Wavelet packet transform-based time of arrival estimation method for orthogonal frequency division multiplexing ultra-wideband signal

This study discusses the estimation of time of arrival (TOA) used for ranging and positioning applications in orthogonal frequency division multiplexing ultra-wideband- (OFDM-UWB) based system. The correlation-based method applied for impulse radio-UWB (IR-UWB) is not suitable for OFDM-UWB because OFDM-UWB signal is much longer than IR-UWB in time domain. This study proposes a new method for TOA estimation of OFDM-UWB signal based on wavelet packet transform (WPT). The author´s method estimates TOA of OFDM-UWB signal through the time information of the frequency band of UWB, which is one of the branches of WPT decomposition of the oversampled received baseband signal. It does not need the whole OFDM signal to estimate TOA of UWB signal because every segment of OFDM-UWB signal in time domain contains all information of UWB frequency band; therefore the resolution of TOA is improved. Signal-to-noise ratio can also be improved because WPT decomposes the power of additive white Gaussian noise equally in all wavelet packet branches, and false alarm rate can be controlled. The author´s method is robust in that it can counter narrow band noise and impulse noise effectively. Numerical results show our method is effective for accurate estimation of TOA for OFDM-UWB signal.