Access point-assisted positioning framework

• US 9,971,014 B2
• Filed: 05/01/2014
• Issued: 05/15/2018
• Est. Priority Date: 05/13/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zhang, Xiaoxin, Homchaudhuri, Sandip, Aldana, Carlos Horacio
• Primary Examiner(s): Phillips, Hassan
• Assistant Examiner(s): George, Ayanah
• Application Number:
  US14/267,717
• Publication Number:
  US 20140334401A1
• Time in Patent Office: 1,475 Days
• Field of Search: None
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: G01S 5/0236 Assistance data, e.g. base station almanac
• CPC Class Codes: H04W 56/002 Mutual synchronization
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Methods, systems, and devices are described for a wireless positioning framework in which an access point (AP) broadcasts a message within a beacon interval that identifies a transmission schedule for a set of stations. The message may include an information element identifying the stations in the set. The set may be determined based on station clock drifts and/or a ranging accuracy sought by the AP. The AP may also provide a station identifier, and frame spacing and delay parameters, which may be used to determine a distinct backoff for each station. Using distinct backoffs allow the stations to avoid collisions when sending the transmissions. The AP may receive the transmissions according to the identified schedule and may determine a range (e.g., round-trip time) for each station in the set based at least on a time at which the respective transmission is received.

Claims

1. A method for wireless positioning, comprising:

determining a set of stations associated with a basic service set;

broadcasting, by an access point, a message including data that identifies a subset of stations from the set of stations for performing a ranging procedure and data that identifies a schedule of transmissions for the subset of stations during the ranging procedure;

receiving a transmission from at least one station from the subset of stations transmitted according to the identified schedule; and

determining a range for the at least one station from the subset of stations based at least on a time at which the respective transmission is received.

2. The method of claim 1, wherein the schedule identifies a distinct backoff for the transmission from the at least one station from the subset of stations.

3. The method of claim 2, wherein the distinct backoff for the at least one station from the subset of stations is based at least on a respective station identifier.

4. The method of claim 1, wherein the schedule of transmissions for the subset of stations comprises a schedule of uplink transmissions for the subset of stations.

5. The method of claim 4, wherein the transmissions from the at least one station from the subset of stations comprises an uplink transmission from the at least one station from the subset of stations.

6. The method of claim 1, wherein the schedule of transmissions for the subset of stations comprises a schedule of downlink transmissions for the subset of stations.

7. The method of claim 6, wherein the transmissions from the at least one station from the subset of stations comprises a downlink transmission from the at least one station from the subset of stations.

8. The method of claim 1, further comprising:

identifying a frame spacing parameter and a delay parameter to be used for determining the schedule.

9. The method of claim 8, further comprising:

adapting one or both of the frame spacing parameter and the delay parameter based at least on the range determined for the at least one station from the subset of stations.

10. The method of claim 8, wherein identifying the frame spacing parameter comprises:

exchanging packets with the at least one station from the subset of stations to determine a plurality of frame spacing parameters for the stations; and

identifying a largest of the plurality of frame spacing parameters to be used for determining the schedule.

11. The method of claim 1, wherein the stations in the subset of stations are identified based at least on a ranging accuracy sought by an access point.

12. The method of claim 1, further comprising:

estimating clock drifts for the set of stations, wherein the stations in the subset of stations are identified based at least on the estimated clock drifts for the set of stations.

13. The method of claim 1, further comprising:

assigning a station identifier to one or more stations from the subset of stations to define an order of transmissions in the schedule.

14. The method of claim 1, further comprising:

defining an order of transmissions in the schedule according to a clock drift or a ranging accuracy sought for at least one respective station in the subset of stations.

15. The method of claim 1, further comprising:

determining a duration of the scheduled transmissions; and

directing at least one station outside the subset of stations to avoid transmissions during the duration of the scheduled transmissions.

