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Reciprocity Calibration for Massive MIMO: Proposal, Modeling and Validation

Vieira, Joao LU ; Rusek, Fredrik LU ; Edfors, Ove LU ; Malkowsky, Steffen LU ; Liu, Liang LU and Tufvesson, Fredrik LU (2017) In IEEE Transactions on Wireless Communications 16(5). p.3042-3056
Abstract
This paper presents a mutual coupling based calibration method for time-division-duplex massive MIMO systems, which enables downlink precoding based on uplink channel estimates. The entire calibration procedure is carried out solely at the base station (BS) side by sounding all BS antenna pairs. An Expectation-Maximization (EM) algorithm is derived, which processes the measured channels in order to estimate calibration coefficients. The EM algorithm outperforms current state-of-the-art narrow-band calibration schemes in a mean squared error (MSE) and sum-rate capacity sense. Like its predecessors, the EM algorithm is general in the sense that it is not only suitable to calibrate a co-located massive MIMO BS, but also very suitable for... (More)
This paper presents a mutual coupling based calibration method for time-division-duplex massive MIMO systems, which enables downlink precoding based on uplink channel estimates. The entire calibration procedure is carried out solely at the base station (BS) side by sounding all BS antenna pairs. An Expectation-Maximization (EM) algorithm is derived, which processes the measured channels in order to estimate calibration coefficients. The EM algorithm outperforms current state-of-the-art narrow-band calibration schemes in a mean squared error (MSE) and sum-rate capacity sense. Like its predecessors, the EM algorithm is general in the sense that it is not only suitable to calibrate a co-located massive MIMO BS, but also very suitable for calibrating multiple BSs in distributed MIMO systems.
The proposed method is validated with experimental evidence obtained from a massive MIMO testbed. In addition, we address the estimated narrow-band calibration coefficients as a stochastic process across frequency, and study the subspace of this process based on measurement data. With the insights of this study, we propose an estimator which exploits the structure of the process in order to reduce the calibration error across frequency. A model for the calibration error is also proposed based on the asymptotic properties of the estimator, and is validated with measurement results. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Massive MIMO, reciprocity calibration, mutual coupling, expectation maximization, validation
in
IEEE Transactions on Wireless Communications
volume
16
issue
5
pages
15 pages
publisher
IEEE--Institute of Electrical and Electronics Engineers Inc.
ISSN
1536-1276
DOI
10.1109/TWC.2017.2674659
language
English
LU publication?
yes
id
7f9779c0-1634-4c58-928f-efe16178911a
alternative location
https://arxiv.org/abs/1606.05156
date added to LUP
2016-06-23 13:25:16
date last changed
2017-05-17 10:37:06
@article{7f9779c0-1634-4c58-928f-efe16178911a,
  abstract     = {This paper presents a mutual coupling based calibration method for time-division-duplex massive MIMO systems, which enables downlink precoding based on uplink channel estimates. The entire calibration procedure is carried out solely at the base station (BS) side by sounding all BS antenna pairs. An Expectation-Maximization (EM) algorithm is derived, which processes the measured channels in order to estimate calibration coefficients. The EM algorithm outperforms current state-of-the-art narrow-band calibration schemes in a mean squared error (MSE) and sum-rate capacity sense. Like its predecessors, the EM algorithm is general in the sense that it is not only suitable to calibrate a co-located massive MIMO BS, but also very suitable for calibrating multiple BSs in distributed MIMO systems. <br/>The proposed method is validated with experimental evidence obtained from a massive MIMO testbed. In addition, we address the estimated narrow-band calibration coefficients as a stochastic process across frequency, and study the subspace of this process based on measurement data. With the insights of this study, we propose an estimator which exploits the structure of the process in order to reduce the calibration error across frequency. A model for the calibration error is also proposed based on the asymptotic properties of the estimator, and is validated with measurement results.},
  author       = {Vieira, Joao and Rusek, Fredrik and Edfors, Ove and Malkowsky, Steffen and Liu, Liang and Tufvesson, Fredrik},
  issn         = {1536-1276},
  keyword      = {Massive MIMO,reciprocity calibration,mutual coupling,expectation maximization,validation},
  language     = {eng},
  month        = {03},
  number       = {5},
  pages        = {3042--3056},
  publisher    = {IEEE--Institute of Electrical and Electronics Engineers Inc.},
  series       = {IEEE Transactions on Wireless Communications},
  title        = {Reciprocity Calibration for Massive MIMO: Proposal, Modeling and Validation},
  url          = {http://dx.doi.org/10.1109/TWC.2017.2674659 },
  volume       = {16},
  year         = {2017},
}