Development of Blind Signal Separation Technologies and their Application to Next-Generation Mobile Communications

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Blind Signal Processing (BSP) is now one of emerging areas in signal processing with theoretical foundations and many potential applications. In fact, BSP has become a very important topic of research and developments in many areas, in particular, in mobile communications, acoustics and speech processing, and biomedical engineering. The BSP techniques principally do not use any training data and do not assume a priori knowledge about parameters of instantaneous mixing or convolutive mixing systems. In this research, we deal with the blind signal (or source) separation (BSS) problem for convolutive mixtures with taking the application of BSS techniques to next-generation mobile communications in consideration. We proposed several procedures for BSS and investigate the effectiveness of the proposed procedures through digital simulation experiments.Roughly speaking, the proposed procedures are classified into the following three categories :(1)Adaptive super-exponential procedures : On-li … More ne BSS techniques in slowly time-varying environments.(2)Robust super-exponential procedures : Off-line BSS techniques in noisy environments.(3)Eigenvector procedures with reference signals : Off-line BSS techniques with a very high success rate of BSS.As for (1) and (2) above, although we proposed the original (multi-channel) super-exponential methods in 2000,we proposed an adaptive version of the original ones, which can be utilized in slowly time-varying environments. As for (3),in connection to the super-exponential methods, we extended the eigenvector method with reference signals for single-input-single-output (SISO) systems proposed by B.Jelonnek and K.D.Kammeyer in 1994 to the case for multi-input-multi-output (MIMO) systems. Our research group will investigate the eigenvector approach with reference signals further in future.Through the developments of the above three types of BSS procedures, we will establish a theoretical foundation for BSS in next-generation mobile communications. We believe that the theoretical foundation gives us a principle for designing advanced source retrievers (or equalizers) in next-generation mobile communications. Less