不确定信道的双向中继通信系统波束成形设计

Design of Beamforming in Two-way Relay Network with Imperfect CSI

本文主要针对双向中继通信系统进行研究:此系统中所有节点均是单天线,两个信源通过多个中继进行信息交换。并且系统中存在单个窃听者分两个阶段分别窃听信源以及中继转发的信号后联合解码。为了提高信源发送信号的质量以及降低窃听者窃听信号的效率,本文提出了极小化中继发送功率的优化模型。由于窃听者信道部分已知,该模型总结为鲁棒性优化问题。我们对约束条件进行放缩,形成了一个二次约束二次优化问题,并利用半正定松弛、秩一分解定理等方法将优化模型转化为半正定优化问题,从而求得原问题的解。数值模拟结果验证了本文提出的算法的有效性。

This paper considers a two-way relay network where two source nodes exchange messages through several relays and each node has a single antenna. In the network, there exists a single-antenna eavesdropper who eavesdrops messages from the two source nodes and relays. In order to improve the quality of service of the two us-ers and reduce the probability of the eavesdropper to decode the signals, we propose a model to minimize the total relay transmit power. Since the channel state information （CSI） of the eavesdropper is imperfectly known, the model is summarized as a robust optimization problem. After we tighten the constraints and eliminate the parameters with uncertainty, it becomes a quadratic constrained quadratic programming problem. Then we use the semi-definite re-laxation method and rank one decomposition theorem to solve the problem. Finally, the optimal solution of the tightened problem is obtained. Simulation results imply that the proposed algorithm is efficient.