Rate, Energy, and Delay Tradeoffs in Wireless Multicast: Network Coding versus Routing

We build on the framework of joint scheduling and network coding optimization. The formulation is extended to include rate, energy, and delay in network coding and routing paradigms. We then study energy-rate and delay-rate relationships to see how minimum energy and delay change as functions of multicast rate demand. The main observation is that as the rate demand approaches maximum achievable rate, the solution tends to increasingly use more diverse, longer paths. This translates into non-linearly higher energy and delay for higher input rates. In the case of energy, we are also able to show that network coding provides more benefits (when compared to routing) at higher rates. Another observation is related to the scheduling over maximal independent sets (MISs). We present results on comparing the performance of scheduling over all, exponentially growing MISs and small randomly selected subsets of MISs. Our results point to the effectiveness of the latter in achieving near-optimal rate and energy while reducing the complexity of the problem.