Comparison of Broadcasting Schemes for Infrastructure to Vehicular Communications

A large set of potential applications being designed for intelligent transportation systems (ITSs) depends on the broadcasting of information and control packets by roadside infrastructure points to vehicles in their vicinity. This paper considers the broadcast capacity of broadcast schemes and evaluates and compares the broadcast capacity of strategies based on time splitting, frequency splitting, and superposition coding. Frequency splitting is shown to always dominate time splitting, and the conditions under which superposition coding dominates the other two are derived. For these regimes, it is shown that the broadcast capacities associated with superposition coding are optimal. A proportionally fair algorithm for scheduling broadcast packets is then proposed, and its performance is compared against that of other schedulers.