An all-digital feed-forward CFO cancellation scheme for HIPERLAN/2 in multipath environment

A multicarrier transmission system is sensitive to carrier frequency offset (CFO) that produces severe inter-carrier interference (ICI). In this work a novel architecture for CFO cancellation is proposed for HIPERLAN/2 type modems. The proposed architecture consists of two parts: a coarse and a fine CFO cancellation subsystem. In the coarse subsystem an extended range correlation type time domain CFO estimation scheme is employed. Then a complex numerically controlled oscillator (CNCO) is used to reduce the main part of the CFO effects. In the fine CFO correction subsystem, a frequency-domain pilot-based estimator is proposed. The proposed scheme measures the phase drift of HIPERLAN/2 pilots in frequency domain and produces an estimation of the relative phase drift of each sample in the time-domain. The result is used to correct the remaining effects of the CFO. The proposed novel architecture is an all-digital feed-forward scheme that means no feedback to the analog front-end of the receiver is required. This fact reduces the implementation complexity.