Multiuser MIMO with implicit channel feedback in massive antenna systems

Murakami, Tomoki; Fukuzono, Hayato; Takatori, Yasushi; Mizoguchi, Masahiro

doi:10.1587/comex.2.336

Cited by 15 publications

(9 citation statements)

References 8 publications

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“…To overcome this problem, beamforming without CSI feedback, or IBF, has been proposed [17]. Figure 2 shows the frame format for a MU-MIMO system when IBF is employed.…”

Section: Ibfmentioning

confidence: 99%

“…Figure 2 shows the frame format for a MU-MIMO system when IBF is employed. It is apparent from this figure that the BS obtains the CSI directly from multiple UTs during period D, by utilizing the channel reciprocity between the transmission and reception in the TDD mode [17]. Moreover, because the number of UTs K is significantly less than the number of antennas at the BS M (Figure 1), the overhead during period B can be decreased using the frame format shown in Figure 1.…”

Section: Ibfmentioning

confidence: 99%

“…Thus, the countermeasure of implicit beamforming (IBF) has been proposed [17]. IBF exploits channel reciprocity in the time-division duplex (TDD) mode, that is, when the transmit frequency is identical to the receive frequency.…”

Section: Introductionmentioning

confidence: 99%

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Effectiveness of Implicit Beamforming with Large Number of Antennas Using Calibration Technique in Multi-User MIMO System

et al. 2017

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This paper examines the effectiveness of implicit beamforming (IBF), which enables transmission without channel state information (CSI) feedback in multi-user multiple-input multiple-output (MU-MIMO) systems with a large number of antennas. First, we explain why CSI feedback from terminal stations to the base station produces a very large overhead. A calibration technique is then introduced, which compensates for the difference between the complex amplitudes of the transmitters and receivers to facilitate CSI-feedback-free beamforming; this technique is called IBF. The efficacy of this calibration technique is demonstrated by measuring the amplitude and phase errors obtained using a 16-element array testbed and by performing a channel capacity evaluation. Finally, the throughput under IEEE802.11ac-based massive MIMO transmission, both with and without CSI feedback, is obtained in terms of the medium access control efficiency.

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“…To overcome this problem, beamforming without CSI feedback, or IBF, has been proposed [17]. Figure 2 shows the frame format for a MU-MIMO system when IBF is employed.…”

Section: Ibfmentioning

confidence: 99%

Section: Ibfmentioning

confidence: 99%

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Effectiveness of Implicit Beamforming with Large Number of Antennas Using Calibration Technique in Multi-User MIMO System

et al. 2017

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“…In order to overcome this issue, beamforming without CSI feedback called implicit beamforming [33] has been proposed. Originally, an adaptive array utilizing the channel reciprocity was proposed to realize interference avoidance using the uplink channel [83], [84].…”

Section: Implicit Beamformingmentioning

confidence: 99%

“…Moreover, we survey the MU-MIMO technology used in next-generation WLAN systems. Furthermore, the latest trend of implicit-beamforming technology in enhanced MU-MIMO is introduced regarding its role in reducing channel state information (CSI) feedback [33]. CSI feedback is introduced into the current WLAN Standard (IEEE802.11n and ac).…”

mentioning

confidence: 99%

Survey of Transmission Methods and Efficiency Using MIMO Technologies for Wireless LAN Systems

Hiraguri

Nishimori

2015

IEICE Trans. Commun.

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SUMMARY Multiple-input multiple-output (MIMO) transmission is attracting interest for increasing the transmission rates of wireless systems. This paper surveys MIMO transmission technology from the viewpoints of transmission methods, access control schemes, and total transmission efficiency. We consider wireless local area networks (WLAN) systems that use MIMO technology; moreover, we focus on multiuser MIMO (MU-MIMO) technology, which will be introduced in next-generation WLAN systems such as IEEE802.11ac. This paper explains the differences in the detailed access control procedures for MIMO and MU-MIMO transmission, including channel state information (CSI) acquisition. Furthermore, the issues related to CSI feedback and solutions are also discussed. Related works on the medium access control (MAC) protocol in MIMO/MU-MIMO transmission are introduced. In addition, the throughput performance using MIMO/MU-MIMO transmission is evaluated considering an IEEE802.11ac-based WLAN system. From the numerical evaluation, it is shown that the overhead due to CSI feedback from the user terminals to the base station causes a decrease in the throughput. We verified that implicit beamforming, which eliminates CSI feedback, is effective for solving this issue. , and commercial products based on these standards will appear in the near future. Moreover, the standardization of next-generation wireless LAN (WLAN) aims to achieve further high performance and high efficiency by using MU-MIMO transmission technology, and a task group for that standard called IEEE802.11ax [22] [32]. However, the transmission rate achieved by SU-MIMO/MU-MIMO transmission is not currently adequately utilized because the overhead of the access control protocol in the medium access control (MAC) layer decreases the transmission efficiency, even though the physical transmission rate has been increased in the PHY layer by the adoption of SU-MIMO/MU-MIMO technology. Therefore, the MAC-service access point (MAC-SAP) throughput including the protocol in the MAC layer decreases greatly creases in multilevel modulation and the number of subcarriers in WLAN systems. The decrease in the transmission efficiency is a significant issue because the ratio of the overhead of the MAC protocol is larger for MU-MIMO transmission. Although there are above issues, the frequency utilization and channel capacity have been evaluated in only PHY-layer.Further, the throughput and delay characteristics in relation to the access control scheme have been evaluated in the MAC layer. Therefore, these studies have been individually evaluated. No adequate evaluation of the throughput and transmission efficiency considering both the PHY and MAC layers has not been published.This paper surveys conventional SU-MIMO/MU-MIMO transmission technology from the viewpoints of both wireless communication systems and transmission efficiency, and the most popular WLAN systems that use SU-MIMO/MU-MIMO technology are chiefly discussed. Moreover, we survey the MU-MIMO technology used in next-generatio...

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High efficient packet aggregation scheme for multi-rate and VoIP packet transmissions in next generation MU-MIMO WLANs

Nomura

Möri

Naito

et al. 2014

2014 International Conference on Advanced Technologies for Communications (ATC 2014)

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In the next generation wireless local area network (WLAN), the multi-user spatial multiplexing combined with packet aggregation can increase the system performance significantly. However, the space channel time may arise due to non-uniformity in the transmission times of wireless frames on the different spatial streams during MU-MIMO transmissions. In addition, for various communication services such as voice communication, the quality of service (QoS) provision is essential in the current WLANs. In this paper, our objectives are reduction of the space channel time and QoS provision for voice communications. Then, we propose a high efficient packet aggregation scheme taking into account the multi-rate and VoIP packet transmissions. The results of computer simulations demonstrate the effectiveness of the proposed scheme under recent WLAN environments.

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Multiuser MIMO with implicit channel feedback in massive antenna systems

Cited by 15 publications

References 8 publications

Effectiveness of Implicit Beamforming with Large Number of Antennas Using Calibration Technique in Multi-User MIMO System

Effectiveness of Implicit Beamforming with Large Number of Antennas Using Calibration Technique in Multi-User MIMO System

Survey of Transmission Methods and Efficiency Using MIMO Technologies for Wireless LAN Systems

High efficient packet aggregation scheme for multi-rate and VoIP packet transmissions in next generation MU-MIMO WLANs

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