APPARATUS TO DETECT INTERFERENCE IN WIRELESS SIGNALS

• US 20100105347A1
• Filed: 10/24/2008
• Published: 04/29/2010
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Anritsu Co (Anritsu Corporation)
• Original Assignee: Anritsu Co (Anritsu Corporation)
• Inventors: Huang, Kee-dyi, Lundquist, Randy L., Venugopal, Vaidyanathan, Thiagarajan, Bhaskar
• Granted Patent: US 9,571,142 B2
• Time in Patent Office: Days
• US Class Current: 455/226.400
• CPC Class Codes: H04B 1/1036 with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters H04B1/123 takes precedence; filter circuits H03H
• CPC Class Codes: H04J 11/0023 Interference mitigation or co-ordination direct sequence spread spectrum [DSSS] systems H04B1/7097; frequency hopping H04B1/713; allocation criteria for ingress interference avoidance H04L5/0062; frequency allocation criteria for requirements on out-of-channel emissions H04L5/0066; arrangements for removing intersymbol interference or baseband equalisers H04L25/03006; peak power aspects in multicarrier modulation H04L27/2614; power management H04W52/00; traffic scheduling H04W72/54, H04W72/541
• CPC Class Codes: H04L 27/0006 Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio for spectrum sharing between different networks H04W16/14

Abstract

An apparatus to detect interference in wireless signals, comprising an antenna for receiving a wireless signal; and wherein the apparatus is operable to identify a dominant waveform in the received signal; subtract the dominant waveform from the received signal to create a modified received signal; and repeat the above steps, recursively substituting the modified received signal for the received signal, until all adjusted reference waveforms have been subtracted.

Claims

1. An apparatus for detecting secondary signals in wireless signals comprising:

an antenna operable to receive a wireless signal, wherein the wireless signal includes at least a first component and a second component from different signal sources; and

a computer readable storage medium and processor operating thereon, wherein the computer readable storage medium includes instructions that when executed cause the apparatus to

identify the first component of the wireless signal, and

remove the first component from the wireless signal, leaving the second component of the wireless signal.

2. The apparatus of claim 1 wherein the wireless signal is a wireless communication signal.

3. The apparatus of claim 1 wherein the first component of the wireless signal includes at least one predefined component in accordance with a signal type of interest and wherein the second component of the wireless signal includes a portion of the signal not included in the first component.

4. The apparatus of claim 1 wherein the computer readable storage medium includes additional instructions that when executed cause the apparatus to:

analyze the spectrum of the second component of the wireless signal; and

display a spectrum of the second component of the wireless signal on a display.

5. The apparatus of claim 1 wherein the computer readable storage medium includes additional instructions that when executed cause the apparatus to:

analyze the first component of the wireless signal;

measure characteristics of the first component of the wireless signal; and

display the first component of the wireless signal along with its characteristics on a display.

6. An apparatus to detect interference in wireless signals, the apparatus comprising:

an antenna operable to receive a wireless signal;

an input means operable to receive input from a user; and

a computer readable storage medium and processor operating thereon, wherein the computer readable storage medium includes instructions that when executed in response to user input cause the apparatus to

(a) identify a dominant waveform in the received signal;

(b) remove the dominant waveform from the received signal to create a modified received signal; and

(c) repeating steps a-b, recursively substituting the modified received signal from step b for the received signal, until all dominant waveforms have been removed.

7. The apparatus of claim 6 wherein identifying a dominant waveform comprises:

cross-correlating the received signal with a set of ideal reference waveforms; and

identifying a waveform with a highest correlation value as the dominant waveform.

8. The apparatus of claim 6 wherein removing the dominant waveform comprises:

measuring frequency, phase, and time offset and power for the dominant waveform;

adjusting an ideal reference waveform corresponding to the dominant waveform according to the measured frequency, phase, and time offset and power to create an adjusted waveform; and

subtracting the adjusted waveform from the received signal.

9. The apparatus of claim 8 wherein the set of ideal reference waveforms is constructed according to the steps of:

acquiring a standard-defined set of reference sequences;

modulating the reference sequences according to a signal type associated with the reference sequences;

interpolating and over-sampling the reference waveforms; and

storing the reference waveforms as a set of ideal reference waveforms.

10. The apparatus of claim 6 wherein the input means is further operable to receive input from the user selecting between spectral analysis and base station analysis and wherein in response to user input the apparatus performs the selected analysis.

11. An apparatus to detect interference in wireless signals comprising:

an antenna operable to receive a wireless signal; and

a computer readable storage medium and processor operating thereon, wherein the computer readable storage medium includes instructions that when executed cause the apparatus to

(a) sample the received signal;

(b) store the received signal;

(c) cross-correlate the received signal with a set of ideal reference waveforms;

(d) identify a dominant waveform in the received signal;

(e) measure frequency, phase, and time offset and power for the dominant waveform;

(f) adjust an ideal reference waveform corresponding to the dominant waveform according to the measured frequency, phase, and time offset and power to create an adjusted reference waveform;

(g) subtract the adjusted reference waveform from the received signal to create a modified received signal; and

(h) repeat steps c-g, recursively substituting the modified received signal from step g for the received signal, until all dominant waveforms have been subtracted.

12. The apparatus of claim 11 wherein the set of ideal reference waveforms is created by the steps of:

acquiring a standard-defined set of reference sequences in discrete time format;

modulating the reference sequences according to a signal type to which the reference waveforms correspond;

storing the reference waveforms.

13. The apparatus of claim 12 wherein the reference sequences are interpolated and oversampled to an Nx sampling rate, wherein the Nx sampling rate is greater than a rate associated with the standard-defined set of reference sequences.

14. The apparatus of claim 13 wherein the cross-correlation is performed at the Nx sampling rate.

15. The apparatus of claim 14 wherein modulating includes pulse shaping or equalization for reference waveforms as specified in the respective signal standards, e.g. 1×

EV-DO, TD-SCDMA or EDGE/GSM.

16. The apparatus of claim 14 wherein modulating includes performing a discrete inverse Fourier transform for reference waveforms corresponding to OFDM signals.

17. The apparatus of claim 11 further comprising:

a display;

wherein the apparatus is operable to perform a Fourier transform on the modified received signal; and

display the transformed modified received signal on the display.

18. The apparatus of claim 11 further comprising:

wherein the apparatus is operable to display each dominant waveform along with its measured power and time offset on a display coupled thereto.

19. The apparatus of claim 11 wherein identifying a dominant waveform includes determining which reference waveform generates a highest correlation value in the cross-correlation.

20. The apparatus of claim 11 wherein the received signal is filtered and pulse-shaped.

21. The apparatus of claim 11 wherein the received signal is a cellular or wireless area network signal.