分析了基于OFDM的认知无线电系统中认知用户和授权用户之间的相互干扰，以及下行链路对认知用户进行功率分配的优化目标，并给出了速率最大化优化目标下的最优功率分配方案。授权用户能够承受的干扰功率成为认知无线电系统功率分配问题的主要限制因素，其限制了认知用户的发射功率和传输速率，认知用户传输产生的干扰必须满足授权用户能够承受的干扰功率限制。%Mutual interference between cognitive user and licensed user in OFDM-based CR systems and the optimization objectives of power allocation for cognitive user in the downlink are analyzed, and the optimal power allocation scheme is presented to maximize the bit rate for cognitive user. The interference power threshold of licensed user is the primary limiting factor of cognitive radio system. It limits transmit power and transmission rate of cognitive user. The interference from the transmission of cognitive user should be less than the interferenee power threshold of licensed user.
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