Power management of a radio data transceiver

• US 8,576,762 B2
• Filed: 09/08/2010
• Issued: 11/05/2013
• Est. Priority Date: 09/08/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Thomas, Tito, Vandwalle, Pierre, Dominguez, Charles Francis, Haque, Tashbeeb
• Primary Examiner(s): Shah, Chirag
• Assistant Examiner(s): Van, Jenkey
• Application Number:
  US12/877,944
• Publication Number:
  US 20110058510A1
• Time in Patent Office: 1,154 Days
• Field of Search: None
• US Class Current: 370/311
• CPC Class Codes: H04W 52/02 Power saving arrangements in wired systems H04L12/12; signaling of mobile application services, e.g. low battery notifications H04W4/20
• CPC Class Codes: H04W 52/0209 in terminal devices terminal devices per se H04W88/02
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 76/38 triggered by timers
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Methods and apparatuses for operating a wireless mobile station configured to communicate with a wireless access point are described. A sleep state may be maintained in which a radio frequency (RF) radio in the wireless mobile station is in a low power state. The wireless station may use a plurality of sleep states, each with a different sleep timer period based upon recent network activity. In one embodiment, a device may have two sleep states with two sleep timers, and in another embodiment a device may have three sleep timers for three sleep states. The first sleep time may be started for a first sleep state and to determine when to awake the device to determine whether there is any network activity. The device then determines whether a first period of network inactivity has occurred and, if so, it starts a second sleep timer for a second sleep state in response to determining that the first period of network inactivity has occurred. The method can further include determining whether a second period of network inactivity has occurred and, in response to determining that a second period of network inactivity has occurred, the device starts a third sleep timer for a third sleep state.

Claims

1. A method for operating a wireless mobile station which is configured to communicate with a wireless access point, the method comprising:

determining, at the wireless mobile station, an interval of the time between successive target beacon transmission times (TBTT);

determining, at the wireless mobile station, a setting representing an interval of time between successive Delivery Traffic Indication Messages (DTIM);

adjusting a first period of a first sleep timer in response to determining the interval of time between successive TBTTs and in response to determining the interval of time between successive DTIMs;

determining a number of times the first sleep timer with the first period has expired; and

adjusting a second period of a second sleep timer in response to determining the number of times the first sleep timer has expired, wherein the second sleep timer with the second period is started without restarting the first sleep timer with the first period if the number of times indicates the first sleep timer has been counting for more than a certain period of time, and wherein the second period of the second timer is longer than the first period of the first timer.

2. The method as in claim 1 wherein the adjusting scales a default value for the period of the first sleep timer based upon the interval of time between successive TBTTs and the interval of time between successive DTIMs.

3. The method as in claim 1 wherein the first period of the first sleep timer determines when the first sleep timer expires and wherein a radio of the wireless mobile station is in a lower power state when the first sleep timer is counting prior to the first sleep timer expiring, wherein each DTIM includes a multiple of TBTTs and wherein the first period of the first sleep timer is adjusted to account for the multiple of TBTT in each DTIM.

4. The method as in claim 3 wherein the wireless mobile station performs the adjusting adaptively in response to a change of the wireless access point.

5. The method as in claim 4 wherein the change of the wireless access point comprises a change from a first wireless access point, having a TBTT interval of “

A”

milliseconds and having a DTIM of nTBTTs, to a second wireless access point, having a TBTT interval of “

B”

milliseconds and having a DTIM of mTBTTs, and wherein the first wireless access point is no longer in communication with the wireless mobile station and the second wireless access point is in communication with the wireless mobile station.

6. The method as in claim 4 wherein the method further comprises:

starting the first sleep timer in response to an expiration of a first awake timer;

starting the first sleep timer in response to an expiration of a second awake timer.

7. A machine readable non-transient storage medium storing executable instructions which when executed by a data processing system cause the data processing system to perform a method as in claim 1.

8. A method for operating a wireless mobile station which is configured to communicate with a wireless access point, the method comprising:

determining, at the wireless mobile station, an interval of the time between successive target beacon transmission times (TBTT);

determining, at the wireless mobile station, a setting representing an interval of time between successive Delivery Traffic Indication Messages (DTIM);

adjusting a period of a sleep timer in response to determining the interval of time between successive TBTTs and in response to determining the interval of time between successive DTIMs;

starting the sleep timer in response to an expiration of a first awake timer; and

starting the sleep timer in response to an expiration of a second awake timer,

wherein the period of the sleep timer determines when the sleep timer expires and wherein a radio of the wireless mobile station is in a lower power state when the sleep timer is counting prior to the sleep timer expiring, wherein each DTIM includes a multiple of TBTTs and wherein the period of the sleep timer is adjusted to account for the multiple of TBTTs in each DTIM,

wherein the wireless mobile station performs the adjusting adaptively in response to a change of the wireless access point and

wherein the second awake timer is started in response to the receipt of data at the wireless mobile station and wherein the first awake timer has a longer duration than the second awake timer.

