Massive MIMO Performance—TDD Versus FDD: What Do Measurements Say?

Flordelis, Jose; Rusek, Fredrik; Tufvesson, Fredrik; Larsson, Erik G.; Edfors, Ove

doi:10.1109/twc.2018.2790912

Cited by 89 publications

(72 citation statements)

References 58 publications

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“…The analytical and numerical results illustrated that mmWave multi-user (MU) channel estimation at the BS in uplink outperforms downlink channel estimation at the users for a fixed overhead, even if the required signalling overhead feedback is not taken into account [39]. The results hold for both fully digital and hybrid architectures at the receiver and transmitter sides and have been verified via the recent field test [43]. Besides, the algorithm mentioned above can work well in sparse and nonsparse environments 5 [2].…”

Section: A Pilot Contamination In Mmwave Systemsmentioning

confidence: 69%

Multi-Cell Hybrid Millimeter Wave Systems: Pilot Contamination and Interference Mitigation

Zhao

Wei

et al. 2018

IEEE Trans. Commun.

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In this paper, we investigate the system performance of a multi-cell multi-user (MU) hybrid millimeter wave (mmWave) communications in a multiple-input multiple-output (MIMO) network. Due to the reuse of pilot symbols among different cells, the performance of channel estimation is expected to be degraded by pilot contamination, which is considered as a fundamental performance bottleneck of conventional multicell MU massive MIMO networks. To analyze the impact of pilot contamination to the system performance, we first derive the closed-form approximation of the normalized mean squared error (MSE) of the channel estimation algorithm proposed in [2] over Rician fading channels. Our analytical and simulation results show that the channel estimation error incurred by the impact of pilot contamination and noise vanishes asymptotically with an increasing number of antennas equipped at each radio frequency (RF) chain at the desired BS. Furthermore, by adopting zero-forcing (ZF) precoding in each cell for downlink transmission, we derive a tight closed-form approximation of the average achievable rate per user. Our results unveil that the intra-cell interference and inter-cell interference caused by pilot contamination over Rician fading channels can be mitigated effectively by simply increasing the number of antennas equipped at the desired BS.

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Section: A Pilot Contamination In Mmwave Systemsmentioning

confidence: 69%

Multi-Cell Hybrid Millimeter Wave Systems: Pilot Contamination and Interference Mitigation

Zhao

Wei

et al. 2018

IEEE Trans. Commun.

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“…Massive multiple-input multiple-output (MIMO) will be an essential part of 5G and beyond wireless communications systems. While massive MIMO performs generally better using time division duplex (TDD) than frequency division duplex (FDD) [1], frequency regulators over the world have assigned large swathes of valuable spectrum as band pairs for FDD operation; furthermore backward compatibility considerations (e.g., with Long-Term Evolution (LTE)) also often require FDD operation. Enabling FDD massive MIMO has thus been a popular research topic in recent years [2]- [4].…”

Section: Introductionmentioning

confidence: 99%

Channel Extrapolation for FDD Massive MIMO: Procedure and Experimental Results

Choi

Rottenberg

Gomez-Ponce

et al. 2019

2019 IEEE 90th Vehicular Technology Conference (VTC2019-Fall)

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Application of massive multiple-input multipleoutput (MIMO) systems to frequency division duplex (FDD) is challenging mainly due to the considerable overhead required for downlink training and feedback. Channel extrapolation, i.e., estimating the channel response at the downlink frequency band based on measurements in the disjoint uplink band, is a promising solution to overcome this bottleneck. This paper presents measurement campaigns obtained by using a wideband (350 MHz) channel sounder at 3.5 GHz composed of a calibrated 64 element antenna array, in both an anechoic chamber and outdoor environment. The Space Alternating Generalized Expectation-Maximization (SAGE) algorithm was used to extract the parameters (amplitude, delay, and angular information) of the multipath components from the attained channel data within the "training" (uplink) band. The channel in the downlink band is then reconstructed based on these path parameters. The performance of the extrapolated channel is evaluated in terms of mean squared error (MSE) and reduction of beamforming gain (RBG) in comparison to the "ground truth", i.e., the measured channel at the downlink frequency. We find strong sensitivity to calibration errors and model mismatch, and also find that performance depends on propagation conditions: LOS performs significantly better than NLOS.

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“…The authors are with Communication Systems Department, EURECOM, Campus SophiaTech, 06410 Biot, France (e-mail: xiwen.jiang@eurecom.fr; florian.kaltenberger@eurecom.fr). system [4], but are clearly suboptimal compared to the case where full channel state information at the transmitter (CSIT) is available [5]. Under the assumption of full CSIT, a hybrid massive MIMO system can achieve the same performance of any fully digital beamforming scheme, as long as the number of RF chains is at least twice the number of data schemes [6].…”

Section: Introductionmentioning

confidence: 99%

Channel Reciprocity Calibration in TDD Hybrid Beamforming Massive MIMO Systems

Jiang

Kaltenberger

2018

IEEE J. Sel. Top. Signal Process.

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Hybrid analog-digital (AD) beamforming structure is a very attractive solution to build low cost massive multipleinput multiple-output (MIMO) systems. Typically these systems use a set of fixed beams for transmission and reception to avoid the need to obtain channel state information at transmitter (CSIT) for each antenna element individually. However, such a method can not fully exploit the potential of hybrid AD beamforming systems. Alternatively, CSIT can be estimated by assuming a model for the propagation channel, whereas this model is only validated in millimeter-wave (mmWave) band thanks to its poor scattering nature. In this paper, we focus on time division duplex (TDD) systems with hybrid beamforming structure and propose a reciprocity calibration scheme that allows to acquire full CSIT. Different to existing CSIT acquisition methods, our approach does not require any assumption on the channel model and can, in theory, estimate the CSIT up to an arbitrary small error.Index Terms-Channel reciprocity calibration, channel state information at transmitter (CSIT), hybrid analog-digital beamforming, massive MIMO, time division duplex (TDD).

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Massive MIMO Performance—TDD Versus FDD: What Do Measurements Say?

Cited by 89 publications

References 58 publications

Multi-Cell Hybrid Millimeter Wave Systems: Pilot Contamination and Interference Mitigation

Multi-Cell Hybrid Millimeter Wave Systems: Pilot Contamination and Interference Mitigation

Channel Extrapolation for FDD Massive MIMO: Procedure and Experimental Results

Channel Reciprocity Calibration in TDD Hybrid Beamforming Massive MIMO Systems

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