在目前的无线传感器/执行器网络(Wireless Sensor and Actuator Networks,WSANs)中,无线传感器及其所传输信息的业务类型趋于多样化;同时,在实时性要求较高的工业系统中,无线网络环境下的丢包将给整个系统带来严重的危害。为提高WSANs...在目前的无线传感器/执行器网络(Wireless Sensor and Actuator Networks,WSANs)中,无线传感器及其所传输信息的业务类型趋于多样化;同时,在实时性要求较高的工业系统中,无线网络环境下的丢包将给整个系统带来严重的危害。为提高WSANs的可靠性,提出了一种基于IEEE 802.11e的WSANs丢包判决器的优化设计方法。该方法采用提供服务质量(Quality of Service,QoS)的IEEE 802.11e作为WSANs的数据通信协议,推导出该协议下的WSANs丢包概率矩阵,并将基于该丢包概率矩阵的龙伯格状态观测器的输出作为丢包的判决阈值,把网络中的丢包现象作为一种故障信号,从而设计出WSANs的丢包判决器。该丢包判决器不仅能有效判断网络中是否出现了丢包,而且还能通过判决器输出的故障信号波形判断丢包原因,即传感器节点故障,或是由于信道环境不稳定造成的随机丢包。最后,通过MATLAB/OMNET++的混合仿真验证了该设计的有效性。展开更多
针对IEEE802.11e Medium Access Control层的QoS机制高负载时存在远端节点冲突和低优先级业务资源被耗尽的问题,提出在牺牲较小带宽的基础上增加一条忙音信道,取代CTS帧在数据信道上的广播,减少远端节点的冲突.仿真结果表明,该方案具有...针对IEEE802.11e Medium Access Control层的QoS机制高负载时存在远端节点冲突和低优先级业务资源被耗尽的问题,提出在牺牲较小带宽的基础上增加一条忙音信道,取代CTS帧在数据信道上的广播,减少远端节点的冲突.仿真结果表明,该方案具有较小的冲突概率,有效地减少了远端节点冲突.同时提出一个解决公平性问题的新思路:在避退时间发送忙音抢占信道,以期提高低优先级业务的接入概率.展开更多
基于IEEE802.11e标准,充分考虑混合式协调功能控制信道访问机制(Hybrid Coordination Function Controlled Channel Access,HCCA)的QoS(Quality of Service)参数,提出一个HCCA软件模拟架构;根据此架构,利用NS2网络仿真工具搭建一个功能...基于IEEE802.11e标准,充分考虑混合式协调功能控制信道访问机制(Hybrid Coordination Function Controlled Channel Access,HCCA)的QoS(Quality of Service)参数,提出一个HCCA软件模拟架构;根据此架构,利用NS2网络仿真工具搭建一个功能完整且易于实施的HCCA平台,并结合资源预留方案对平台的有效性和合理性进行仿真验证。展开更多
In this paper, we propose an analytical model for the performance evaluation of IEEE 802.1 le enhanced distributed channel access （EDCA）. Different from most previous analytical studies based on the saturation assum...In this paper, we propose an analytical model for the performance evaluation of IEEE 802.1 le enhanced distributed channel access （EDCA）. Different from most previous analytical studies based on the saturation assumption, we extend the analytical model to non-saturation conditions. An empty state is introduced into the Markov chain to represent the status of transmission queue being empty. This model can be used to calculate the traffic priority, throughput, and MAC layer delay with various configurations of contention parameters. A detailed simulation is provided to validate the proposed model. With the help of this model, the contention parameters can be configured appropriately to achieve specific quality-of-service （QoS） requirements.展开更多
Communication over wireless links identifies significant challenges for routing protocols operating. This paper proposes a Cross-layer design based Multipath Routing Protocol (CMRP) for mobile ad hoc networks, by mean...Communication over wireless links identifies significant challenges for routing protocols operating. This paper proposes a Cross-layer design based Multipath Routing Protocol (CMRP) for mobile ad hoc networks, by means of the node energy signal from the physical layer. The purpose is to optimize routing decision and path quality. The nodes’ mobility behavior is predicted using a notion of “Signal Fading Degree, SFD”. Especially, in combination of the IEEE 802.11e standard at the MAC layer, we determine that the IEEE 802.11e makes a significant contribution to performance improvement of CMRP. Performance evaluation of AODV in legacy 802.11 and CMRP in IEEE 802.11e shows that, as a function of speed of node mobility, a tremendous reduction achieved, in metrics such as the average end-to-end delay, route overhead, route discovery frequency, normalized routing load - almost more than 80%, 40%, 40%, and 40%. In the case of varying number of sessions, the reduction for route discovery frequency and normalized routing load are up to 70% and 80%.展开更多
