A cross layer based cooperative broadcast protocol for multichannel VANET

Abstract

In multichannel environment of Vehicular Ad Hoc Network (VANET), the control channel (CCH) is exclusively dedicated for broadcast communication. Generally, immoderate transmission of packets has heightened the level of contention and collision at CCH, so a controlled flow is needed. The proposed Cross-Layer based Cooperative Broadcast Protocol (CLCBP) is designed to manage safety traffic at CCH, where a receiver-oriented MAC layer based prioritization scheme is used. A modified 2-D Markov chain model is achieved to theoretically investigate vehicle's queue's backoff procedure, where a density dependent dynamic contention window is shown as a convenient way to control collision. So, the collision density information from network layer is used to adjust the contention window at MAC layer. Additionally, a fuzzy logic technique is used to evaluate rebroadcast probability of receiver on the basis of its efficiency, collision density and packet's priority. In order to meet the delay constraint, the backoff slot duration for vehicles gets lowered with increasing value of rebroadcast probability. The simulation results show that the proposed scheme maintains a good balance between coverage delay, reachability, and saved rebroadcast in comparison with the other broadcast schemes.