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Enhanced time resolution in band limitted communication systems

We consider the problem of providing highly accurate time delay or ranging estimates in bandwidth limited 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. To achieve higher resolution, we describe a new approach that synthetically generates a wider bandwidth probing signal using several signals with low bandwidth and processing their returns appropriately at the receiver. The lower bandwidth signals are the outputs of a full tree uniform multirate decomposition of a large bandwidth virtual probing signal. We show that by properly combining the returns corresponding to these low bandwidth signals, we effectively synthesize the return corresponding to the virtual large bandwidth signal. We also show that the approach is robust to oscillator phase mismatches that occur when switching from one sub-signal to another and yields superior performance when compared to traditional techniques.