STFDMA: A novel technique for ad-hoc V2V networks exploiting radio channels frequency diversity

Device to Device (D2D) communication underlaying a cellular infrastructure has attracted a great deal of attention due to its potential of enhancing capacity while reducing load and energy consumption, among other features. In turn, vehicle to vehicle (V2V) communication is envisioned as a special case of D2D, where vehicles driving closely exchange messages about the driving conditions to improve the safety on the road with little support from the base station (BS). In safety applications, however, it is essential that the communication can be maintained even if the cellular infrastructure is not available due to a coverage hole or a temporary network failure. In this paper, we present a novel technique called self-organizing time-frequency division multiple access (STFDMA) to allow vehicles to communicate efficiently in an ad-hoc manner while network assistance is not available. It has two main advantages compared to the very well known IEEE 802.11p standard: (i) It is compatible with envisioned fifth generation (5G) cellular networks, and (ii) it has a deterministic medium access delay, unlike carrier sense multiple access with collision avoidance (CSMA/CA), method used in 802.11p. This is achieved by (i) reconstructing the channel gains over frequency of one device to the neighboring ones, (ii) allocating resources in a distributed manner, and (iii) adapting the transmission to the estimated channel quality.