Channel Equalization And PAPR Reduction For ICA Based FBMC-OQAM Systems

With the rapid development of the information industry,wireless communications technology has experienced rapid progress.Commercial orthogonal frequency division multiplexing(OFDM)technology in the fourth generation mobile communication systems can effectively combat the multipath fading of wireless channels,but it has some disadvantages,such as the need for additional cyclic prefix,high out-of-band power emission and sensitivity to carrier frequency offset,which make it difficult to meet the requirements of the future mobile communications systems.Filter bank multicarrier with offset quadrature amplitude modulation(FBMC-OQAM)technology uses a prototype filter with good time-frequency localization characteristics,which can solve the problems existed in OFDM.Therefore,it has a good application prospect in the fifth generation mobile communication network.However,the FBMC-OQAM system still faces many challenges in the research of channel equalization techniques and peak-toaverage power ratio(PAPR)reduction schemes.Channel equalization is an extremely important part of the whole mobile communications system,and the existing FBMC-OQAM system needs to use channel estimation to obtain the channel state information required for channel equalization,which reduces the spectral efficiency of the system.In this paper,an independent component analysis(ICA)based FBMC-OQAM system is proposed.Thus,an FBMCOQAM system based on ICA is proposed.The basic idea is to perform semi-blind channel equalization through high-order statistics.An OQAM based phase correction method is proposed to eliminate the phase ambiguity introduced by ICA based FBMCOQAM system.By combining linear precoding with quadrant ambiguity elimination,the ambiguity can be totally eliminated.Simulation results show that ICA based semiblind equalization scheme with unknown channel state information can achieve almost the same BER performance as zero-forcing with perfect channel state information.Therefore,the ICA based FBMC-OQAM system can enhance the spectral efficiency while achieving a reliable communication.As a multi-carrier system,FBMC-OQAM system has the common problem of high PAPR.However,the existing PAPR reduction schemes in FBMC-OQAM system will cause signal distortion or need to send additional sideband information.Hence,two blind PAPR reduction schemes,namely blind selective mapping(BSLM)and hybrid selective mapping(HSLM)based blind PAPR reduction scheme,are proposed for ICAbased FBMC-OQAM systems.The basic principle of BSLM is to reduce the PAPR by designing the phase adjustment factors.The introduced phase ambiguity can be blindly eliminated at the receiver without sending extra sideband information.In order to further reduce the PAPR of the system,HSLM based PAPR reduction scheme is proposed by combining BSLM with the existing extended selective mapping based scheme.The introduced phase ambiguity can be directly eliminated by the phase shifting process of ICA based semi-blind equalization.Simulation results show that the proposed BSLM algorithm and HSLM algorithm can not only effectively reduce the PAPR of the ICA based FBMC-OQAM system,but also improve the spectrum efficiency of the system.