Transmultiplexer is a major component of multicarrier communication system. Traditionally, it was implemented using SSB modulator and analog filters. But due to the limitation of high level of cross talk and interference in analog device, it has been replaced by DFT based transmultiplexer system. DFT based transmultiplexer comprises digital filter bank and multirate devices to provides better reduction in interference and cross talk. However, it provide relatively large overlapping sidelobes (-13dB). An alternative scheme known as cosine modulation where the design of synthesis and analysis part of the transmultiplexer is the cosine modulated filter bank. This paper reviews various recent patents in filter bank, transmultiplexer and its applications.
Keywords: Transmultiplexer, DFT, CMFB, filter bank, interchannel interference, crosstalk, polyphase
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