Research Area:  Vehicular Ad Hoc Networks
A major issue in VANETs is the high mobility of the nodes. Broadcasting helps in improving the performance of the VANETs in terms of secure routing. However, broadcasting is a major overhead in VANETs. Broadcasting is still a widely used technique in wireless ad hoc networks and is mainly used to transmit network control information and application oriented data. The Optimized Link State Routing Protocol (OLSR) uses a multipoint relay scheme (MPR) to flood the network with control messages involving topology and other technical data. The method generally adopted is flooding which sometimes may lead to congestion in the network. The OLSR technique also has the capability of reducing retransmissions that are redundant and obsolete. We have proposed a MPR selection technique for a robust broadcast in VANETs. Our proposed method tries to cover all the 2-hop MPR nodes m times. It also considers the weaker 2-hop MPR nodes set and compensates by providing an alternate solution to counteract the same. In fact, the proposed method determines the strength of the 2-hop MPR set before the start of the transmission and also tries to control the flooding of the transmission control messages. The proposed method is capable of recovering faster when there are broken communication links using the concept of friend MPR nodes. This is made possible with the help of the control packets which carry information regarding the RMPR and the Friend MPR nodes. The RMPR nodes are analyzed using a network simulator (NS2) and mathematical modeling. The values were obtained from the graph readings that were supplied to the simulator. The performance analysis has been tabulated in the results and discussion section. We have studied the performance of the proposed RMPR–OLSR protocol with the existing MMPR–OLSR and the OLSR protocols. The protocols were assessed by studying the network performance when the number of nodes was increased. It was assessed based on the nature of the traffic within the network. The delay for the proposed RMPR–OSLR was lesser than the other two methods (even with an increase in the number of nodes). Similarly, the packet drop for RMPR–OLSR was lesser than MMPR–OLSR and OLSR. The throughput of the RMPR–OLSR was found to increase by than the other existing protocols. The channel utilization was found to be more improved than the other protocols. In fact, the packet delivery ratio (PDR) of the proposed protocol was more than the other two protocols. Thus, the proposed protocol is capable of improving the overall throughput of the network and also helps in maximizing the PDR with respect to the MPR selection technique employed by OLSR.
Author(s) Name:  M. Usha,B. Ramakrishnan
Journal name:  Wireless Personal Communications
Publisher name:  Springer
Volume Information:  volume 110, pages 355–380 (2020)
Paper Link:   https://link.springer.com/article/10.1007/s11277-019-06732-0