Efficient Integer Frequency Offset Estimation Architecture for Enhanced OFDM Synchronization

An integer frequency offset (IFO), in orthogonal

frequency-division multiplexing (OFDM) systems, causes a circular

shift of the sub-carrier indices in the frequency domain.IFO

can be mitigated through strict RF front-end design but this

is challenging and expensive. Therefore, IFO is estimated and

removed at baseband, allowing the RF front-end specification

to be relaxed, thus reducing system cost. For applications

susceptible to Doppler shift, and multi-standard radios requiring

wide frequency range access, careful RF design may be

insufficient without IFO estimation. This paper proposes a novel

approach for IFO estimation with reduced power consumption

and computational cost. A four-fold resource sharing architecture

reduces computational cost, while a multiplierless technique and

carefully optimised wordlengths yield further power reduction

while maintaining a good accuracy. The novel method is shown

to achieve excellent performance, similar to the theoretically

achievable bound. In fact, performance is significantly better

than conventional techniques, while being much more efficient.

When implemented for IEEE 802.16-2009, the proposed method

saves 78% power over the conventional technique on low-power

FPGA devices. The method is applicable to IEEE 802.11 and

IEEE 802.22.