Nexthop selection mechanism for nodes with heterogeneous transmission range in VANETs

The frequent relocating of vehicles will significantly degrade the routing performance of a VANET. One of the proposed routing approaches to relieve this drawback adopts a greedy fashion to relay the packets hop-by-hop by selecting the nearest neighboring vehicle to the destination as the nexthop forwarder. It is an efficient method of packet routing when the transmission range of each vehicle in the VANET is of the same fixed length. Recently, as heterogeneous wireless networks have become popular, wireless terminals are generally equipped with multiple wireless access network interfaces to improve the quality of transmission and to gain a good signal while relocating. However, the greedy approach of nexthop forwarder selection will not always use the minimum hop counts of the routing path for VANET heterogeneous transmission range nodes. In this paper, we propose a nexthop selection mechanism for VANETs which takes the heterogeneous environment into consideration. A minimum hop count prediction method is firstly proposed to help the current packet-carrying vehicle node to estimate the minimum hop counts required from each neighbor to the destination. Subsequently, based on the estimated values, the routing decision can be made. The simulation results show that our proposed method exhibits better performance in terms of the average end-to-end delay and the packet delivery ratio comparisons than the compared methods.