Non-coherent two-way relaying: Rate bounds for the high SNR regime
ABSTRACT Rate bounds for the non-coherent two-way relaying channel under the high SNR assumption are derived. No channel knowledge is assumed at neither the terminals nor at the relays. An upper and lower bound on the achievable rates are derived and shown that they differ only by a constant in the high SNR regime. As corollary from the analysis, the degrees of freedom of the non-coherent two-way channel are derived. Additionally, it is shown that the degrees of freedom can be achieved by an AF scheme.
Article: Non-Coherent Energy Detection with Orthogonal Signaling for an Uncoded Two-Way Relay Channel[show abstract] [hide abstract]
ABSTRACT: In this correspondence, we investigate a two-phase two-way relay protocol for a scenario without channel coding or channel estimation. The considered configuration represents practical sensor networks, where the nodes wish to exchange some low rate messages (e.g. 1 bit) via a shared relay under a strict complexity or latency constraint (corresponding to our assumptions of no-coding and no-channel estimation). A new scheme which incorporates a single-threshold non-coherent energy detection and a digital network coding process at the relay node is proposed. The energy detection is optimized for both phases of the protocol and a threshold that exhibits no error floors is derived in a closed form. Numerical results validate the efficiency of the proposed scheme and introduce the two-way relay channel as an efficient structure also for non-coherent and uncoded systems.