Efficient Data Dissemination in Vehicular Ad Hoc Networks

Data services for in-vehicle consumption are expected to become a primary driver in the development of future vehicular networks. Due to download rate limitations of present wide-area cellular connectivity such as 3G (the likely `pipe´ to/from vehicles for long range connectivity), direct peer-to-peer data sharing among vehicles can supplement vertical downloading with horizontal dissemination. This paper studies the inter-vehicle data dissemination problem based on a WAVE/802.11p vehicular ad hoc network, using network coding. We first derive the probability mass functions (PMFs) of dissemination completion time in a prototypical three-node case for both random broadcast and with network coding, to quantify the benefits of the latter. For a one dimensional (1-D) infinite lattice network, we next provide analytical results for the steady state dissemination velocity of a data set, using network coding. The gains from such network coding, relative to the baseline scheme of random broadcast, and with perfect feedback, in presence of Rayleigh fading wireless links for this network are estimated using simulations.