Linear expansions for frequency selective channels in OFDM

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Elsevier GMBH

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Modeling the frequency selective fading channels as random processes, we employ a linear expansion based on the Karhumen-Loeve (KL) series representation involving a complete set of orthogonal deterministic vectors with a corresponding uncorrelated random coefficients. Focusing on OFDM transmissions through frequency selective fading, this paper pursues a computationally efficient, pilot-aided linear minimum mean square error (MMSE) uncorrelated KL series expansion coefficients estimation algorithm. Based on such an expansion, no matrix inversion is required in the proposed MMSE estimator. Moreover, truncation in the linear expansion of channel is achieved by exploiting the optimal truncation property of the KL expansion resulting in a smaller computational load on the estimation algorithm. The performance of the proposed approach is studied through analytical and experimental results. We first exploit the performance of the MMSE channel estimator based on the evaluation of minimum Bayesian MSE. We also provide performance analysis results studying the influence of the effect of SNR and correlation mismatch on the estimator performance. Simulation results confirm our theoretical results and illustrate that the proposed algorithm is capable of tracking fast fading and improving performance.


Dr. Cirpan received Peskin Award from Stevens Institute of Technology as well as Prof. Nazim Terzioglu award from the Research fund of The University of Istanbul. He is a Member of IEEE and Member of Sigma Xi.

Anahtar Kelimeler

Bayesian channel estimation, OFDM systems, Linear expansions, Fading channels, Systems, Equalization, Algorithms, Computer simulation, Error analysis, Estimation, Fading (radio), Matrix algebra, Random processes, Minimum mean square error (MMSE), Orthogonal frequency division multiplexing


AEÜ - International Journal of Electronics and Communications

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Şenol, H., Çırpan, H. A. & Panayırcı, E. (2006). Linear expansions for frequency selective channels in OFDM. AEÜ - International Journal of Electronics and Communications, 60(3), 224-234. doi:10.1016/j.aeue.2005.03.008