the proposed scheme. A Non Ad Hoc (NOAH) routing
algorithm was also implemented.
In the simulation, 5 different network sizes in terms of number of nodes were considered. The
network sizes with the following number of nodes were considered: 4, 6, 8, 10, and 30 nodes.
Simulations were run for each network size, and the topologies were assumed to be general. Data
packets were assumed to be 1000 bytes long and of type CBR. A single hop network set up was
assumed with packets sent directly to the receiver. The RTS and CTS packets were transmitted on
the control channel and the DATA and ACK packets were transmitted on the data channels. We
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also took into account 2 channel switching times, each assumed to be 224µs. For detailed
simulation environment see the table below.
Table1. MAC Layer and other Parameter Settings
Parameter Value
SIFS 10 µs
DIFS 50 µs
EIFS 364µs
CIFS 56 (µs)
Slot time 20 µs
Data rate 2 Mbps
Basic rate 2 Mbps
Control Channel 1
Data Channels 4
Switching time 224µs
Data Type CBR
Packet size 1000 bytes
CW max 1023
CW min 7
Short Retry Limit 7
Long Retry Limit 4
PLCP Length 192 bits
PLCP rate 1 Mbps
RTS 20 bytes
CTS 14 bytes
ACK 14 bytes
MAC Header – Data 28 bytes
MAC Header rate Basic rate
Routing Agent NOAH
Network Sizes 4,6,8,10 and 30 nodes
PLCP Header 6 Bytes
Control Channel
Propagation Delay
2µs
Data Channel Propagation
Delay
4µs
PLCP Preamble 18 Bytes
7.0 Simulation Results
7.1 Analysis of dropped packets
In this segment, we analyze the number of dropped packets in evaluating the performance of the
proposed scheme. The emphasis is on the number of dropped packets caused by longer system
response times. The efficiency of service points is therefore investigated. In this case the service
time of the control channel is examined. The services time affects the number of dropped packets
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from the buffer. This metric relates to the utilization of channels in the sense that, if the utilization
of the channel is poor, longer system response times are expected, and more packets are dropped
as a result. Improving the utilization of channels causes fewer packets to be dropped. The
improvement in the utilization of the channel and the dropping of fewer packets is a sufficient
indicator of the effectiveness of the proposed scheme in addressing the MSC. In Fig 7, the
scheme is evaluated in a network with 4 nodes.
Fig 7. Analyzing dropped packets in a network with 4 nodes.
The CSA dropped the least number of packets demonstrating that the scheme did experience
fewer and shorter delays as a result of improved channel utilization. The packets were not
subjected to longer waiting durations before they were processed. In CSA, the next pair does not
wait for the current pair to finish its transmission; it proactively reserves it during the course of
the ongoing data transmission. The improved service rates in the CSA effectively address the
effects of the MSC.
The nodes were increased to 6 in Fig 8. The nodes were grouped into three transmitters and three
receivers, generating three data flows. The CSA scheme did drop fewer packets as compared to
the AMCP. All the data flows dropped fewer packets, a clear indication that the proposed CSA
scheme is effective in addressing the MSC.
Fig 8. The performance of the CSA in a network with 6 nodes
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In Fig 9, the network size was scaled up. The number of nodes was increased to 10. The number
of data flows was more that the number of the data channels. As a result, the contending fifth data
flow had an effect on the overall performance of the network. The two schemes did experience
the highest number of dropped packets, which degraded the performance of the two schemes.
Fig 9. The performance of the CSA in a general network with 10 nodes
In the nutshell, the proposed scheme performed better than the AMCP. However, it was
outperformed in the 1st data flow. This is due to its longer transmission durations and the effects
of the interfering fifth data flow. The CSA is scalable and its performance improves as the
network increase in size. This shows that the scheme addresses effectively the MSC challenge.
The results in Fig 10 validate this argument.
Fig 10. The total number of dropped packets in a network with 30 nodes
In Fig 10, the number of nodes was increased to 30 nodes. The ratio of data channels to data
flows was almost one to four (1:4). In any given time, there were about 4 data flows contending
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for 1 data channel. The amount of interference was high and the network resources were limited.
The performance of CSA was superior and it improved as the size of the network was increased.
It dropped fewer packets in each of the transmitting nodes. The number of dropped packets was
less than the ones which were dropped in Fig 9. The results illustrate that the CSA scheme is
more scalable and effective in addressing the MSC.
7.2 Packet Drop Rate
In these last set of results, the frequency at which the packets were dropped is analyzed. The
reduction of the end-to-end delay shows that the proposed scheme is effective in addressing the
MSC. It shows to what extent the system service rate and response time affect the behavior of the
queue and the buffering of packets. If the service rate is poor, the queue builds up at a very faster
rate, degrading the performance of the network. Lastly, it is a measure of how effective a system
is in reducing the idle durations of channels and how it improves the utilization of the channels.
In Fig 11, the effects of packet drop rate on system performance are analyzed in a network with 4
nodes. A system with shorter waiting times is desired as it suffers lower packet drop rates.
Fig 11. Impact of transmission delays in a network with 4 nodes
The transmission delays have a huge impact on the AMCP in Fig 11, and its packet drop rate is
higher than that of the proposed scheme. The higher drop rate shows that the scheme is more
prone to the MSC which result in the poor utilization of channels causing longer idle durations.
The CSA had a lower packet drop rate owing to its ability to address the effects of the MSC. Its
response time is superior resulting in lower packet drop rate, and shorter end-to-end delays.
In Fig 12, the CSA scheme also outperformed the AMCP. The network size was increased to 6
nodes to create a congested network state which is ideal for testing the scalability of protocols.
The results demonstrate that the CSA is more scalable and more efficient in addressing the effects
of the MSC.
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Fig 12. The analysis of the effect of MSC in a network with 6 nodes
Lastly, the size of the network was increased to 30 nodes in Fig 13. The data flows were almost 4
times the number of the channels resulting in a heavily congested and over loaded network. The
CSA was superior and had lower packet drop rate in all but 2 nodes. It is superior, more scalable
and effective in addressing the effects of the MSC. It improves the utilization of the channels, the
system service rate, and the system response time furthermore, it also reduces the idle durations
of the channels and the end-to-end delay.
The performance of the two schemes is poor in the central nodes largely due to the fact that as the
inter arrival rate of packets increases, the buffers fill up at a faster rate while the congestion also
increases steadily. When these to occurrences take places simultaneously, the performance of the
network is degraded. However, performance thereafter improves with the passage of time when
the schemes take advantage of spatial reuse. The TCP protocol also adjusts its transmission
window when it detects congestion resulting in fewer packets being dropped. The superiority of
the CSA is demonstrated by the fact that its drop rate is lower packets in comparison with that of
the reference model.
Fig 13. Evaluation of the CSA in a congested network
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8.0 Conclusion
The proposed CSA protocol reduces the MSC and limits it to the first cycle. It also reduces the
idle durations of the channels and the signaling overhead cost. The system service rate and system
response time are also improved which in turn improves the overall system performance. The
results demonstrate that the CSA performs better in large and congested networks, which
illustrate the scalability and the effectiveness properties of the scheme. In this case, a large
network has 10 or more nodes. A distinguishable pattern was observed in large networks. The
performance of the network worsens in the middle nodes before it improves again in the last
nodes. This is caused by congestion and an increase in the data traffic however; it improves in the
last nodes due to spatial reuse and the adjustment of the TCP window.
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