A link transmission-quality based geographic routing in Urban VANETs

Vehicular Ad Hoc Networks (VANETs) have been paid significant increasing attentions. However, the inherent characteristics of VANETs, such as the dynamic network topology, uneven distribution of vehicles, frequent disconnections etc., bring great challenges for designing an efficient routing protocol in urban environment. In this paper, we first introduce a new routing metric called link transmission quality (LTQ), which exploits the effect of links' position along the routing path and also takes both transmission cost and forwarding reliability into consideration, to evaluate the performance of a multi-hop link. Next, with the help of back-bone nodes selected based on specified criterions, road segments are assigned different weights according to the value of calculated LTQ. Finally, a novel geographic routing protocol based on LTQ in urban VANETs, named as LTQGR, is proposed, where the routing path with the lowest aggregated weights is selected for packets transmission. When data packets are forwarded along the optimized route, one forwarding strategy is presented to guarantee the efficient transmission. Simulation results show that our proposed LTQGR outperforms GPSR and another ETX-based protocol HLAR in terms of the average transmission delay, packet delivery ratio and routing overheads.