On the Design of Linear Transceivers for Multiuser Systems with Channel Uncertainty
On the Design of Linear Transceivers for Multiuser Systems with Channel Uncertainty
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DOI：
10.1109/jsac.2008.080817
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发表时间：
2008-08
影响因子：
16.4
通讯作者：
M. B. Shenouda;T. Davidson
中科院分区：
文献类型：
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作者：
M. B. Shenouda;T. Davidson
我们考虑在不确定信道状态信息（CSI）存在的情况下多用户通信系统的线性收发器的设计，重点是在每个接收器上具有单个天线的下行链路系统。对于具有上下互易性的系统，我们考虑了信道不确定性的随机模型，并提出了一种有效的联合设计算法，用于基站的线性先验矩阵和接收机的均衡增益，以最小化信道不确定性下的平均均方误差（MSE）。该设计基于广播和多址信道（MAC）之间的MSE对偶性在CSI不确定情况下的推广，以及用于双MAC的鲁棒收发器设计的凸公式。对于采用量化信道反馈的系统，我们考虑了信道不确定性的确定性有界模型。并且我们研究了在所有允许的信道上最小化最坏情况MSE的鲁棒下行收发器的设计。虽然我们表明设计问题是np困难的，但我们也提出了一种基于有效可解凸二次方程的迭代局部优化算法。我们的框架非常灵活，可以结合不同的有界不确定性模型以及各种功率约束。特别是，我们研究了一个“系统范围”的不确定性模型，尽管最终的设计问题仍然是NP困难的，但它确实导致了一个比“每个用户”不确定性模型简单得多的迭代局部设计算法。我们对下行链路的极大极小设计方法可以扩展到上行链路，并且我们为最终的上行链路设计提供了明确的公式。仿真结果表明，所提出的鲁棒线性收发器设计方法可以显著降低下行链路对不确定CSI的灵敏度，并且可以提供比现有鲁棒设计更好的性能。
We consider the design of linear transceivers for multiuser communication systems in the presence of uncertain channel state information (CSI), with an emphasis on downlink systems with a single antenna at each receiver. For systems with uplink-downlink reciprocity, we consider a stochastic model for the channel uncertainty, and we propose an efficient algorithm for the joint design of the linear preceding matrix at the base station and the equalizing gains at the receivers so as to minimize the average mean-square-error (MSE) over the channel uncertainty. The design is based on a generalization, derived herein, of the MSE duality between the broadcast and multiple access channels (MAC) to scenarios with uncertain CSI, and on a convex formulation for the design of robust transceivers for the dual MAC. For systems in which quantized channel feedback is employed, we consider a deterministically-bounded model for the channel uncertainty, and we study the design of robust downlink transceivers that minimize the worst- case MSE over all admissible channels. While we show that the design problem is NP-hard, we also propose an iterative local optimization algorithm that is based on efficiently-solvable convex conic formulations. Our framework is quite flexible, and can incorporate different bounded uncertainty models as well as a variety of power constraints. In particular, we study a "system-wide" uncertainty model, and although the resulting design problem is still NP hard, it does result in a significantly simpler iterative local design algorithm than the "per-user" uncertainty model. Our approaches to the minimax design for the downlink can be extended to the uplink, and we provide explicit formulations for the resulting uplink designs. Simulation results indicate that the proposed approaches to robust linear transceiver design can significantly reduce the sensitivity of the downlink to uncertain CSI, and can provide improved performance over that of existing robust designs.