Joint Precoding and Multivariate Backhaul Compression for the Downlink of Cloud Radio Access Networks
Joint Precoding and Multivariate Backhaul Compression for the Downlink of Cloud Radio Access Networks
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DOI：
10.1109/tsp.2013.2280111
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发表时间：
2013-11-01
影响因子：
5.4
通讯作者：
Shamai, Shlomo
中科院分区：
文献类型：
--
作者：
Park, Seok-Hwan;Simeone, Osvaldo;Shamai, Shlomo
这项工作研究了云无线接入网络下行链路的预编码和回程压缩策略的联合设计。在这些系统中，中央编码器通过有限容量回程链路连接到多个多天线基站（BS）。在中央编码器处，预编码之后进行压缩，以产生通过相应回程链路传送到每个基站的速率受限比特流。在当前最先进的方法中，针对不同基站的信号是独立压缩的。相比之下，这项工作建议利用不同基站信号的联合压缩（也称为多元压缩），以便更好地控制移动站（MS）处的加性量化噪声的影响。在功率和回程容量约束下，制定了关于量化噪声的预编码矩阵和联合相关矩阵最大化加权和速率的问题。提出了一种迭代算法来实现问题的驻点。此外，为了能够实际实现跨基站的多元压缩，提出了一种基于最小均方误差（MMSE）估计和每基站压缩的连续步骤的新颖架构。还讨论了针对不完美信道状态信息的鲁棒设计。从数值结果来看，证实所提出的联合预编码和压缩策略优于基于预编码和压缩的单独设计或跨BS的独立压缩的传统方法。
This work studies the joint design of precoding and backhaul compression strategies for the downlink of cloud radio access networks. In these systems, a central encoder is connected to multiple multi-antenna base stations (BSs) via finite-capacity backhaul links. At the central encoder, precoding is followed by compression in order to produce the rate-limited bit streams delivered to each BS over the corresponding backhaul link. In current state-of-the-art approaches, the signals intended for different BSs are compressed independently. In contrast, this work proposes to leverage joint compression, also referred to as multivariate compression, of the signals of different BSs in order to better control the effect of the additive quantization noises at the mobile stations (MSs). The problem of maximizing the weighted sum-rate with respect to both the precoding matrix and the joint correlation matrix of the quantization noises is formulated subject to power and backhaul capacity constraints. An iterative algorithm is proposed that achieves a stationary point of the problem. Moreover, in order to enable the practical implementation of multivariate compression across BSs, a novel architecture is proposed based on successive steps of minimum mean-squared error (MMSE) estimation and per-BS compression. Robust design with respect to imperfect channel state information is also discussed. From numerical results, it is confirmed that the proposed joint precoding and compression strategy outperforms conventional approaches based on the separate design of precoding and compression or independent compression across the BSs.