Carrier Frequency Offset Estimation in Multiantenna Transmission Systems Based on Single-Carrier Modulation

The implementation challenges in building compact and low-cost radios for future wireless systems are continuously growing. This is partially due to the introduction of multiantenna transmission techniques, calling for several parallel radio implementations in a single terminal, with considerably reduced implementation resources (size and cost) for individual radios. In this context, one important aspect is the so-called "dirty RF" theme stemming from the unavoidable physical limitations of the used analog electronics. This has started to draw wide attention in both academic and industrial communities. One concrete example is the carrier frequency offset (CFO) problem, caused by frequency instability of the used oscillators and the mobility of the terminals, which can severely degrade the system performance. In this paper, we consider the CFO estimation problem in multi-antenna system context utilizing single-carrier modulation. One efficient pilot based algorithm with built-in diversity against fading channel state is proposed and a lower bound for the estimation error variance is derived analytically. This analysis reveals additional elements for further improving the estimator performance, in terms of pilot structure design. Extensive computer simulations are then used to further assess the estimator performance and to verify the analysis results.