文摘在目前的无线传感器/执行器网络(Wireless Sensor and Actuator Networks,WSANs)中,无线传感器及其所传输信息的业务类型趋于多样化;同时,在实时性要求较高的工业系统中,无线网络环境下的丢包将给整个系统带来严重的危害。为提高WSANs的可靠性,提出了一种基于IEEE 802.11e的WSANs丢包判决器的优化设计方法。该方法采用提供服务质量(Quality of Service,QoS)的IEEE 802.11e作为WSANs的数据通信协议,推导出该协议下的WSANs丢包概率矩阵,并将基于该丢包概率矩阵的龙伯格状态观测器的输出作为丢包的判决阈值,把网络中的丢包现象作为一种故障信号,从而设计出WSANs的丢包判决器。该丢包判决器不仅能有效判断网络中是否出现了丢包,而且还能通过判决器输出的故障信号波形判断丢包原因,即传感器节点故障,或是由于信道环境不稳定造成的随机丢包。最后,通过MATLAB/OMNET++的混合仿真验证了该设计的有效性。
文摘针对IEEE802.11e Medium Access Control层的QoS机制高负载时存在远端节点冲突和低优先级业务资源被耗尽的问题,提出在牺牲较小带宽的基础上增加一条忙音信道,取代CTS帧在数据信道上的广播,减少远端节点的冲突.仿真结果表明,该方案具有较小的冲突概率,有效地减少了远端节点冲突.同时提出一个解决公平性问题的新思路:在避退时间发送忙音抢占信道,以期提高低优先级业务的接入概率.
文摘基于IEEE802.11e标准,充分考虑混合式协调功能控制信道访问机制(Hybrid Coordination Function Controlled Channel Access,HCCA)的QoS(Quality of Service)参数,提出一个HCCA软件模拟架构;根据此架构,利用NS2网络仿真工具搭建一个功能完整且易于实施的HCCA平台,并结合资源预留方案对平台的有效性和合理性进行仿真验证。
基金Project (No. 60332030) supported by the National Natural ScienceFoundation of China
文摘In this paper, we propose an analytical model for the performance evaluation of IEEE 802.1 le enhanced distributed channel access （EDCA）. Different from most previous analytical studies based on the saturation assumption, we extend the analytical model to non-saturation conditions. An empty state is introduced into the Markov chain to represent the status of transmission queue being empty. This model can be used to calculate the traffic priority, throughput, and MAC layer delay with various configurations of contention parameters. A detailed simulation is provided to validate the proposed model. With the help of this model, the contention parameters can be configured appropriately to achieve specific quality-of-service （QoS） requirements.
文摘Communication over wireless links identifies significant challenges for routing protocols operating. This paper proposes a Cross-layer design based Multipath Routing Protocol (CMRP) for mobile ad hoc networks, by means of the node energy signal from the physical layer. The purpose is to optimize routing decision and path quality. The nodes’ mobility behavior is predicted using a notion of “Signal Fading Degree, SFD”. Especially, in combination of the IEEE 802.11e standard at the MAC layer, we determine that the IEEE 802.11e makes a significant contribution to performance improvement of CMRP. Performance evaluation of AODV in legacy 802.11 and CMRP in IEEE 802.11e shows that, as a function of speed of node mobility, a tremendous reduction achieved, in metrics such as the average end-to-end delay, route overhead, route discovery frequency, normalized routing load - almost more than 80%, 40%, 40%, and 40%. In the case of varying number of sessions, the reduction for route discovery frequency and normalized routing load are up to 70% and 80%.
