Outage Performance for Two-Way AF Relaying with Asymmetric Date Rate Requirements and Imperfect CSI over Nakagami-m Fading

The system outage probability of two-way amplify and-forward (AF) relaying system with asymmetric data rate requirements and imperfect channel state information (CSI) over Nakagami-m fading channels is investigated. With different asymmetric data rate requirements patterns taken into account, an exact expression and a closed-form tight lower bound for system outage probability are derived, which indicate that under highly asymmetric data rate requirements, system outage probability is only determined by the unidirectional way with the higher data rate requirement. For more insights into the impact of imperfect CSI on system outage probability performance, the asymptotic system outage probability at high SNR region is derived, which revels that the Error Floor (EF) phenomenon exists due to the presence of imperfect CSI even though a noiseless channel is adopted. Moreover, we can conclude that under highly asymmetric data rate requirements patterns, the estimation quality of the channel hop pertaining with the higher data rate requirements has larger degradation effect on the level of EF. Numerical results and simulations are performed to validate our analysis and the new results can provide valuable guidelines in practical wireless system designs.