Improving Transmission Rate for the Two-Way Relay Channel by User Cooperation

We analyze the impact of user cooperation in the two-way relay channel (TWRC) by letting each user send a quantized version of its received signal in addition to its own message. The proposed scheme is based on quantize-forward (QF) and partial decode-forward (PDF) relaying with sliding window decoding at the relay, and QF relaying with backward decodings at each user. For Gaussian channels, examples show that although there is no improvement on the sum rate, the individual rate can be significantly increased. Moreover, as the power of one user approaches infinity, the transmission rate of the other user asymptotically achieves the capacity by reaching the cut-set bound. Hence, such user cooperation may be useful in networks where users have different priorities.