Pilot contamination elimination precoding in multi-cell massive MIMO systems

Liu, Binyue; Cheng, Yao; Yuan, Xiaojun

doi:10.1109/pimrc.2015.7343317

Cited by 12 publications

(10 citation statements)

References 18 publications

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“…Consider the system model of scenario PuC. The covariance of the channel estimation error matrix using orthogonal pilot transmissions given by (17) and an MMSE estimator given by (18) is…”

Section: B Precoded and Uncombined Pilot Transmission (Puc)mentioning

confidence: 99%

“…The intuition is that if a selected UE exhibits multipath angles of arrival (AoA) at its serving BS, which do not overlap with the AoAs of UEs in the neighboring cells, these UEs can reuse the same pilot sequence as the selected UE, without any contamination among the pilots of different cells. In [17], the UEs within each cell employ the same pilot sequence while the UEs in the different cells are assigned orthogonal pilot sequences. The impact of intra-cell pilot contamination is mitigated later in the downlink data transmission phase.…”

Section: Introductionmentioning

confidence: 99%

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Pilot Precoding and Combining in Multiuser MIMO Networks

Moghadam

Shokri‐Ghadikolaei

Fodor

et al. 2017

IEEE J. Select. Areas Commun.

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Abstract-Although the benefits of precoding and combining data signals are widely recognized, the potential of these techniques for pilot transmission is not fully understood. This is particularly relevant for multiuser multiple-input multiple-output (MU-MIMO) cellular systems using millimeter-wave (mmWave) communications, where multiple antennas have to be used both at the transmitter and the receiver to overcome the severe path loss. In this paper, we characterize the gains of pilot precoding and combining in terms of channel estimation quality and achievable data rate. Specifically, we consider three uplink pilot transmission scenarios in a mmWave MU-MIMO cellular system: 1) nonprecoded and uncombined, 2) precoded but uncombined, and 3) precoded and combined. We show that a simple precoder that utilizes only the second-order statistics of the channel reduces the variance of the channel estimation error by a factor that is proportional to the number of user equipment (UE) antennas. We also show that using a linear combiner designed based on the second-order statistics of the channel significantly reduces multiuser interference and provides the possibility of reusing some pilots. Specifically, in the large antenna regime, pilot precoding and combining help to accommodate a large number of UEs in one cell, significantly improve channel estimation quality, boost the signal-to-noise ratio of the UEs located close to the cell edges, alleviate pilot contamination, and address the imbalanced coverage of pilot and data signals.Index Terms-multiuser MIMO, multiple antenna UEs, channel estimation, millimeter-wave, transceiver design.

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“…Consider the system model of scenario PuC. The covariance of the channel estimation error matrix using orthogonal pilot transmissions given by (17) and an MMSE estimator given by (18) is…”

Section: B Precoded and Uncombined Pilot Transmission (Puc)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pilot Precoding and Combining in Multiuser MIMO Networks

Moghadam

Shokri‐Ghadikolaei

Fodor

et al. 2017

IEEE J. Select. Areas Commun.

View full text Add to dashboard Cite

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“…In TDD systems, one of the main impediments specific to massive MIMO is pilot contamination [2], [4], [5]. CSI is acquired via uplink training that is used for downlink beamforming relying on channel reciprocity.…”

Section: Introductionmentioning

confidence: 99%

An Overview of Massive MIMO Technology Components in METIS

et al. 2017

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As the standardization of full dimension multiple-input multiple-output (MIMO) systems in the 3 rd Generation Partnership Project progresses, the research community has started to explore the potential of very large arrays as an enabler technology for meeting the requirements of 5 th generation systems. Indeed, in its final deliverable, the European 5G project Mobile and Wireless Communication Enablers for the 2020 Information Society (METIS) identifies massive MIMO as a key 5G enabler and proposes specific technology components that will allow the cost efficient deployment of cellular systems taking advantage of hundreds of antennas at cellular base stations. These technology components include handling the inherent pilot-data resource allocation trade-off in a near optimal fashion, a novel random access scheme supporting a large number of users, coded channel state information for sparse channels in frequency division duplexing systems, managing user grouping and multi-user beamforming, and a decentralized coordinated transceiver design. The aggregate effect of these components enables massive MIMO to contribute to the METIS objectives of delivering very high data rates and managing dense populations.

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“…Some recent works shed light on appropriate pilot allocation as a candidate to tackle pilot contamination. There are three types of pilot allocation: one is to allocate orthogonal pilots within a cell assuming full pilot reuse among different cells [8], [15], [16], another is reusing a single pilot sequence among users within a cell, while users in different cells employ orthogonal pilots [17], and the other is finding the pilot reuse rule among different cells whereas all users within a cell are guaranteed to be assigned orthogonal pilots [11], [18]- [20].…”

Section: Introductionmentioning

confidence: 99%

“…All these works show that appropriate pilot assignment is important in reducing pilot contamination, but they all suggest coordination-based solutions which have implementation issues. On the other hand, reusing the same pilot within a cell is considered in [17], whereas interfering cells have orthogonal pilots. The pilot reuse within a cell causes intra-cell interference, which is eliminated by the downlink precoding scheme suggested in the same paper.…”

Section: Introductionmentioning

confidence: 99%

Pilot Reuse Strategy Maximizing the Weighted-Sum-Rate in Massive MIMO Systems

Sohn

Yoon

Moon

2017

IEEE J. Select. Areas Commun.

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Abstract-Pilot reuse in multi-cell massive multi-input multioutput (MIMO) system is investigated where user groups with different priorities exist. Recent investigation on pilot reuse has revealed that when the ratio of the coherent time interval to the number of users is reasonably high, it is beneficial not to fully reuse pilots from interfering cells. This work finds the optimum pilot assignment strategy that would maximize the weighted sum rate (WSR) given the user groups with different priorities. A closed-form solution for the optimal pilot assignment is derived and is shown to make intuitive sense. Performance comparison shows that under wide range of channel conditions, the optimal pilot assignment that uses extra set of pilots achieves better WSR performance than conventional full pilot reuse.

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Pilot contamination elimination precoding in multi-cell massive MIMO systems

Cited by 12 publications

References 18 publications

Pilot Precoding and Combining in Multiuser MIMO Networks

Pilot Precoding and Combining in Multiuser MIMO Networks

An Overview of Massive MIMO Technology Components in METIS

Pilot Reuse Strategy Maximizing the Weighted-Sum-Rate in Massive MIMO Systems

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