Dynamic channel partition and reservation for structured channel access in vehicular networks

A large portion of vehicular safety applications require reliable broadcasting. IEEE 802.11p has been shown to have doubtful performance in this aspect [2]. In [1] we have proposed a Dynamic Channel Reservation (DCR) protocol to provide low packet loss probability for vehicular communication by exploiting the unique structure of vehicular networks (VANET), and employing a dynamic TDMA mechanism. In this work, we address the situation when there is asymmetric traffic demands from vehicles on the two sides of a roadway, under which condition the throughput performance of unmodified DCR would be significantly degraded, due to its static partition and allocation of TDMA channels to each side of the road. We therefore augment DCR by designing a protocol to dynamically allocate channels to the two sides of the road according to their time-varying traffic demands. Our design replaces the need for vehicles on the two sides to contend for each TDMA channel with a mechanism for them to contend for the boundary between the contiguous sets of channels allocated to the two sides. Preliminary ns-2 simulations show that our design enhances DCR and delivers low packet loss rate and higher throughput regardless of the level of asymmetry of the traffic demand