Reliable uncoded communication in the SIMO MAC via low-complexity decoding

We consider a multiple access channel with a large number of transmitters sending symbols from a constellation to the receiver of a multi-antenna base station. We investigate the joint decoding of the signals from all the users using a low complexity convex relaxation of the maximum likelihood decoder (constellation search). We show that, in a rich scattering environment, and in the asymptotic limit of a large number of transmitters, reliable communication is possible even without employing coding at the transmitters.