Multiple access relay channel: Achievable rates over orthogonal channels

Abstract

Abstract In this paper, we consider the multiple access relay channel (MARC) in which two users want to communicate with a destination in the presence of a common intermediate node, the relay. This paper considers the case in which the relay can partially listen to both the users until it can estimate their signals. Specifically, a two-phase transmission scheme, (i) listening phase, and (ii) forwarding phase, is designed toward deriving the achievable rate region. In particular, the achievable rate region is basically derived in the cases of additive Gaussian channel and Rayleigh fading channel. Our numerical results show that (i) the derived achievable rate region contains the available rate region in the literature, and (ii) the sum rate has a concave relation with the number of channel uses in the listening phase.