A New Path Division Multiple Access for the Massive MIMO-OTFS Networks

Li, Muye; Zhang, Shun; Gao, Feifei; Fan, Pingzhi; Dobre, Octavia A.

doi:10.1109/jsac.2020.3018826

Cited by 109 publications

(73 citation statements)

References 43 publications

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“…with Ψ p k,k [l, l ] defined as in (26). Using rectangular shaping pulses and after a suitable approximation of the cross ambiguity function as illustrated in the derivation in [18] and omitted here for the sake of brevity, the simplified version of Ψ p k,k [l, l ] is given by (27).…”

Section: Otfs Modulation and The Proposed Estimation Algorithm A Otfs Input-output Relationmentioning

confidence: 99%

“…The definition of the refinement interval and grid step is not mandatory and depends on the hardware capabilities of the system. Note that other iterative schemes based on coarse and refined estimation over discretized Doppler-delay-angle grids can be found in literature (see, e.g., [26] and references therein). However, our scheme relies on a rigorous derivation of OTFS with rectangular pulses and fractional Doppler and delay shifts, thus differs significantly from the approach proposed in [26], where OTFS is seen as a pre-and post-processing for an inner OFDM modulation, for which CS algorithms can be applied (due to the orthogonality of received samples, as discussed in Section II).…”

Section: Algorithm 2: Csi Estimationmentioning

confidence: 99%

“…The idea of exploiting the channel sparsity in multi-carrier systems is well established and shared by other estimation techniques in the current literature, which generally applies concepts from compressed sensing (CS) (e.g., see [19]- [26]), for both OFDM and OTFS modulations. However, it should be noticed that CS is meaningful when the measurements (i.e., the pilot symbols) are obtained in the dual domain with respect to the domain in which the channel is sparse.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

OTFS vs. OFDM in the Presence of Sparsity: A Fair Comparison

Gaudio

Colavolpe

2022

IEEE Trans. Wireless Commun.

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Many recent works in the literature declare that Orthogonal Time-Frequency-Space (OTFS) modulation is a promising candidate technology for high mobility communication scenarios. However, a truly fair comparison with its direct concurrent and widely used Orthogonal Frequency-Division Multiplexing (OFDM) modulation has not yet been provided. In this paper, we present such a fair comparison between the two digital modulation formats in terms of achievable communication rate. In this context, we explicitly address the problem of channel estimation by considering, for each modulation, a pilot scheme and the associated channel estimation algorithm specifically adapted to sparse channels in the Doppler-delay domain, targeting the optimization of the pilot overhead to maximize the overall achievable rate. In our achievable rate analysis we consider also the presence of a guard interval or cyclic prefix. The results are supported by numerical simulations, for different time-frequency selective channels including multiple scattering components and under non-perfect channel state information resulting from the considered pilot schemes. This work does not claim to establish in a fully definitive way which is the best modulation format, since such choice depends on many other features which are outside the scope of this work (e.g., legacy, intellectual property, ease and know-how for implementation, and many other criteria). Nevertheless, we provide the foundations to properly compare multi-carrier communication systems in terms of their information theoretic achievable rate potential, within meaningful and sensible assumptions on the channel models and on the receiver complexity (both in terms of channel estimation and in terms of soft-output symbol detection).

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Section: Otfs Modulation and The Proposed Estimation Algorithm A Otfs Input-output Relationmentioning

confidence: 99%

Section: Algorithm 2: Csi Estimationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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OTFS vs. OFDM in the Presence of Sparsity: A Fair Comparison

Gaudio

Colavolpe

2022

IEEE Trans. Wireless Commun.

