Precoding Design for Cognitive Two-Way Relay Networks
The authors study precoding design for Cognitive Two-Way Relay Networks (C-TWRNs). In C-TWRN, the multi-antenna secondary transmitter not only transmits its own signal to the secondary receiver, it also acts as relay to help forwarding signals of two primary users via two-way relaying in the licensed frequency band. Their objective is to design linear relay transceiver or precoder such that the achievable rate of the secondary user is maximized while maintaining rate requirements of the primary users. To achieve this goal, different relay strategies, i.e., Amplify-and-Forward (AF), bit level XOR based Decode-and-FORward (DFXOR) and symbol level SUPerposition coding based Decode-and-Forward (DF-SUP), are considered.