Method and apparatus for initial ranging for establishing a time reference for a predefined signature signal

摘要

A method and apparatus is provided for performing initial ranging at a receiver for establishing a time reference for a predefined received signature signal (30) for establishing a time reference overcoming round trip time between a receiver and a transmitter. There is performed (316, 3161) matched filtering in at least two matched sub-filters (M1, M2, M3, M4), each sub-filter having a matched filter sub-sequence (43—1, 2; 3, 4; 5,6; 7,8) corresponding to a fragment (39) of the basic sequence (33) of the predefined signature signal (30), 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 (43) correlating with a respective fragment of the received signature signal.

主权项

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.