MAP: Contention-free MAC protocol for VANETs with PLNC

We present MAP, a contention-free MAC protocol for fast and reliable multi-hop data dissemination in vehicular ad hoc networks which takes advantage of two-packet collisions to improve network capacity. MAP addresses both the problem of unwanted collisions due to hidden nodes in CSMA/CA-based networks, and the problem of excessive control messages in dense TDMA-based vehicular networks. MAP operation introduces: (i) a dynamic subdivision of the space into multiple sub-spaces using one relay node each, and (ii) a deterministic medium access that is free of control messages, while being favorable to physical-layer networking coding transmissions. MAP implements judicious broadcast phases to guarantee fast and reliable transmissions, while nodes can join or leave the dissemination process anytime. Numerical results show that with MAP, we can achieve fast and reliable all-to-all dissemination in large multi-hop VANETS compared to conventional techniques.