Mixture PLL-based loop for joint CFO and channel estimation in slow time-varying OFDM environment

This work deals with joint carrier recovery and channel estimation for orthogonal frequency-division-multiplexing (OFDM) systems over slow time-varying Rayleigh channel. In this paper, we propose a less complex algorithm based on a mixture PLL-based loop for estimating and tracking parameters in non-linear model. The algorithm can work with both the physical channel model (assuming time delays information) and the equivalent discrete-time channel model. In the algorithm, we combine two techniques the PLL-based loop and the Sequential Monte Carlo Sampling in order to track the channel complex gains and unknown carrier frequency offset (CFO). Afterwards, the channel matrix can be simply constructed, and then the data symbol can be estimated with free intercarrier interference (ICI) by using MMSE equalizer. It is shown that our algorithm has a good performance in terms of MSE and BER and approaches the BER of the ideal case for which the channel response and CFO are known. Moreover, the proposed mixture has less complexity compared to the mixture with kalman filter.