Receiver timing recovery for adaptive wavelet packet modulated signals

Wavelet packet modulation (WPM) utilizes an adaptive symbol structuring at the transmitter to circumvent known joint time and frequency interference components. The key to unlocking the orthogonally-multiplexed WPM symbols free of intersymbol interference on wireless channels lies in a maximum likelihood decision directed (MLDD) synchronization scheme that: 1) quickly converges in conjunction with the transmit symbol structure adaptation, 2) accommodates the WPM pulse dilation and overlapping effects, and 3) approaches the Cramer-Rao jitter performance bound. An MLDD receiver symbol timing recovery algorithm with these characteristics is presented here in all-digital form, with fixed-rate sampling at the receiver and optional interpolation.