Resolving rate anomaly in IEEE 802.11p multi-rate vehicle-to-infrastructure networks using TXOP differentiation

In this paper, we investigate the impact of Transmission Opportunity (TXOP) on the amount of successfully transferred data in IEEE 802.11p based multi-rate Vehicle-to-Infrastructure networks used for drive-thru Internet applications. We then analyze the rate anomaly problem that exists in such networks among vehicles with distinct data transmission rates. Essentially, the vehicle with the lowest data rate captures the channel for a long time compared to the high data rate peer, resulting in poor use of the wireless medium and reduced performance for all vehicles. This anomaly in the performance is a result of unfair channel time allocation for vehicles when they use distinct data rates. The aim of this paper is to resolve this rate anomaly problem by adjusting the TXOP of each vehicle proportional to its data rate. The analytical results are verified using extensive simulations.