Analysis of Cyclic-Prefix Correlation Statistics and their Use in OFDM Timing and Frequency Synchronization

Abstract

OFDM systems generally utilize a periodic extension, or cyclic prefix, to aid in equalization at the receiver. The cyclic prefix also incorporates a special autocorrelation structure into the signal that can be used for timing, carrier recovery, and delay-spread estimation. Central to these techniques is estimating the N-lag correlation function at the receiver, and in this paper, we analyze this function and its estimation error and discuss the resulting performance effects. Often overlooked is the dispersive nature of the channel, as many techniques are derived under a non-dispersive model out of convenience. The dispersive channel also results in correlated estimation error, which can significantly certain algorithms.