In this paper, we propose a channel tracking method for massive multi-input and multi-output systems under both time-varying and spatial-varying circumstance. Exploiting the characteristics of massive antenna array, a spatial-temporal basis expansion model is designed to reduce the effective dimensions of up-link and down-link channel, which decomposes channel state information into the time-varying spatial information and gain information. We firstly model the users movements as a one-order unknown Markov process, which is blindly learned by the expectation and maximization (EM) approach. Then, the up-link time varying spatial information can be blindly tracked by Taylor series expansion of the steering vector, while the rest up-link channel gain information can be trained by only a few pilot symbols. Due to angle reciprocity (spatial reciprocity), the spatial information of the down-link channel can be immediately obtained from the up-link counterpart, which greatly reduces the complexity of down-link channel tracking. Various numerical results are provided to demonstrate the effectiveness of the proposed method.
@article{arxiv.1802.10461,
title = {Time Varying Channel Tracking with Spatial and Temporal BEM for Massive MIMO Systems},
author = {Jianwei Zhao and Hongxiang Xie and Feifei Gao and Weimin Jia and Shi Jin and Hai Lin},
journal= {arXiv preprint arXiv:1802.10461},
year = {2018}
}