Abstract: The main drawback of the distributed TDMA (time division multiple access) protocol in vehicular ad hoc networks (VANET) is the failure to fully utilize wireless channel resources, such as node idle time slots. Aiming at the fact that the VANET has no central node and the network topology changes rapidly, a cooperative relaying distributed TDMA (CR-DTDMA) method is proposed to cooperatively relay data using idle time slots of the nodes. CR-DTDMA implements a network handshake protocol to determine cooperative relay nodes, independent of the relevant data transmission confirmation mechanism. The control information of the network handshake protocol is transmitted by the message piggyback mechanism, and no special control package needs to be sent. Theoretical analysis and simulation results show that CR-DTDMA significantly improves the data relay forwarding probability and reduces the relay forwarding delay and packet loss rate.

Key words: mobile ad hoc networks, vehicular ad hoc networks, time division multiple access (TDMA), reliability

摘要： 车载自组网中的分布式时分多址（TDMA）协议的主要缺陷是未能充分利用无线信道资源，如节点空闲时隙问题。针对车载自组网无中心节点且网络拓扑结构快速变化的特点，提出一种协作中继分布式TDMA方法（CR-DTDMA），以便利用节点空闲时隙协作中继转发数据。CR-DTDMA实现一种网络握手协议来确定协作中继节点，不依赖相关数据传输确认机制，而且网络握手协议的控制信息都采用消息搭载机制传递，不需要发送专门的控制包。分析与模拟表明，CR-DTDMA提高了数据中继转发概率，降低了中继转发时延和丢包率。

关键词: 移动自组网, 车载自组网, 时分多址（TDMA）, 可靠性