A low complexity fine timing offset and channel estimation algorithm for cooperative diversity OFDM system

In this paper, two estimators are proposed for calculating fine timing and channel impulse response (CIR) of a CD-OFDM based communication system. The proposed low complexity algorithms are designed to operate with asynchronous nodes having independent timing and carrier frequency offsets. These algorithms fully exploit the specially designed structure of time domain preamble used for cooperative communications. For the sake of reducing complexity, both estimators use the correlation results of the same preamble. Moreover, CIR is estimated in time domain thus making multiple FFT operations redundant. Further, fine timing estimator is based on a simple but robust idea of first channel tap identification in cooperative communications scenario. The performance of these algorithms is evaluated in rayleigh fading environment using monte carlo simulations and performance is found better than other comparable algorithms.