The design of Low Complexity Cosine Modulated Filter Bank Transmultiplexer (LC CMFB TMUX) is given in this paper. CMFB TMUX is designed and the coefficients of the transmitting and receiving low-pass filters are synthesized in Canonic Signed Digit (CSD) format using Genetic Algorithm (GA). Chromosomes are encoded as ternary digit strings. Modified crossover and mutation techniques are used to preserve the canonical property of the Signed Power of Two (SPT) representations. Simulation results show that LC CMFB TMUX designed using the proposed algorithm has better Signal to Interference Ratio (SIR) and frequency responses than those of LC CMFB TMUX obtained by rounding the coefficients of low-pass filters.

In a communication system, if the channel bandwidth is larger than the coherent bandwidth of the communication channel, frequency selective fading occurs and Intersymbol Interference (ISI) is very large (Goldsmith, 2005). Multicarrier Modulation (MCM) is an efficient method for reducing the ISI. Its basic idea is to divide the channel spectrum into parallel, narrowband subchannels having bandwidth less than the coherent bandwidth of the channel (Bingham, 1990).

Orthogonal Frequency Division Multiplexing (OFDM) is known as an efficient way of implementing MCM. Computationally, efficient fast fourier transform algorithms can be used for its implementation; but the frequency responses of the transmitting and receiving filters in OFDM are poor and the communication system is prone to different interference signals. Filter bank transmultiplexer can also be used for the implementation of MCM (Vaidyanathan, 1993). It can use filters of larger length than the rectangular filters of OFDM and hence, the resulting filters will have much better frequency responses. Better stopband attenuation and subchannelization result in both the lower levels of Interchannel Interference (ICI) and greater robustness to narrow band interference.

Telecommunications Journal, Finite Impulse Response Filter, Frequency Response, Genetic Algorithm, Signed Power of Two Representations, Canonic Signed Digit, CSD, Signal to Interference Ratio, SIR, Finite Impulse Response, FIR, Linear Time Invariant, LTI, Intersymbol Interference, ISI, Multicarrier Modulation, MCM, Orthogonal Frequency Division Multiplexing , OFDM.