Network coding over time-varying networks by means of virtual graphs

We present a method for network coding over time-varying networks with attractive tradeoffs between throughput and decoding-delay. We model the time-varying networks as a sequence of topology graphs. The method relies on designing a deterministic network code for a fixed virtual graph derived from the actual sequence of topologies, and on exploiting proper buffering in order to implement the code over the actual network. We show that, under certain conditions, this approach can achieve the maximum achievable throughput over the given time-varying network. We also present simulation results that validate the theoretical findings.