A practical method for wireless channel reciprocity exploitation through relative calibration

Guillaud, Maxime; Slock, Dirk; Knopp, Raymond

doi:10.1109/isspa.2005.1580281

Cited by 208 publications

(178 citation statements)

References 4 publications

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“…However the feedback constraint can be overcome by exploiting the UL/DL channel reciprocity in TDD mode. Nonetheless as previously mentioned in [8], [6], [9], the UL/DL channel reciprocity only applies to the propagation part, and not to the overall digital channel response due to radio frequency (RF) circuit mismatches. Additional studies have proposed calibration solutions to compensate the RF impairments and make the channel reciprocity a reality in practice [9], [6].…”

Section: Lte-tdd and Spatial Interweavementioning

confidence: 99%

“…Unlike the "absolute" calibration it does not require any equipment and compensates the non reciprocal RF using the relation between the UL/DL channels. Subsequently, the authors in [9] assume that the calibration parameters are invariant during a long period (typically seconds). This assumption allows to exploit several versions of the UL/DL channels over the time, and to derive the calibration parameters through a total least squares (TLS) formulation [10].…”

Section: Lte-tdd and Spatial Interweavementioning

confidence: 99%

“…Then, assuming that the channel is constant during one frame duration (10ms), we store one UL/DL channel estimate by frame (K frames) at eNB. This first step corresponds to relative calibration training phase (described in [9]) which is performed using all the 300 subcarriers.…”

Section: A Transmission Parametersmentioning

confidence: 99%

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Design and implementation of spatial interweave LTE-TDD cognitive radio communication on an experimental platform

Kouassi

Deneire

Zayen

et al. 2013

IEEE Wireless Commun.

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Abstract-Cognitive radio, which enables smart use of wireless resources, is a key ingredient to achieve high spectral efficiency. LTE, the latest evolution of cellular standards, is widely adopted and also targets high spectral efficiency. Hence, to enable wide adoption of cognitive radio, using LTE as the physical layer is a natural choice. Targeting a real-time implementation of LTEbased cognitive radio, we focus on spatial interweave cognitive radio, in which a secondary user uses an antenna array to perform null-beamforming in the primary user's direction, hence reusing the spectrum spatially. To allow this, without any help from the primary system, we use the time division duplex (TDD) mode and take advantage of the channel reciprocity. However, this reciprocity is jeopardized by the mismatch between the RF front-ends. Hence, we design a calibration protocol to restore it. The whole system is implemented and evaluated on EURECOM's experimental OpenAirInterface platform. Performance results are presented, showing the feasibility of spatial interweave cognitive radio on a real-time platform.Index Terms-Spatial interweave cognitive radio, beamforming, channel estimation, reciprocity calibration, LTE-TDD platform.

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Section: Lte-tdd and Spatial Interweavementioning

confidence: 99%

Section: Lte-tdd and Spatial Interweavementioning

confidence: 99%

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Design and implementation of spatial interweave LTE-TDD cognitive radio communication on an experimental platform

Kouassi

Deneire

Zayen

et al. 2013

IEEE Wireless Commun.

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“…The papers [6]- [8] have so far presented a low-cost relative calibration, which compensates for mismatch of analogue gains in multiple antennas based on uplink and downlink channel measurements. More precisely, the calibration parameter in the relative calibration is given by the radio of measured uplink and downlink channel parameters.…”

Section: Introductionmentioning

confidence: 99%

“…The first approach is the relative calibration technique [6]- [8] mentioned above which transmits (receives) calibration signals to (from) another wireless node. This approach is robust to power-dependent analogue characteristics, because the calibration signal is transmitted with the same power as data signal.…”

Section: Introductionmentioning

confidence: 99%

Antenna Array Calibration Based on Frequency Selection in OFDMA/TDD Systems

Hara

Yano

Kubo

2009

IEICE Trans. Commun.

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SUMMARYThis paper proposes a new antenna array calibration technique which uses frequency selection in orthogonal frequency division multiple access (OFDMA)/time division duplexing (TDD) systems. In the proposed method, subbands or frequencies of good channel conditions are initially selected for channel measurements. The relative calibration is performed at the selected subbands, which compensates for mismatch of analogue gains in multiple antennas using the measured uplink and downlink channel parameters. Furthermore, the calibration parameters are interpolated in the frequency domain for the whole bandwidth. The proposed calibration maintains accurate channel reciprocity for the whole bandwidth compared to the conventional calibration which does not use the frequency selection. The proposed calibration technique is effective in exploiting channel reciprocity at both base station and terminals with feasible amount of feedback and low-cost operation.

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Paired and Unpaired Spectrum

Anderson¹

2009

LTE – The UMTS Long Term Evolution

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Expansion of consumer demand for cellular communications, as well as for the multitude of other wireless applications, places a corresponding strain on the basic physical resource needed to support them: spectrum. The suitability of spectral resources to a particular application is governed by a range of inter-related factors of a technological, commercial and regulatory nature. Technological considerations influencing the choice of frequency band include propagation characteristics, antenna size and separation, the viability of Radio Frequency (RF) circuitry, and design implications resulting from the need to coexist with systems operating in neighbouring spectrum without causing (or suffering from) undue interference. These considerations determine in part the commercial viability of a system. Signal range and spectral efficiency govern coverage and capacity, and hence determine the required number of base station sites and the capital outlay, whilst terminal costs and form factor affect the acceptability of products in the marketplace.From a regulatory perspective, in spite of significant coordination at an international level through the International Telecommunications Union (ITU), regional variations in governmental policy regarding spectrum and technology are inescapable due to the differing needs of each region and the different historical factors which have shaped their presentday spectrum allocations. Thus, the availability of globally-harmonized spectrum for a particular technology cannot be guaranteed. Furthermore, in many regions, a tendency towards technology neutrality within viable spectrum assignments (see, for example, [1]) is beginning to liberalize the traditional one-to-one mappings between technologies and their addressable spectrum and is hence opening up new markets.Against this background, a key design goal of LTE has been to enable deployment in a diverse range of spectrum environments in terms of bandwidth, uplink-downlink duplex LTE -The UMTS Long Term Evolution: From Theory to Practice

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A practical method for wireless channel reciprocity exploitation through relative calibration

Cited by 208 publications

References 4 publications

Design and implementation of spatial interweave LTE-TDD cognitive radio communication on an experimental platform

Design and implementation of spatial interweave LTE-TDD cognitive radio communication on an experimental platform

Antenna Array Calibration Based on Frequency Selection in OFDMA/TDD Systems

Paired and Unpaired Spectrum

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