Listen interval (LI) selection for WLAN client

• US 9,210,656 B2
• Filed: 07/31/2012
• Issued: 12/08/2015
• Est. Priority Date: 07/31/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Mannemala, Chaitanya, Frederiks, Guido Robert, Ranganath, Ashok, Pujari, Sunit
• Primary Examiner(s): Lai, Andrew
• Assistant Examiner(s): Shih, Albert
• Application Number:
  US13/563,157
• Publication Number:
  US 20140036746A1
• Time in Patent Office: 1,225 Days
• Field of Search: 370/311
• US Class Current: 1/1
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 76/28 Discontinuous transmission [DTX]; Discontinuous reception [DRX]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

The listen interval of a WLAN client is selected to have one of a plurality of values, including a start listen interval (SLI) and one or more longer listen intervals (e.g., transient listen interval (TLI), maximum listen interval (MLI)). The listen interval is set to SLI in response to (1) detecting that an applications processor of the WLAN client is in an awake state, (2) detecting transmit/receive activity on the wireless link, and (3) failing to detect an expected beacon signal on the wireless link. If the listen interval is set to MLI (or TLI) and the WLAN client fails to detect an expected beacon signal (beacon miss), the listen interval is temporarily set to SLI. If the WLAN client then detects an expected beacon signal before detecting a predetermined number of consecutive beacon misses, the listen interval is immediately returned to the original listen interval MLI (or TLI).

Claims

1. A method comprising:

periodically waking up a wireless local area network (WLAN) client at a first interval to detect a beacon signal, wherein beacon signals are periodically transmitted on a wireless link at a beacon interval, wherein the first interval is equal to a plurality of beacon intervals;

determining that the WLAN client has not detected a beacon signal on the wireless link while periodically waking up at the first interval, and in response, waking up the WLAN client at a next beacon interval; and

determining that the WLAN client has detected a beacon signal on the wireless link while waking up at the next beacon interval, and in response, periodically waking up the WLAN client at the first interval to detect beacon signals transmitted on the wireless link.

2. A method comprising:

periodically waking up a wireless local area network (WLAN) client at a first interval to detect a beacon signal, wherein beacon signals are periodically transmitted on a wireless link at a beacon interval, wherein the first interval is equal to a plurality of beacon intervals;

determining that the WLAN client fails to detect a beacon signal on the wireless link while periodically waking up at the first interval, and in response, waking up the WLAN client at a next beacon interval;

incrementing a beacon miss counter for each beacon interval in which the WLAN client fails to detect a beacon signal, wherein the beacon miss counter is incremented until the WLAN client detects a beacon signal;

determining that the WLAN client detects a beacon signal, and in response, determining if the beacon miss counter exceeds a predetermined threshold;

upon determining that the beacon miss counter does not exceed a threshold, waking up the WLAN client at the first interval; and

upon determining that the beacon miss counter exceeds a threshold, waking up the WLAN client at the beacon interval.

3. A method comprising:

periodically waking up a wireless local area network (WLAN) client at a first interval to detect a beacon signal, wherein beacon signals are periodically transmitted on a wireless link at a beacon interval, wherein the first interval is equal to a plurality of beacon intervals;

determining whether or not the WLAN client detects a beacon signal on the wireless link upon waking up;

identifying a beacon miss if the WLAN client does not detect a beacon signal on the wireless link upon waking up, and in response to identifying a beacon miss while the WLAN client is periodically waking up at the first interval, waking up at a next beacon interval and reducing the first interval at which the WLAN client periodically wakes up to the beacon interval; and

determining that the WLAN client detects a beacon signal on the wireless link upon waking up at the beacon interval, and in response, returning the interval at which the WLAN client periodically wakes up to the first interval.

4. The method of claim 3, further comprising:

identifying a plurality of consecutive beacon misses with the WLAN client; and

continuing to periodically wake up the WLAN client at the beacon interval in response to identifying a first number of consecutive beacon misses with the WLAN client.

5. A method comprising:

selecting an interval for waking up a wireless local area network (WLAN) client to detect a beacon signal, wherein beacon signals are periodically transmitted on a wireless link at a beacon interval, wherein the interval can be selected to have a first period equal to the beacon interval or a second period, wherein the second period equal to a first plurality of beacon intervals;

waking up at a next beacon interval and selecting the interval to have the first period in response to detecting that an applications processor of the WLAN client is in an awake state;

waking up at a next beacon interval and selecting the interval to have the first period in response to detecting activity on the wireless link; and

waking up at a next beacon interval and selecting the interval to have the first period in response to failing to detect an expected beacon signal on the wireless link.

