Orthogonal frequency division multiplexing (OFDM) systems are highly sensitive to carrier frequency errors. In this paper, a new method utilizing pilots to do frequency synchronization in frequency domain is proposed with large estimation range. It needs no such prerequisite assumption that a perfect symbol timing synchronization [IEEE Transactions on Communications 42 (1994) 2908; 45 (1997) 1613] has been done before performing integer carrier frequency synchronization. Also, a new adjusting model for fine carrier frequency is proposed. Simulation and performance analysis show that our overall frequency estimator has high accuracy. The corresponding FPGA circuit through test in high definition TV (HDTV) prototype in Team of Expert Engineering Group (TEEG) in China proves its availability and feasibility.

Most existing methods for HPA predistortion with memory effects are based on polynomial or indirect learning structures. Few papers concern about the memory predistortion with LUT based techniques. Based on the previously presented method, we propose an improved two-dimensional LUT indexing method for HPA predistortion with memory. Computer simulations and corresponding analysis demonstrate that the proposed method has more effective predistortion capabilities but lower computational complexity.