干扰温度约束下的最优源功率控制与协作波束成形

摘要

We investigate,subject to interference temperature constraint of primary user,how to optimize cognitive source transmit power and cognitive relay beamforming weights in order to maximize the signalto-noise ratio (SNR) at the cognitive destination.We show that the SNR maximization problem can be converted into a generalized Rayleigh quotient problem and the optimal relay beamforming weights are equal to the eigenvector corresponding to the maximum eigenvalue of a matrix consisting of associated channel coefficients and source transmit power.Two types of interference temperature constraints,strict and loose,are considered.For the strict case,analytical solutions of the optimal source transmit power and relay beamforming weights are provided.For the loose case,a stringent interval containing the optimal source transmit power is deduced and a steepest descent based algorithm is shown that the optimal solution can be achieved efficiently.%文中研究在主用户干扰温度约束下,如何优化认知源节点发送功率以及认知中继波束成形权值来最大化认知目的节点的信噪比.信噪比最大化问题被转化为广义Rayleigh商问题,最优中继波束成形权值等于相关信道系数与源节点发送功率构成的矩阵的最大特征值所对应的特征向量.文中考虑了严格与宽松两种干扰温度约束,对于严格约束,给出了最优源节点发送功率与中继波束成形权值的解析解；对于宽松约束,推导了包含最优源发送功率的一个紧缩区间,并在该区间内使用基于最速下降的梯度方法有效计算最优解.