Clear channel assessment in wireless communications

• US 8,565,255 B1
• Filed: 01/25/2011
• Issued: 10/22/2013
• Est. Priority Date: 10/09/2002
• Status: Expired due to Term

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Tang, Kevin Hsiao-Cheng, Hsu, Yungping, Hu, Guorong, Feng, Weishi
• Primary Examiner(s): Banks Harold, Marasha D
• Assistant Examiner(s): Sharma, Gautam
• Application Number:
  US13/013,142
• Time in Patent Office: 1,001 Days
• Field of Search: None
• US Class Current: 370/445
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 17/00 Monitoring; Testing of line transmission systems H04B3/46; arrangements for monitoring or testing transmission systems employing electromagnetic waves other than radio waves H04B10/07
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02

Abstract

A transceiver including: an antenna configured to a receive a first signal transmitted on a radio frequency channel; and a peak-to-sidelobe ratio determination unit configured to generate a second signal based on a ratio, in which the ratio is based on a peak value and a sidelobe value, and the peak value and the sidelobe value are determined based on a non-correlated version of the first signal. The transceiver further includes a carrier sense unit configured to, based on the second signal, generate a third signal indicating (i) whether the radio frequency channel is busy or (ii) whether the first signal is valid.

Claims

1. A transceiver comprising:

a receiver configured to a receive a first signal transmitted on a radio frequency channel;

a determination device configured to (i) based on a correlated version of the first signal, determine a peak value and a sidelobe value, (ii) based on the peak value and the sidelobe value, determine a peak-to-sidelobe ratio, and (ii) generate a second signal based on the peak-to-sidelobe ratio;

a distance device configured to determine a consecutive peak-to-peak distance based on the correlated version of the first signal; and

a channel assessment device configured to, based on the second signal and the consecutive peak-to-peak distance, generate a third signal indicating (i) whether the radio frequency channel is busy, or (ii) whether the first signal is valid.

2. The transceiver of claim 1, further comprising:

a signal strength module configured to generate a fourth signal based on the first signal, wherein the fourth signal indicates a gain value; and

a detection device configured to generate a fifth signal based on (i) a first threshold, and (ii) a difference between the fourth signal and a filtered version of the fourth signal,

wherein the channel assessment device is configured to generate the third signal based on the fifth signal.

4. The transceiver of claim 2, wherein the determination device is configured to generate the second signal based on whether the correlated version of the first signal includes at least one of (i) a valid direct sequence spread spectrum signal, or (ii) a valid header modulated using a Barker spreading sequence.

5. The transceiver of claim 2, further comprising a sixth device configured to:

compare demodulated data with predetermined preamble data, wherein the demodulated data is generated based on the first signal; and

in response to the demodulated data matching the predetermined preamble data, generate a sixth signal indicating whether a preamble of the first signal is valid.

6. The transceiver of claim 5, wherein the channel assessment device is configured to generate the third signal based on sixth signal.

7. The transceiver of claim 2, wherein the determination device is configured to generate the second signal to have (i) a first state in response to the peak-to-sidelobe ratio being greater than a second threshold, and (ii) a second state in response to the peak-to-sidelobe ratio being less than a third threshold.

8. The transceiver of claim 7, wherein the third threshold is less than the second threshold.

9. The transceiver of claim 7, wherein the determination device is configured to generate the second signal based on (i) whether the consecutive peak-to-peak distance is less than a predetermined distance, and (ii) whether the peak-to-sidelobe ratio is greater than the second threshold.

10. The transceiver of claim 7, wherein:

the difference between the fourth signal and the filtered version of the fourth signal indicates a change in gain for the first signal; and

the channel assessment device is configured to generate the fifth signal based on (i) whether the change in gain exceeds a fourth threshold, and (ii) whether the change in gain is less than a fifth threshold.

11. The transceiver of claim 10, wherein the channel assessment device comprises:

a timer configured to generate a timeout signal subsequent to a predetermined timer period; and

a control device configured to, based on (i) the timeout signal, and (ii) at least one of the second signal or the fifth signal, generate the third signal indicating the radio frequency channel is idle.

