Improving aggregate utility in IEEE 802.11p based vehicle-to-infrastructure networks

IEEE802.11p, also known as wireless access in vehicular environment defines amendments to IEEE 802.11 to support intelligent transportation systems applications, by enabling both vehicle-to-vehicle and vehicle-to-infrastructure (V2I) communications. The medium access control layer in IEEE 802.11p is based on IEEE 802.11e enhanced distributed channel access, while the physical layer is based on IEEE 802.11a standard. This paper investigates the problem of improving the aggregate utility in IEEE 802.11p based V2I networks, while ensuring fairness among the competing vehicles. Firstly, we consider a V2I network in drive-thru Internet scenario, formed by vehicles moving on a multi-lane highway with different mean velocities in different lanes, in which all the competing vehicles use the same data rate. For error-prone channels, we derive analytical expressions for the class specific optimal minimum contention window ( $$CW_{\min }$$ C W min ) values that simultaneously maximize the aggregate data transferred and provide fairness among vehicles belonging to distinct mean velocity classes in the sense of equal chance of communicating with the road side units. We also obtain an analytical expression for the maximum aggregate data transferred in the presence of channel error. In the second part, we extend the analytical model to compute the amount of successfully transferred data in a multi-rate multi-lane V2I network. In addition to the unfairness problem caused by the distinct velocities, vehicles in such networks suffer from a performance anomaly problem as well, due to the use of distinct data rates. We determine analytical expressions for the $$CW_{\min }$$ C W min values required to simultaneously resolve both the problems. Results show that, with proper tuning of $$CW_{\min }$$ C W min the aggregate data transferred in the network improves significantly. The analytical results are corroborated using extensive simulation studies.