Sensitivity of autocorrelation frequency offset estimation in a FH-OFDM system

A new aspect of carrier frequency offset (CFO) estimation is studied in a frequency-hopping (FH) orthogonal frequency division multiplexing (OFDM) system.Unlike in a traditional nonhopped OFDM system,in FH-OFDM system it is important to verify how accurately frequency-switching must be performed before the CFO estimation can take place with adequate performance.The accuracy of frequency-switching is evaluated through frequency-hopping timing offset (FHO) and frequency-hopping phase offset (PHO) between the received signal and the signal produced by the local frequency-hopping synthesizer of the receiver.The performance of selected autocorrelation algorithms is simulated in multi-path fading channel under the FHO and PHO,and the results are compared with the performance of ideal frequency-switching and the corresponding analytical Cramer-Rao bound.It is found that the CFO estimators based on autocorrelation principle are quite robust to the FHO less than half the hopping period.