Design of farrow interpolator for ofdm receivers with asynchronous sampling

Orthogonal frequency-division multiplexing (OFDM) is a technique well suited for wireless broad-band communications. A drawback of OFDM is its sensitivity to carrier frequency offset (CFO) and sampling frequency offset (SFO). In a digital OFDM receiver with asynchronous frequency reference, the sampled baseband signal contain both CFO and SFO which must be precisely estimated and compensated to ensure satisfactory performance. When the offsets are accurately estimated, the compensation of CFO is normally achieved by a digital frequency shift mixer in discrete-time domain while the compensation of SFO is mainly accomplished through a re-sampler, capable of arbitrary sampling rate conversion (SRC) ratio. In this paper, we consider the design of a typical re-sampler, i.e., the Farrow Interpolator, for SFO compensation in a digital OFDM receiver with asynchronous sampling. The effect of SFO compensation on OFDM signals with the Farrow Interpolator is analyzed and a design criterion based on signal-to-interference ratio (SIR) is proposed for the design of the Farrow Interpolator. Design examples and simulation results are included to show performance improvement by employing the proposed design method when the SRC ratio is low.