CFO estimation for QAM-FBMC systems considering non-orthogonal prototype filters

The carrier frequency offset (CFO) on the orthogonal frequency division multiplexing (OFDM) and offset-QAM-filter-bank based multi-carrier (FBMC) have been well studied. However, the impact of the CFO on the QAM-FBMC systems is complicated because of an unavoidable interferences from non-orthogonal prototype filters. In this paper, we analyze the impact of the CFO on the QAM-FBMC systems, and propose the method of the CFO estimation. By the analysis of the CFO, the CFO is separated to the integer part and fractional part. For the integer part estimation, we propose the pilot design to guarantee the relative high power at pilot subcarrier location in up-sampled frequency domain. For the fractional part estimation, we formulate the inner product equation between two preamble symbols, and suggest the approximated estimation for lack of the channel information. Simulation results show the performance of the CFO estimation in AWGN and pedestrian channel, and also show that the proposed approximated estimation works well with a slight performance degradation.