两跳多中继网络中改进的前向放大中继策略

单源单宿多中继多天线系统中，中继总功率受限的最大化系统传输速率问题为非凸优化问题.针对此问题分别提出TFSA (Target Function Simplified Algorithm)和CCSA（Constrain Conditions Simplified Algorithm）两种优化算法.TFSA通过缩放信道矩阵与其共轭转置矩阵乘积的特征值使此问题成为凸优化，并使用传统凸优化方法获得其最优数值解；CCSA通过缩小此优化问题的约束集并转换自变量使之成为凸优化，再利用拉格朗日算法获得其解析解，能够实现算法复杂度和系统性能的折衷.实验仿真表明，TFSA算法能逼近最优算法实现的系统性能； CCSA与已有算法比较获得了一定的速率增益，且实现复杂度低.

Advanced Amplify-and-Forward Relaying Schemes for Two-Hop MIMO Multi-Relay Networks

In a single-source single-destination multi-relay MIMO network, the problem to achieve the maximum transmit rate with the total relay power constraint is proved to be non convex. This paper proposed two advanced algorithms: TFSA (Target Function Simplified Algorithm) and CCSA (Constrain Conditions Simplified Algorithm), respectively. TFSA transforms the problem into a convex optimization one by approximating eigenvalues of the product of channel matrix and its transposed conjugate matrix, so that traditional convex optimization methods can achieve the optimal numerical solution of this problem. CCSA makes the problem become convex optimization by reducing the constraint set and transforming variables. It achieves a closed form solution with the Lagrange method, so as to implement the tradeoff between the algorithm complexity and system performance. The simulation results show that TFSA approaches performance of the optimal algorithm and CCSA can get performance gains over the existing schemes with a low implement complexity.