Low-Complexity Block Turbo Equalization for OFDM Systems in Time-Varying Channels

Fang, Kun; Rugini, Luca; Leus, Geert

doi:10.1109/tsp.2008.929129

Cited by 98 publications

(65 citation statements)

References 29 publications

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“…Numerical results revealed that at 30 dB SNR the time frequency based scheme with 32 pilot carriers outperformed the conventional system by 24 dB in BER for a 2 × 2 MIMO-OFDM system to demonstrate that the authors' time-frequency-based method is robust to large Doppler frequency variations. Similar doubly selective methods were proposed by Hrycak et al [53], Cano et al [54], and Fang et al [55] who achieved better BER performance by use of soft MMSE block equalizer (BE) which exploits banded structure of the frequency domain channel matrix to achieve compensation in high Doppler spreads. Using the same approach are Schniter [56] and Hrycak and Matz [57] who obtained excellent performance including significant Doppler diversity in conjunction with channel coding by basing operation on time domain, while Parrish et al [58] obtained similar results with time-synchronization protocols.…”

Section: Time-partitioning-based Schemesmentioning

confidence: 76%

Doppler Shift Compensation Schemes in VANETs

Nyongesa¹,

Djouani²,

Olwal³

et al. 2015

Mobile Information Systems

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Over the last decade vehicle-to-vehicle (V2V) communication has received a lot of attention as it is a crucial issue in intravehicle communication as well as in Intelligent Transportation System (ITS). In ITS the focus is placed on integration of communication between mobile and fixed infrastructure to execute road safety as well as nonsafety information dissemination. The safety application such as emergence alerts lays emphasis on low-latency packet delivery rate (PDR), whereas multimedia and infotainment call for high data rates at low bit error rate (BER). The nonsafety information includes multimedia streaming for traffic information and infotainment applications such as playing audio content, utilizing navigation for driving, and accessing Internet. A lot of vehicular ad hoc network (VANET) research has focused on specific areas including channel multiplexing, antenna diversity, and Doppler shift compensation schemes in an attempt to optimize BER performance. Despite this effort few surveys have been conducted to highlight the state-of-the-art collection on Doppler shift compensation schemes. Driven by this cause we survey some of the recent research activities in Doppler shift compensation schemes and highlight challenges and solutions as a stock-taking exercise. Moreover, we present open issues to be further investigated in order to address the challenges of Doppler shift in VANETs.

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Section: Time-partitioning-based Schemesmentioning

confidence: 76%

Doppler Shift Compensation Schemes in VANETs

Nyongesa¹,

Djouani²,

Olwal³

et al. 2015

Mobile Information Systems

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“…Encouraged by the development of MMSE-based turbo equalization schemes [10,11], a large number of lowcomplexity iterative OFDM equalization schemes have been proposed [17][18][19]. They exploit the banded nature of the frequency domain channel matrix to bring down the equalization complexity to linear with the number of subcarriers.…”

Section: Introductionmentioning

confidence: 99%

“…As in references [18][19][20], we also exploit the banded nature of the system matrix in SIC-MAP. The performance and computational complexity of the proposed scheme is compared with that of MMSE-TE-OND2, suggested in [18], and TE-BLK2, the best performing equalizer in a group of three [19]. In [18,19], a windowing technique is used to make the energy more concentrated along the diagonal.…”

Section: Introductionmentioning

confidence: 99%

“…The performance and computational complexity of the proposed scheme is compared with that of MMSE-TE-OND2, suggested in [18], and TE-BLK2, the best performing equalizer in a group of three [19]. In [18,19], a windowing technique is used to make the energy more concentrated along the diagonal. The windowing mentioned in those articles will also work in our proposed scheme.…”

Section: Introductionmentioning

confidence: 99%

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Low-complexity iterative receiver design for mobile OFDM systems

Namboodiri

Liu

Spasojević

2012

EURASIP J. Adv. Signal Process.

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Iterative receivers with minimum mean square error turbo equalization are computationally involved, as they require some form of matrix inversion. In this article, we propose a low complexity iterative receiver that implements successive interference cancelation-based MAP decoding (SIC-MAP) in doubly dispersive channels for orthogonal frequency division multiplexing systems. SIC-MAP leverages the soft feedback symbol estimates to remove the intercarrier interference from the received data. Numerical simulation results show that the proposed scheme achieves BER performance comparable to that of the equalization schemes proposed in Schniter et al. and Fang et al. but with significant computational savings. A low-complexity least squares-based iterative channel estimation scheme using soft feedback information is also proposed. This scheme is especially suitable when the number of significant channel taps is higher than the number of pilots, a phenomenon that is encountered by receivers in Single Frequency Networks (for example, DVB deployments in Europe).

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“…For OFDM transmission over doubly selective channels, an LMMSE turbo equalizer coined with windowing is proposed in . In , the authors proposed a block LMMSE turbo equalization for OFDM transmission over doubly selective channels. For CP‐based SC transmission over doubly selective channels, the authors in proposed a soft‐out frequency‐domain LMMSE iterative equalization method.…”

Section: Introductionmentioning

confidence: 99%

Turbo equalization of doubly selective channels

Barhumi

2012

Wireless Communications

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In this paper we discuss turbo equalization for transmission over doubly selective channels. The maximum a-posteriori (MAP) algorithm is used for detection as well as for channel decoding. The detection/decoding constituents can exchange soft information in an iterative manner resulting in the so-called turbo-equalization. The time-varying multi-path fading channel is modeled using the basis expansion model (BEM). In this BEM, the time-varying channel is viewed as a bank of time-invariant FIR filters and the time-variation is captured by means of time-varying complex exponential basis functions. Therefore, the time-varying transition tables that characterize the time-varying channel can also follow the BEM. This allows for a lower complexity MAP detector with comparable complexity to the MAP detector for time-invariant channels.

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Low-Complexity Block Turbo Equalization for OFDM Systems in Time-Varying Channels

Cited by 98 publications

References 29 publications

Doppler Shift Compensation Schemes in VANETs

Doppler Shift Compensation Schemes in VANETs

Low-complexity iterative receiver design for mobile OFDM systems

Turbo equalization of doubly selective channels

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