Achievable rates of a state-dependent relay channel with orthogonal components

A relay channel, with orthogonal components, is considered in the case that the spectrum is shared by another user. Upper bounds on the achievable capacity is obtained when noisy observations of the interference signal is non-causally available at the three nodes forming the relay channel. Then, a causal encoding technique is proposed such that the source and the relay can at first estimate the interference signal and then start transmission to the destination. In addition, rigorous numerical examples are studied to illustrate the benefit of having noisy observations of the interference signal at the three nodes forming the relay channel.