On the Node Energy Efficiency of Full Duplex Two-way Ultra-Reliable Short Packet Communications

Full-duplex (FD) is a promising technique to improve the spectrum efficiency in wireless communications. However, it is noteworthy that there is a game for both node performances in a two-way channel, since self-interference can not be eliminated completely in FD communications. In this paper, we investigate the node energy efficiency (EE) for FD two-way ultra-reliable short packet communications in an additive white Gaussian noise (AWGN) channel. We focus on two cases. One is that the two nodes are noncooperative, each node only intends to maximize its own EE at any moment. The other one is that two nodes are cooperative, i.e., either of them is willing to improve their optimal EE simultaneously. For the first case, we establish a Game in terms of node EE and design an iterative algorithm to search for a Nash Equilibrium. In the second case, we establish a convex optimization problem of node EE and find the optimal solution by a standard convex optimization algorithm. It is shown by numerical results that the iterative algorithm converges and each node can achieve a higher optimal EE with a lower transmit power if they cooperate with each other.