Research Area:  Vehicular Ad Hoc Networks
Vehicular ad hoc networks have been used for improving driving experiences by providing safety, efﬁciency and info-tainment applications. Due to high mobility of vehicles, network topology changes frequently, and highly dynamictopology results in lost connection. The geographic routing protocol is used since it does not rely on the establishment oftopology. With the popularity of heterogeneous wireless network links, heterogeneous communication range should betaken into consideration when selecting relay from candidate set. The greedy geographic routing protocol with the principleof selecting nearest node to destination may not ensure high packet delivery ratio and low end-to-end delay in this situation.This paper proposes a GPSR-based routing protocol called ETD-GPSR which incorporates the metric expected trans-mission delay (ETD) for data dissemination with heterogeneous communication range in VANETs. The neighbortable with asymmetric wireless links is established with the help of acknowledgement lists and intermediate nodes. Thus,potential good forward links overshadowed by poor reverse links can be found during the periodic beacon messageexchange. Attaching each link with expected transmission delay which takes link quality, link delay and communicationrange into consideration, the vehicle with the minimum ETD is selected as next hop. Simulation results show that in urbanenvironment with heterogeneous communication range, using the metric ETD has increased the packet delivery ratio anddecreased the end-to-end delay.
Author(s) Name:  Sha Wang,Chuanhe Huang and Danxin Wang
Journal name:  Wireless Networks
Publisher name:  Springer