A Survey on VANET Unicast Routing Protocols

MANET is a naive approach for the intelligent transport system. The routing protocols in VANETs are important and necessary issue. The difference between VANET and MANET is the mobility pattern and rapidly changing topology. MANETs routing protocols are not effectively applied into VANETs. In this paper, we have made a survey about routing techniques in VANET. We have introduced unicast protocol for VANET. Carry-and-forward is the new and key concern for designing routing protocols in VANETs. We have also discussed the multi-hop forwarding and carry-and-forward techniques which reduces the delay. We have also elaborated the temporary network fragmentation problem and the broadcast storm problem. Rapid change in topology causes temporary network fragmentation problem which influences the performance of data transmissions. The broadcast storm problem affects the rate of message delivery in VANETs. The key challenge is to solve these problems to provide routing protocols with the min communication delay, the min communication overhead, and the min time complexity. We have discussed the challenges and perspectives of routing protocols for VANETs are finally discussed.