An adaptive semi-blind algorithm for channel identification in ofdm (original) (raw)
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International Journal of Electrical and Computer Engineering (IJECE), 2018
The OFDM technique i.e. Orthogonal frequency division multiplexing has become prominent in wireless communication since its instruction in 1950's due to its feature of combating the multipath fading and other losses. In an OFDM system, a large number of orthogonal, overlapping, narrow band sub-channels or subcarriers, transmitted in parallel, divide the available transmission bandwidth. The separation of the subcarriers is theoretically optimal such that there is a very compact spectral utilization. This paper reviewed the possible approaches for blind channel estimation in the light of the improved performance in terms of speed of convergence and complexity. There were various researches which adopted the ways for channel estimation for Blind, Semi Blind and trained channel estimators and detectors. Various ways of channel estimation such as Subspace, iteration based, LMSE or MSE based (using statistical methods), SDR, Maximum likelihood approach, cyclostationarity, Redundancy and Cyclic prefix based. The paper reviewed all the above approaches in order to summarize the outcomes of approaches aimed at optimum performance for channel estimation in OFDM systems. Keyword: Blind, semi blind and trained channel estimation LMSE-least mean square error Maximum likelihood MSE-Mean square error OFDM-Orthogonal frequency division multiplexing SDR-semi definite approach SDR-semi definite relaxation