Pilot Contamination and Precoding in Multi-Cell TDD Systems

Jose, Jubin; Ashikhmin, Alexei; Marzetta, Thomas L.; Vishwanath, Sriram

doi:10.1109/twc.2011.060711.101155

Cited by 1,248 publications

(1,100 citation statements)

References 28 publications

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“…In addition, the temporal parameter α and R jlm ∀l are assumed known by BS j. Based on the approach [6], [10],ỹ r,jm [n+1] can be described as the received signal of a single-input single-output (SISO) system with the effective channel to be w H jm [n + 1]g jjm [n + 1], while any other term constitutes the uncorrelated additive Gaussian noise. Thus, the desired signal power is…”

Section: Asymptotic Performance Analysismentioning

confidence: 99%

“…Specifically, the exploration of its behavior by including channel imperfections is imperative, in order to understand its real limits, given that the acquisition of perfect and timely CSI is crucial. Such imperfections include pilot contamination [6]- [13], [19], [20], transceiver hardware impairments [21], [22], and phase noise drift [23]. For example, the error induced in the channel due to the pilot contamination effect constitutes a bottleneck, since it saturates the performance with the number of antennas.…”

Section: Introductionmentioning

confidence: 99%

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Deterministic Equivalent Performance Analysis of Time-Varying Massive MIMO Systems

Papazafeiropoulos

Ratnarajah

2015

IEEE Trans. Wireless Commun.

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Abstract-Delayed channel state information at the transmitter (CSIT) due to time variation of the channel, coming from the users' relative movement with regard to the BS antennas, is an inevitable degrading performance factor in practical systems. Despite its importance, little attention has been paid to the literature of multi-cellular multiple-input massive multiple-output (MIMO) system by investigating only the maximal ratio combining (MRC) receiver and the maximum ratio transmission (MRT) precoder. Hence, the contribution of this work is designated by the performance analysis/comparison of/with more sophisticated linear techniques, i.e., a minimum-mean-square-error (MMSE) detector for the uplink and a regularized zero-forcing (RZF) precoder for the downlink are assessed. In particular, we derive the deterministic equivalents of the signal-to-interference-plus-noise ratios (SINRs), which capture the effect of delayed CSIT, and make the use of lengthy Monte Carlo simulations unnecessary. Furthermore, prediction of the current CSIT after applying a Wiener filter allows to evaluate the mitigation capabilities of MMSE and RZF. Numerical results depict that the proposed achievable SINRs (MMSE/RZF) are more efficient than simpler solutions (MRC/MRT) in delayed CSIT conditions, and yield a higher prediction at no special computational cost due to their deterministic nature. Nevertheless, it is shown that massive MIMO are preferable even in time-varying channel conditions.

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Section: Asymptotic Performance Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Deterministic Equivalent Performance Analysis of Time-Varying Massive MIMO Systems

Papazafeiropoulos

Ratnarajah

2015

IEEE Trans. Wireless Commun.

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“…Currently, pilot contamination reduction schemes in massive MIMO systems can be classified into three groups: channel estimation [6][7][8][9][10][11], precoding [12], and pilot scheduling [13][14][15][16][17][18][19][20]. In [6], pilot contamination was tackled by a multi-cell precoding method based on the minimum mean square error channel estimation.…”

Section: Introductionmentioning

confidence: 99%

“…In [6], pilot contamination was tackled by a multi-cell precoding method based on the minimum mean square error channel estimation. Under the assumption of spatially correlated channels, it has been found that the pilot contamination would disappear by exploiting the covariance information of user channels and using a coordinated pilot assignment strategy among cells [7].…”

Section: Introductionmentioning

confidence: 99%

Pilot contamination reduction in massive MIMO systems based on pilot scheduling

Liu

Cao

et al. 2018

J Wireless Com Network

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The pilot contamination caused by sharing the non-orthogonal pilots among users is considered to be a bottleneck of the massive multi-input multi-output (MIMO) systems. This paper proposes a pilot scheduling scheme based on the degradation to address this problem. Through computing the degradation of the users, the proposed scheduling assigns the optimal pilot sequence to the user who suffers from the greatest degradation in a greedy way. Moreover, the proposed scheme is further optimized with an extra set of orthogonal pilot sequences, which is called pilot scheduling scheme based on user grouping. Simulation results show that the target cell's achievable sum rate of the proposed scheme is much higher than the random pilot scheduling (RPS) and the smart pilot assignment (SPA) schemes; also, our scheme can reduce the impact of shadowing fading on the target cell's achievable sum rate effectively.

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“…(time-division duplex, TDD)에서 진행되었다 [4][5][6][7] . 하 지만 기존의 통신 표준에서는 주파수분할 이중 직교빔포밍의 대표적인 예로 PU2RC와 discrete Fourier transform(DFT) 코드북(codebook) [8] 이 있다.…”

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Limited Feedback Precoding for Correlated Massive MIMO Systems

Lim¹,

Chae²

2014

The Journal of Korean Institute of Communications and Informati

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In this paper, we propose a compressive sensing-based channel quantization feedback mechanism that is appropriate for practical massvie multiple-input multiple-output (MIMO) systems. We assume that the base station (BS) has a compact uniform square array that has a highly correlated channel. To serve multiple users, the BS uses a zero-forcing precoder. Our proposed channel feedback algorithm can reduce the feedback overhead as well as a codebook search complexity. Numerical simulations confirm our analytical results.

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Pilot Contamination and Precoding in Multi-Cell TDD Systems

Cited by 1,248 publications

References 28 publications

Deterministic Equivalent Performance Analysis of Time-Varying Massive MIMO Systems

Deterministic Equivalent Performance Analysis of Time-Varying Massive MIMO Systems

Pilot contamination reduction in massive MIMO systems based on pilot scheduling

Limited Feedback Precoding for Correlated Massive MIMO Systems

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