WIRELESS ACCESS NETWORK BASE STATION AND METHOD FOR DETERMINING LOCATION INFORMATION FOR A MOBILE STATION USING UPLINK TIME-DIFFERENCE OF ARRIVAL

• US 20080014960A1
• Filed: 07/12/2006
• Published: 01/17/2008
• Est. Priority Date: 07/12/2006
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Chou, Joey
• Granted Patent: US 7,570,962 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 5/02216 Timing or synchronisation of the receivers
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

Embodiments of a base station, a communication system and a method for determining current location information of a mobile station using uplink time-difference of arrival (U-TDOA) in a wireless access network are generally described herein. Other embodiments may be described and claimed. In some embodiments, a first timing adjustment is determined from receipt of the ranging frame from the mobile station within the granted uplink time-slot, and a second timing adjustment is received from the non-serving base station. The second timing adjustment may be determined by the non-serving base station based on receipt of a ranging frame from the mobile station.

Claims

1. A method for determining current location information of a mobile station comprising:

informing a non-serving base station of ranging frame parameters for the mobile station to use when transmitting a ranging frame;

sending an initiate ranging message to the mobile station, the mobile station responsively transmitting the ranging frame within a granted uplink time-slot in accordance with the ranging frame parameters;

determining a first timing adjustment from receipt of the ranging frame from the mobile station within the granted uplink time-slot; and

receiving a second timing adjustment from the non-serving base station, the second timing adjustment being determined by the non-serving base station based on receipt of the ranging frame from the mobile station.

2. The method of claim 1 wherein the mobile station is currently associated with a serving base station, and

wherein the method further comprises:

granting the uplink time-slot to the mobile station for use when transmitting the ranging frame; and

generating a first uplink time-difference of arrival (U-TDOA) parameter from a timing advance and the first and the second timing adjustments.

3. The method of claim 2 wherein the non-serving base station reserves an uplink time-slot for receipt of the ranging frame from the mobile station in response to being informed by the serving base station, the uplink time-slot being selected based on a time indicated by the ranging frame parameters provided by the serving base station.

4. The method of claim 3 wherein when a second non-serving base station is unavailable to be used for determining the current location information of the mobile station, the method further comprises:

mathematically rotating coordinate axis with respect to the serving base station to place the mobile station on one axis to allow calculation of the current location information of the mobile station by solving a simplified equation using the first U-TDOA parameter.

5. The method of claim 4 further comprising using a directional antenna and received signal strength of the ranging frame to improve accuracy of the current location information.

6. The method of claim 3 wherein when a second non-serving base station is used for location determination, the method further comprises:

informing the second non-serving base station of the ranging frame parameters that the mobile station will use when transmitting the ranging frame, the second non-serving base station responsively reserving an uplink time-slot for receipt of the ranging frame from the mobile station;

receiving a third timing adjustment from the second non-serving base station, the third timing adjustment being determined by the second non-serving base station based on receipt of the ranging frame from the mobile station within the reserved uplink time-slot; and

generating a second U-TDOA parameter from the timing advance and the first and third timing adjustments,

wherein the current location information of the mobile station is calculated based on both the first U-TDOA parameter and the second U-TDOA parameter.

7. The method of claim 2 further comprising:

providing the timing advance to the mobile station within the initiate ranging message; and

receiving the ranging frame from the mobile station within the granted uplink time-slot,

wherein the mobile station, the serving base station and the non-serving base station operate synchronously,

wherein the mobile station transmits the ranging frame advanced by an amount indicated by the timing advance, and

wherein the non-serving base station receives the ranging frame within an uplink time-slot granted by the non-serving base station.

8. The method of claim 7 wherein the serving base station and the non-serving base station communicate with associated mobile stations using same frequencies, and

wherein the serving base station and the non-serving base station both use the received ranging frame to respectively determine the first and the second timing adjustments.

9. The method of claim 3 wherein when the serving base station and the non-serving base station use different frequencies for communicating with associated mobile stations, the method further comprises sending a mobile scan message to the mobile station after receiving the ranging frame from the mobile station,

wherein the mobile scan message further instructs the mobile station to refrain from communicating with the serving base station for a period of time defined in the mobile scan message,

wherein in response to receipt of the mobile scan message, the mobile station sends a second ranging frame on a frequency currently being used by the non-serving base station, and

wherein the non-serving base station determines the second timing adjustment based on receipt of the second ranging frame from the mobile station.

10. The method of claim 3 further comprising updating the current location information of the mobile station by repeating the informing and the sending, wherein the first timing adjustment is provided to the mobile station as the timing advance for use by the mobile station in transmitting another ranging frame for the updating.

11. The method of claim 1 wherein the ranging frame parameters include one or more of a frame number, start time, number of symbols, encoding rate or modulation level for the mobile station to use in generating and transmitting the ranging frame.

12. The method of claim 2 further comprising:

communicating orthogonal frequency division multiplexed frames with the mobile station comprising voice over internet protocol communications;

receiving a request from an emergency services network for the current location information of the mobile station, where the serving base station performs the informing, the granting, the sending, the determining and the receiving in response to the request; and

providing current location information based on at least the first U-TDOA parameter to the emergency services network.

