Robust Tomlinson-Harashima Source and Linear Relay Precoders Design in Amplify-and-Forward MIMO Relay Systems
Robust Tomlinson-Harashima Source and Linear Relay Precoders Design in Amplify-and-Forward MIMO Relay Systems
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DOI：
10.1109/tcomm.2012.031712.100514
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发表时间：
2012-04
影响因子：
8.3
通讯作者：
F. Tseng;Min-Yao Chang;Wen-Rong Wu
中科院分区：
文献类型：
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作者：
F. Tseng;Min-Yao Chang;Wen-Rong Wu
现有的放大转发（AF）多输入多输出（MIMO）中继系统中的收发器设计通常假设完美的信道状态信息（CSI）的可用性。不完美CSI的稳健设计较少被考虑。在本文中，我们提出了一个强大的非线性收发器设计的系统与汤姆林森Harashima预编码器（THP），线性中继预编码器，和最小均方误差（MMSE）接收机。由于涉及到两个预编码器和不完美的CSI，所以鲁棒的收发器设计是困难的。为了克服这个困难，我们首先提出在THP之后级联额外的酉预编码器。酉预编码不仅简化了优化过程，而且提高了MMSE接收机的性能。然后，我们采用原始分解将原优化问题分为一个子问题和一个主问题。利用我们的公式，可以解决子问题，并且可以将两个预编码器问题转换为单个中继预编码器问题。然而，主问题是无法解决的。然后，我们提出了一个下界的目标函数和转移到凸优化问题的主问题。一个封闭形式的解决方案，然后可以获得的Karush-Kuhn-Tucker（KKT）条件。仿真结果表明，所提出的收发器可以显着优于现有的线性收发器与完美或不完美的CSI。
Existing transceiver designs in amplify-and-forward (AF) multiple-input-multiple-output (MIMO) relay systems often assume the availability of perfect channel state informations (CSIs). Robust designs for imperfect CSI have less been considered. In this paper, we propose a robust nonlinear transceiver design for the system with a Tomlinson-Harashima precoder (THP), a linear relay precoder, and a minimum-mean-squared-error (MMSE) receiver. Since two precoders and imperfect CSIs are involved, the robust transceiver design is difficult. To overcome the difficulty, we first propose cascading an additional unitary precoder after the THP. The unitary precoder can not only simplify the optimization but also improve the performance of the MMSE receiver. We then adopt the primal decomposition dividing the original optimization problem into a subproblem and a master problem. With our formulation, the subproblem can be solved and the two-precoder problem can be transferred to a single relay precoder problem. The master problem, however, is not solvable. We then propose a lower bound for the objective function and transfer the master problem into a convex optimization problem. A closed-form solution can then be obtained by the Karush-Kuhn-Tucker (KKT) conditions. Simulations show that the proposed transceiver can significantly outperform existing linear transceivers with perfect or imperfect CSIs.