On OTFS Modulation for High-Doppler Fading Channels

Murali, K.; Chockalingam, A.

doi:10.48550/arxiv.1802.00929

Cited by 4 publications

(8 citation statements)

References 12 publications

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“…Refs. [22]- [25] propose various types of simplified receiver structures, usually based on iterative approaches. Some discussion of a discrete signal model, modulator design, and performance analysis is given in [26], [27].…”

Section: A Related Papersmentioning

confidence: 99%

“…2. The transmitter first maps the 2D sequence of information symbols x[k, l] residing along the points of the reciprocal lattice Λ ⊥ , see (25), in the delay-Doppler domain to a 2D sequence of complex numbers X[n, m] residing along the points of the lattice Λ, (8), in the time-frequency domain. This is done through a combination of the finite symplectic Fourier transform and windowing.…”

Section: B Otfs Modulation and Demodulationmentioning

confidence: 99%

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Orthogonal Time Frequency Space Modulation

Hadani

Rakib

Tsatsanis

et al. 2017

2017 IEEE Wireless Communications and Networking Conference (WCNC)

934

638

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This paper introduces a new two-dimensional modulation technique called Orthogonal Time Frequency Space (OTFS) modulation. OTFS has the novel and important feature of being designed in the delay-Doppler domain. When coupled with a suitable equalizer, OTFS modulation is able to exploit the full channel diversity over both time and frequency. Moreover, it converts the fading, time-varying wireless channel experienced by modulated signals such as OFDM into a time-independent channel with a complex channel gain that is essentially constant for all symbols.This design obviates the need for transmitter adaptation, and greatly simplifies system operation. The paper describes the basic operating principles of OTFS as well as a possible implementation as an overlay to current or anticipated standardized systems. OTFS is shown to provide significant performance improvement in systems with high Doppler, short packets, and/or large antenna array. In particular, simulation results indicate at least several dB of block error rate performance improvement for OTFS over OFDM in all of these settings.

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Section: A Related Papersmentioning

confidence: 99%

Section: B Otfs Modulation and Demodulationmentioning

confidence: 99%

Orthogonal Time Frequency Space Modulation

Hadani

Rakib

Tsatsanis

et al. 2017

2017 IEEE Wireless Communications and Networking Conference (WCNC)

934

638

View full text Add to dashboard Cite

show abstract

“…It can be checked that Φ e,(l) k , B (l) , and Σ e,(l) k only correspond to the non-zero positions in the sparse vector h (ul) k . Hence, the inversion operation in (44) would be much simpler than that in (23). Fortunately, when only one element in α k is updated at each iteration, Σ e,(l) k can be sequentially derived from Σ e,(l−1) k , whose details can be found in the appendix of [34].…”

Section: F Low Complex Em-vbmentioning

confidence: 99%

“…For the VB method, the computational complexity mainly depends on the calculation of the matrix inverse Σ k in (23), where a computational complexity in the order of O(N 3 L 3 ) is required.…”

Section: G Complexity Analysismentioning

confidence: 99%

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Uplink-aided High Mobility Downlink Channel Estimation over Massive MIMO-OTFS System

Liu¹,

Zhang²,

Gao³

et al. 2020

Preprint

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Although it is often used in the orthogonal frequency division multiplexing (OFDM) systems, application of massive multiple-input multiple-output (MIMO) over the orthogonal time frequency space (OTFS) modulation could suffer from enormous training overhead in high mobility scenarios.In this paper, we propose one uplink-aided high mobility downlink channel estimation scheme for the massive MIMO-OTFS networks. Specifically, we firstly formulate the time domain massive MIMO-OTFS signal model along the uplink and adopt the expectation maximization based variational Bayesian (EM-VB) framework to recover the uplink channel parameters including the angle, the delay, the Doppler frequency, and the channel gain for each physical scattering path. Correspondingly, with the help of the fast Bayesian inference, one low complex approach is constructed to overcome the bottleneck of the EM-VB. Then, we fully exploit the angle, delay and Doppler reciprocity between the uplink and the downlink and reconstruct the angles, the delays, and the Doppler frequencies for the downlink massive channels at the base station. Furthermore, we examine the downlink massive MIMO channel estimation over the delay-Doppler-angle domain. The channel dispersion of the OTFS over the delay-Doppler domain is carefully analyzed and is utilized to associate one given path with one specific delay-Doppler grid if different paths of any user have distinguished delay-Doppler signatures. Moreover, when all the paths of any user could be perfectly separated over the angle domain, we design the effective path scheduling algorithm to map different users' data into the orthogonal delay-Doppler-angle domain resource and achieve the parallel and low complex downlink 3D channel estimation. For the general case, we adopt the least square estimator with reduced dimension to capture the downlink delay-Dopplerangle channels. Various numerical examples are presented to confirm the validity and robustness of the proposed scheme.

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Channel Estimation for Orthogonal Time Frequency Space (OTFS) Massive MIMO

Shen

Dai

Han

et al. 2019

ICC 2019 - 2019 IEEE International Conference on Communications (ICC)

148

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Orthogonal time frequency space (OTFS) modulation outperforms orthogonal frequency division multiplexing (OFDM) in high-mobility scenarios. One challenge for OTFS massive MIMO is downlink channel estimation due to the large number of base station antennas. In this paper, we propose a 3D structured orthogonal matching pursuit algorithm based channel estimation technique to solve this problem. First, we show that the OTFS MIMO channel exhibits 3D structured sparsity: normal sparsity along the delay dimension, block sparsity along the Doppler dimension, and burst sparsity along the angle dimension. Based on the 3D structured channel sparsity, we then formulate the downlink channel estimation problem as a sparse signal recovery problem. Simulation results show that the proposed algorithm can achieve accurate channel state information with low pilot overhead.

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On OTFS Modulation for High-Doppler Fading Channels

Cited by 4 publications

References 12 publications

Orthogonal Time Frequency Space Modulation

Orthogonal Time Frequency Space Modulation

Uplink-aided High Mobility Downlink Channel Estimation over Massive MIMO-OTFS System

Channel Estimation for Orthogonal Time Frequency Space (OTFS) Massive MIMO

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