Abstract: Based on the characteristics of cognitive radio and transmission properties of OFDM, an adaptive resource allocation algorithm in OFDM cognitive radio system is proposed. In traditional sub-carrier allocation process, the user with the highest priority can choose sub-carrier first, but the sub-carrier with the best channel gain isn’t always used by the user, which will result in low utilization of sub-carrier. Aiming at this problem, in the proposed algorithm, the priority of the sub-carrier allocation is determined by fairness threshold in order to achieve a tradeoff between capacity and fairness. In addition, by keeping the interference introduced to the primary users within a tolerable range in sub-carrier allocation and power allocation, the algorithm can guarantee communication requirement among secondary users. Simulation results show that the proposed algorithm can not only satisfy the fairness but also improve system capacity.

Key words: resource allocation, fairness threshold, cognitive radio, OFDM

摘要： 根据认知无线电的特点和正交频分复用（OFDM）的传输特性，提出了一种针对认知OFDM无线电系统的自适应资源分配算法。在传统的子载波分配过程中，具有优先权的用户将优先选择载波，但信道增益最大的载波并不一定会被其使用，这将导致载波利用效率下降。针对这一问题，该算法在载波分配过程中，通过公平度门限来决定载波分配的优先级，从而实现容量和公平度的折中。同时，在子载波和功率分配中使次用户对主用户的干扰功率限制在主用户可容忍的干扰极限内，保证了每个用户的通信要求。仿真结果表明，该算法在满足公平性的同时还提升了系统的容量。

关键词: 资源分配, 公平度门限, 认知无线电, 正交频分复用