VANETs城市场景下基于自适应时延的Geocast路由协议

Adaptive Delay-based Geocast Protocol in Urban VANETs

基于广播式的Geocast路由协议能够在特定的地理区域内高效地发布数据。然而,广播模式引起冗余重播,易导致广播风暴问题。另外,由于城市场景下建筑物的影响,现有的多数广播抑制方案难以应用于城市环境。为此,提出面向城市的基于自适应时延的Geocast路由协议UGAD。UGAD采用了基于自适应时延的广播抑制方案,降低发生广播风暴的概率。同时,考虑到交叉路口的地理优势,给位于交叉路口的车辆"优惠"时延,使其具有优先转发数据包权力,从而提高数据包到达率。此外,考虑到城市道路的复杂性,UAGD采用基于交叉路口转发IF和贪婪转发GF两个模式,依据不同的道路情况选择不同的转发模式,从而降低冗余重播,并保持高的数据包到达率。最后,针对城市场景进行仿真,结果表明提出的UGAD具有高的数据包到达率,低的数据包重播率。

The broadcast-based geocast enables efficient data dissemination to vehicles within a given geographical region, but when dealing with broadcast, unnecessary retransmissions must be suppressed by controlling the packet forwarding to avoid the broadcast storm problem. However, most of existing broadcast suppression methods do not work in urban environments since buildings block the communication between two vehicles. In this paper, we propose Urban Geocast based on Adaptive Delay （UGAD） protocol which adopts delay-based broadcast suppression scheme for urban environments. UGAD makes vehicles at intersections rebroadcast quickly by assigning them preferential delay values. Furthermore, vehicles use two different forwarding modes as parameters in order to fulfill the requirements of geocast. This develops the packet arrival ratio within a given geocast region, while reducing redundant rebroadcasts. Simulation results in an urban scenario show that UGAD achieves high packet arrival ratio as well as low packet rebroadcast ratio compared with existing methods