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在基于正交频分复用(OFDM)的认知无线电系统中,主用户会受到次用户带内子载波以及邻带子载波的带外泄漏功率的干扰。为了在保护主用户通信性能的前提下高效利用机会频谱,该文提出了求解次用户子载波间的最优功率分配方案的方法,通过求解一个凸优化问题获得最优功率分配方案。较之迭代分块注水算法,该方法特别考虑了邻带子载波功率泄漏的影响。仿真结果表明:采用这种方法所获得的功率分配方案在满足各主用户干扰功率上限的条件下使得次用户信道容量最大化。
In cognitive radio systems based on Orthogonal Frequency Division Multiplexing (OFDM), the primary user suffers from out-of-band leakage power of secondary-user in-band subcarriers and adjacent subcarriers. In order to make efficient use of opportunistic spectrum under the premise of protecting the communication performance of primary users, this paper proposes a method to solve the optimal power allocation scheme among sub-carriers of sub-users and obtains the optimal power allocation scheme by solving a convex optimization problem. Compared with the iterative partitioned waterflooding algorithm, this method specially considers the influence of adjacent sub-carrier power leakage. The simulation results show that the power allocation scheme obtained by this method maximizes the sub-user channel capacity under the condition that the upper limit of the interference power of each primary user is satisfied.