MMSE subcarrier equalization for filter bank based multicarrier systems

Filter bank based multicarrier systems (FBMC) offer a number of benefits over conventional orthogonal frequency division multiplexing (OFDM) with cyclic prefix (CP). One benefit is the improved spectral efficiency by not using a redundant CP and by having much better control of out-of-band emission. Another advantage is the ease of accommodating multiple users in an FDMA fashion especially in the uplink, i. e. the multiple access channel (MAC). On the other hand, more elaborate equalization concepts are needed compared to the single-tap per-subcarrier equalizer sufficient in the OFDM with CP case. In this contribution we will present an efficient linear minimum mean square error (MMSE) equalization concept. Since FBMC systems employ offset-quadrature-amplitude-modulation (OQAM), a fractionally spaced per-subcarrier equalizer will be derived, which takes into account the inter-subcarrier interference due to frequency selective multipath fading. Still this is handled with decoupled per-subcarrier equalizers. Simulation results will show that OQAMFBMCs allow for savings in transmit power which have to be paid with a practicable amount of computational overhead.