Partial FFT Demodulation: A Detection Method for Doppler Distorted OFDM Systems

Yerramalli, Srinivas; Stojanovic, Milica; Mitra, Urbashi

doi:10.21236/ada531988

Cited by 5 publications

(8 citation statements)

References 11 publications

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“…where R and U are expressed as (11) and U = M−1 k=0 w k · g H k F k respectively. R indicates the residual noise distribution after equalization.…”

Section: B Residual Interference In Hcmentioning

confidence: 99%

“…Both of the two technologies have been studied in channel scenarios with both multipath and Doppler spread [4]- [11], especially for OFDM which is convenient to employ methods such as pulse shaping [10] or partial FFT demodulation [11]. Among all these proposals, FDE is still is an attractive technique for mitigation of the inter-carrier interference (ICI) involved by the doubly-dispersive channels.…”

Section: Introductionmentioning

confidence: 99%

“…Thus several practical proposals to cancel or suppress the intersymbol interference (ISI)/ICI in time-variant (TV) channels by avoiding complex block equalization [4] have been proposed in recent years [5]- [9], [11] minimum mean square error (MMSE) equalization to avoid noise enhancement [5]. Nonlinear processes such as decision feedback and successive detection are employed by [4]- [7] to cancel ICI.…”

Section: Introductionmentioning

confidence: 99%

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Performance Analysis of Hybrid Carrier System with MMSE Equalization over Doubly-Dispersive Channels

et al. 2012

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A hybrid carrier (HC) system employing a frequency domain linear equalization based on minimum mean square error (MMSE) criterion is analyzed in this letter. The analytical studies prove that HC modulation scheme achieves a trade-off between circularly prefixed orthogonal frequency division multiplexing (OFDM) and single-carrier (SC) systems in terms of resisting doubly-selective fading. By dispersing the aggregated residual interference effectively, the HC system with particular modulation orders outperform OFDM and SC systems within a specific signal noise ratio (SNR) interval. Both analysis and simulation results over a typical double selective fading channel verify the superiority of HC modulation in suppressing residual interferences.Index Terms-Hybrid carrier (HC), minimum mean square error (MMSE), frequency domain linear equalization, doublyselective fading.

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“…where R and U are expressed as (11) and U = M−1 k=0 w k · g H k F k respectively. R indicates the residual noise distribution after equalization.…”

Section: B Residual Interference In Hcmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Performance Analysis of Hybrid Carrier System with MMSE Equalization over Doubly-Dispersive Channels

et al. 2012

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“…A series of approaches that concentrate on the ICI suppression before the fast Fourier transform (FFT) demodulation have been proposed in OFDM systems [6]- [12]. In general, these methods can be grouped into two categories, with the partial fast Fourier transform (P-FFT) and its revised versions being the first category that mitigate the ICI from the time domain [6]- [8], [10], [11] and the fractional fast Fourier transform (F-FFT) and its revised versions being the second one from the frequency domain [9], [10], [12]. Specifically, the P-FFT, first proposed in [11], divides the block duration into several non-overlapping intervals to reduce the channel variation.…”

Section: Introductionmentioning

confidence: 99%

Inter-Carrier Interference Mitigation for Differentially Coherent Detection in Underwater Acoustic OFDM Systems

Huang¹,

Li²

2021

Preprint

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Suppressing the inter-carrier interference (ICI) is crucial for differentially coherent detection in underwater acoustic (UWA) orthogonal frequency division multiplexing (OFDM) systems due to the fact that the UWA channel is inherently violently Doppler-shifted. In this paper, we propose a new ICI suppression method, referred to as the partially-shifted fast Fourier transform (PS-FFT), which eliminates the ICI from both the time and frequency domains. Specifically, the PS-FFT first divides the received signal in the entire block duration into several short non-overlapping ones to reduce the channel variation in the time domain. It then applies the Fourier transform at several predefined frequencies to the received signal in each of these intervals to compensate Doppler shifts in the frequency domain. Finally, it weightedly combines the multiple demodulator outputs at each carrier as one output for symbol detection, with the combiner weights being solved by the stochastic gradient algorithm. Simulation results show that the PS-FFT dramatically outperforms the existing classical methods, the partial fast Fourier transform (P-FFT) and the fractional fast Fourier transform (F-FFT), for both medium and high Doppler factors and large carrier numbers in terms of the mean squared error (MSE). Numerically, the MSE of the PS-FFT is reduced by 61.83% − 84.89% compared to that of the F-FFT when the input signal-to-noise ratio (SNR) at the receiver ranges from 10 dB to 30 dB at a Doppler factor of 3 × 10 −4 and a carrier number of 1024 where the P-FFT even cannot work.

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“…Among them, simple carrier frequency offset (CFO) compensation has been adopted in [13], [14]. Besides, a newly-emerging technique referred to as partial FFT demodulation was also proposed in [15], [16], which can counteract more complicated time variations within each OFDM block.…”

Section: Introductionmentioning

confidence: 99%

Eigendecomposition-Based Partial FFT Demodulation for Differential OFDM in Underwater Acoustic Communications

Han

Zhang

et al. 2018

IEEE Trans. Veh. Technol.

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Differential orthogonal frequency division multiplexing (OFDM) is practically attractive for underwater acoustic communications since it has the potential to obviate channel estimation. However, similar to coherent OFDM, it may suffer from severe inter-carrier interference over time-varying channels. To alleviate the induced performance degradation, we adopt the newly-emerging partial FFT demodulation technique in this paper and propose an eigendecomposition-based algorithm to compute the combining weights. Compared to existing adaptive methods, the new algorithm can avoid error propagation and eliminate the need for parameter tuning. Moreover, it guarantees global optimality under the narrowband Doppler assumption, with the optimal weight vector of partial FFT demodulation achieved by the eigenvector associated with the smallest eigenvalue of the pilot detection error matrix. Finally, the algorithm can also be extended straightforwardly to perform subband-wise computation to counteract wideband Doppler effects.

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Partial FFT Demodulation: A Detection Method for Doppler Distorted OFDM Systems

Cited by 5 publications

References 11 publications

Performance Analysis of Hybrid Carrier System with MMSE Equalization over Doubly-Dispersive Channels

Performance Analysis of Hybrid Carrier System with MMSE Equalization over Doubly-Dispersive Channels

Inter-Carrier Interference Mitigation for Differentially Coherent Detection in Underwater Acoustic OFDM Systems

Eigendecomposition-Based Partial FFT Demodulation for Differential OFDM in Underwater Acoustic Communications

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