Analysis of Nonorthogonal Training in Massive MIMO Under Channel Aging With SIC Receivers

Chopra, Ribhu; Murthy, Chandra R.; Suraweera, Himal A.; Larsson, Erik G.

doi:10.1109/lsp.2018.2889955

Cited by 17 publications

(6 citation statements)

References 16 publications

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“…However, at high mobilities, the performance of CF-mMIMO becomes comparable to, if not worse than both cellular mMIMO and small cells. This strengthens the observation made in [20], that the effect of channel aging on wireless communication systems is highly dependent on the system model, and warrants careful analysis.…”

Section: Numerical Resultssupporting

confidence: 84%

Uplink Performance Analysis of Cell-Free mMIMO Systems under Channel Aging

Chopra¹,

Murthy²,

Papazafeiropoulos³

2021

Preprint

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In this paper, we investigate the impact of channel aging on the uplink performance of a cell-free (CF) massive multiple-input multiple-output (mMIMO) system with a minimum mean squared error (MMSE) receiver. To this end, we present a new model for the temporal evolution of the channel, which allows the channel to age at different rates at different access points (APs). Under this setting, we derive the deterministic equivalent of the per-user achievable signal-tointerference-plus-noise ratio (SINR). In addition to validating the theoretical expressions, our simulation results reveal that, at low user mobilities, the SINR of CF-mMIMO is nearly 5 dB higher than its cellular counterpart with the same number of antennas, and about 8 dB higher than that of an equivalent small-cell network with the same number of APs. On the other hand, at very high user velocities, and when the channel between the UEs the different APs age at same rate, the relative impact of aging is higher for CF-mMIMO compared to cellular mMIMO. However, when the channel ages at the different APs with different rates, the effect of aging on CF-mMIMO is marginally mitigated, especially for larger frame durations.

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Section: Numerical Resultssupporting

confidence: 84%

Uplink Performance Analysis of Cell-Free mMIMO Systems under Channel Aging

Chopra¹,

Murthy²,

Papazafeiropoulos³

2021

Preprint

Self Cite

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“…Since both x 0 and x q , q ≥ 1, experience the same fading channel, we first define x = γ 0 x 0 + M q=1 γ q x q , which are the signals to be recovered by FD-DFE. Given the observations shown in (12), the outputs of the FD-DFE are given bŷ…”

Section: B Design and Performance Of Fd-dfementioning

confidence: 99%

OTFS-NOMA: An Efficient Approach for Exploiting Heterogenous User Mobility Profiles

Ding

Schober

Fan

et al. 2019

IEEE Trans. Commun.

148

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This paper considers a challenging communication scenario, in which users have heterogenous mobility profiles, e.g., some users are moving at high speeds and some users are static. A new nonorthogonal multiple-access (NOMA) transmission protocol that incorporates orthogonal time frequency space (OTFS) modulation is proposed. Thereby, users with different mobility profiles are grouped together for the implementation of NOMA. The proposed OTFS-NOMA protocol is shown to be applicable to both uplink and downlink transmission, where sophisticated transmit and receive strategies are developed to remove inter-symbol interference and harvest both multi-path and multi-user diversity.Analytical results demonstrate that both the high-mobility and low-mobility users benefit from the application of OTFS-NOMA. In particular, the use of NOMA allows the spreading of the high-mobility users' signals over a large amount of time-frequency resources, which enhances the OTFS resolution and improves the detection reliability. In addition, OTFS-NOMA ensures that low-mobility users have access to bandwidth resources which in conventional OTFS-orthogonal multiple access (OTFS-NOMA) would be solely occupied by the high-mobility users. Thus, OTFS-NOMA improves the spectral efficiency and reduces latency. generally allocated more transmission power and the other user, referred to as the 'strong user', is allocated less power. As such, the two users can be served in the same time-frequency resource, which improves the spectral efficiency compared to orthogonal multiple access (OMA). In the case that users have similar channel conditions, grouping users with different QoS requirements can facilitate the implementation of NOMA and effectively exploit the potential of NOMA [6]-[8]. Various existing studies have shown that the NOMA principle can be applied to different communication networks, such as millimeter-wave networks [9], [10], massive multiple-input multiple-output (MIMO) systems [11], [12], visible light communication networks [13], [14], and mobile edge computing [15]. This paper considers the application of NOMA to a challenging communication scenario, where users have heterogeneous mobility profiles. Different from the existing works in [16],[17], the use of orthogonal time frequency space (OTFS) modulation is considered in this paper because of its superior performance in scenarios with doubly-dispersive channels [18]- [20].Recall that the key idea of OTFS is to use the delay-Doppler plane, where users' signals are orthogonally placed. Compared to conventional modulation schemes, such as orthogonal frequency-division multiplexing (OFDM), OTFS offers the benefit that the time-invariant channel gains in the delay-Doppler plane can be utilized, which simplifies channel estimation and signal detection in high-mobility scenarios. The impact of pulse-shaping waveforms on the performance of OTFS was studied in [21], and the design of interference cancellation and iterative detection for OTFS was investigated in [22]. The diversity achieve...

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“…More recent papers have studied CE for massive multiple-input-multiple-output (MIMO)-NOMA systems. [37][38][39][40][41][42][43][44] Papers 37,39 and 41 focus on CE as a principle and provide practical estimators for different uplink massive MIMO-NOMA designs. The rest of the papers on uplink massive MIMO have different topics, even though they include channel estimators in their respective analyses.…”

Section: Introductionmentioning

confidence: 99%

Successive interference cancelation‐inspired channel estimation for downlink non‐orthogonal multiple access

Sekokotoana

Takawira

Oyerinde

2021

Trans Emerging Tel Tech

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This paper proposes a channel estimation (CE) scheme composed of two successive interference cancelation-inspired approaches for a two-user power domain downlink non-orthogonal multiple access system. One approach is intended for the weaker user, and the other approach is intended for the stronger user. Both CE approaches employ a constant step-size least mean squares (CSS-LMS) algorithm, using partial pilots to estimate a Rayleigh flat fading channel with a Jake's Doppler spectrum. Closed-form analytical expressions for the CE error variance are presented for each approach and the mean square error (MSE) is used as the performance metric. Through simulation, the CE performance of the stronger user and the weaker user is assessed for different probabilities of error in detection of the unknown pilot. A reasonable probability of error in detection is then selected and employed in evaluating the CE performance of both schemes against their theoretical analyses. Overall, the theoretical analysis matches the simulation results.

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Analysis of Nonorthogonal Training in Massive MIMO Under Channel Aging With SIC Receivers

Cited by 17 publications

References 16 publications

Uplink Performance Analysis of Cell-Free mMIMO Systems under Channel Aging

Uplink Performance Analysis of Cell-Free mMIMO Systems under Channel Aging

OTFS-NOMA: An Efficient Approach for Exploiting Heterogenous User Mobility Profiles

Successive interference cancelation‐inspired channel estimation for downlink non‐orthogonal multiple access

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