International Research Journal of Innovations in Engineering and Technology - IRJIET International Open Access, Monthly, Peer Reviewed, Reputed Journal ISSN (online): 2581-3048

Impact Factor (2025): 6.9

DOI Prefix: 10.47001/IRJIET

Hybrid LS-MMSE Channel Estimation for OFDM Systems Over Frequency-Selective Rayleigh Fading Channel

Mustafa GhanimCollege of Communication Engineering, University of Technology- IraqAyman N. MuhiCollege of Communication Engineering, University of Technology- IraqMohaimen Q. AlgburiCollege of Communication Engineering, University of Technology- Iraq

Vol 10 No 4 (2026): Volume 10, Issue 4, April 2026 | Pages: 276-286

International Research Journal of Innovations in Engineering and Technology

OPEN ACCESS | Research Article | Published Date: 25-04-2026

doi Logo doi.org/10.47001/IRJIET/2026.104040

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Abstract

To achieve reliable orthogonal frequency division multiplexing (OFDM) communications in frequency-selective fading channels, accurate channel estimation is critical. The traditional least squares (LS) estimator enhances noise at pilot locations, whereas the traditional pilot-only minimum mean square error (MMSE) estimator adds residual interpolation error that remains independent of signal-to-noise ratio (SNR). This paper suggests an Adaptive Full-Band Hybrid LS-MMSE channel estimator which removes both of the limitations by a one-step linear minimum mean square error (LMMSE) Wiener filter of size NxNP analytically computed based on the complete channel frequency-domain cross-correlation matrix using the exponential power delay profile (PDP). The proposed estimator directly interpolates all pilot measurements to estimates in the entire frequency band in a single step, ensuring the Hybrid MSE results better than LS and MMSE results at any SNR. Monte Carlo simulated 16-QAM OFDM system with N = 64 subcarriers, NP = 16 pilots and L = 6 tap Rayleigh fading channel show consistent performance improvements. The proposed method has a NMSE of -18.21 dB (4.83 dB gain over LS and 3.14 dB gain over MMSE) and a BER of 0.0649, and spectral efficiency of 8.4 bits/s/Hz at SNR = 28 dB. The estimator is computationally tractable, and it achieves the Cramer-Rao Lower Bound at high SNR, making it a high-performance solution to 5G and beyond OFDM systems.

Keywords

OFDM; Channel estimation; LS; MMSE; Rayleigh fading;5G; Wireless communications


Citation of this Article

Mustafa Ghanim, Ayman N. Muhi, & Mohaimen Q. Algburi. (2026). Hybrid LS-MMSE Channel Estimation for OFDM Systems Over Frequency-Selective Rayleigh Fading Channel. International Research Journal of Innovations in Engineering and Technology - IRJIET, 10(4), 276-286. Article DOI https://doi.org/10.47001/IRJIET/2026.104040

Licence Copyright (c) 2026 International Research Journal of Innovations in Engineering and Technology creative common licence This work is licensed under Creative common Attribution Non Commercial 4.0 Internation Licence
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