Adaptive packet detection for detecting packets in a wireless medium

• US 20050190786A1
• Filed: 02/22/2005
• Published: 09/01/2005
• Est. Priority Date: 02/20/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Airgo Networks, Inc. (Qualcomm, Inc.)
• Inventors: Mishra, Partho, Jones, Vincent K. IV, Awater, Geert Arnout, van Nee, D.J. Richard, Wong, Brian Leslie, Liu, Arnold
• Granted Patent: US 7,466,667 B2
• Time in Patent Office: Days
• US Class Current: 370/465
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

In a packet detector, one or more tests are performed for packet detection according to packet detection parameters associated with the one or more tests, a rate of false detection is measured, and the packet detection parameters are adjusted accordingly to reduce the rate of false detection. The rate of false detection might be determined by analyzing post-detection and processing of a signal deemed to be a signal representing a packet for a failure of decoding indicative of a false detection. Such analysis might include testing for a failed SFD search, training symbol anomalies, poor conditioning of metrics used to determine frequency offset and OFDM timing, incorrect data fields, or the like.

Claims

1. A wireless receiver that receives a received signal from a wireless channel and detects from the received signal the presence of a packet, the wireless receiver comprising:

a packet detector having an adaptive packet detection process;

logic to process the received signal when the packet detector indicates presence of a packet;

a false detection determiner for determining whether the signal indeed represents a packet; and

logic for adjusting the adaptive packet detection process when a false detection metric is outside a target range.

2. The wireless receiver of claim 1, wherein the false detection metric is a false detection rate.

3. The wireless receiver of claim 2, wherein the target range is bounded by a maximum false detection rate and the logic for adjusting the adaptive packet detection process includes logic to adjust a detection threshold to be more selective for detection when the maximum false detection rate is approached, equaled and/or exceeded.

4. The wireless receiver of claim 1, wherein the false detection metric is a rate a signal is assumed to be a packet, but is not, compared with the number of times signals are assumed to be packets.

5. The wireless receiver of claim 1, wherein the false detection determiner includes logic to search for an SFD, a failure of such search being determined to be a false detection.

6. The wireless receiver of claim 1, wherein the false detection determiner includes logic to determine if training symbol anomalies exist, the existence of which is determined to be due to a false detection.

7. The wireless receiver of claim 1, wherein poor conditioning of frequency offset metrics is a condition that is deemed to be a false detection.

8. The wireless receiver of claim 1, wherein poor conditioning of OFDM timing is a condition that is deemed to be a false detection.

9. The wireless receiver of claim 1, wherein the presence of incorrect data in a decoded frame is determined to be a false detection.

10. The wireless receiver of claim 1, wherein the false detection determiner includes logic to identify packets from nonparticipating networks wherein identification of a packets from a nonparticipating networks is deemed to be a false detection.

11. The wireless receiver of claim 1, wherein the false detection determiner uses a detection metric on a first portion of a received signal presumed to be a packet preamble and uses the detection metric on a second portion of the received signal and deems the signal to be a false detection if one or both uses indicate a false detection.

12. The wireless receiver of claim 1, wherein the false detection determiner includes logic to detect an incorrect signal or service field and deem such to be a false detection.

13. The wireless receiver of claim 1, wherein the false detection determiner includes logic to detect an anomaly in packet structure and deem such to be a false detection.

14. The wireless receiver of claim 1, wherein the false detection determiner deems an unexpected rise in received signal power as a false detect if the wireless receiver is processing a signal as an assumed packet.

15. The wireless receiver of claim 1, wherein the adaptive packet detection process, based on the logic for adjusting the adaptive packet detection process and/or the false detection metric, adjusts the threshold for a given detection test accordingly.

16. The wireless receiver of claim 15, wherein the adjustment of the threshold is such that when the false detection rate is higher than a maximum desired false detection rate, the threshold for a given test is raised by a first incremental value, when the false detection rate is lower than a minimum desired false detection rate, the threshold for the given test is lowered by the same or a different incremental value, and when the false detection rate is between the minimum desired false detection rate and the maximum desired false detection rate, the threshold value is not modified.

17. The wireless receiver of claim 16, wherein increments and decrements are not made regardless of the false detection rate beyond some range.

18. The wireless receiver of claim 1, wherein the packet detector detects packets according to an energy level of incoming signals.

19. The wireless receiver of claim 1, wherein the packet detector detects packets according to a differential energy level of incoming signals.

20. The wireless receiver of claim 1, wherein the packet detector detects packets according to a cross-correlation test.

21. The wireless receiver of claim 1, wherein the packet detector detects packets according to an auto-correlation test.

22. A wireless MIMO receiver that receives a received MIMO signal from a wireless channel and detects from the received MIMO signal the presence of a packet using a plurality of receive antennas, the wireless MIMO receiver comprising:

a packet detector having an adaptive packet detection process;

logic to process the received signal when the packet detector indicates presence of a packet;

a false detection determiner for determining whether the signal indeed represents a packet; and

logic for adjusting the adaptive packet detection process when a false detection metric is outside a target range.

23. The wireless MIMO receiver of claim 22, wherein the false detection metric is a false detection rate and the target range is a false detection rate below a predetermined threshold.

24. A wireless receiver that receives a received signal from a wireless channel and detects from the received signal the presence of a packet using a plurality of receive antennas, wherein the wireless channel is selected from among a plurality of wireless channels, the wireless receiver comprising:

a channel selector for selecting a channel among a plurality of wireless channels on which to receive signals;

a packet detector having an adaptive packet detection process for each of the plurality of channels;

logic to process the received signal when the packet detector indicates presence of a packet on the selected channel;

a false detection determiner for determining whether the signal indeed represents a packet;

logic for adjusting the adaptive packet detection process when a false detection metric is outside a target range; and

logic for adjusting a signal processing step according to the false detection metric for the selected channel.

25. The wireless receiver of claim 24, wherein the false detection metric is a false detection rate and the target range is a false detection rate below a predetermined threshold.