Carrier frequency offset estimation using hidden pilots for MC-DS-CDMA systems

This paper develops a new hidden pilots based algorithm for the carrier frequency offset (CFO) estimation of multicarrier DS-CDMA (MC-DS-CDMA) systems. Multiple CFO of different users in the uplink of MC-DS-CDMA systems may violate the orthogonality among subcarriers and induce both inter-carrier interference (ICI) and inter-user interference (IUI). This algorithm utilizes mutually orthogonal hidden pilots for each user and implements fast Fourier transform (FFT) to the received signal matrix after the average operation on its column vectors, so the interference including the IUI caused by users¿ data symbols are greatly depressed and CFOs can be estimated with the performance close to the conventional pilot-based CFO estimator without the requirement of extra transmission bandwidth. The simulation results verify the effectiveness of the proposed approach with CFOs in the fine tracking phase and the slowly time-varying flat-fading channels.