9. The method as in claim 8 wherein the radio is in a higher power state and is configured to receive data while either of the first or the second awake timers are counting.

10. The method as in claim 9 wherein the sleep timer has one of a plurality of time periods based upon recent network activity.

11. A method for operating a wireless mobile station which is configured to communicate with a wireless access point, the method comprising:

starting a first sleep timer for a first sleep state, the first sleep timer configured to count for a first sleep period of time, wherein a radio frequency (RF) radio of the wireless mobile station is in a low power state when the first sleep timer is counting for the first sleep period of time;

changing the RF radio from the low power state to a high power state in response to the first sleep timer expiring to check if there is network activity, wherein the first sleep timer in the first sleep state is restarted if there is no network activity and wherein the RF radio, in the high power state, is configured to listen for a beacon from the wireless access point at a target beacon transmission time (TBTT) for the network activity;

determining a first period of network inactivity for at least a specific time period has occurred, wherein the first sleep timer expired more than once during the first period of network inactivity;

starting a second sleep timer for a second sleep state in response to determining that the first period of network inactivity has occurred, the second sleep timer being configured to count for a second sleep period of time, the second sleep period of time being longer than the first sleep period of time for the first sleep timer.

12. The method as in claim 11 wherein the second sleep period of time exceeds the first sleep period of time which is an interval of time between successive TBTTs.

13. The method as in claim 12 wherein the second sleep period of time is an interval of time between successive DTIMs (Delivery Traffic Indication Messages).

14. The method as in claim 13 wherein the wireless mobile station communicates with the wireless access point using a protocol defined in an IEEE 802.11 specification.

15. The method as in claim 14, the method further comprising:

determining a second period of network inactivity has occurred, the second period of network inactivity exceeding in time duration the first period of network inactivity;

starting a third sleep timer for a third sleep state in response to determining that the second period of network inactivity has occurred;

wherein only one of the first, second and third sleep timers controls the RF radio'"'"'s sleeping at any one time.

16. The method as in claim 15, the method further comprising:

exiting one of the first, second and third sleep states in response to receiving a beacon signal that indicates data is pending for the wireless mobile station.

17. A mobile station for use with a wireless access point, the mobile station comprising:

a radio frequency (RF) radio;

an antenna coupled to the RF radio;

a processor coupled to the RF radio, the processor configured to control power states of the RF radio, the power states includes at least a first sleep state associated with a first sleep timer and a listening timer, and wherein the processor is configured to

start the first sleep timer to enter the first sleep state, wherein the power state of the RF radio is in a low power state when the first sleep timer is counting,

in response to the first sleep timer expiring, start the listening timer to

determine if a condition is satisfied for the RF radio to exit from the first sleep state, wherein the RF radio is in a high power state to listen for network activity when the listening timer is counting, wherein the condition includes a period of network inactivity for the first sleep state, wherein the condition is satisfied if the period of network activity is longer than a specific time period, and wherein the first sleep timer expires more than once during the period of network inactivity if the condition is satisfied, and restart the first sleep timer to remain in the first sleep state if the condition to exit the first sleep state is not satisfied.

18. The mobile station as in claim 17, wherein the power states include at least one awake state, and wherein the RF radio consumer less power during the sleep state than during the awake state.

19. The mobile station as in claim 17, wherein the determination comprises:

receiving a beacon signal at a target beacon transmission time (TBTT), wherein the RF radio exits from the sleep state if the beacon signal indicates an availability of data for the mobile station from the wireless access point.

20. A mobile station for use with a wireless access point, the mobile station comprising:

a radio frequency (RF) radio;

an antenna coupled to the RF radio;

a processor coupled to the RF radio, the processor configured to control power states of the RF radio, the power states includes at least a first sleep state associated with a first sleep timer and a listening timer, and wherein the processor is configured to

start the first sleep timer to enter the first sleep state, wherein the power state of the RF radio is in a low power state when the first sleep timer is counting,

in response to the first sleep timer expiring, start the listening timer to determine if a condition is satisfied for the RF radio to exit from the first sleep state, wherein the RF radio is in a high power state when the listening timer is counting, wherein the determination comprises;

receiving a beacon signal at a target beacon transmission time (TBTT), wherein the RF radio exits from the sleep state if the beacon signal indicates an availability of data for the mobile station from the wireless access point, and

starting a second sleep timer to enter a second sleep state, wherein the condition indicates the mobile station has been remaining in the first sleep state longer than a period of time, and wherein the power state of the RF radio is in the low power state when the second sleep timer is counting, and

restart the first sleep timer to remain in the first sleep state if the condition to exit the first sleep state the condition is not satisfied.

21. The mobile station as in claim 20, wherein the second sleep timer counts longer than the first sleep timer.