Automatic calibration method using transmitting signals of an adaptive array for TDD systems

Nishimori, Kentaro; Cho, K.; Takatori, Yasushi; Hori, Toshikazu

doi:10.1109/25.966592

Cited by 93 publications

(41 citation statements)

References 5 publications

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“…To realize IBF, a calibration technique that compensates for the difference between the complex amplitudes of the transmitters and receivers at the BS is required [20]. Figure 3 shows the calibration circuit configuration.…”

Section: Basic Calibration Principlementioning

confidence: 99%

“…As shown in this figure, we obtain T i R j (i = 1, 2, j = 2, 1), where T i and R j are the complex amplitudes of the transmitter and receiver, respectively. Because the calibration value required by the kth branch is T k /R k [20], the relative calibration values can be obtained from the circuit shown in Figure 3. This concept can be extended to a large number of antennas [21], and the configuration for this case is shown in Figure 4.…”

Section: Basic Calibration Principlementioning

confidence: 99%

“…However, it is necessary to calibrate the amplitude and phase errors between the branches of the array, because of individual differences in the radio frequency (RF) devices of the receivers and transmitters [18,19]. Thus, various automatic calibration methods for adaptive BS antennas that are well suited to TDD communication systems have been proposed in previous studies [20,21].We note that some of these methods allow the transmitter and receiver calibration values to be obtained automatically [20][21][22][23][24]. In recent research, the calibration method for massive antennas utilizing the channel reciprocity in a TDD system is proposed [25][26][27].…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we extend the calibration system described in [20,21] for applicability to MU-MIMO systems with a large number of antennas at the BS. Our testbed assumes a 16-element MIMO system.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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Section: Basic Calibration Principlementioning

confidence: 99%

Section: Basic Calibration Principlementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

et al. 2017

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“…Calibration schemes, i.e., how calibration coefficients are calculated, have been investigated in several papers [8]- [10]. Nishimori et al propose an automatic calibration scheme using transmit signals, and design special radio frequency (RF) circuits with directional couplers [8].…”

Section: Introductionmentioning

confidence: 99%

Weighted-Combining Calibration on Multiuser MIMO Systems with Implicit Feedback

Fukuzono

Murakami

Kudo

et al. 2015

IEICE Trans. Commun.

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SUMMARYImplicit feedback is an approach that utilizes uplink channel state information (CSI) for downlink transmit beamforming on multiple-input multiple-output (MIMO) systems, relying on over-the-air channel reciprocity. The implicit feedback improves throughput efficiency because overhead of CSI feedback for change of over-the-air channel responses is omitted. However, it is necessary for the implicit feedback to calibrate circuitry responses that uplink CSI includes, because actual downlink and uplink channel responses do not match due to different transmit and receive circuitry chains. This paper presents our proposed calibration scheme, weighted-combining calibration (WCC); it offers improved calibration accuracy. In WCC, an access point (AP) calculates multiple calibration coefficients from ratios of downlink and uplink CSI, and then combines coefficients with minimum mean square error (MMSE) weights. The weights are derived using a linear approximation in the high signal to noise power ratio (SNR) regime. Analytical mean square error (MSE) of calibration coefficients with WCC and calibration schemes for comparison is expressed based on the linear approximation. Computer simulations show that the analytical MSE matches simulated one if the linear approximation holds, and that WCC improves the MSE and signal to interference plus noise power ratio (SINR). Indoor experiments are performed on a multiuser MIMO system with implicit feedback based on orthogonal frequency division multiplexing (OFDM), built using measurement hardware. Experimental results verify that the channel reciprocity can be exploited on the developed multiuser MIMO-OFDM system and that WCC is also effective in indoor environments. key words: multiple-input multiple-output (MIMO), channel reciprocity, implicit feedback, calibration, minimum mean square error (MMSE)

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MassiveMIMOChannel Estimation Schemes

Abu-Rgheff¹

2019

5G Physical Layer Technologies

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Automatic calibration method using transmitting signals of an adaptive array for TDD systems

Cited by 93 publications

References 5 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

Weighted-Combining Calibration on Multiuser MIMO Systems with Implicit Feedback

MassiveMIMOChannel Estimation Schemes

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