SIMO Channel Estimation Using Space-Time Signal Subspace Projection and Soft Information
SIMO Channel Estimation Using Space-Time Signal Subspace Projection and Soft Information
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DOI：
10.1109/tsp.2012.2196695
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发表时间：
2012-08-01
影响因子：
5.4
通讯作者：
Yang, Kehu
中科院分区：
文献类型：
--
作者：
Cai, Shu;Matsumoto, Tad;Yang, Kehu
我们考虑了具有移动用户和基站的时隙无线通信系统的信道估计，其中基站采用M元（M > 1）天线阵列。上行单输入多输出（SIMO）信道通常通过在每个时隙内的训练序列来估计。为了提高信道估计的性能，通常通过将信道估计投影到相应的空间信号子空间来改进信道估计。然而，当可分辨多径射线的数量大于天线阵列元素的数量时，这种投影将无法工作，这使得信道矩阵满行秩。本文给出了这种全行秩情况下的空时信号模型下的信道估计，并提出了一种利用训练数据序列和未知数据序列进行空时信号子空间投影的新方法。为了进一步提高信道估计的精度，可以利用解码器反馈的软信息。利用这些软信息，我们提出了另一种新的信道估计方法。这种方法近似地遵循最大似然（ML）准则，因此被称为近似的ML信道估计。数值结果表明，这些方法可以单独或联合使用，以提高训练序列信道估计的性能。
We consider the channel estimation of a time-slotted wireless communication system with a mobile user and a base station, where the base station employs an M-element (M > 1) antenna array. The uplink single-input multiple-output (SIMO) channel is usually estimated by training sequence within each time slot. To improve the estimation performance, the channel estimate is often refined by projecting it to the corresponding spatial signal subspace. However, this projection will not work when the number of resolvable multipath rays is larger than that of the antenna array elements, which makes the channel matrix full row rank. In this paper, we formulate the channel estimation under the space-time signal model for this full-row-rank case, and propose a new method by space-time signal subspace projection using both training and unknown data sequences. To further improve the accuracy of the channel estimate, the soft information fed back from the decoder can be used. By involving this soft information, we propose another new channel estimation method. This method approximately follows the maximum likelihood (ML) criterion and is therefore referred to as the approximated ML channel estimation. Numerical results show that these methods can be performed separately or jointly to improve the performance of channel estimation by training sequences.