Design of branch-hopped wavelet packet division multiplexing schemes

Wavelet packet division multiplexing (WPDM) is a high-capacity, flexible and robust orthogonal multiplexing technique in which wavelet packet basis functions are chosen as the coding waveforms. Branch-hopped WPDM (BH-WPDM) is an extension of WPDM which incorporates hopping strategies analogous to those of frequency-hopped schemes. It is based on an efficient modular switched transmultiplexer structure which provides the advantages of hopping whilst retaining many of the desirable features of WPDM. In previous work we have identified classes of slow and fast BH-WPDM schemes and have evaluated a number of switching strategies. In the present paper we provide a method for re-designing the filters within the transmultiplexer modules to provide further robustness to narrow frequency-selective fading channels under a given switching strategy.