Detecting and eliminating spurious energy in communications systems via multi-channel processing

• US 20060030267A1
• Filed: 03/29/2005
• Published: 02/09/2006
• Est. Priority Date: 03/29/2004
• Status: Active Grant

• Current Assignee: EDGEWATER WIRELESS SYSTEMS INC.
• Original Assignee: Engim, Inc.
• Inventors: Bhardwaj, Manish, Shih, Garret
• Granted Patent: US 7,835,701 B2
• Time in Patent Office: Days
• US Class Current: 455/63.100
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 1/109 by improving strong signal performance of the receiver when strong unwanted signals are present at the receiver input

Abstract

The present invention allows multi-channel communications equipment to detect and eliminate a false interpretation of interference as a valid signal. The solution is based on the observation that the simultaneous arrival of energy on two independent channels is an impossible event. So, when such an event happens, it is a reliable signature of confusing out-of-band energy for a valid signal.

Claims

1. A method of determining spurious channel activity comprising:

determining when plural channels become active near simultaneously;

when plural channels become active near simultaneously comparing the signal strengths of the plural channels to identify a spurious channel responsive to the compared signal strengths.

2. The method of claim 1, wherein determining when plural channels become active near simultaneously comprises:

receiving for each of the plural channels a respective channel activity signal, the channel activity signal being asserted responsive to activity on the respective one of the plural channels;

determining near simultaneity responsive to one of the channel activity signals being asserted within a predetermined time window of another of the channel activity signals.

3. The method of claim 2, wherein the predetermined time window is user selectable.

4. The method of claim 2, wherein the predetermined time window is between about 2 microseconds and about 4 microseconds.

5. The method of claim 1, wherein the channels are wireless communication channels.

6. The method of claim 1, wherein the plural channels are compliant with IEEE 802.11 standards.

7. The method of claim 1, wherein a spurious channel is identified responsive to the compared signal strengths differing by more than a predetermined amplitude.

8. The method claim 7, wherein the predetermined amplitude is user selectable.

9. A spurious channel activity detector comprising:

at least two modems, each modem assigned to a respective channel and configured to assert a channel-activity signal responsive to its respective channel becoming active; and

a spurious signal detector coupled to the at least two modems adapted to identify near simultaneity responsive to more than one channel activity signals being asserted within a predetermined time window.

10. The detector of claim 9, wherein the predetermined time window is user selectable.

11. The detector of claim 9, wherein the predetermined time window is between about 2 microseconds and about 4 microseconds.

12. The detector of claim 9, wherein the channels are wireless communication channels.

13. The detector of claim 9, wherein the plural channels are compliant with IEEE 802.11 standards.

14. The detector of claim 9, further comprising a signal-strength comparator coupled to the at least two modems, each modem providing a signal indicative of a signal strength of its respective channel, the signal-strength comparator adapted to identify a spurious channel responsive to the compared signal strengths differing by more than a predetermined amplitude.

15. The method claim 14, wherein the predetermined amplitude is user selectable.

16. A spurious channel activity detector comprising:

means for determining when plural channels become active near simultaneously;

when plural channels become active near simultaneously;

means for comparing the signal strengths of the plural channels; and

means for identifying a spurious channel responsive to the compared signal strengths.