Blind Transmission and Detection Designs With Unique Identification and Full Diversity for Noncoherent Two-Way Relay Networks

This paper considers blind detection for a two-way relay system in which two source nodes exchange information with each other via a relay node using an amplify-and-forward (AF) protocol. The channel coefficients are assumed to be nonreciprocal, i.e., the channel gain between two nodes is not identical to that in the reverse link between the same nodes. An effective signaling and transmitting scheme using four M-ary phase-shift keying (M-PSK) constellation sets is proposed to achieve a unique identification of the transmitted symbols and the channel coefficients in a noise-free transmission. Blind receivers with full diversity are derived for Rayleigh fading channels with Gaussian noise by the generalized likelihood ratio test (GLRT) and least squares error (LSE) criteria. Constellation selections are investigated for the source nodes to transmit at a uniform bit rate in each time slot. Power-allocation schemes are discussed to improve further the average error probability of the source nodes in the blind detection. Simulation results are provided to validate the proposed designs.