Vehicular Ad Hoc Networks (VANETs) are critical for the advancement of Intelligent Transportation Systems (ITS), enabling real-time vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications. However,...Vehicular Ad Hoc Networks (VANETs) are critical for the advancement of Intelligent Transportation Systems (ITS), enabling real-time vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications. However, ensuring Quality of Service (QoS) in VANETs is challenging due to high mobility, dynamic topologies, and interference. This study evaluates the performance of Medium Access Control (MAC) protocols implemented on a Software-Defined Radio (SDR) platform to address these challenges. The research highlights the use of QoS-prescribed scheduling algorithms and multi-user detection techniques to optimize key performance metrics such as packet delivery ratio (PDR), throughput, and scalability. Simulation results demonstrate significant improvements under varying mobility and channel conditions, achieving stable communication and high user capacity in both fixed and high-mobility scenarios. The findings underscore the potential of SDR-based VANET solutions for enhancing reliability, scalability, and efficiency in dynamic vehicular environments. Future directions include incorporating iterative methods and real-world testing to further refine QoS delivery in VANETs.展开更多
Vehicular Ad Hoc Networks (VANETs) play a pivotal role in the advancement of Intelligent Transportation Systems (ITS), facilitating real-time communication among vehicles (V2V) and between vehicles and infrastructure ...Vehicular Ad Hoc Networks (VANETs) play a pivotal role in the advancement of Intelligent Transportation Systems (ITS), facilitating real-time communication among vehicles (V2V) and between vehicles and infrastructure (V2I). However, maintaining reliable Quality of Service (QoS) in these dynamic environments remains challenging due to high mobility, frequent topology changes and interference. This paper proposes a robust cross-layer framework that integrates channel prediction and dynamic rate adaptation to address these challenges. The framework employs advanced multi-user detection techniques, including matched filters, successive interference cancellation (SIC), decorrelators and MMSE receivers, combined with adaptive multi-factor spreading, multi-code and multi-modulation transmission strategies. The study evaluates the framework’s performance through extensive simulations using a Software-Defined Radio (SDR) platform. Key findings demonstrate significant improvements in packet reception rate, throughput and spectral efficiency under various mobility and channel conditions. The proposed approach effectively mitigates interference and adapts to dynamic network environments, showcasing its potential to enhance reliability, scalability and efficiency in VANETs. Future work will explore real-world implementation and iterative algorithmic enhancements to further optimize QoS delivery in highly variable vehicular communication scenarios.展开更多
In this paper, we propose an aware-based adaptive opportunistic retransmission control scheme for wireless multimedia Mesh networks. The proposed scheme provides maximum retransmis-sion count optimization based on env...In this paper, we propose an aware-based adaptive opportunistic retransmission control scheme for wireless multimedia Mesh networks. The proposed scheme provides maximum retransmis-sion count optimization based on environment-aware to improve packet relay probability. The scheme discriminates the types of packet loss in wireless link by means of environment information and selects the retransmission count by taking the IEEE 802.11 wireless channel characteristics into consideration. Furthermore, the maximum retransmission count of MAC is adjusted adaptively. Extensive simulations demonstrate that the proposed scheme significantly reduces packet collision probability and packet loss rate, and thus improves network throughput.展开更多
A novel distributed cognitive radio multichannel medium access protocol without common control channel was proposed.The protocol divided a transmission interval into two parts for exchanging control information and da...A novel distributed cognitive radio multichannel medium access protocol without common control channel was proposed.The protocol divided a transmission interval into two parts for exchanging control information and data,respectively.In addition to evaluating system saturation throughput of the proposed protocol,a three-dimensional multi channel Markov chain model to describe the sate of the cognitive users (CUs) in dynamic spectrum access was presented.The proposed analysis was applied to the packet transmission schemes employed by the basic,RTS/CTS access mechanism adopted in the normal IEEE 802.11.Analyzing the advantage of the two methods,a hybrid access mechanism was proposed to improve the system throughput.The simulation results show that the experiment results are close to the value computed by the model (less than 5%),and the proposed protocol significantly improves the performance of the system throughput by borrowing the licensed spectrum.By analyzing the dependence of throughput on system parameters,hybrid mechanism dynamically selecting access mechanism can maintain high throughput.展开更多