12. The transceiver of claim 2, wherein the detection device comprises:

a gain device configured to determine a change in gain for the first signal; and

a first control device configured to generate the fifth signal based on (i) whether the change in the gain is greater than a second threshold, and (ii) whether the change in the gain is less than a third threshold.

13. The transceiver of claim 12, wherein the channel assessment device is configured to, based on at least one of the second signal or the fifth signal, generate the third signal indicating the radio frequency channel is idle.

14. The transceiver of claim 12, wherein channel assessment device comprises:

a timer configured to generate a timeout signal subsequent to a predetermined time period; and

a second control device configured to, based on (i) the timeout signal, and (ii) at least one of the second signal or the fifth signal, generate the third signal indicating that the radio frequency channel is idle.

15. The transceiver of claim 1, wherein the channel assessment device is configured to:

receive demodulated data corresponding to the first signal;

generate a fourth signal indicating whether a preamble of the first signal is valid based on (i) the demodulated data, and (ii) predetermined preamble data; and

generate the third signal based on the fourth signal.

3. A transceiver comprising:

an antenna configured to a receive a first signal transmitted on a radio frequency channel;

a determination unit configured to generate a second signal based on a peak-to-sidelobe ratio, wherein the peak-to-sidelobe ratio is based on a peak value and a sidelobe value, and wherein the peak value and the sidelobe value are determined based on a correlated version of the first signal;

a channel assessment device configured to, based on the second signal, generate a third signal indicating (i) whether the radio frequency channel is busy, or (ii) whether the first signal is valid;

a signal strength module configured to generate a fourth signal based on the first signal; and

a detection device configured to generate a fifth signal to have (i) a first state when a first threshold is greater than a difference between the fourth signal and a filtered version of the fourth signal, or (ii) a second state when the first threshold is less than the difference between the fourth signal and the filtered version of the fourth signal,

wherein the channel assessment device is configured to generate the third signal based on the fifth signal.

16. A method comprising:

receiving a first signal transmitted on a radio frequency channel;

based on a correlated version of the first signal, determining a peak value and a sidelobe value;

based on the peak value and the sidelobe value, determining a peak-to-sidelobe ratio;

generating a second signal based on the peak-to-sidelobe ratio;

determining a consecutive peak-to-peak distance based on the correlated version of the first signal; and

based on the second signal and the consecutive peak-to-peak distance, generating a third signal indicating (i) whether the radio frequency channel is busy, or (ii) whether the first signal is valid.

17. The method of claim 16, further comprising:

generating a fourth signal based on the first signal, wherein the fourth signal indicates a gain value;

generating a fifth signal based on (i) a first threshold, and (ii) a difference between the fourth signal and a filtered version of the fourth signal; and

generating the third signal based on the fifth signal.

19. The method of claim 17, further comprising generating the second signal based on whether the correlated version of the first signal includes at least one of (i) a valid direct sequence spread spectrum signal, or (ii) a valid header modulated using a Barker spreading sequence.

20. The method of claim 17, further comprising:

generating demodulated data based on the first signal;

comparing the demodulated data to predetermined preamble data; and

in response to the demodulated data matching the predetermined preamble data, generating a sixth signal indicating whether a preamble of the first signal is valid.

18. A method comprising:

receiving a first signal transmitted on a radio frequency channel;

generating a second signal based on a ratio, wherein the ratio is based on a peak value and a sidelobe value, and wherein the peak value and the sidelobe value are determined based on a correlated version of the first signal;

based on the second signal, generating a third signal indicating (i) whether the radio frequency channel is busy, or (ii) whether the first signal is valid;

generating a fourth signal based on the first signal; and

generating a fifth signal to have (i) a first state when a first threshold is greater than a difference between the fourth signal and a filtered version of the fourth signal, and (ii) a second state when the first threshold is less than the difference between the fourth signal and the filtered version of the fourth signal,

wherein the third signal is generated based on the fifth signal.