Channel estimation techniques based on intrinsic interference mitigation for FBMC/OQAM systems

Filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) emerges as a noteworthy alternative to orthogonal frequency division multiplexing (OFDM). FBMC/OQAM addresses the limitations of OFDM by utilizing real-valued, even-symmetrical prototype filters with smaller side lobes and faster spectrum decay. This results in lower out-of-band energy and higher spectral efficiency (SE). However, the orthogonality condition of FBMC/OQAM in the real domain introduces an intrinsic interference (II) component that poses challenges for channel estimation (CE). The conventional straightforward OFDM CE techniques cannot be applied directly. To obtain a precise CSI with the FBMC/OQAM system, Kalman filter (KF) is altered and incorporated into the use of AP and coding. The first proposed method, KalCod, employs a data spreading method to diminish the II effect. The simulation results indicate that KalCod has a superior capacity to the other CE methods, while still maintaining a reasonable level of complexity. In the second proposed method, modified Kalman-auxiliary pilot (KAP), an AP is used to eliminate the II at pilot symbols then updating the channel coefficients using modified KF. When used as a CE method for FBMC/OQAM systems, the modified KAP outperforms its competitors in terms of estimation accuracy, simpler implementation, as well as higher throughput and spectral efficiency.