Shitz), “Oblivious relaying for primitive interference relay channels

Abstract—1Consider a relay node that needs to operate without knowledge of the codebooks (i.e., modulation, coding) employed by the assisted source-destination pairs. This paper studies the performance of relaying under this condition, termed oblivious relaying, for the primitive relay channel (PRC) and the primitive interference relay channel (PIRC). "Primitive " refers to the fact that the relay-to-destinations links use orthogonal resources with respect to the other links. Assuming discrete memoryless models, the capacity of a PRC with oblivious relaying is derived, along with the capacity region of the PIRC with oblivious relaying and interference-oblivious decoding (i.e., each decoder is unaware of the codebook used by the interfering transmitter). In all cases, capacity is achieved by Compress-and-Forward (CF) with time-sharing. Performance without time-sharing is discussed as well. Finally, it is shown that for the general (non-oblivious) Gaussian PRC, the achievable rate by CF (with Gaussian inputs and test channels and no time-sharing) is suboptimal by at most half bit with respect to the cut-set bound. I