Sum Achievable Rate Maximization in Orbital Angular Momentum-Based Amplify-and-Forward Two-Way Relay Networks

In this letter, to enlarge wireless coverage and increase spectrum efficiency, we propose the orbital angular momentum (OAM)-based amplify-and-forward two-way relay network. Our objective is to maximize the sum achievable rate under individual transmission power constraints. We propose to employ the alternating optimization to alternatively optimize the power distribution matrices at the relay and two sources. For the former optimization, the Lagrangian dual method is utilized. For the latter optimization, the conventional interior point method can be applied. Since the interior point method has high computational complexity, we propose a low-complexity primal decomposition based algorithm, which is shown through simulations achieving the optimal solution to the optimization problem of power distribution matrices at two sources.