Bounds on Maximum Rate-Per-Unit-Energy for Networks with Regenerative Relays

In this paper, the multi-hop relay network with transmissions over orthogonal AWGN channels is optimized in terms of maximum rate-per-unit-energy. For such a scenario, the optimal regenerative-forwarding strategy is still unknown. Furthermore, among the known ones any outperforms, in all situations, the others. The results for four different cases and discussion on the energy allocation and routing requirements are provided. First, as a comparative example, a lower bound is obtained by considering the traditional multi-hop relaying network where all communication are point-to-point reliable. The solution for this scenario is shown to have good distributed properties. Then, an accumulative strategy which is known to achieve the capacity for allcast communication is solved. In this case, the solution requires exhaustive computation. To maintain the point-to-point distributed properties a unicast strategy is investigated, with relays not decoding the source message but a bin index transmitted by the previous relay. Finally, an upper- bound on the above regenerative techniques is derived and analyzed.