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IQ Imbalance in Multiuser Systems: Channel Estimation and Compensation

Nikolaos Kolomvakis (Institutionen för signaler och system, Signalbehandling) ; Michail Matthaiou ; Mikael Coldrey (Institutionen för signaler och system, Signalbehandling)
IEEE Transactions on Communications (0090-6778). Vol. 64 (2016), 7, p. 3039-3051.
[Artikel, refereegranskad vetenskaplig]

In this paper, we consider the uplink of a single-cell multi-user single-input multiple-output (MU-SIMO) system with in-phase and quadrature-phase imbalance (IQI). Particularly, we investigate the effect of receive (RX) IQI on the performance of MU-SIMO systems with large antenna arrays employing maximum-ratio combining (MRC) receivers. In order to study how IQI affects channel estimation, we derive a new channel estimator for the IQI-impaired model and show that the higher the value of signal-to-noise ratio (SNR) the higher the impact of IQI on the spectral efficiency (SE) of MRC receivers. Moreover, a novel pilot-based joint estimator of the augmented MIMO channel matrix and IQI coefficients is described and then, a low-complexity IQI compensation scheme is proposed which is based on the IQI coefficients' estimation and it is independent of the channel gain. The performance of the proposed compensation scheme is analytically evaluated by deriving a tractable approximation of the ergodic SE assuming transmission over Rayleigh fading channels with large-scale fading. Furthermore, we investigate how many MSs should be scheduled in massive MIMO systems with IQI and show that the highest SE loss occurs at the optimal operating point. Finally, by deriving asymptotic power scaling laws, and proving that the SE loss due to IQI is asymptotically independent of the number of BS antennas, we show that massive multiple-input multiple-output (MIMO) is resilient to the effect of RX IQI.

Nyckelord: Channel estimation; I/Q imbalance; massive MIMO; spectral efficiency

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Denna post skapades 2016-04-13. Senast ändrad 2017-09-14.
CPL Pubid: 234639


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