6. The method of claim 5, further comprising increasing the interval from the first period to the second period in response to detecting an absence of activity on the wireless link for a first number N of consecutive occurrences of the first period.

7. The method of claim 6, wherein the interval can be selected to have a third period, greater than the second period, the method further comprising increasing the interval from the second period to the third period in response to detecting the absence of activity on the wireless link for a second number M of consecutive occurrences of the second period.

8. The method of claim 7, wherein interval can be selected to have the third period, greater than the second period, wherein the third period is equal to a second plurality of the beacon intervals.

9. A wireless local area network (WLAN) client comprising:

a link activity detection circuit that detects an absence of transmit and receive activity on a wireless link used by the WLAN client;

a beacon detection circuit that determines whether an expected beacon signal is detected on the wireless link;

an applications processor that runs one or more applications on the WLAN client; and

a listen interval control circuit coupled to the link activity detection circuit, the beacon detection circuit and the applications processor, wherein the listen interval control circuit selects a listen interval for waking up the WLAN client to detect beacon signals transmitted on the wireless link and a control processor wakes up the WLAN client at a next beacon interval and based on input received from at least one of the link activity detection circuit or the beacon detection circuit; and

a control processor coupled to the listen interval control circuit, wherein the control circuit wakes up the WLAN client at a next beacon interval based on input received from at least one of the link activity detection circuit or the beacon detection circuit.

10. The WLAN client of claim 9, wherein the control processor wakes up the WLAN client in response to a listen interval value provided by the listen interval control circuit.

11. The WLAN client of claim 9, wherein the listen interval control circuit includes means for selecting the listen interval to have a first period or a second period, greater than the first period, in response to information received from the link activity detection circuit, the beacon detection circuit and the applications processor.

12. The WLAN client of claim 9, wherein the listen interval control circuit is coupled to the beacon detection circuit by a control line that carries a control signal that indicates whether or not an expected beacon signal is detected on the wireless link.

13. The WLAN client of claim 9, wherein the listen interval control circuit is coupled to the link activity detection circuit by a control line that carries a control signal that indicates whether or not the link activity detection circuit detects activity on the wireless link.

14. The WLAN client of claim 9, wherein the listen interval control circuit is coupled to the applications processor by a control line that carries a control signal that indicates whether or not the applications processor is in an awake state.

15. A non-transitory computer readable medium storing computer program product for setting a listening interval (LI) for a wireless local area network (WLAN) client, the program product, when executed by a computer, causing the computer to perform the functions of:

selecting an interval for waking up a wireless local area network (WLAN) client to detect a beacon signal, wherein beacon signals are periodically transmitted on a wireless link at a beacon interval, wherein the interval can be selected to have a first period equal to the beacon interval or a second period equal to a plurality of beacon intervals;

waking up at a next beacon interval and selecting the interval to have the first period in response to detecting that an applications processor of the WLAN client is in an awake state;

waking up at a next beacon interval and selecting the interval to have the first period in response to detecting transmit/receive activity on the wireless link; and

waking up at a next beacon interval and selecting the interval to have the first period in response to failing to detect an expected beacon signal on the wireless link.

16. A non-transitory computer readable medium storing computer program product for setting a listening interval (LI) for a wireless local area network (WLAN) client, the program product, when executed by a computer, causing the computer to perform the functions of:

periodically waking up a wireless local area network (WLAN) client at a first interval to detect a beacon signal, wherein beacon signals are periodically transmitted on a wireless link at a beacon interval, wherein the first interval is equal to a plurality of beacon intervals;

determining whether or not the WLAN client detects a beacon signal on the wireless link upon waking up;

identifying a beacon miss if the WLAN client does not detect a beacon signal on the wireless link upon waking up, and in response to identifying a beacon miss while the WLAN client is periodically waking up at the first interval, waking up at a next beacon interval and reducing the first interval at which the WLAN client periodically wakes up to the beacon interval; and

determining that the WLAN client detects a beacon signal on the wireless link upon waking up at the beacon interval, and in response, returning the interval at which the WLAN client periodically wakes up to the first interval.