Efficient network architectures for sensor reachback

What makes network architecture efficient? And how do we measure efficiency? In this paper, we study architectural issues in the context of the sensor reachback problem, from an information theoretic perspective. Specifically, we find that in an information-theoretically optimal reachback network, all of the following statements hold: 1) There exists a solution to the problem of transporting the sources over the channels if and only if a suitably defined multicommodity flow is feasible. 2) If a solution exists, then a solution exists based on separate source and channel coding only. 3) When multiple solutions exist, under a natural linear cost model defined in terms of Shannon information, an optimal solution is given by a minimum-cost multicommodity flow. Based on these results we can make a number of statements about what constitutes optimal system architecture for an important class of communication networks, where optimality is defined in a pure information theoretic sense, but has a very clear and intuitive network flow interpretation.