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“…Since the introduction of OTFS modulation in [7], the potential of signal processing in the DD domain has been realized and numerous works have emerged. These works address fundamental and practical issues of OTFS modulation including a discrete-time vectorized formulation of input-output relationships and analysis of OTFS [17], channel estimation and detection for MIMO-OTFS systems [12,15,18], new path division multiple access for massive MIMO-OTFS systems [11] among others. A performance evaluation of OTFS modulation for 5G new radio (5G NR) millimeter wave communication systems can be found in [6].…”

Section: Related Workmentioning

confidence: 99%

Performance Assessment of OTFS Modulation in High Doppler Airborne Communication Networks

et al. 2022

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Emerging 5G and future 6G mobile networks are expected to cater for high mobility scenarios ranging from vehicle-to-vehicle communications to unmanned aerial vehicles and airborne platforms. Communications in this type of deployments suffer from severe Doppler shifts which require new modulation waveforms. Orthogonal time frequency space (OTFS) modulation has recently been proposed as a promising technology for coping with high Doppler channels. OTFS converts a time-varying fading channel into a time-independent channel in the two-dimensional delay-Doppler (DD) domain. The transmit symbols are multiplexed into a nearly constant channel with a complex channel gain in the DD domain. In this paper, we consider a high Doppler airborne communication network where relative mobile node speeds can be above 1200 m/s. The considered system represents a mobile ad-hoc network where the airborne mobile nodes can join or leave the network. Furthermore, each node is equipped with an antenna array that supports directed communication among mobile nodes. The Doppler shifts in this airborne communication network are in the order of 52-72 kHz and may potentially be even higher depending on the selected carrier frequency and the relative speed among the airborne platforms. As such, OTFS modulation is used in this work to efficiently compensate for the high Doppler shifts in the DD domain. In particular, a comprehensive performance assessment in terms of bit error rate (BER) is conducted to reveal the potential of OTFS modulation in dealing with such extreme transmission scenarios. The impact of physical layer parameters, number of delay-Doppler bins in the DD domain used for OTFS modulation, directed versus two-ray channels, and the combination of multiple-input multiple-output (MIMO) systems with OTFS modulation on the BER is assessed. It is shown that both OTFS modulation over a two-ray channel as well as MIMO-OTFS modulation provide a reliable airborne communication network with low BER.

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“…denote the uplink channel vector from the q-th user to the BS in the delay-Doppler domain, where (•) T denotes the transpose of vectors or matrices. Since a ULA is considered at the BS, the channel vector h q (τ, ν) can be written as [14, Example 1.8], [15]…”

Section: System Modelmentioning

confidence: 99%

Performance Analysis of OTFS-based Uplink Massive MIMO with ZF Receivers

Feng

Ngo

Flanagan

et al. 2021

2021 IEEE International Conference on Communications Workshops (ICC Workshops)

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This paper considers an orthogonal time frequency space (OTFS)-based uplink massive multiple-input-multipleoutput (MIMO) system, in which all users transmit symbols to a base station (BS) that is equipped with an one-dimensional uniform linear array (ULA) in the delay-Doppler domain. The zero-forcing (ZF) decoding scheme is applied at the BS. Different from most existing OTFS works, this paper mainly focuses on the performance analysis. Furthermore, in contrast to the existing massive MIMO works, which assume favorable propagation (FP) conditions, here, we investigate the low but non-zero probability scenario that massive MIMO fails in providing FP. This results in a scenario where the channel matrix cannot be diagonalized with massive MIMO. Thus, to facilitate the performance analysis, a low-complexity approximation of the inverse of the Gram matrix, i.e., the Neumann series expansion, is presented. With this, a simple signal-to-noise-ratio (SNR) approximation is firstly derived, which illuminates the impact of the OTFS system parameters. Moreover, by exploiting the properties of circulant matrices, a compact expression for the OTFS multi-path correlation matrix (OTFS-MPCM) is derived.

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A New Path Division Multiple Access for the Massive MIMO-OTFS Networks

Cited by 109 publications

References 43 publications

OTFS vs. OFDM in the Presence of Sparsity: A Fair Comparison

OTFS vs. OFDM in the Presence of Sparsity: A Fair Comparison

Performance Assessment of OTFS Modulation in High Doppler Airborne Communication Networks

Performance Analysis of OTFS-based Uplink Massive MIMO with ZF Receivers

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