Frequency synchronisation in OFDM - a Bayesian analysis

The Bayesian approach offers three key advantages in the present problem of estimating the frequency offset when synchronising a mobile to a base station in an orthogonal frequency division multiplexing system: a systematic way to include important information via prior probabilities; ability to update our probability distributions consistently using Bayes´ theorem; access to reliability measures for the actual estimate at hand. We show that the Bayesian approach in these ways enables fast frequency acquisition without pilots at low SNR, and also provides a good indicator of when the mobile is sufficiently synchronised to transmit for the first time. Our analysis and simulations indicate that oversampling and ing of subcarriers can speed up the acquisition further. When pilot and (incomplete) channel information is available, it can be successfully included via priors to significantly improve the synchronisation performance.