Multi-beam uncoordinated random access MAC for underwater communication networks

Abstract

We consider a multi-beam directional network where the nodes have digital antenna arrays capable of performing post-reception digital beamforming without prior knowledge of angle-of-arrival. Post-reception digital beamforming has greatly advanced uncoordinated random access in directional networks where, in the past, scheduling of beams was a bottleneck. A key trade off in these systems is number of antennas and corresponding beam-width. We demonstrate, through numerical simulations, that the random access MAC under consideration, MB-URAM, does not perform as well as the idealized version originally presented [Kuperman et al. 2016]. We demonstrate how interference between coincident nodes cause a significant number of packet drops even with a very large number of antennas. Finally, we suggest how to mitigate the effect of the interference and introduce ideas to do so.