Capacity maximisation of handheld MIMO terminal with adaptive matching in indoor environment

Plicanic, Vanja; Vasilev, Ivaylo; Tian, Ruiyuan; Lau, Buon Kiong

doi:10.1049/el.2011.1358

Cited by 14 publications

(21 citation statements)

References 6 publications

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“…Both mobile terminals had been fabricated and measured in an anechoic chamber. As in [2], the two user scenarios measured were free space (FS) and two hands (TH). The dual-antenna prototypes cover both LTE Band 18 (0.815 -0.875 GHz) and LTE Band 9 (1.75-1.88 GHz) with a maximum reflection coefficient of -6 dB.…”

Section: Methods and Resultsmentioning

confidence: 99%

“…Each of the two terminals is fully enclosed in a volume of 130 × 66 × 9 mm 3 . Prototype A is similar in design to the dual-antenna terminal in [2]. In FS, it features a 6 dB impedance bandwidth of 85 MHz and antenna isolation of 5.3 dB at the frequency of operation (0.860 GHz).…”

Section: Methods and Resultsmentioning

confidence: 99%

“…To compensate for user effects in MIMO terminals, adaptive impedance matching (AIM) was studied in [2] for a realistic dual-antenna terminal prototype using measured data in an indoor office environment. For a two-hand scenario, the results show that AIM can provide capacity gains of 44% and 22% in the 0.8 GHz and 2.3 GHz bands, respectively, relative to the conventional 50 ohm match.…”

mentioning

confidence: 99%

“…The main motivation is to gain insight into the antenna parameters that give rise to performance gains from AIM in MIMO terminals. In this paper, we focus only on a two-hand scenario, similar to [2]. To obtain the capacity performance, measured antenna parameters from fabricated prototypes (with and without phantom hands) were combined with a simulated propagation environment characterized by uniform 3D angular power spectrum (APS), which corresponds to a multipath-rich indoor environment.…”

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confidence: 99%

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On user effect compensation of MIMO terminals with adaptive impedance matching

Vasilev

Plicanic²,

Lau

2013

2013 IEEE Antennas and Propagation Society International Symposium (APSURSI)

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On user effect compensation of MIMO terminals with adaptive impedance matchingVasilev, Ivaylo; Plicanic, Vanja; Lau, Buon Kiong General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. I. INTRODUCTION The performance degradation of multiple-input multipleoutput (MIMO) terminals from user proximity is an issue of growing importance, due to the ever increasing demand for higher throughput as well as the many relevant user scenarios to consider (see [1] and references therein).To compensate for user effects in MIMO terminals, adaptive impedance matching (AIM) was studied in [2] for a realistic dual-antenna terminal prototype using measured data in an indoor office environment. For a two-hand scenario, the results show that AIM can provide capacity gains of 44% and 22% in the 0.8 GHz and 2.3 GHz bands, respectively, relative to the conventional 50 ohm match. Nevertheless, the study focused on assessing the potential application of AIM using real measurements, and it considered only one terminal. In [3], the tuning range and user influence on a reconfigurable planar inverted-F antenna (PIFA) with a fixed capacitor are presented. A relatively wide tuning range was shown, but the matching network used had only a few achievable states. Moreover, the study focused on comparing user-induced mismatch and absorption losses between high-Q and low-Q antennas.In this work, we present a study on the potential of AIM in the 0.8 GHz band based on two fabricated MIMO terminals of significantly different antenna properties. In particular, two MIMO terminal prototypes were considered: one that has good impedance matching but poor isolation and narrowband behavior, and another one that has poorer matching but higher isolation and larger bandwidth. The main motivation is to gain insight into the antenna parameters that give rise to

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Section: Methods and Resultsmentioning

confidence: 99%

Section: Methods and Resultsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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On user effect compensation of MIMO terminals with adaptive impedance matching

Vasilev

Plicanic²,

Lau

2013

2013 IEEE Antennas and Propagation Society International Symposium (APSURSI)

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“…However, the work focused on the mismatch between the PAs and the antennas, and it did not provide channel measurements in different usage conditions. In [4] a realistic mobile terminal subject to a two-hand grip was measured in an indoor environment. The results indicated MIMO channel capacity gains of up to 44%.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of adaptive impedance matching in an indoor environment

