A Unified Approach for Calculating the Outage Performance of Two-Way AF Relaying Over Fading Channels

Amplify-and-forward-based two-way relaying (TWR-AF) promises significant benefits in wireless networks. In this paper, we aim to obtain unified expressions to determine the outage probability of TWR-AF, regardless of different channel fadings. To this end, a visual integral region-based geometric analysis (GA-IR) approach is introduced, which does not depend on the specific functional forms of the channel fading distributions. Applying this method, we have derived the expressions of both individual and system outage probabilities with adjustable accuracy. Importantly, our analysis is then extended to multiuser and multirelay TWR-AF, and a unified expression and a concise lower bound are achieved. It has been shown that all the presented expressions apply to unequal transmitted power values and conventional fading channels, providing valuable and unified insights into practical system pretest evaluation and designs. By performing simulations over several representative fading channels [e.g., Rayleigh, Nakagami-m, Rice (Nakagami-n), and generalized-K (KG)] , the accuracy and generality of the provided expressions are presented. Utilizing these results, the outage performance for TWR-AF can be figured out flexibly and efficiently.