Enhanced localization in wireless personal area networks

We consider the problem of providing highly accurate time delay or ranging estimates using multiple receptions of ranging signals in multi-band communication systems. Prior research has shown that the variance of the time delay estimation error in white Gaussian noise is inversely proportional to the time duration of a power limited probe signal and the square of its mean square bandwidth. Applying this fact to the multi-band systems, we show that traditional ranging techniques decrease the estimation variance by a factor of M by properly combining M probing signals from M different sub-bands. In contrast, we describe a novel ranging approach that reduces the variance of the time delay estimate by M-3 in white Gaussian noise. The new technique synthesizes the return corresponding to a virtual large bandwidth signal by appropriately merging the returns of M low bandwidth ranging signals from M different sub-bands. These low bandwidth signals can be generated by decomposing a high time resolution large. bandwidth signal using a full-tree wavelet decomposition filter bank The corresponding perfect reconstruction synthesis filter bank is used at the receiver to combine the received signals. Alternatively, we show that the procedure can rely on the preamble sequences used in the proposed IEEE 802.15.3a wireless personal area network standard and other communication systems. We study the effect of fading and multipath channels on the performance of the proposed scheme. Simulation results are provided to compare the performance of this scheme with traditional ones.