Power Allocation for Cognitive Two-Way AF Relay Networks with Asymmetric Traffic Requirements

In this paper, we study the power allocation for two-way amplify-and-forward relay networks with asymmetric traffic requirements in cognitive radio. The proposed power allocation scheme is achieved by minimizing the weaker link’s individual outage probability under the sum-power constraint and interference power threshold (IPT) constraints of the primary user (PU). Particularly, for the purpose of accomplishing the power allocation more realistically, the interference to each other between PU and secondary user (SU) and relay is taken into consideration. And the closed-form solution is derived for the optimum power allocation scheme of each case. Numerical results confirm that the proposed scheme improves the system performance compared with the equal power allocation scheme under various traffic requirements. The outage probability of SU communication is limited by the IPT constraints of PU and is affected significantly by the IPT level of PU. Furthermore, regardless of the symmetric or asymmetric traffic requirements, the proposed power allocation scheme is more suitable for cognitive two-way relaying networks.