OTFS Channel Estimation and Data Detection Designs With Superimposed Pilots

Mishra, Himanshu B.; Singh, Prem; Prasad, Abhishek K.; Budhiraja, Rohit

doi:10.1109/twc.2021.3110659

Cited by 64 publications

(44 citation statements)

References 30 publications

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“…In [2], a simple CE method based on thresholding is proposed to solve (15) with respect to h using a pilot pattern with only one pilot symbol x p transmitted per frame. It operates as follows: for 1 ≤ k ≤ L p , entries k such that |y p (k)| ≥ 𝜆 (real positive detection threshold), determine the support vector b of h where we set (above the threshold) b(k) = 1 and h(k) = y p (k)∕x p .…”

Section: Description Of the Selected State-of-the-art Methodsmentioning

confidence: 99%

“…Note that from {l i , k i } P i=1 one can calculate {𝜏 i , 𝜈 i } P i=1 using (8). Finally, CE quantifies the sparse vector h from (15). In the next section, the proposed algorithms to solve this problem will be presented.…”

Section: Problem Formulationmentioning

confidence: 99%

“…In this section, various algorithms for sparse CE in OTFS systems are presented. A straightforward way to solve problem (15) with the pilot pattern adopted in this work is to use a greedy approach. Thus, the first algorithm is a mere adaptation of the GOMP method [17,18].…”

Section: Proposed Algorithmsmentioning

confidence: 99%

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Sparse channel estimation algorithms for OTFS system

et al. 2022

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Orthogonal time-frequency space (OTFS) modulation, which has recently been proposed in the literature, is one of the promising techniques designed in the 2D Delay-Doppler domain adapted to combat high Doppler fading channels. However, channel estimation in high Doppler scenarios in advanced mobile-communication systems is still a challenging task. In this paper, the problem of channel estimation in the Delay-Doppler domain of the OTFS is focused on. First, a simple adaptation of the generalized orthogonal matching pursuit procedure, which will serve as a baseline method in this work, is proposed. Then, iterative algorithms are derived beneficiating from the sparsity of the channel. The unknown channel vector is separated into an unknown sparse support vector corresponding to the delay and Doppler taps, and an unknown vector of channel gains. These algorithms involve 𝓁 1 -norm minimization and a two-stage iterative procedure to recover alternatively the channel support and its coefficients. The estimation problem is also addressed from a Bayesian point of view. The sparse representation is reformulated as a specific marginalization of the maximum a posteriori problem on the support of the channel. To deal with the intractability of this problem, two existing techniques are adapted to this context, namely: The Monte Carlo Markov chain with the Gibbs sampler and variational mean-field approximation with the variational Bayesian expectation-maximization procedure. Finally, to assess the performance of the proposed algorithms, their complexity and performance are compared against existing methods. Experimental tests, conducted in high-mobility scenarios and low-latency applications, show that the proposed schemes are slightly more expensive in terms of complexity load but perform significantly better in terms of normalized mean square error and bit error rate.

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Section: Description Of the Selected State-of-the-art Methodsmentioning

confidence: 99%

Section: Problem Formulationmentioning

confidence: 99%

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Sparse channel estimation algorithms for OTFS system

et al. 2022

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“…In this case, the insertion of guard symbols results in nonnegligible delay-Doppler resource overhead and reduces the spectral efficiency. A scheme of superimposed pilot design is developed in [17], where the pilot symbols are placed on the whole delay-Doppler grids and overlapped with all data symbols, but the delay and Doppler parameters are still estimated by the frame with the EP designs. Message passing based methods are proposed to estimate channel parameters and design a data detector in [13], [16], [18].…”

Section: A Related Workmentioning

confidence: 99%

DFT-Spread Orthogonal Time Frequency Space System with Superimposed Pilots for Terahertz Integrated Sensing and Communication

Wu¹,

Chen²,

Chen³

2022

Preprint

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Terahertz (THz) integrated sensing and communication (ISAC) is a promising interdisciplinary technology that realizes simultaneously transmitting Terabit-per-second (Tbps) and millimeter-level accurate environment or human activity sensing. However, both communication performance and sensing accuracy are influenced by the Doppler effects, which are especially severe in the THz band. Moreover, peak-to-average power ratio (PAPR) degrades the THz power amplifier (PA) efficiency. In this paper, a discrete Fourier transform spread orthogonal time frequency space (DFT-s-OTFS) system is proposed to improve the robustness to Doppler effects and reduce PAPR for THz ISAC. Then, a two-phase sensing parameter estimation algorithm is developed to integrate sensing functionality into the DFT-s-OTFS waveform. Meanwhile, a scheme of superimposed pilots is designed, which reduces the pilot overhead and improves the spectral efficiency. Based on the superimposed pilots, a low-complexity iterative channel estimation and data detection method is proposed to recover the data symbols of DFT-s-OTFS. The proposed DFTs-OTFS waveform can improve the PA efficiency by 10% on average compared to OTFS. Simulation results demonstrate that the proposed two-phase sensing estimation algorithm for THz DFT-s-OTFS systems is able to realize millimeter-level range estimation accuracy and decimeter-per-second-level velocity estimation accuracy. Moreover, the effectiveness of the iterative method for data detection aided by superimposed pilots in DFTs-OTFS systems is validated by the simulations and the bit error rate performance is not degraded by the Doppler effects.

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“…The other one is to separate the pilot area and data area within one OTFS block by using a large number of guard symbols [31], [33], which will lower the spectral efficiency of OTFS system. Although [34] and [35] proposed superimposed pilots and data based strategy to jointly estimate the channel and recover the data symbols, the restriction on the signal-to-interference-plus-noise ratio will also incur additional limits on its utilization.…”

mentioning

confidence: 99%

Joint Channel Estimation and Data Detection for Hybrid RIS aided Millimeter Wave OTFS Systems

Li¹,

Zhang²,

Gao³

et al. 2022

Preprint

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For high mobility communication scenario, the recently emerged orthogonal time frequency space (OTFS) modulation introduces a new delay-Doppler domain signal space, and can provide better communication performance than traditional orthogonal frequency division multiplexing system. This article focuses on the joint channel estimation and data detection (JCEDD) for hybrid reconfigurable intelligent surface (HRIS) aided millimeter wave (mmWave) OTFS systems. Firstly, a new transmission structure is designed. Within the pilot durations of the designed structure, partial HRIS elements are alternatively activated. The time domain channel model is then exhibited. Secondly, the received signal model for both the HRIS over time domain and the base station over delay-Doppler domain are studied. Thirdly, by utilizing channel parameters acquired at the HRIS, an HRIS beamforming design strategy is proposed. For the OTFS transmission, we propose a JCEDD scheme over delay-Doppler domain. In this scheme, message passing (MP) algorithm is designed to simultaneously obtain the equivalent channel gain and the data symbols. On the other hand, the channel parameters, i.e., the Doppler shift, the channel sparsity, and the channel variance, are updated through expectationmaximization (EM) algorithm. By iteratively executing the MP and EM algorithm, both the channel and the unknown data symbols can be accurately acquired. Finally, simulation results are provided to validate the effectiveness of our proposed JCEDD scheme.

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OTFS Channel Estimation and Data Detection Designs With Superimposed Pilots

Cited by 64 publications

References 30 publications

Sparse channel estimation algorithms for OTFS system

Sparse channel estimation algorithms for OTFS system

DFT-Spread Orthogonal Time Frequency Space System with Superimposed Pilots for Terahertz Integrated Sensing and Communication

Joint Channel Estimation and Data Detection for Hybrid RIS aided Millimeter Wave OTFS Systems

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