16. An apparatus for wireless positioning, comprising:

a schedule identification module implemented in a processor to determine a set of stations associated with a basic service set;

a transmitter configured to broadcast a message including data that identifies a subset of stations from the set of stations for performing a ranging procedure and data that identifies a schedule of transmissions for the subset of stations during the ranging procedure;

a receiver configured to receive a transmission from at least one station from the subset of stations transmitted according to the identified schedule; and

a determinator implemented in the processor to determine a range for the at least one station from the subset of stations based at least on a time at which the respective transmission is received.

17. The apparatus of claim 16, wherein:

the schedule identifies a distinct backoff for the transmission from the at least one station from the subset of stations; and

the distinct backoff for the at least one station from the subset of stations is based at least on a respective station identifier.

18. The apparatus of claim 16, wherein the schedule of transmissions for the subset of stations comprises a schedule of uplink transmissions for the subset of stations and the transmissions from the at least one station from the subset of stations comprises an uplink transmission.

19. The apparatus of claim 16, wherein the schedule of transmissions for the subset of stations comprises a schedule of downlink transmissions for the subset of stations and the transmissions from the at least one station from the subset of stations comprises a downlink transmission.

20. The apparatus of claim 16, wherein the determinator is further configured to:

identify a frame spacing parameter and a delay parameter to be used for determining the schedule.

21. The apparatus of claim 20, wherein the determinator is further configured to:

adapt one or both of the frame spacing parameter and the delay parameter based at least on the at least on the range determined for the at least one station from the subset of stations.

22. The apparatus of claim 20, wherein the determinator is configured to identify the frame spacing parameter by:

exchanging packets with the at least one station from the subset of stations to determine a plurality of frame spacing parameters for the stations; and

identifying a largest of the plurality of frame spacing parameters to be used for determining the schedule.

23. The apparatus of claim 16, wherein

the stations in the subset of stations are identified based at least on a ranging accuracy sought by an access point.

24. The apparatus of claim 16, wherein the determinator is further configured to:

estimate clock drifts for the set of stations, wherein the stations in the subset of stations are identified based at least on the estimated clock drifts for the set of stations.

25. The apparatus of claim 16, wherein the determinator is further configured to:

assign a station identifier to one or more stations from the subset of stations to define an order of uplink transmissions in the schedule.

26. The apparatus of claim 16, wherein the determinator is further configured to:

define an order of transmissions in the schedule according to a clock drift or a ranging accuracy sought for at least one respective station in the subset of stations.

27. A device for wireless positioning, comprising:

a processor; and

a memory in electronic communication with the processor, the memory embodying instructions executable by the processor to;

determine a set of stations associated with a basic service set;

broadcast a message including data that identifies a subset of stations from the set of stations for performing a ranging procedure and data that identifies a schedule of transmissions for the subset of stations during the ranging procedure;

receive a transmission from at least one station from the subset of stations transmitted according to the identified schedule; and

determine a range for the at least one station from the subset of stations based at least on a time at which the respective transmission is received.

29. The device of claim 27, wherein the instructions are executable to cause the processor to:

identify a frame spacing parameter and a delay parameter to be used for determining the schedule; and

adapt one or both of the frame spacing parameter and the delay parameter based at least on the range determined for the at least one station from the subset of stations.

30. The device of claim 27, wherein the instructions are executable to cause the processor to:

estimate clock drifts for the set of stations, wherein the stations in the subset of stations are identified based at least on the estimated clock drifts for the set of stations.

28. A computer program product for wireless positioning, the computer program product comprising a non-transitory computer-readable medium storing instructions executable by a processor to:

determine a set of stations associated with a basic service set;

broadcast a message including data that identifies a subset of stations from the set of stations for performing a ranging procedure and data that identifies a schedule of transmissions for the subset of stations during the ranging procedure;

receive a transmission from at least one station from the subset of stations transmitted according to the identified schedule; and

determine a range for at the least one station from the subset of stations based at least on a time at which the respective transmission is received.