Compensation of IQ imbalance and phase noise in OFDM systems

Tubbax, J.; Côme, B.; Perre, Liesbet Van der; Donnay, S.; Engels, M.; Man, H. De; Moonen, Marc

doi:10.1109/twc.2004.843057

Cited by 184 publications

(81 citation statements)

References 22 publications

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“…Therefore, the modulation level and its power efficiency in the HC-OFDM systems are the same as those in the OFDM systems. But twice the digital signal processings of modulation/demodulation are necessary to send two data sequences, and a phase compensator is indispensable to correct the imbalance between IQ channels caused by carrier frequency offset and fading [25].…”

Section: System Modelmentioning

confidence: 99%

“…A data sequence is demodulated by reversing the process of the modulation as follows: GI deletion, S/P conversion, OFDM demodulation (FFT), coherent detection, subcarrier decoding with MRC, P/S conversion and data decision. Since the OFDM signal is affected by multipath fading, the channel estimation is necessary for the purpose of phase compensation and coherent detection [25]- [27]. In order to theoretically evaluate the optimal advantage of the Hermite-symmetric subcarrier coding, the perfect channel estimation is assumed in this paper.…”

Section: System Modelmentioning

confidence: 99%

“…In this paper, in order to theoretically verify the effectiveness of a combination of the repetition coding, the characteristic of the Fourier transform, and the simultaneous transmission of the two data sequences with the aid of a phase compensator over fading channels [25], we derive closed-form equations for BER and throughput of wireless OFDM systems employing the Hermite-symmetric subcarrier coding, which we call 'HC-OFDM' hereafter. Because of the dual channel transmission, higher-level modulation to keep the same bit rate like the RC-OFDM systems is unnecessary, while double carrier power is consumed.…”

Section: Introductionmentioning

confidence: 99%

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Performance Analysis of Hermite-Symmetric Subcarrier Coding for OFDM Systems over Fading Channels

Sasamori

Handa

2012

IEICE Trans. Fundamentals

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SUMMARYOrthogonal frequency division multiplexing (OFDM) has great advantages such as high spectrum efficiency and robustness against multipath fading. In order to enhance the advantages, an Hermitesymmetric subcarrier coding for OFDM, which is used for transmission systems like the asymmetric digital subscriber line (ADSL) and multiband OFDM in ultra-wideband (UWB) communications, is very attractive. The subcarrier coding can force the imaginary part of the OFDM signal to be zero, then another data sequence can be simultaneously transmitted in the quadrature channel. In order to theoretically verify the effectiveness of the Hermite-symmetric subcarrier coding in wireless OFDM (HC-OFDM) systems, we derive closed-form equations for bit error rate (BER) and throughput over fading channels. Our analytical results can theoretically indicate that the HC-OFDM systems achieve the improvement of the performances owing to the effect of the subcarrier coding.

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Section: System Modelmentioning

confidence: 99%

Section: System Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Performance Analysis of Hermite-Symmetric Subcarrier Coding for OFDM Systems over Fading Channels

Sasamori

Handa

2012

IEICE Trans. Fundamentals

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“…In [33]- [35], the system model of OFDM transmission with I/Q imbalance and phase noise is introduced and dierent compensation schemes are proposed. In [36], a system performance analysis of the joint eects of nonlinear PA and phase noise is presented.…”

Section: Introductionmentioning

confidence: 99%

Ofdm Interference Analysis With Dirty Rf

Zheng¹

2011

Proceedings of the 1st International Conference on Pervasive and Embedded Computing and Communication Systems

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When passing through the RF analog electronics devices of the transceiver, the information signal is subject to various distortions named 'dirty RF' eects. Some distortions are inherent to analog radio devices, such as high power ampliers (HPA) at the transmitter and DAC/ADC. Others, such as phase noise and I/Q imbalance, result from various impairments in the transceiver RF front end devices. Regardless of the nature, each factor degrades the communication system performance.Owning to a number of advantages, such as the ability to provide a high data rate in a fading environment and relatively simple structure of the frequency domain equalizer, OFDM is considered as a strong candidate for future wireless broadband systems. OFDM performance, however, is very sensitive to the above RF impairments, such as nonlinear distortions from HPA, I/Q imbalance, phase noise etc.While inherently observed in any transceiver, in the most of part the dirty RF eects so far have been analyzed separately and techniques for their mitigation have been elaborated separately too. Meanwhile, when aecting jointly the above impairments may strengthen each other and moreover, techniques for mitigation of one factor may enhance the impact of another one. Kulkiessaan läpi lähetin-vastaanottimen analogisten RF-osien, informaatiosignaali altistuu lukuisille vääristymille, joita kutsutaan dirty RF -ilmiöiksi. Jotkin vääristymät ovat luontaisia analogisille radiolaitteille, kuten tehovahvistimille (HPA) lähettimessä ja DA/AD -muuntimille. Toiset, kuten vaihekohina ja I/Q-epätasapaino ovat puolestaan seurausta lähetin-vastaanottimen RF-etupään aiheuttamasta signaalin laadun heikkenemisestä. Riippumatta vääristymän aiheuttajasta, kukin edellä mainittu tekijä alentaa tietoliikennejärjestelmän suorituskykyä.Johtuen lukuisista eduistaan, kuten kyvystään tarjota korkeita datanopeuksia häipyvässä ympäristössä sekä verrattain yksinkertaisesta taajuusalueen ekvalisaattorin rakenteesta, OFDM:ää pidetään vahvana ehdokkaana tulevaisuuden langattomiin laajakaistajärjestelmiin. OFDM:n suorituskyky on kuitenkin erittäin herkkä yllä mainitulle RFosien aiheuttamalle signaalin laadun heikkenemiselle, kuten tehovahvistimen, I/Q-epätasapainon, vaihekohinan jne. aiheuttamille epälineaarisille vääristymille.Vaikka RF-ilmiöt ovatkin osa jokaista lähetin-vastaanotinta, dirty RF -ilmiöitä kuten myös menetelmiä niiden vähentämiseksi, on analysoitu yksittäin, muista irrallaan. Kuitenkin, vaikuttaessaan yhtäaikaa, em. ilmiöt voivat vahvistaa toistaan ja lisäksi yhden ilmiön heikentämiseen tähtäävän menetelmän käyttö voi vahvistaa toista ilmiötä.Tämän työn tavoitteena on luoda simulaatiomalli ja analysoida OFDM:ää, kun I/Q-epätasapaino-, tehovahvistin-ja vaihekohina-ilmiöt otetaan samanaikaisesti huomioon.

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“…However, IQ imbalance, caused by non-ideal radio frequency (RF) front-ends, can severely degrade system performance [2]. The effects of IQ imbalance on OFDM systems have been investigated [2] and several schemes have been proposed to compensate for IQ imbalance [3,4,5]. In [4] and [5], two or more pilot symbols are used to compensate for IQ imbalance.…”

Section: Introductionmentioning

confidence: 99%