Short preamble-based estimation of highly frequency selective channels in FBMC/OQAM

Channel estimation in multicarrier systems employing filter banks with offset quadrature amplitude modulation (FBMC/OQAM) is known to face challenges related to the interference effect intrinsic to these systems. Most of the methods reported thus far rely on the assumption of (almost) flat subchannels - implying a low frequency selective channel - to more easily tackle this problem. Others, more recent ones, relax this assumption but they either depend on a model for the channel or they concentrate on per-subchannel estimation and often require long training sequences. This paper revisits this problem by proposing a method that makes no assumption on the channel frequency selectivity, while using a very short preamble for training. The latter is optimized with respect to the channel estimation mean squared error. The superiority of the proposed method over classical ones is demonstrated via simulation results for both mildly and highly frequency selective channels.