一种新的基于跨层的Ad Hoc网络的MAC协议设计

为了提高Ad Hoc网络的性能,提出一种新的基于跨层的MAC协议,它能自适应的选择802.11b物理层规范中的两种不同的物理层数据单元格式进行传输。由于具有短导频的物理层数据单元格式比具有长导频的物理层数据格式占用更少的信道时间,基于跨层的MAC协议在一定条件下,采用具有短导频的物理层数据单元进行传输以减少物理层的开销,提高网络性能。其基本思想是如果需要通信的两个节点都支持具有短导频的物理层数据格式,则采用具有短导频的物理层数据格式进行传输,否则,采用具有长导频的物理层数据格式进行传输。同时提出一种自适应的网络分配向量计算算法,该算法能够根据MAC数据包的持续时间值判断节点是否支持具有短导频的物理层数据格式,不需要修改802.11b的帧格式。通过NS仿真证明,基于跨层的MAC协议能够提高网络的性能,如端到端的时延、吞吐量和传包率。

A Novel Cross-layer based MAC Protocol for Ad Hoc Networks

A novel cross-layer based MAC was proposed to enhance performances of Ad hoc networks.The main idea was to adap- tively choose long PLCP (physical layer convergence protocol) PPDU (PLCP protocol data unit) or short PLCP PPDU because short PLCP PPDU has less duration of time than that of long PLCP PPDU.Thus using short PLCP PPDU could improve performance of Ad Hoc networks,especially in high data rate.The paper designed a algorithm to adaptively choose long or short PLCP PPDU by duration field of frames and compute network allocation vector (NAV).It did not need to modify frame format of 802.11b,thus is compliant with 802.11b.The proposed MAC protocol and 802.11b were evaluated by NS.Performance results reveal that the proposed MAC protocol performs better than the 802.11b in term of average end-to-end delay,aggregate throughput and average delivery.