Noncoherent Energy Detection With Orthogonal Signaling for an Uncoded Two-Way Relay Channel

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 strict complexity or latency constraint (corresponding to our assumptions of no-coding and no-channel estimation). A new scheme that incorporates single-threshold noncoherent energy detection and a digital network coding process at the relay node is proposed. Energy detection is optimized for both phases of the protocol, and a threshold that exhibits no error floors is derived in closed form. Numerical results validate the efficiency of the proposed scheme and introduce the two-way relay channel as an efficient structure for noncoherent and uncoded systems as well.