Comparison of Linear, Widely Linear and Fresh Equalizers for FBMC-OQAM Systems with Different Numerologies

This paper deals with the equalization of rectilinear and quasi-rectilinear modulated signals over frequency selective channels. This study is motivated by the fact that offset quadrature amplitude modulation based filter bank multi-carrier, one of the most prominent post orthogonal frequency division multiplexing contenders for beyond 5G wireless communication systems, employs offset quadrature modulation. This modulation is known to be cyclo-stationary and non-second order circular. Three minimum mean squared error based equalizing structures have been developed, referred to as linear (LE), widely linear (WLE) and widely linear Fresh (WL Fresh) equalizers. For the proposed equalizers, both symbol spaced and fractionally spaced processing have been evaluated, in synchronous DL/UL and asynchronous UL scenarios, with mixed numerologies transmissions. The simulation results show the ability of WL Fresh equalizer to suppress inter-numerology and inter-symbol interferences over frequency selective channels, outperforming the WLE and LE equalization schemes.