一种面向车联网的两级分布式多信道MAC协议

Two-level distributed multi-channel MAC protocol for vehicular networks

近年来,随着无线传感网的发展,多信道MAC协议受到更加广泛的关注,研究者针对节点会聚和信道利用率问题提出了多种数据传递方法。文中基于车载网应用需求,提出一种两级分布式多信道MAC协议(Two-Level Distributed Multi-channel MAC,TLDM-MAC)。该协议设计了特定的多信道结构,通过空间域和时间域两级分布将控制周期分散部署到各个信道不相交的时间片上,有效提高信道利用率;定义了基于归属信道的节点会聚规则,提高会聚成功率;并引入Hadamard矩阵映射方法划分处于同一信道的节点的控制周期,进一步降低节点在控制周期中的信道冲突。仿真结果表明,和已有的典型多信道MAC协议相比,文中提出的TLDM-MAC协议的节点会聚成功率、网络吞吐量和数据包时延性能都有了明显的改进。

Multi-channel MAC protocols have attracted attention with the development of wireless sensor networks. Aimed at the problems of node rendezvous and channel utilization ratio, multiple data delivery approaches are proposed. To meet the application requirements of vehicular networks, this paper presents a two-level distributed multi-channel MAC protocol （TLDM-MAC） protocol. With the design of a sophisti- cated multi-channel structure, two-level distribution in both the space domain and the time domain is ap- plied to the placement of control periods. They are decentralized in disjoint time slices in each channel to enhance the channel utilization ratio. Home channel based node rendezvous rules are defined to increase the rendezvous success ratio. Furthermore, to decrease the channel collision of nodes within the control pe- riod, a mapping mechanism with Hadamard matrix is introduced to partition the control periods of the nodes tuned in the same channel. Simulation results show that, compared with the existing typical multi- channel MAC protocols, the TLDM-MAC protocol exhibits explicitly higher performance,including the im- proved node rendezvous success ratio, network throughput and time delay of data delivery.