Vasilev

Plicanic²,

Tian

et al. 2014

2014 IEEE Antennas and Propagation Society International Symposium (APSURSI)

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Experimental study of adaptive impedance matching in an indoor environmentVasilev, Ivaylo; Plicanic, Vanja; Tian, Ruiyuan; Lau, Buon Kiong General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Abstract-In recent years, adaptive impedance matching (AIM) has been used to compensate for severe performance degradation in terminal antennas due to user proximity. In particular, user effect compensation is critical for multiple-input multiple-output (MIMO) terminals, to achieve high data rates. In this study, the AIM performance of a MIMO terminal is measured for three user scenarios at two locations in an indoor office environment, using real impedance tuners. It was established that AIM leads to MIMO capacity gains of up to 25%, corresponding to 2.2 dB of power gain. On the other hand, the insertion loss of the tuners was found to be about 0.3 dB for free-space conditions. These results suggest that AIM can offer significant net performance gains in practice. Moreover, we provide physical insight into the similar AIM results for the two measured locations, representing geometrical line-of-sight (LOS) and non-LOS links, respectively.

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Efficient evaluation of specific absorption rate for MIMO terminals

Li¹,

Lau²

2014

Electron. lett.

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, "Efficient evaluation of specific absorption rate (SAR) for MIMO terminals," Electron. Lett., vol. 50, no. 22, pp. 1561-1562, Oct. 23, 2014 1 Efficient evaluation of specific absorption rate (SAR) for MIMO terminals H. Li and B. K. Lau Department of Electrical and Information Technology, Lund University, 221 00 Lund, Sweden E-mail: Hui.Li@eit.lth.se Abstract: Multi-antenna enabled terminal devices are required to comply with the standards for limiting human exposure to electric fields. However, when compared to traditional single-antenna terminals, a comprehensive evaluation of specific absorption rate (SAR) for multi-antenna terminals is impractical. This is because both the power allocation and phase of the electric fields from different antennas are arbitrary in practical MIMO operation, hence requiring exhaustive evaluation over all possible cases. In this context, this paper first proposes time averaged simultaneous peak SAR (TASPS) as an efficient metric to evaluate exposure when more than one antenna is transmitting simultaneously. Then, it is analytically derived that TASPS will be below a given exposure limit, as long as the stand-alone peak SAR for each antenna is smaller than that limit. Thus, SAR evaluation is greatly simplified since only stand-alone SAR needs to be measured. Several examples of dual-antenna mobile handsets are shown to illustrate and validate the analytical result.Introduction: The initial focus of multiple-input multiple-output (MIMO) in wireless communications was to improve the downlink (e.g., LTE), meaning that the uplink transmission still only involved one antenna. With the recent launch of LTE-Advanced (LTE-A) [1], multi-antennas can also be used to enhance the uplink. As in the case of single-antenna transmission, devices with multi-antenna transmission are required to comply with the standards for limiting human exposure to electric fields. The exposure of the body to a RF electromagnetic field is usually measured by specific absorption rate (SAR). In a MIMO terminal, stand-alone SAR measures the exposure when only one antenna is transmitting, with the other antennas terminated by their source impedances. In contrast, simultaneous SAR characterises the exposure when more than one antenna is transmitting. In this case, the power level and phase of each transmitting antenna vary rapidly due to MIMO pre-coding and link adaptation. Thus, the superposition of fields from different antennas, i.e., the total electric field, at a given point also varies rapidly. To capture the true simultaneous SAR values, field measurements should be performed quickly over time and at multiple spatial points. Such a comprehensive evaluation is not only technically challenging, but also prohibitively expensive and time-consuming.So far, there are few literatures on SAR evaluation for multi-antennas [2-4], especially for simultaneous SAR. In particular, field summation schemes based on conventional scalar probes and the corresponding testing methodologies were proposed in [4] for simultaneous pea...

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Capacity maximisation of handheld MIMO terminal with adaptive matching in indoor environment

Cited by 14 publications

References 6 publications

On user effect compensation of MIMO terminals with adaptive impedance matching

On user effect compensation of MIMO terminals with adaptive impedance matching

Experimental study of adaptive impedance matching in an indoor environment

Efficient evaluation of specific absorption rate for MIMO terminals

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