Research On The Channel Equalization In Filter Bank Multicarrier Modulation Systems

In the recent years,the research on filter bank multicarrier(FBMC)modulation system has been re-proposed and deeply explored by the scholars because of two features of FBMC: firstly,the system can obtain the expected frequency spectrum constraints by optimizing the sub channel in the frequency domain;secondly,the system can use the channel resources more effectively under the case that no redundant CP is used.However,when the data is transmitted through FBMC system,the time domain and frequency domain aliasing interferences will be made by the characteristics of the filter function.Furthermore,when the signal passes through the channel with random time-varianti,the signal will be disturbed to a certain extent due to multipath transmission features of channel and unpredictability of fading.Therefore,it is very necessary to research the channel equalization problem of FBMC.The channel equalization problem of FBMC is researched in this paper and the contents consist of the following three parts:1.The FBMC system equivalent channel and interference on FBMC system is analyzed based on FBMC system structure and then the interference on FBMC system is researched and quantized to understand that the interference on FBMC system consists of two parts: one part is the inherent interference caused by the imperfect prototype filter,and the other is the fading interference caused by multipath transmission features of channel and unpredictability of fading.2.In order to eliminate the interference,the embedded equalization design scheme based on the fast convolution is proposed.Such embedded equalization method accomplishes the dual purpose of filtering and equalizing by adjusting the weight coefficients of the receiver,namely,the equalization coefficients are embedded in the weight coefficients.Moreover,the low-complexity subcarrier frequency domain equalization is achieved by using the asymptotic property of channel Toeplitz matrix and fast convolution properties.Finally,it verifies the feasibility of the scheme and compares the scheme with several traditional equalization schemes.The results show that such embedded equalization can better improve the system symbol error rate performance in the channel with subcarrier having high-frequency selectivity.Moreover,because the embedded equalization is based on the fast convolution design and the equalization coefficient has high adjustability,it makes the equalization scheme more flexible.3.When considering the embedded equalization design based on fast convolution in the receiving terminal,the system symbol error rate performance is not well.Therefore,the improvement scheme is proposed.Such method achieves the embedded equalization in the system transmitting terminal and then improves the embedded equalization design based on the fast convolution by using the amplitude-phase controlled equalization strategy.The results show that such improvement scheme has better symbol error rate performance by comparing with unimproved embedded equalization scheme under the case that the channel function characteristics are satisfactory.