Squaring Back off Based Media Access Control for Vehicular Ad-hoc Networks

Inter-vehicle communications have great potential to induce great interest in research and industry. Vehicular ad hoc networks (VANETs) may significantly improve passenger safety and comfort. The deployment of VANETs is a challenging task in weakly interconnected and in highly overloaded networks both. A good back off technique can reduce a large number of collisions in the MAC layer I VANET. This will reduce the collision probability and hence increases the utilization of network resources. A uniform random distribution has been employed to choose the back off value in the Binary Exponential Back off (BEB) technique used in the IEEE 802.11 MAC protocol. This random choosing VANETs leads to unnecessary idle times and reduced throughput. This paper proposes a new back off technique called “Squaring Back off (SB)” in which the differences between the consecutive contention window sizes are reduced to a negligible value. Here, the value of the back off timer is based on the size of the contention window. The size of the contention window is varied in accordance with the result of the previous transmission. A successful transmission reduces the size of the contention window whereas a failure leads to the increase in the contention window size. Simulation results indicate that the proposed technique provides better throughputs and less idle times than the logarithmic and Fibonacci based techniques when used in a mobile ad-hoc environment. Squaring back off based media access control can prove very useful for vehicular ad-hoc networks.