Frequency Domain Re-Sampler for Clock Sampling Offset in MIMO ODFM Systems

In OFDM systems the oscillators used at the digital to analog converter (DAC) and analog to digital converter (ADC) to derive sampling instants at the transmitter and receiver will never have exactly the same period. Thus sampling instants slowly shift relative to each other. In this paper we investigate the performance of a frequency domain re-sampler for a MIMO OFDM system which was developed for a proposed IEEE 802.11n TGn proposal. We present analysis and simulation to demonstrate that this technique results in negligible performance loss relative to perfect sample timing. In addition, the complexity of the technique is compared to a competing technique based upon a variable digital delay filter (Farrow filter). It is shown that the frequency domain re-sampler results in a lower complexity design. Also memory requirements for the design are causal and very low.