Beacon assisted hybrid asynchronous wireless communications protocol

• US 20030114204A1
• Filed: 12/13/2001
• Published: 06/19/2003
• Est. Priority Date: 12/13/2001
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Korfhage, Stephen, OʼDea, Robert J., Allen, Vernon Anthony, DʼSouza, Ralph
• Granted Patent: US 6,671,525 B2
• Time in Patent Office: Days
• US Class Current: 455/574
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 52/0225 using monitoring of external events, e.g. the presence of a signal
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A beacon assisted asynchronous method of wireless communication according to the present invention enables initiating and target devices (12, 14) to remain in sleep mode most of the time and to periodically wake up to asynchronously, and directly, communicate with one another. Specifically, each of the initiating and target devices (12, 14) transmits a beacon while operating in a default transmit/receive mode (40, 40a, 42, 42a) and subsequently listens for a response. Alternatively, the initiating device (12) may enter a data packet message mode to receive a beacon from the target device (14) and to subsequently transmit a data packet message to the target device (14) after receiving the first beacon. The initiating device (12) minimizes the length of time in which it must wait to receive the target device beacon by timing a corresponding target beacon receive period based on stored data such as information based on previous communication with the target device (14).

Claims

1. A method of asynchronously communicating with a target wireless device, comprising:

occasionally entering a first wake up mode from a default sleep mode to transmit an initiating device beacon and to listen for target device transmissions;

entering a second wake up mode if a data packet message must be transmitted to the target wireless device;

during the second wake up mode;

waiting to receive a target beacon directly from the target wireless device;

transmitting the data packet message directly to the target wireless device after receiving the target device beacon directly from the target wireless device; and

reverting to the default sleep mode upon termination of either the first or the second wake up mode.

2. The method of claim 1, further comprising listening for an acknowledgement message responsive to the data packet message and transmitted directly from the target wireless device.

3. The method of claim 2, further comprising reverting to the default sleep mode immediately after termination of the listening for an acknowledgement message responsive to the data packet message transmitted directly from the target wireless device and until a subsequent occurrence of one of the occasionally entering a first wake up mode from a default sleep mode to transmit a source beacon packet and the entering a second wake up mode if a data packet message must be transmitted to the target wireless device.

4. The method of claim 1, wherein the waiting to receive a target device beacon directly from a target wireless device further comprises adjusting a timing of a target device beacon receive period based on stored information to ensure receipt of the target device beacon.

5. The method of claim 4, wherein the adjusting of the timing of a target device beacon receive period based on stored information to ensure receipt of the target device beacon comprises adjusting the timing of a target device beacon receive period based on previous communication with the target wireless device.

6. The method of claim 5, further comprising adjusting respective timings of subsequent second wake up modes based on the previous communication with the target wireless device to minimize a time period during which the waiting to receive a target device beacon directly from the target wireless device occurs.

7. The method of claim 1, further comprising adjusting, based on device clock drift parameters, the occasionally entering a first wake up mode from a default sleep mode to transmit an initiating device beacon and to listen for a target device beacon.

8. The method of claim 1, wherein the transmitting of the data packet message directly to the target wireless device is executed in a temporally contiguous manner relative to the waiting to receive a target device beacon directly from the target wireless device.

9. The method of claim 1, further comprising reverting to the occasionally entering a first wake up mode from a default sleep mode to transmit an initiating device beacon after termination of the entering a second wake up mode rather than the first wake up mode if a data packet message must be transmitted to the target wireless device.

10. The method of claim 1, wherein the occasionally entering a first wake up mode from a default sleep mode to transmit an initiating device beacon and to listen for a received target device beacon is executed in one of a periodic and a pseudorandom manner.

16. The method of claim 10, wherein the, if necessary, entering a data packet message period at the initiating device to enable the initiating device to receive the target beacon from the target device is periodically executed every predetermined number of frames.

11. A method of wireless communication, comprising:

transmitting initiating and target beacons from initiating and target devices, respectively, during respective initiating and target device transmit periods;

listening for the initiating and target beacons at the target and initiating devices, respectively, during respective target and initiating device receive periods;

if necessary, entering a data packet message period at the initiating device to enable the initiating device to receive the target beacon from the target device regardless of a timing of the target beacon;

at the initiating device, transmitting the data packet message to the target device after receiving the target beacon from the target device; and

subsequently returning to a default sleep mode at the target device after either transmitting the acknowledgement message or upon expiration of the target device receive period, and at the initiating device after either receiving the acknowledgement message or upon expiration of the initiating device receive period.

12. The method of claim 11, further comprising, at the initiating device, listening for an acknowledgement message from the target device indicating that the target device received the data packet message.

13. The method of claim 11, further comprising, if necessary, adjusting the initiating device transmit period to compensate for processor drift at at least one of the target and initiating devices to avoid beacon interference.

14. The method of claim 13, wherein the, if necessary, adjusting the initiating device receive period at the initiating device to compensate for processor drift at at least one of the target and initiating devices to avoid beacon interference comprises, if necessary, delaying the initiating device transmit period, and consequently the initiating device receive period, by at least one initiating device transmit/receive period.

15. The method of claim 11, wherein the, if necessary, entering a data packet message period at the initiating device to enable the initiating device to receive the target beacon from the target device comprises, if necessary, maintaining the initiating device receive period at the initiating device until the initiating device receives the target beacon from the target device.

17. A wireless communications network, comprising:

an initiating device including a processor for periodically causing the initiating device to wake up from a default sleep mode to transmit an initiating device beacon and to subsequently receive a target device message during a default initiating device transmit/receive mode;

the processor further for also causing the initiating device to enter a data packet message mode to enable the initiating device to listen for the target device message until the target device message is received, and to transmit a data packet message upon receipt of the target device message; and

the processor for causing the initiating device to return to the default sleep mode subsequent to termination of either the default transmit/receive mode or the data packet message mode.

18. he wireless communications network of claim 17, further comprising, at the initiating device, listening for an acknowledgement message indicating receipt of the target device data packet message.

19. The wireless communications network of claim 17, wherein the processor is further for enabling the initiating device to directly and asynchronously communicate with target wireless devices.

20. The wireless communications network of claim 17, wherein the processor is further for alternatively causing the initiating device to enter the data packet message mode when the initiating device would otherwise be in the default sleep mode.