Joint Resource Allocation for OFDM-Based Cognitive Two-Way Multiple AF Relays Networks With Imperfect Spectrum Sensing

In consideration of an orthogonal-frequency-division-multiplexing access cognitive two-way relay network with imperfect spectrum sensing, we propose a joint resource allocation algorithm to maximize the total transmission rate of secondary users (SUs) under maximum transmit power constraints and interference temperature constraints. To solve this joint optimization problem, we use the Lagrange dual decomposition method, discrete searching approach, and the Hungarian algorithm to obtain the optimal power allocation, the subcarrier pairing matrix, and the relay selection matrix. Moreover, the analyses of feasibility, sensitivity, convergence, and calculation complexity of the proposed algorithm are given. The effectiveness and validity of this algorithm with imperfect spectrum sensing are proved by the simulations of system performance and comparisons with the algorithm with perfect spectrum sensing. The results also indicate that our algorithm can provide protection for primary user (PU), while SUs and relays opportunistically access the spectrum occupied by PU.