论文部分内容阅读
本文考虑认知无线电系统中一对认知源目的节点在一组认知中继节点协助下与一对授权发射机和接收机共存的场景,研究了多个单天线认知中继节点在授权接收机处平均干扰功率门限约束及自身独立的平均发射功率约束下,最大化认知目的节点处信干噪比(SINR)的分布式波束成形,从而开发“空谱空洞”的问题.提出了两种波束成形方案:1)最大化SINR的最优策略;2)基于迫零准则的次优策略.最优策略将分布式的波束成形系数求解问题通过半定松弛转化为准凸的优化问题,从而利用二分法及内点法求解;并证明了求得的最优半定松弛解即为原优化问题的最优解.次优策略直接迫零对授权接收机造成干扰,并将来自授权发射机的干扰信号抑制为零.该方法对应的优化问题没有迭代运算,且约束函数简单,算法复杂度低.最后通过数值仿真分析了中继数、认知节点最大的发射功率和授权接收机的干扰功率门限等因素对两类算法平均传输速率的影响,并且通过对比实验验证了考虑授权发射机干扰信号影响带来的性能增益.
In this paper, we consider a scenario where a pair of cognitive source nodes in a cognitive radio system coexist with a pair of authorized transmitters and receivers with the assistance of a group of cognitive relay nodes. We consider that multiple single-antenna cognitive relay nodes Receiver interference power threshold constraint and its own independent average transmit power constraints, to maximize the cognitive destination node SINR distributed beamforming, thereby developing “empty spectral hole ” issue. Two schemes of beamforming are proposed: 1) the optimal strategy to maximize SINR; 2) the suboptimal strategy based on zero-forcing criterion.The optimal strategy transforms the problem of solving the distributed beamforming coefficients to semi- The optimal problem is solved by the dichotomy and interior point method, and the optimal semi-definite relaxation solution obtained is proved to be the optimal solution of the original optimization problem.The suboptimal strategy directly causes zero interference to the authorized receiver, The interference signal from the authorized transmitter is suppressed to zero.The optimization problem corresponding to this method has no iterative operation, the constraint function is simple and the algorithm complexity is low.Finally, by numerical simulation, the maximum number of relays, Influence and interference power threshold authorized receiver two types of algorithms and other factors average transmission rate, and by considering the comparative experiments authorization signal transmitter interference impact performance gains.