Semi-adaptive channel estimation technique for LTE systems

Channel estimation in orthogonal frequency division multiplexing (OFDM) systems is required for coherent demodulation. This paper deals with channel estimation in the OFDM based LTE system. In particular, two pilot-aided techniques are presented: the low-pass filter based estimator (LPFE), and the robust minimum mean square error estimator (MMSE). These techniques are characterized by their low complexity relative to other complex estimation techniques. A semi-adaptive channel estimator is proposed in this paper. In the proposed estimator, channel delay spread and Doppler frequency are used to adapt the interpolation filters in order to enhance the estimator performance while maintaining low complexity relative to the fully adaptive estimator. Simulation results show that there is performance improvement using the proposed adaptive scheme when applied to LTE systems.