Adaptive Filtering Techniques using Cyclic Prefix in OFDM Systems for Multipath Fading Channel Prediction

• Published in: Circuits, systems, and signal processing Vol. 35; no. 10; pp. 3595 - 3618
• Main Authors: Kohli, Amit Kumar, Kapoor, Divneet Singh
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.10.2016; Springer Nature B.V
• Subjects: Algorithms; Channels; Circuits and Systems; Dynamical systems; Electrical Engineering; Electronics and Microelectronics; Engineering; Fading; Filtering systems; Instrumentation; Mathematical models; Orthogonal Frequency Division Multiplexing; Signal,Image and Speech Processing; Symbols; Systems analysis; Tracking; Wireless networks; Multipath fading; Kalman filter; Channel estimation; Orthogonal frequency division multiplexing; Cyclic prefix; Space–time block code; Least mean square; Recursive least squares algorithm
• ISSN: 0278-081X; 1531-5878
• DOI: 10.1007/s00034-015-0214-2

This paper presents adaptive channel prediction techniques for wireless orthogonal frequency division multiplexing (OFDM) systems using cyclic prefix (CP). The CP not only combats intersymbol interference, but also precludes requirement of additional training symbols. The proposed adaptive algorithms exploit the channel state information contained in CP of received OFDM symbol, under the time-invariant and time-variant wireless multipath Rayleigh fading channels. For channel prediction, the convergence and tracking characteristics of conventional recursive least squares (RLS) algorithm, numeric variable forgetting factor RLS (NVFF-RLS) algorithm, Kalman filtering (KF) algorithm and reduced Kalman least mean squares (RK-LMS) algorithm are compared. The simulation results are presented to demonstrate that KF algorithm is the best available technique as compared to RK-LMS, RLS and NVFF-RLS algorithms by providing low mean square channel prediction error. But RK-LMS and NVFF-RLS algorithms exhibit lower computational complexity than KF algorithm. Under typical conditions, the tracking performance of RK-LMS is comparable to RLS algorithm. However, RK-LMS algorithm fails to perform well in convergence mode. For time-variant multipath fading channel prediction, the presented NVFF-RLS algorithm supersedes RLS algorithm in the channel tracking mode under moderately high fade rate conditions. However, under appropriate parameter setting in 2 × 1 space–time block-coded OFDM system, NVFF-RLS algorithm bestows enhanced channel tracking performance than RLS algorithm under static as well as dynamic environment, which leads to significant reduction in symbol error rate.