MIMO全双工双向通信系统平均保密和速率的优化

研究多入多出（Multiple Input Multiple Output，MIMO）同时同频全双工双向通信系统中，合法节点在接收信息的同时向对方发送保密信息，并发送零空间人工噪声干扰窃听节点的物理层安全方案的优化问题.针对窃听信道状态信息仅统计分布已知，且存在残余自干扰的情况，首先推导出系统平均保密和速率的闭合表达式，进一步给出其下界.在此基础上，以最大化系统该下界为目标，对两节点的信息信号与人工噪声的功率分配因子、信息信号的功率分配矩阵进行联合优化.采用迭代的方法进行优化，每轮迭代中，先固定前者，优化后者，再固定后者，优化前者.使用DC（Difference of Concave/Convex，DC）规划优化信息信号功率分配矩阵，使用遗传算法优化信息信号与人工噪声的功率分配因子.对所提方案进行了仿真验证，证明理论推导正确，优化算法能有效地提高系统的平均保密和速率.

The Optimization of Average Secrecy Sum Rate for MIMO Full Duplex Two-Way Communication Systems

The optimization of physical layer security scheme in the multiple input multiple output(MIMO) fullduplex two-way communication system is studied,where legitimate nodes send confidential information and null space artificial noise while receiving information.For the case where the eavesdropping's channel state information is only statistically known and there is residual self-interference,the closed-form expression of the average achievable secrecy sum rate is first derived,then its lower bound is further given.Aiming at maximizing the lower bound,the power allocation factors of the artificial noise and the information signal,along with the power allocation matrices of the information signal are jointly optimized.An iterative method is used.In each iteration,we first fix the former and optimize the latter,then fix the latter and optimize the former.The DC (Difference of Concave/Convex,DC) programming and the genetic algorithm are used to optimize the information’s power allocation matrices as well as the power allocation factors of the information signal and artificial noise respectively.The simulation results prove that the theoretical derivation is correct,and the optimization algorithm can effectively improve the average secrecy sum rate.