Channel Estimation in Hybrid Precoding Based mmWave and massive MIMO Systems
Hybrid analog and digital precoding has become a means of exploiting both beamforming and spatial multiplexing gains in hardware constrained mmWave cellular systems. In addition to the use of analog beamforming, multiple radio frequency (RF) chains and digital domain processing allow a support of multi-stream MIMO techniques. Before any of the promised gains can be harnessed by hybrid solutions, challenges of estimating channel parameters in mmWave frequencies have to be resolved first. Classical channel estimation techniques developed for lower-frequency MIMO systems may not be applicable for mmWave MIMO due to the employment of directional beamforming and large number of antennas. The sparse nature of the mmWave channel can be exploited to help design channel estimators with high resolution and low implementation complexity.
In our group, we studied the design of low-complexity channel estimation techniques for mmWave channels with hybrid precoding. The sparse feature of mmWave channels has been leveraged in developing adaptive channel estimation algorithms using tools from compressed sensing and adaptive compressed sensing fields. We also investigated amplitude comparison based AoDs and AoAs estimation via analog beamforming and combining in mmWave MIMO systems. Our developed channel estimation methods provide promising channel estimation performance with low complexity.
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A. Alkhateeb, O. El Ayach, G. Leus, R. W. Heath Jr, “Channel Estimation and Hybrid Precoding for Millimeter Wave Cellular Systems,” IEEE Journal of Selected Topics in Signal Processing, vol.8, no.5, pp.831-846, Oct. 2014 October, 2014
The code that implements the algorithms in the paper is available here.
D. Zhu, J. Choi, and R. W. Heath, Jr., “ Auxiliary beam pair design in mmWave cellular systems with hybrid precoding and limited feedback,” Proc. of the IEEE Int. Conf. on Acoustics, Speech, and Signal Proc., pp. 3391 – 3395, Shanghai, China, March, 2016. Video of presentation
A. Alkhateeb, G. Leus, R. W. Heath Jr, “Compressed-Sensing Based Multi-User Millimeter Wave Systems: How Many Measurements Are Needed?”,” in Proc. of IEEE International Conf. on Acoustics, Speech and Signal Processing (ICASSP), Brisbane, Australia, , April, 2015
A. Alkhateeb, O. El Ayach, G. Leus, R. W. Heath Jr, “Hybrid precoding for millimeter wave cellular systems with partial channel knowledge,” Information Theory and Applications Workshop (ITA), San Diego, CA, Feb. 2013
A. Alkhateeb, O. El Ayach, G. Leus, R. W. Heath Jr, “Single-sided Adaptive Estimation of Multi-path Millimeter Wave Channels,” IEEE 15th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), pp.125-129, June, 2014
This work is supported in part by the National Science Foundation under Grant No. 1218338 and 1319556, and by gifts from Huawei Technologies, Inc and Nokia.