This paper proposes a new multi-channel Medium Access Control (MAC) protocol named as Dual Reservation Code Division Multiple Access (CDMA) based MAC protocol with Power Control (DRCPC). The code channel is divided in...This paper proposes a new multi-channel Medium Access Control (MAC) protocol named as Dual Reservation Code Division Multiple Access (CDMA) based MAC protocol with Power Control (DRCPC). The code channel is divided into common channel,broadcast channel and several data chan-nels. And dynamic power control mechanism is implemented to reduce near-far interference. Compared with IEEE 802.11 Distributed Coordination Function (DCF) protocol,the results show that the pro-posed mechanism improves the average throughput and limits the transmission delay efficiently.展开更多
In order to improve the throughput performance of the secondary users （SUs） in the cognitive radio （CR） environment, a quality of service （QoS） based media access control （MAC） protocol is proposed. In this pr...In order to improve the throughput performance of the secondary users （SUs） in the cognitive radio （CR） environment, a quality of service （QoS） based media access control （MAC） protocol is proposed. In this protocol, the CR node maps the channel state as a vector, and the transmitter and the receiver obtain the final channel map through an AND operation to prepare for an optional channel set. Data from the upper application layer are classified into two priority levels according to the QoS requirement. The data of each level relate to different contention windows so that the priority of real time data can be guaranteed. A two-dimensional discrete-time Markov chain is utilized to evaluate the system performance, and mathematical expressions of the system throughput are derived. Simulation results show that compared with the IEEE 802. 11 distributed coordination function （DCF）, the proposed MAC protocol can achieve higher throughput.展开更多
针对现有能够应用于太赫兹超高速无线网络的能量和频谱感知的媒介接入控制(energy and spectrum-aware media access control,ES-MAC)及IEEE802.15.3c协议存在的时隙申请量未及时更新、超帧结构不合理及分配时隙时未合并同一对节点之间...针对现有能够应用于太赫兹超高速无线网络的能量和频谱感知的媒介接入控制(energy and spectrum-aware media access control,ES-MAC)及IEEE802.15.3c协议存在的时隙申请量未及时更新、超帧结构不合理及分配时隙时未合并同一对节点之间的时隙请求等问题,提出了一种高吞吐量低时延MAC(high throughput low delay MAC,HLMAC)协议。通过设计一种新的超帧结构,使节点及时得到时隙分配信息,大大降低数据接入时延;通过更新时隙请求量和合并同一对节点的时隙请求,增加了数据发送量,提高了网络吞吐量。理论分析表明了HLMAC协议的有效性,仿真结果显示它比ES-MAC协议增加了65.7%的网络吞吐量,同时降低了30%的接入时延。展开更多
提出一种分析模型,基于信号流图和母函数方法分析了无线局域网中EDCA(enhanced distribution channel access)机制的MAC(medium access control)接入延时.得到了MAC接入延时的概率分布和相关的数字特征,包括接入延时的均值、方差、标准...提出一种分析模型,基于信号流图和母函数方法分析了无线局域网中EDCA(enhanced distribution channel access)机制的MAC(medium access control)接入延时.得到了MAC接入延时的概率分布和相关的数字特征,包括接入延时的均值、方差、标准差和变异系数.仿真结果与模型的分析结果吻合良好,验证了模型和计算方法的正确性.进一步分析了各类AC(access category)的发送概率、碰撞概率、挂起概率和延时均值随终端数目变化的规律;分析了MAC接入延时的成因;指出了AIFS(arbitration inter frame spacing)值对MAC接入延时的影响;指出接入延时的变异系数大于1,因此,采用负指数分布作为MAC接入延时的近似分布,会错误地估计系统的服务能力.展开更多
文摘Vehicular Ad Hoc Networks (VANETs) are critical for the advancement of Intelligent Transportation Systems (ITS), enabling real-time vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications. However, ensuring Quality of Service (QoS) in VANETs is challenging due to high mobility, dynamic topologies, and interference. This study evaluates the performance of Medium Access Control (MAC) protocols implemented on a Software-Defined Radio (SDR) platform to address these challenges. The research highlights the use of QoS-prescribed scheduling algorithms and multi-user detection techniques to optimize key performance metrics such as packet delivery ratio (PDR), throughput, and scalability. Simulation results demonstrate significant improvements under varying mobility and channel conditions, achieving stable communication and high user capacity in both fixed and high-mobility scenarios. The findings underscore the potential of SDR-based VANET solutions for enhancing reliability, scalability, and efficiency in dynamic vehicular environments. Future directions include incorporating iterative methods and real-world testing to further refine QoS delivery in VANETs.
文摘Vehicular Ad Hoc Networks (VANETs) play a pivotal role in the advancement of Intelligent Transportation Systems (ITS), facilitating real-time communication among vehicles (V2V) and between vehicles and infrastructure (V2I). However, maintaining reliable Quality of Service (QoS) in these dynamic environments remains challenging due to high mobility, frequent topology changes and interference. This paper proposes a robust cross-layer framework that integrates channel prediction and dynamic rate adaptation to address these challenges. The framework employs advanced multi-user detection techniques, including matched filters, successive interference cancellation (SIC), decorrelators and MMSE receivers, combined with adaptive multi-factor spreading, multi-code and multi-modulation transmission strategies. The study evaluates the framework’s performance through extensive simulations using a Software-Defined Radio (SDR) platform. Key findings demonstrate significant improvements in packet reception rate, throughput and spectral efficiency under various mobility and channel conditions. The proposed approach effectively mitigates interference and adapts to dynamic network environments, showcasing its potential to enhance reliability, scalability and efficiency in VANETs. Future work will explore real-world implementation and iterative algorithmic enhancements to further optimize QoS delivery in highly variable vehicular communication scenarios.
