This paper develops a linear minimum mean-square error (LMMSE) channel estimator for single and multicarrier systems that takes advantage of the mutual coupling in antenna arrays. We model the mutual coupling through multiport networks and express the single-user multiple-input multiple-output (MIMO) communication channel in terms of the impedance and scattering parameters of the antenna arrays. We put forward a novel scattering description of the communication channel which requires only the scattering parameters of the arrays as well as the terminated far-field embedded antenna patterns. In multi-antenna single-carrier systems under frequency-flat channels, we show that neglecting the mutual coupling effects leads to inaccurate characterization of the channel and noise correlations. We also extend the analysis to frequency-selective multicarrier channels wherein we further demonstrate that the coupling between the antenna elements within each array increases the number of resolvable channel taps. Standard LMMSE estimators based on existing inaccurate channel models become sub-optimal when applied to the new physically consistent model. We hence develop a new LMMSE estimator that calibrates the coupling and optimally estimates the MIMO channel. It is shown that appropriately accounting for mutual coupling through the developed physically consistent model leads to remarkable performance improvements both in terms of channel estimation accuracy and achievable rate. We demonstrate those gains in a rich-scattering environment using a connected array of slot antennas both at the transmitter and receiver sides.
翻译:本文开发了一种线性最小均方误差(LMMSE)信道估计器,适用于单载波和多载波系统,利用天线阵列中的互耦合效应。 我们通过多端口网络模拟互耦合效应,并根据天线阵列的阻抗和散射参数来表示单用户多输入多输出(MIMO)通信信道。我们提出了一种新的散射描述通信信道的方法,只需使用阵列的散射参数以及终端远场嵌入式天线图案。在频率平坦的多天线单载波系统中,我们展示了忽略互耦合效应会导致信道和噪声相关性特性不准确的问题。我们还将分析扩展到频率选择性多载波信道上,其中我们进一步展示了每个阵列中天线元素之间的耦合会增加可分辨信道分量的数量。在现有不准确信道模型基础上,基于标准的LMMSE估计器成为次优,因此我们开发了一种新的LMMSE估计器,其中校准耦合并优化估计MIMO信道。研究结果显示,通过开发的物理一致模型适当地考虑互耦合效应,可以在信道估计精度和可实现的速率方面取得显着的性能提升。我们使用发射端和接收端的连通槽天线阵列在丰富散射环境下证明了这些收益。