Improved PAPR Reduction for Wavelet Packet Modulation using Multi-Pass Tree Pruning

A new multi-node pruning algorithm is presented to overcome high peak-to-average power ratio (PAPR) of transmitted signals in multicarrier modulation systems such as orthogonal frequency division multiplexing (OFDM) and wavelet packet modulation (WPM). Specifically, a wavelet packet tree pruning technique with multiple node and multiple pass processing is proposed for the reduction of PAPR in WPM systems. Multiple tree structures are generated for the modulation of a given data input, and the output of tree with the smallest PAPR is selected for transmission. A full wavelet packet tree is dynamically pruned via joining of multiple non-leaf or non-terminal nodes to achieve a minimized PAPR. The information about the pruned tree is sent as side information similar to techniques such as selective mapping (SLM) in OFDM systems. Using a small level of redundancy for side information, the proposed scheme achieves significant reduction in PAPR at the expense of acceptable computational complexity. The complementary cumulative distribution function (CCDF) of the PAPR optimized signal shows about a 5 dB improvement over the original WPM signal.