单收发器分布式多跳认知媒体接入控制协议优化设计

Cognitive medium access control protocol optimization design for distributed multi-hop network using single transceiver

针对移动自组网(MANET)媒体接入控制(MAC)协议中存在的多收发器限制、信道负载失衡等问题,并兼顾多跳和控制开销等性能,提出一种单收发器多跳分布式认知MAC协议优化模型。首先基于功率节省模式(PSM)机制,利用通知传输指示消息(ATIM)窗口和DATA窗口时间分割实现认知MAC协议的信道感知和数据传输功能;其次对功率值非均匀量化和格雷编码,降低移动性导致的浮点型开销;然后设计了多跳分布式信道协作机制,以此为基础,重定义信道切换规则,确保信道之间负载均衡;最后对信道空出时间(CVT)、信道开启时间(COT)、吞吐量和信道负载时间进行仿真。结果表明,新协议无需多收发器支撑,各信道之间CVT、COT、负载时间差值分别降低了13 ms、20ms和100 s,对应吞吐量提高了1.5%,实现了协议在收发器数、信道负载均衡、吞吐量和控制开销等性能方面的优化。

A novel optimized model of distributed multi-hop Cognitive Medium Access Control(C-MAC)protocol with a single transceiver was proposed to handle two restrictions in MAC protocol of Mobile Ad Hoc NETwork(MANET).One is the restriction of multiple transceivers and payload imbalance in different channels,and the other one is the restriction of multi-hop and control overhead.Firstly,channel sensing and data transmission of the new C-MAC protocol were realized in ATIM(Announcement Traffic Indication Message)window and DATA window respectively based on Power Saving Mode(PSM),which made them separated in time domain.Secondly,power value was nonuniform quantized and Gray encoded to decrease float overhead caused by node mobility.Then,a distributed cooperation mechanism was raised for multi-hop networking,based on which channel switching rule was redefined to guarantee that channels would be used fairly and balanced.Last,metrics as Channel Vacate Time(CVT),Channel Opening Time(COT),throughput and channel payload time were considered by simulation.Results show that,the novel protocol could execute independently without several transceivers,the difference values of CVT,COT and payload time among different channels reduce by 13 ms,20 ms and 100 s respectively,and corresponding throughput rises about 1.5%,all of which realize the optimization of protocol performance in transceiver restriction,payload balance,throughput and overhead control.