关键词: 协作通信, 认知无线电, 功率和子载波分配, 放大转发, 公平性, 频谱共享

Abstract: In OFDM-based cognitive radio network, the Amplify-and-Forward（AF） scheme is used by cognitive users as cooperative strategy for data transmission. This paper presents a power and subcarrier allocation and pairing scheme（OFDM-PASA）. It is considered that an interference-limited environment, with a transmit sum-power constraint over all channels as well as an aggregate average interference constraint towards Primary User（PU）. The Lagrange decomposition algorithm and sub-gradient algorithm are used to solve the problem of power allocation, and subcarrier allocation and pairing algorithm is also derived. It is shown by simulation results that proportional fairness（maximize-pro-fair） is a well-balanced criterion between efficiency and fairness compared with maximize-total fairness and maximize-worst fairness. In addition, the proposed new resource allocation and subcarrier pairing strategies can achieve substantial transmission efficiency and fairness for the secondary user over the other methods when the Signal-to-Noise Ratio（SNR） is low.

Key words: cooperative communication, cognitive radio, power and subcarriers allocation, amplify-and-forward, fairness, spectrum sharing