Method for searching for a useful signal in a multiplexing band

Patent metadata

Field	Value
Publication number	US-9768897-B2
Application number	US-201314412648-A
Country	US
Kind code	B2
Filing date	Jul 5, 2013
Priority date	Jul 5, 2012
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A method of searching for the presence of a useful signal of predefined spectral width ΔB in a multiplexing band having a spectral width greater than ΔB, includes calculating a frequency signal representative of a power spectral density in the multiplexing band, calculating a non-useful signal by filtering the frequency signal by means of a filter capable of suppressing all or part of signals having a spectral width equal to or smaller than ΔB, calculating a power ratio signal representative of the ratio of the frequency signal to the non-useful signal, and comparing the power ratio signal with a predefined threshold value. The method may be employed using a computer program product, a receiver unit, and/or a station of a digital telecommunications system comprising such a receiver unit.

First claim

The invention claimed is:

1. A method of searching for a useful signal in a general signal received by a receiver station, said useful signal corresponding to a radioelectric signal having a predefined spectral width ΔB transmitted by a terminal in a multiplexing band having a spectral width greater than ΔB, said general signal corresponding to all the radioelectric signals received in the multiplexing band, the method comprising:
generating, from the general signal received by the receiver station, a frequency signal representative of a power spectral density of the general signal sampled at elementary frequencies of the multiplexing band;
generating a non-useful signal, the generating the non-useful signal including filtering of the frequency signal using a filter to suppress from said frequency signal all or part of each signal having a spectral width equal to or smaller than ΔB;
generating a power ratio signal, representative of a ratio, at each elementary frequency, of the frequency signal to the non-useful signal;
comparing the power ratio signal with a defined threshold value; and
identifying an elementary frequency for which said power ratio signal has a local maximum value greater than said threshold value as a central frequency of a useful signal present in the general signal.

2. The method of claim 1 wherein the elementary frequencies are separated by a sampling interval Δb smaller than ΔB, and said method comprises:
generating an averaged signal by averaging the frequency signal with a sliding window on the elementary frequencies, the sliding window having a width substantially equal to ΔB;
filtering of the averaged signal to generate the non-useful signal; and
the generating the power ratio signal includes determining, at each elementary frequency, a ratio of the averaged signal to the non-useful signal.

3. The method of claim 2 wherein the sliding window is a rectangular window.

4. The method of claim 1 , comprising selecting the defined threshold value to correspond to a value of a power ratio signal above which a probability to decode a useful signal with errors is lower than 5%.

5. The method of claim 1 wherein the elementary frequencies are separated by a sampling interval Δb smaller than ΔB/4.

6. A non-transitory computer-readable memory medium whose contents contain instructions which when executed by at least one processor of a receiver station cause the at least one processor of the receiver station to perform a method, the method comprising:
generating, from a general signal received by the receiver station, a frequency signal representative of a power spectral density of the general signal sampled at elementary frequencies of a multiplexing band, the multiplexing band having a bandwidth greater than a spectral width ΔB of signals transmitted in the multiplexing band;
generating a non-useful signal, the generating the non-useful signal including filtering of the frequency signal to suppress from said frequency signal all or part of each signal having a spectral width equal to or smaller than ΔB;
generating a power ratio signal, representative of a ratio, at each elementary frequency, of the frequency signal to the non-useful signal;
comparing the power ratio signal with a defined threshold value; and
identifying an elementary frequency for which said power ratio signal has a local maximum value greater than said threshold value as a central frequency of a useful signal present in the general signal.

7. A receiver, comprising:
one or more memories;
one or more signal processors, wherein the one or more signal processors of the receiver, in operation:
generate, from a general signal received by the receiver, a frequency signal representative of a power spectral density of a general signal sampled at elementary frequencies of a multiplexing band, the multiplexing band having a bandwidth greater than a spectral width ΔB of signals transmitted in the multiplexing band;
generate a non-useful signal, the generating of the non-useful signal including filtering of the frequency signal to suppress from said frequency signal all or part of each signal having a spectral width equal to or smaller than ΔB;
generate a power ratio signal, representative of a ratio, at each elementary frequency, of the frequency signal to the non-useful signal;
compare the power ratio signal with a defined threshold value; and
identify an elementary frequency for which said power ratio signal has a local maximum value greater than said threshold value as a central frequency of a useful signal present in the general signal.

8. A station of a digital telecommunications system, comprising:
an antenna system; and
signal processing circuitry of the station coupled to the antenna system, wherein the signal processing circuitry of the station, in operation:
generates, from a general signal received by the station, a frequency signal representative of a power spectral density of the general signal sampled at elementary frequencies of a multiplexing band, the multiplexing band having a bandwidth greater than a spectral width ΔB of signals transmitted in the multiplexing band;
generates a non-useful signal, the generating of the non-useful signal including filtering of the frequency signal to suppress from said frequency signal all or part of each signal having a spectral width equal to or smaller than ΔB;
generates a power ratio signal, representative of a ratio, at each elementary frequency, of the frequency signal to the non-useful signal;
compares the power ratio signal with a defined threshold value; and
identifies an elementary frequency for which said power ratio signal has a local maximum value greater than said threshold value as a central frequency of a useful signal present in the general signal.

Assignees

• Sigfox

Inventors

• Artigue Cédric

Classifications

• H04J1/12

  Arrangements for reducing cross-talk between channels {(in line transmission systems H04B3/32; in cables or lines H04B3/26 - H04B3/30)} · CPC title

• H04B17/336 Primary

  Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] · CPC title

• H04W88/02

  Terminal devices · CPC title

• H04B7/2621

  using frequency division multiple access [FDMA] (H04B7/2615 takes precedence) · CPC title

• H04J1/02 Primary

  Details · CPC title