Patent ID: 9351266
Filing Date: 2016-05-24
CPC Classification: H04B,H04W

Claim Text:
1. A method for performing initial ranging at a receiver for establishing a time reference for a predefined received signature signal issued by a transmitter, the signature signal comprising a basic sequence, the method comprising the following steps: receiving an incoming signature signal; removing one or more cyclic prefixes in the received signature signal; performing fast Fourier transformation on the received signature signal after the one or more cyclic prefixes are removed; performing, on the output of the fast Fourier transformation, matched filtering in at least two matched sub-filters, each matched sub-filter having a matched filter sub-sequence corresponding to a fragment of the basic sequence of the predefined signature signal, wherein the sub-sequences of the matched sub-filters correspond to the complete basic sequence, wherein the fragments do not overlap one another with respect to the basic sequence, the matched filtering by each respective sub-filter providing peaks in dependence of the respective sub-sequence correlating with a respective fragment of the received signature signal; performing an inverse fast Fourier transformation on the output of the matched filtering; performing alias discarding on the output of the inverse fast Fourier transformation; aligning, after the alias discarding is performed, the outputs of the at least two sub-filters, such that the provided peaks are aligned in time; summing the outputs of the sub-filters; performing peak detection on the summed output, detecting one or more peaks; determining that the detected peak and/or peaks meets a predefined threshold; and as a result of determining that the detected peak and/or peaks meets the predefined threshold; deeming that the incoming signature signal corresponds to the predefined signal and establishing a time reference from position of the detected peak and/or peaks.