Radar detector and radar detecting method for WLAN systems according to 802.11 wireless communication standards

• US 20050270218A1
• Filed: 05/19/2005
• Published: 12/08/2005
• Est. Priority Date: 06/01/2004
• Status: Active Grant

• Current Assignee: Newlogic Technologies GmbH (Wipro Limited)
• Original Assignee: Newlogic Technologies GmbH (Wipro Limited)
• Inventors: Chiodini, Alain
• Granted Patent: US 7,280,067 B2
• Time in Patent Office: Days
• US Class Current: 342/20
• CPC Class Codes: G01S 7/021 Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks

Abstract

The present invention relates to a radar detector and a radar detecting method for WLAN systems according to 802.11 wireless communication standards, and particularly concerns the radar detection for 802.1 l h dynamic frequency selection mechanism. The essence of the innovation consists in projecting the received phase vector on the signal subspace orthogonal to the expected radar pulse subspace and taking the norm of the resulting vector. The closer the norm is to zero, the more likely the received signal is to be a radar pulse. The invention is able to detect both, sinusoidal radar signals and chirp-like radar signals.

Claims

1. Apparatus for the use in WLAN systems according to 802.11 wireless communication standards,

characterized in that it comprises a radar signal detector.

2. Apparatus according to claim 1, characterized in that the radar signal detector comprises means for determining the actual phase Φ

of a received signal, means for calculating the angular frequency to and initial phase φ

from the actual phase signal, means for determining the phase ramp corresponding the angular frequency and initial phase and for calculating a difference signal Φ

−

φ

by subtracting the initial phase from the actual phase, means for generating a complex exponential signal, I and Q, from the difference signal, means for calculating a figure of merit from the complex exponential signal, and means for making a decision regarding the nature of the incoming signal by comparing the figure of merit and the angular frequency estimate (o to a couple of predefined threshold values.

3. Method for detecting signals in WLAN systems according to 802.11 wireless communication standards,

characterized in that radar signals are detected.

4. Method according to claim 3, characterized in that sinusoidal radar signals are detected.

5. Method according to claim 3, characterized in that chirp-like pulsed radar signals are detected.

6. Method according to claim 3, characterized in the step of projecting the received phase vector on the signal subspace orthogonal to the expected radar pulse subspace and taking the norm of the resulting vector.

7. Method according to claim 3, characterized in the steps of:

capturing a number of samples of received I- and Q signals, converting the signals to digital I- and Q signals, performing a DC offset compensation on the digital signals, determining the actual phase Φ

of the digital signal, determining the angular frequency ω and

initial phase φ

of the signal, reconstructing the phase ramp corresponding to the angular frequency and initial phase, calculating a difference signal Φ

−

φ

by subtracting the initial phase from the actual phase, generating a complex exponential signal, I and Q, and accumulating its values, calculating a figure of merit by taking the absolute value of the resulting sum, making a decision regarding the nature of the incoming signal by comparing the figure of merit and the angular frequency estimate co to a couple of predefined threshold values.

8. Method according to claim 4, characterized in that chirp-like pulsed radar signals are detected.

9. Method according to claim 4, characterized in the step of projecting the received phase vector on the signal subspace orthogonal to the expected radar pulse subspace and taking the norm of the resulting vector.

10. Method according to claim 5, characterized in the step of projecting the received phase vector on the signal subspace orthogonal to the expected radar pulse subspace and taking the norm of the resulting vector.

11. Method according to claim 4, characterized in the steps of:

capturing a number of samples of received I- and Q signals, converting the signals to digital I- and Q signals, performing a DC offset compensation on the digital signals, determining the actual phase Φ

of the digital signal, determining the angular frequency ω and

initial phase φ

of the signal, reconstructing the phase ramp corresponding to the angular frequency and initial phase, calculating a difference signal Φ

−

φ

by subtracting the initial phase from the actual phase, generating a complex exponential signal, I and Q, and accumulating its values, calculating a figure of merit by taking the absolute value of the resulting sum, making a decision regarding the nature of the incoming signal by comparing the figure of merit and the angular frequency estimate ω

to a couple of predefined threshold values.

12. Method according to claim 5, characterized in the steps of:

capturing a number of samples of received I- and Q signals, converting the signals to digital I- and Q signals, performing a DC offset compensation on the digital signals, determining the actual phase Φ

of the digital signal, determining the angular frequency ω and

initial phase φ

of the signal, reconstructing the phase ramp corresponding to the angular frequency and initial phase, calculating a difference signal Φ

−

φ

by subtracting the initial phase from the actual phase, generating a complex exponential signal, I and Q, and accumulating its values, calculating a figure of merit by taking the absolute value of the resulting sum, making a decision regarding the nature of the incoming signal by comparing the figure of merit and the angular frequency estimate ω

to a couple of predefined threshold values.

13. Method according to claim 6, characterized in the steps of:

capturing a number of samples of received I- and Q signals, converting the signals to digital I- and Q signals, performing a DC offset compensation on the digital signals, determining the actual phase Φ

of the digital signal, determining the angular frequency ω and

initial phase φ

of the signal, reconstructing the phase ramp corresponding to the angular frequency and initial phase, calculating a difference signal Φ

−

φ

by subtracting the initial phase from the actual phase, generating a complex exponential signal, I and Q, and accumulating its values, calculating a figure of merit by taking the absolute value of the resulting sum, making a decision regarding the nature of the incoming signal by comparing the figure of merit and the angular frequency estimate ω

to a couple of predefined thresh values.