MIMO双向中继网络的预编码设计与功控策略

Joint Precoding Design and Power Control in MIMO Two-Way Relay Network

为加强MIMO双向中继系统的空间复用增益,研究一种低复杂度的发送和接收预编码矩阵.利用子空间对齐方法,将双向MIMO信道分解为多路单入单出(SISO)的子信道形式,使得两个源用户能够使用网络编码获取更好的空间复用增益.同时通过矩阵计算和转化,给出了一种优化的功率分配方案.在确定优化矩阵后,该方案能够为每个子信道独立地进行优化功率分配,并且能够得到各节点间优化功率分配的闭合表达式,从而将算法复杂度从O(n3)降低为O(n).仿真结果表明,在典型场景下,所提方案在具有更低复杂度的优势下,系统性能接近优化的梯度下降迭代方案,优于传统单纯前向放大转发方式(AF),有2.99 bit/(s·Hz)的性能增益.

In order to enhance spatial multiplexing gain of multiple input multiple output（ MIMO） two-way relay networks,the transceiver precoding matrixes for all nodes with low complexity were investigated. Using subspace alignment scheme,the bi-directional MIMO channel can be decoupled into several single input single output（ SISO） sub-channels. It is accessible for source nodes to use network coding to obtain better spatial multiplexing gain. By calculating and transforming the matrices, an optimal power control method for MIMO two-way relay network was presented. This method can independently optimize each sub-channel power allocation with the fixed precoding matrix. Moreover,a closed-form solution for power allocation among relay nodes and users is derived which considerable decreases the complexity from O（ n^3） to O（ n）. Simulation results show that the performance of the proposed approach is close to the iterative gradient descent solution and outperform the traditional pure amplify-and-forward（ AF） two-way mode 2. 99 bit /（ s·Hz） gains with less computational load in typical scenarios.