Optimal PHY and MAC Protocols for Power-Limited Ad-hoc Networks

We consider a power-limited ad-hoc network with coherent radios in a slow-fading environment, and we analyze the performance of different physical layer (PHY) and medium access (MAC) schemes in such a network. Most of the existing analysis assume that PHY is based on the nearest neighbor decoding, which is not optimal in this case. Instead, we focus on the MLE detector. We show that, since some of the interference is mitigated by the MLE detector, the network design paradigm changes significantly: a non-coordinated PHY and MAC, in addition to a low complexity, exhibit better performance than more complex coordinated, currently used PHY and MAC schemes. Our results suggest that most of the complexity should be invested in a receiver design instead of intricate MAC or signaling protocols. We also present a novel algorithm, using Monte-Carlo method, to calculate bounds on the rates that can be achieved with MLE detector. We show that these rates can be achieved with a detector of linear complexity.