基金Supported by the National Natural Science Foundation of China (No. 60972038)the Jiangsu Province Universities Natural Science Research Key Grant Project (07KJA-51006)+1 种基金the Open Research Fund of National Mobile Communications Research Laboratory, Southeast University (N200911)Jiangsu Province Graduate In-novative Research Plan (CX09B_149Z)
文摘In this paper, we propose an aware-based adaptive opportunistic retransmission control scheme for wireless multimedia Mesh networks. The proposed scheme provides maximum retransmis-sion count optimization based on environment-aware to improve packet relay probability. The scheme discriminates the types of packet loss in wireless link by means of environment information and selects the retransmission count by taking the IEEE 802.11 wireless channel characteristics into consideration. Furthermore, the maximum retransmission count of MAC is adjusted adaptively. Extensive simulations demonstrate that the proposed scheme significantly reduces packet collision probability and packet loss rate, and thus improves network throughput.
基金Project(61071104) supported by the National Natural Science Foundation of China
文摘A novel distributed cognitive radio multichannel medium access protocol without common control channel was proposed.The protocol divided a transmission interval into two parts for exchanging control information and data,respectively.In addition to evaluating system saturation throughput of the proposed protocol,a three-dimensional multi channel Markov chain model to describe the sate of the cognitive users (CUs) in dynamic spectrum access was presented.The proposed analysis was applied to the packet transmission schemes employed by the basic,RTS/CTS access mechanism adopted in the normal IEEE 802.11.Analyzing the advantage of the two methods,a hybrid access mechanism was proposed to improve the system throughput.The simulation results show that the experiment results are close to the value computed by the model (less than 5%),and the proposed protocol significantly improves the performance of the system throughput by borrowing the licensed spectrum.By analyzing the dependence of throughput on system parameters,hybrid mechanism dynamically selecting access mechanism can maintain high throughput.
基金Supported by the Science Foundation of Shanghai Mu-nicipal Commission of Science and Technology under contract 045115012.
文摘This paper proposes a new multi-channel Medium Access Control (MAC) protocol named as Dual Reservation Code Division Multiple Access (CDMA) based MAC protocol with Power Control (DRCPC). The code channel is divided into common channel,broadcast channel and several data chan-nels. And dynamic power control mechanism is implemented to reduce near-far interference. Compared with IEEE 802.11 Distributed Coordination Function (DCF) protocol,the results show that the pro-posed mechanism improves the average throughput and limits the transmission delay efficiently.
基金The National Science and Technology Major Project( No. 2010ZX03006-002-01 )the National Basic Research Program of China ( 973 Program) ( No. 2011CB302905)the Science and Technology Support Program of Jiangsu Province ( No. BE2011177)
文摘In order to improve the throughput performance of the secondary users （SUs） in the cognitive radio （CR） environment, a quality of service （QoS） based media access control （MAC） protocol is proposed. In this protocol, the CR node maps the channel state as a vector, and the transmitter and the receiver obtain the final channel map through an AND operation to prepare for an optional channel set. Data from the upper application layer are classified into two priority levels according to the QoS requirement. The data of each level relate to different contention windows so that the priority of real time data can be guaranteed. A two-dimensional discrete-time Markov chain is utilized to evaluate the system performance, and mathematical expressions of the system throughput are derived. Simulation results show that compared with the IEEE 802. 11 distributed coordination function （DCF）, the proposed MAC protocol can achieve higher throughput.
文摘针对现有能够应用于太赫兹超高速无线网络的能量和频谱感知的媒介接入控制(energy and spectrum-aware media access control,ES-MAC)及IEEE802.15.3c协议存在的时隙申请量未及时更新、超帧结构不合理及分配时隙时未合并同一对节点之间的时隙请求等问题,提出了一种高吞吐量低时延MAC(high throughput low delay MAC,HLMAC)协议。通过设计一种新的超帧结构,使节点及时得到时隙分配信息,大大降低数据接入时延;通过更新时隙请求量和合并同一对节点的时隙请求,增加了数据发送量,提高了网络吞吐量。理论分析表明了HLMAC协议的有效性,仿真结果显示它比ES-MAC协议增加了65.7%的网络吞吐量,同时降低了30%的接入时延。
基金Supported by the Program for New Century Excellent Talents in University of China under Grant No.NCET-05-0657(新世纪优秀人才支持计划)the Foundation for Distinguished Young Scientists of Hubei Province of China under Grant No.2006ABB028(湖北省青年杰出人才基金)
文摘提出一种分析模型,基于信号流图和母函数方法分析了无线局域网中EDCA(enhanced distribution channel access)机制的MAC(medium access control)接入延时.得到了MAC接入延时的概率分布和相关的数字特征,包括接入延时的均值、方差、标准差和变异系数.仿真结果与模型的分析结果吻合良好,验证了模型和计算方法的正确性.进一步分析了各类AC(access category)的发送概率、碰撞概率、挂起概率和延时均值随终端数目变化的规律;分析了MAC接入延时的成因;指出了AIFS(arbitration inter frame spacing)值对MAC接入延时的影响;指出接入延时的变异系数大于1,因此,采用负指数分布作为MAC接入延时的近似分布,会错误地估计系统的服务能力.
