To decode or to amplify: Mix and match for the two-way two-relay network

We study the problem of how two terminals exchange messages with the help of two relays. An upper bound and the achievable rate regions under amplify-forward (AF) and decode forward (DF) are derived. Then we mix these two strategies and propose three mixed strategies. We evaluate the performance of these strategies under different channel cases. It is shown that not only the basic strategies have their best performance in some scenarios, but also the mixed strategies match well under certain circumstances. Furthermore, some strategies can achieve or approach the upper bound under certain conditions.