Pilot-based carrier frequency offset estimation in MC-DS-CDMA system
Dai Xian-hua · Journal of Communications · 2008
A pilot-based multiple carrier frequency offset (CFO) estimation algorithm was proposed for the uplink o multicarrier DS-CDMA (MC-DS-CDMA) system. By exploiting the low-pass property of the CFO vector, a novel comb pilot transmission scheme was designed to approximately acquire the single user signals on the pilot subcarriers at the re ceiver end. With the phase-angle averaging method to deal with the phase-angle of the quotient of two neighboring sam ple signals on the pilot subcarriers, the good result of the multiple CFO estimation was achieved. Further, the discrete Fourier transform (DFT) was employed and consequently improved the algorithm’s robustness to the interference. The simulation results show that with small number of users (3) and high signal to noise ratio (SNR) (15dB), the phase-angle averaging method may obtain the mean of CFO estimation error below 1%; while under the conditions o multiple users and low SNR(5dB), the DFT method can still reach the mean of CFO estimation error equal to 0.1% fo the normalized CFO scale (?0.5,0.5). The proposed algorithm is applicable for the fine CFO estimation through the fre quency selective fading slow time-vary channels.