System and Method for Low Power Signaling in a Wireless Local Area Network

• US 20150208349A1
• Filed: 09/30/2014
• Published: 07/23/2015
• Est. Priority Date: 01/17/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: RAMAMURTHY, Harish, KIM, Joonsuk, LlU, Yong, HANSEN, Christopher
• Granted Patent: US 10,015,741 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04W 52/0212 managed by the network, e.g. network or access point is master and terminal is slave
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0229 where the received signal is a wanted signal
• CPC Class Codes: H04W 52/0235 where the received signal is a power saving command
• CPC Class Codes: H04W 52/028 switching on or off only a part of the equipment circuit blocks
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/08 Access point devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A station, a method performed by a station and a corresponding method performed by an access point (AP) of a network to allow the station to operate a wireless local area network (WLAN) radio in a sleep state until the WLAN radio is ready to receive a beacon from the AP. The station includes a low power (LP) radio configured to receive a wake up signal from an AP of a network to which the station is connected. The station further includes a WLAN radio configured to operate in a sleep state until the WLAN radio receives an indication from the LP radio that the wakeup signal has been received, wherein WLAN radio is further configured to operate in a fully awake state after receipt of the indication to receive a beacon from the AP indicating a data transmission is pending for the station.

Claims

1. A method, comprising:

receiving, by a low power (LP) radio of a station, a wake up signal from an access point (AP) of a network the station is connected, the wake up signal configured to fully wake a wireless local area network (WLAN) radio of the station; and

receiving, by the WLAN radio of the station, a beacon indicating a data transmission is pending for the station.

2. The method of claim 1, further comprising:

activating, by the station, a crystal of the WLAN radio and the LP radio at a beginning of a duty cycle,

wherein the wake up signal turns a physical layer (PHY) of the station on.

3. The method of claim 2, wherein the beacon is received at substantially 50 μ

s after the wake up signal is received, wherein the 50 μ

s corresponds to an approximate time for the PHY of the station to turn on.

4. The method of claim 1, further comprising:

activating, by the station, the LP radio at a beginning of a duty cycle,

wherein the wake up signal turns a crystal of the WLAN radio and a PHY of the station on.

5. The method of claim 4, wherein the beacon is received between 3 to 5 ms after the wake up signal is received, wherein the 3 to 5 ms corresponds to an approximate time for the crystal and the PHY of the station to turn on.

6. The method of claim 1, further comprising:

sending, by the LP radio, an activation signal based on the wakeup signal directly to the WLAN radio that causes the WLAN radio to fully awake.

7. The method of claim 1, further comprising:

sending, by the LP radio, an indication of the receipt of the wakeup signal to a processor of the station; and

sending, by the processor, an activation signal to the WLAN radio that causes the WLAN radio to fully awake.

8. The method of claim 1, further comprising:

receiving, by the LP radio of the station, a poll from the AP requesting a power mode status of the WLAN radio;

determining, by the station, the power mode status of the WLAN radio; and

transmitting, by the LP radio of the station, a station indication signal to the AP, the station indication signal indicating the power mode status.

9. The method of claim 1, further comprising:

receiving, prior to receiving the beacon, a NOW signal, wherein the NOW signal wakes up a medium access control (MAC) module of the station.

10. A method, comprising:

determining, by an access point (AP) of a network, at least one station of the network to receive a data transmission;

transmitting, by the AP, a wake up signal to a low power (LP) radio of the at least one station, the wake up signal configured to wake a wireless local area network (WLAN) radio of the at least one station; and

transmitting, by the AP, a beacon to the WLAN radio of the at least station, the beacon indicating the data transmission is pending for the at least one station.

11. The method of claim 10, further comprising:

setting a timer when the wakeup signal is transmitted.

12. The method of claim 11, wherein the beacon is transmitted a predetermined time period after the wake up signal is transmitted, the predetermined time period being measured by the timer.

13. The method of claim 12, wherein the predetermined time period is one of between 25 to 100 μ

s when a crystal of the WLAN radio is already activated and between 3 to 5 ms when the crystal of the WLAN radio is deactivated.

14. The method of claim 10, further comprising:

transmitting, by the AP, a poll to the LP radio of the at least one station, the poll requesting a power mode status of the WLAN radio of the at least one station; and

receiving, by the AP, a station indication signal from the LP radio of the at least one station, the station indication signal indicating the power mode status.

15. The method of claim 11, further comprising:

transmitting, by the AP, a NOW signal after the timer has been set and before transmitting the beacon,

wherein the NOW signal occupies a medium to be used to transmit the beacon, and

wherein the NOW signal wakes up a medium access control (MAC) module of the at least one station.

16. A station, comprising:

a low power (LP) radio configured to receive a wake up signal from an access point (AP) of a network to which the station is connected; and

a wireless local area network (WLAN) radio configured to operate in a sleep state until the WLAN radio receives an indication from the LP radio that the wakeup signal has been received, wherein WLAN radio is further configured to operate in a fully awake state after receipt of the indication to receive a beacon from the AP indicating a data transmission is pending for the station.

17. The station of claim 16, wherein the WLAN radio includes a crystal and a physical layer (PHY), wherein the sleep state includes the crystal being powered on and the PHY being in an off or standby state and the fully awake state includes the crystal being powered on and the PHY being powered on.

18. The station of claim 16, wherein the WLAN radio includes a crystal and a physical layer (PHY), wherein the sleep state includes the crystal being powered off and the PHY being in an off or standby state and the fully awake state includes the crystal being powered on and the PHY being powered on.

19. The station of claim 16, wherein the LP radio is configured to operate in a sleep state until activated by a start of a duty cycle.

20. The station of claim 16, further comprising:

a processor configured to receive a further indication from the LP radio that the wakeup signal was received and provide the indication to the WLAN radio.