Zero-padding or cyclic prefix for MDFT-based filter bank multicarrier communications

Cruz–Roldán, Fernando; Blanco–Velasco, Manuel; Godino-Llorente, Juan Ignacio

doi:10.1016/j.sigpro.2011.12.023

Cited by 12 publications

(6 citation statements)

References 24 publications

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“…Nevertheless, this advantage was partly given up in[66] and a CP-based OFDM/OQAM system was proposed for the sake of facilitating the data reception process. See also[21].…”

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confidence: 99%

Preamble-based channel estimation in OFDM/OQAM systems: A review

et al. 2013

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Filter bank-based multicarrier (FBMC) systems based on offset quadrature amplitude modulation (FBMC/OQAM) have recently attracted increased interest (in applications including DVB-T, cognitive radio, and powerline communications) due to their enhanced flexibility, higher spectral efficiency, and better spectral containment compared to conventional OFDM. FBMC/OQAM suffers, however, from an imaginary inter-carrier/inter-symbol interference that complicates signal processing tasks such as channel estimation. Most of the methods reported thus far in the literature rely on the assumption of (almost) flat subchannels to more easily tackle this problem, with the aim of addressing it in a way similar to OFDM. However, this assumption may be often quite inaccurate, due to the high frequency selectivity of the channel and/or the small number of subcarriers employed to cope with frequency dispersion in fast fading environments. In such cases, severe error floors are exhibited at medium to high signal-to-noise ratio (SNR) values, that cancel the advantage of this modulation over OFDM. Moreover, the existing methods provide estimates of the subchannel responses, most commonly in the frequency domain. The goal of this paper is to revisit this problem through an alternative formulation that focuses on the estimation of the channel impulse response itself and makes no assumption on the degree of frequency selectivity of the subchannels. The possible gains in estimation performance offered by such an approach are investigated through the design of optimal (in the mean squared error sense) preambles, of both the full and sparse types, and of the smallest possible duration of only one pilot FBMC symbol. Existing preamble designs for flat subchannels are then shown to result as special cases. The case of longer preambles, consisting of two consecutive pilot FBMC symbols, is also analyzed. Simulation results are presented, for both mildly and highly frequency selective channels, that demonstrate the significant improvements in performance offered by the proposed approach over both OFDM and the optimal flat subchannel-based FBMC/OQAM method. Most notably, no error floors appear anymore over a quite wide range of SNR values.

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“…Nevertheless, this advantage was partly given up in[66] and a CP-based OFDM/OQAM system was proposed for the sake of facilitating the data reception process. See also[21].…”

mentioning

confidence: 99%

Preamble-based channel estimation in OFDM/OQAM systems: A review

et al. 2013

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“…In 2002, the work by Muquet et al [1] provided a comprehensive evaluation for CP-OFDM and ZP-OFDM, which concludes that using ZP can enhance channel estimation and guarantee signal recovery. Ten years later, the debate of using either CP or ZP is extended to filter-bank multi-carrier systems (FBMC) [2], which shows that a circulant channel matrix can be obtained at the receiver by using either of the two guard interval schemes. The circulant matrix is diagonalised using a discrete Fourier transform (DFT), thus enables one-tap equalisation in the frequency-domain.…”

Section: Introductionmentioning

confidence: 99%

Experimental Validation of Zero Padding in SEFDM Systems Using Over-the-Air Transmission

Ozan

Grammenos

Darwazeh

2022

2022 13th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP)

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Non-orthogonal spectrally efficient frequency division multiplexing (SEFDM) saves bandwidth by compressing the frequency spacing between the subcarriers. This is at the cost of introducing inter-carrier interference (ICI) between the subcarriers. This self-created ICI compounded by the signal degradation caused during wireless propagation in multipath environments, complicates the task of channel estimation and equalisation. Recent studies suggest that combining zero padding (ZP) with SEFDM signals can simplify the challenge of channel estimation and equalisation in the frequency-domain. In this work, we validate experimentally the new ZP scheme through over-the-air transmission of radio frequency (RF) signals. Experimental results prove that using ZP in SEFDM enhances the channel estimation and equalisation accuracy, in comparison to conventional cyclic prefix (CP)-SEFDM. In addition, it is shown that ZP-SEFDM offers robustness against timing offsets.

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“…It is derived by changing the roles of analysis and synthesis filters in FBs. Transmultiplexer systems are often used in channel coding application in communication such as Code division multiple access (CDMA), frequency division multiple access (FDMA), and time division multiple access (TDMA) [1][2][3][4] while filter banks are typically used for source coding applications such as data compression [4][5][6][7][8][9]. The main advantage of configuring Transmultiplexer is to improve bandwidth efficiency which is achieved by using the full channel bandwidth, thereby leaving no gaps in the frequency bands allocated to the input signals.…”

Section: Introductionmentioning

confidence: 99%

“…The main advantage of configuring Transmultiplexer is to improve bandwidth efficiency which is achieved by using the full channel bandwidth, thereby leaving no gaps in the frequency bands allocated to the input signals. A detailed discussion of multirate systems is given in [3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%