A novel backoff algorithm in CSMA/CA-based medium access control (MAC) protocols for clustered sensor networks was proposed. The algorithm requires that all sensor nodes have the same value of contention window (CW) i...A novel backoff algorithm in CSMA/CA-based medium access control (MAC) protocols for clustered sensor networks was proposed. The algorithm requires that all sensor nodes have the same value of contention window (CW) in a cluster, which is revealed by formulating resource allocation as a network utility maximization problem. Then, by maximizing the total network utility with constrains of minimizing collision probability, the optimal value of CW (Wopt) can be computed according to the number of sensor nodes. The new backoff algorithm uses the common optimal value Wopt and leads to fewer collisions than binary exponential backoff algorithm. The simulation results show that the proposed algorithm outperforms standard 802.11 DCF and S-MAC in average collision times, packet delay, total energy consumption, and system throughput.展开更多
太赫兹无线局域网(Wireless Local Area Network,WLAN)是实现大带宽、短距离无线接入的重要技术途径,受太赫兹波束极窄特性影响,现有的低频WLAN媒体接入控制(Media Access Control,MAC)地址已不能直接复用于太赫兹WLAN。针对太赫兹波束...太赫兹无线局域网(Wireless Local Area Network,WLAN)是实现大带宽、短距离无线接入的重要技术途径,受太赫兹波束极窄特性影响,现有的低频WLAN媒体接入控制(Media Access Control,MAC)地址已不能直接复用于太赫兹WLAN。针对太赫兹波束极窄特性导致的信道利用率低问题,提出了负载自适应的混合接入MAC协议(Load-Adaptive Hybrid Access MAC Protocol,LAHA-MAC)。通过记录上一次工作扇区的节点数量自适应地选择信道接入方式。当工作扇区节点数量N小于接入方式选择阈值N*时,该机制采用基于竞争的接入方式,能够同时获得较高的吞吐量和较低的端到端时延;当节点数量N大于接入方式选择阈值N*时,该机制采用基于调度的接入方式,能够避免节点之间的碰撞,提高传输效率。考虑到可能出现的接入方式选择错误,该机制能够实现灵活地接入方式切换。当信道中节点碰撞次数N col大于切换阈值N*col时,将基于竞争的接入方式切换为基于调度的接入方式。仿真结果表明,该机制能够在网络负载动态变化的情况下有效提高信道利用率。展开更多
In view of the problem that existing Media Access Control(MAC) protocols can not pro-vide real-time monitor on network conditions,this paper puts forward a new MAC protocol- Predict and Feedback MAC(PFMAC) which can p...In view of the problem that existing Media Access Control(MAC) protocols can not pro-vide real-time monitor on network conditions,this paper puts forward a new MAC protocol- Predict and Feedback MAC(PFMAC) which can predict the channel's congestion level reasonably.The dominant idea of the new scheme is to record the channel's busy or idle situation in the backoff stage by sending Sensor Nodes(SNs),and according to the congestion level every SN can change the contention window adaptively when send packets successfully to minimize collisions,saving energy and channel resources.The result of simulation shows that compared with other MAC protocols,the PFMAC protocol can improve network throughput and reduce energy consumption in high speed network en-vironment.展开更多
基金Project(60772088) supported by the National Natural Science Foundation of China
摘要A novel backoff algorithm in CSMA/CA-based medium access control (MAC) protocols for clustered sensor networks was proposed. The algorithm requires that all sensor nodes have the same value of contention window (CW) in a cluster, which is revealed by formulating resource allocation as a network utility maximization problem. Then, by maximizing the total network utility with constrains of minimizing collision probability, the optimal value of CW (Wopt) can be computed according to the number of sensor nodes. The new backoff algorithm uses the common optimal value Wopt and leads to fewer collisions than binary exponential backoff algorithm. The simulation results show that the proposed algorithm outperforms standard 802.11 DCF and S-MAC in average collision times, packet delay, total energy consumption, and system throughput.
摘要太赫兹无线局域网(Wireless Local Area Network,WLAN)是实现大带宽、短距离无线接入的重要技术途径,受太赫兹波束极窄特性影响,现有的低频WLAN媒体接入控制(Media Access Control,MAC)地址已不能直接复用于太赫兹WLAN。针对太赫兹波束极窄特性导致的信道利用率低问题,提出了负载自适应的混合接入MAC协议(Load-Adaptive Hybrid Access MAC Protocol,LAHA-MAC)。通过记录上一次工作扇区的节点数量自适应地选择信道接入方式。当工作扇区节点数量N小于接入方式选择阈值N*时,该机制采用基于竞争的接入方式,能够同时获得较高的吞吐量和较低的端到端时延;当节点数量N大于接入方式选择阈值N*时,该机制采用基于调度的接入方式,能够避免节点之间的碰撞,提高传输效率。考虑到可能出现的接入方式选择错误,该机制能够实现灵活地接入方式切换。当信道中节点碰撞次数N col大于切换阈值N*col时,将基于竞争的接入方式切换为基于调度的接入方式。仿真结果表明,该机制能够在网络负载动态变化的情况下有效提高信道利用率。
基金Supported by the 948 Project (2012-4-21)the Ph.D.Programs Foundation of Ministry of Education of China(20100062120008)the Scientific Research Fund of Heilongjiang Provincial Education Department(11553022)
摘要In view of the problem that existing Media Access Control(MAC) protocols can not pro-vide real-time monitor on network conditions,this paper puts forward a new MAC protocol- Predict and Feedback MAC(PFMAC) which can predict the channel's congestion level reasonably.The dominant idea of the new scheme is to record the channel's busy or idle situation in the backoff stage by sending Sensor Nodes(SNs),and according to the congestion level every SN can change the contention window adaptively when send packets successfully to minimize collisions,saving energy and channel resources.The result of simulation shows that compared with other MAC protocols,the PFMAC protocol can improve network throughput and reduce energy consumption in high speed network en-vironment.