Date Added: Aug 2012
In this paper, an adaptive modulation scheme for the Two-Way Relay Channel (TWRC) is proposed. The modulation used at each user is adaptively selected according to their own channel. When the channels are asymmetric, i.e., the channels are with unbalanced bit message rate, the worse channel is the bottleneck of the transmission. The authors propose a scheme by applying buffer technique and hierarchical modulation at the relay with a modified XOR operation to achieve the unbalanced transmission. Monte-Carlo simulation is also provided to demonstrate the performance of the proposed scheme.