Combined PA/NPA CFO Recovery for FBMC Transmissions over Doubly-Selective Fading Channels

This paper deals with carrier frequency offset recovery for burst-mode filter-bank multicarrier transmission over channels affected by severe time-frequency selective fading. Unlike previously proposed algorithms, whereby frequency is recovered either relying on known pilot symbols multiplexed with the data stream (pilot-aided, or PA, approach), or exploiting specific properties of the multicarrier signal structure in a non-pilot-aided (NPA) fashion, here we present and discuss an algorithm based on the maximum likelihood principle, which can be qualified as combined PA/NPA since it takes advantage both of pilot symbols and also indirectly of data symbols through knowledge and exploitation of their specific modulation format. The algorithm requires the availability of the statistical properties of channel fading up to second-order moments. It is shown that the above approach allows to improve on both estimation accuracy and frequency acquisition range of previously published schemes.