Weighted Least Square Based Iterative Channel Estimation for Uplink NOMA-OFDM Systems

Balogun, Muyiwa B.; Takawira, Fambirai; Oyerinde, Olutayo O.

doi:10.1109/icspcs47537.2019.9008698

Cited by 8 publications

(7 citation statements)

References 16 publications

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“…Since 𝜀 is a monotonically decreasing function of 𝛼, as can be seen in Figure 3, the inverse function f −1 FP_K (⋅) must exist. Note that (20) is not the accurate expression of  𝜀 0 because it is derived from (17), which is a simplified expression of the false comparison probability 𝜀. The calculated  𝜀 0 using (20) is higher than the actual value since 𝜀 obtained by using (17) is lower than its actual value.…”

Section: Fuzzy Boundmentioning

confidence: 97%

“…Note that (20) is not the accurate expression of  𝜀 0 because it is derived from (17), which is a simplified expression of the false comparison probability 𝜀. The calculated  𝜀 0 using (20) is higher than the actual value since 𝜀 obtained by using (17) is lower than its actual value. Nevertheless, the calculated  𝜀 0 can still indicate the resolution of the proposed comparison scheme.…”

Section: Fuzzy Boundmentioning

confidence: 97%

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LMMSE channel estimation for OFDM systems with channel correlation function selection

Mei

Liu

et al. 2021

IET Communications

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In the linear minimum mean square error (LMMSE) estimation for orthogonal frequency division multiplexing (OFDM) systems, the channel correlation function (CCF) is required. Some methods have been proposed to calculate the CCF. Instead of providing a novel method to obtain the CCF, a scheme is developed for the estimator to select among different CCFs. In this paper, an enhanced LMMSE estimation is proposed that is able to select the best-matched CCF within a candidate set. To this end, a parameter comparison scheme is proposed, in which the possible channel statistics for the LMMSE estimation can be evaluated using the sampled noise MSE. Analytical expressions are thus derived to indicate the accuracy of the proposed scheme. Furthermore, fuzzy bound is provided as the performance metric, which reflects the resolution of the parameter comparison scheme. As an example of application, the enhanced LMMSE method is used with the block pilot pattern in the OFDM systems, and the possible CCF candidates for typical scenarios are presented. The complexity of the estimator is also analyzed and a simplified parameter comparison algorithm is proposed to reduce the complexity. Finally, the theoretical analysis and performance comparison are demonstrated by simulation experiments.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Section: Fuzzy Boundmentioning

confidence: 97%

Section: Fuzzy Boundmentioning

confidence: 97%

LMMSE channel estimation for OFDM systems with channel correlation function selection

Mei

Liu

et al. 2021

IET Communications

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“…Considering the advantages of both NOMA and OFDM, in recent years, the scientific community has shown some interest in analyzing systems based on the joint use of these techniques. Some studies that can be found in the literature on NOMA-OFDM systems include: performance analysis in terms of BER [32], a proposal of methodologies for the decoding of the superimposed signals and power allocation [15,33], analysis of channel estimation effects, and channel quantization in terms of BER [34,35], energy efficiency analysis versus bandwidth spectrum efficiency [36], performance analysis considering index modulation techniques [37,38] among others. However, to the best of the authors' knowledge, there are very few works that study the performance of NOMA-OFDM systems in the presence of HPAs.…”

Section: Introductionmentioning

confidence: 99%

Bit Error Rate Analysis of NOMA-OFDM in 5G Systems With Non-Linear HPA With Memory

et al. 2021

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The orthogonal frequency division multiplexing (OFDM) and the non-orthogonal multiple access (NOMA) scheme are presented as promising techniques to meet the requirement of fifth-generation (5G) communication systems. Although much attention has recently been devoted to study these techniques, some scenarios have still been less explored. Considering that a fundamental part of any communication system is the use of power amplifiers, this paper presents an analytical evaluation of the bit error rate (BER) of NOMA-OFDM systems in the presence of a high power amplifier (HPA) with memory. Considering that the non-linear distortions generated by the HPA can be modeled using a polynomial model with memory, new theoretical expressions are developed to obtain the BER of the system. Specifically, exact BER expressions for a downlink NOMA-OFDM system with two users are presented and verified by Monte Carlo simulation results. The obtained numerical results demonstrate that the performance degradation of both users is highly dependent on the non-linear distortions, even when the successive interference cancellation (SIC) technique is performed perfectly.INDEX TERMS 5G, bit error rate, high power amplifier, non-linearity, non-orthogonal multiple access, orthogonal frequency division multiplexing.

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“…As with grant-based NOMA approaches, channel estimation is equally important for the success of grant-free NOMA approaches. Papers [25][26][27][28][29][30][31][32][33][34][35][36] have considered CE in uplink NOMA for single-input-single-output (SISO)-NOMA. In the work presented in papers 25-28,31, code-domain (mostly sparse coding multiple access [SCMA]) NOMA systems are considered.…”

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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Weighted Least Square Based Iterative Channel Estimation for Uplink NOMA-OFDM Systems

Cited by 8 publications

References 16 publications

LMMSE channel estimation for OFDM systems with channel correlation function selection

LMMSE channel estimation for OFDM systems with channel correlation function selection

Bit Error Rate Analysis of NOMA-OFDM in 5G Systems With Non-Linear HPA With Memory

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

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