A closed-form sum-rate lower bound for amplify-and-forward multi-way relay networks

In this letter, we investigate the sum-rate performance of the multi-way relay network (MWRN) with amplify-and-forward (AF) relaying, where multiple users exchange information with the help of a relay node. We consider a full exchange scenario where each user has to decode messages form all the other users. We analyze the sum-rate lower and upper bounds of the AF MWRN, and derive a closed-form expression for the average sum-rate low bound when the number of users is sufficient large. Numerical results show that the derived bound is tight.