The study on the algorithm of frequency offset estimation in broadband wireless access systems

An improved algorithm of frequency offset estimation applied in broadband wireless access system based on IEEE 802.16e-OFDMA is proposed in the paper. In the algorithm, a synchronization sequence frame is made up of Zadoff-Chu sequences with four times repetition instead of original preamble to accomplish frequency offset estimation. First, the received signal is conjugate related with local synchronization sequences to eliminate the influence of synchronization sequence, and then the fine frequency synchronization is achieved by taking two times of frequency offset estimation. The algorithm has better estimation accuracy and larger estimation span. Furthermore all processes of the frequency offset estimation are taken before FFT which can save the time of system synchronization and reduce the complexity of the system. Simulations in AWGN channel and Rayleigh channel verify the validity of the algorithm.