Multicast/geocast routing protocols for safety and comfort applications in VANET

Abstract

The high mobility of vehicles and frequent network fragmentation problems together with the transmission range limitation of the Dedicated Short Range Communication (DSRC) devices makes a real challenge in the design of group data communications in VANET. Thus, a multi-hop relaying system based on cooperation between vehicles is adopted for the communication of group messages. The multi-hop relaying strategy can extend the transmission range of DSRC devices. However, it also introduces a lot of challenges: First, timeliness is a main feature of delivery messages. For example, to avoid potential accidents, emergency message should arrive at endangered vehicles timely so that drivers are able to react to the emergency on time. Second, multi-hop system degrades a lot the transmission reliability and scalability of the delivered message that can extremely degrade the network's QoS, delay and throughput in particular. The more are the hop-counts in a wireless path, the less reliable is the wireless communication, since the overall reliability is computed considering all links in a wireless path. Third, multihop system also increases the vehicles' fuel consumption. For this reason, power efficiency is becoming a major issue in VANET, and green communications have attracted more attention by both academic and industry researchers. Besides the fuel consumption optimization, the design of new protocols minimizing the total power consumption for message communication in a group helps also to reduce the interference, and to minimize the transmission collision, that's what motivated us to propose in this thesis two new robust geocast routing protocols, ours proposals for safety and comfort applications in VANET and two multicast routing protocols: (i) the first work illustrates the problem of reducing transmission interferences for multicast safety messages in VANET. We propose a heuristic algorithm called Time-Limited Reliable Broadcast Incremental Power (TRBIP) to construct a safety message delivery tree. (ii) the second work describes the distributed version of our designed routing protocol called DTRBIP. This routing protocol handles both Delay-sensitive and Delay-tolerant applications through multicast scheme in urban and highway environments.