13. A serving base station comprising:

network interface circuitry to inform a non-serving base station of ranging frame parameters for a mobile station to use when transmitting a ranging frame;

a wireless transceiver to send an initiate ranging message to the mobile station, the mobile station to responsively transmit the ranging frame within a granted uplink time-slot in accordance with the ranging frame parameters; and

processing circuitry to determine a first timing adjustment from receipt of the ranging frame from the mobile station within the granted time uplink time-slot,

wherein the wireless transceiver receives a second timing adjustment from the non-serving base station, the second timing adjustment being determined by the non-serving base station based on receipt of the ranging frame from the mobile station.

14. The serving base station of claim 13 wherein the mobile station is currently associated with the serving base station, and

wherein the serving base station grants the uplink time-slot to the mobile station for use when transmitting the ranging frame, and

wherein the processing circuitry generates a first uplink time-difference of arrival (U-TDOA) parameter from a timing advance and the first and the second timing adjustments.

15. The serving base station of claim 14 wherein the non-serving base station reserves an uplink time-slot for receipt of the ranging frame from the mobile station in response to being informed by the serving base station, the uplink time-slot being selected based on a time indicated by the ranging frame parameters provided by the serving base station.

16. The serving base station of claim 15 wherein when a second non-serving base station is unavailable to be used for determining the current location information of the mobile station, the processing circuitry mathematically rotates coordinate axis with respect to the serving base station to place the mobile station on one axis to allow calculation of the current location information of the mobile station by solving a simplified equation using the first U-TDOA parameter.

17. The serving base station of claim 16 wherein the wireless transceiver is coupled to a directional antenna, and

wherein the processing circuitry uses the directional antenna and received signal strength of the ranging frame to improve accuracy of the current location information.

18. The serving base station of claim 15 wherein when a second non-serving base station is used for location determination, the serving base station uses network interface circuitry to inform the second non-serving base station of the ranging frame parameters that the mobile station will use when transmitting the ranging frame, the second non-serving base station responsively reserving an uplink time-slot for receipt of the ranging frame from the mobile station,

wherein the wireless transceiver receives a third timing adjustment from the second non-serving base station, the third timing adjustment being determined by the second non-serving base station based on receipt of the ranging frame from the mobile station within the reserved uplink time-slot,

wherein the processing circuitry generates a second U-TDOA parameter from the timing advance and the first and third timing adjustments,

wherein the processing circuitry calculates the current location information of the mobile station based on both the first U-TDOA parameter and the second U-TDOA parameter.

19. The serving base station of claim 14 wherein the wireless transceiver provides the timing advance to the mobile station within the initiate ranging message and receives the ranging frame from the mobile station within the granted uplink time-slot,

wherein the mobile station, the serving base station and the non-serving base station operate synchronously,

wherein the mobile station transmits the ranging frame advanced by an amount indicated by the timing advance, and

wherein the non-serving base station receives the ranging frame within an uplink time-slot granted by the non-serving base station.

20. The serving base station of claim 19 wherein the serving base station and the non-serving base station communicate with associated mobile stations using a same set of frequencies, and

wherein the serving base station and the non-serving base station both use the received ranging frame to respectively determine the first and the second timing adjustments.

21. The serving base station of claim 15 wherein when the serving base station and the non-serving base station use different sets of frequencies for communicating with associated mobile stations, the serving base station configures the wireless transceiver to send a mobile scan message to the mobile station after receiving the ranging frame from the mobile station,

wherein the mobile scan message further instructs the mobile station to refrain from communicating with the serving base station for a period of time defined in the mobile scan message,

wherein in response to receipt of the mobile scan message, the mobile station sends a second ranging frame on a frequency currently being used by the non-serving base station, and

wherein the non-serving base station determines the second timing adjustment based on receipt of the second ranging frame from the mobile station.

22. The serving base station of claim 15 wherein the wireless transceiver provides the first timing adjustment to the mobile station as the timing advance for use by the mobile station in transmitting another ranging frame for updating the current location information.

23. The serving base station of claim 13 wherein the ranging frame parameters include one or more of a frame number, start time, number of symbols, encoding rate or modulation level for the mobile station to use in generating and transmitting the ranging frame.

24. The serving base station of claim 14 wherein the wireless transceiver communicates orthogonal frequency division multiplexed frames with the mobile station comprising voice over internet protocol communications,

wherein the network interface circuitry receives a request from an emergency services network for the current location information of the mobile station, where the wireless transceiver informs the non-serving base station and sends the initiate ranging request to the mobile station in response to the request, and

wherein the network interface circuitry provides the current location information based on at least the first U-TDOA parameter to the emergency services network.

25. A communication system comprising:

the base station comprising network interface circuitry to inform a non-serving base station of ranging frame parameters for a mobile station to use when transmitting a ranging frame;

a wireless transceiver to send an initiate ranging message to the mobile station, the mobile station to responsively transmit the ranging frame within a granted uplink time-slot in accordance with the ranging frame parameters; and

processing circuitry to determine a first timing adjustment from receipt of the ranging frame from the mobile station within the granted time uplink time-slot, wherein the wireless transceiver receives a second timing adjustment from the non-serving base station, the second timing adjustment being determined by the non-serving base station based on receipt of the ranging frame from the mobile station; and

one or more substantially omnidirectional antennas coupled to the wireless transceiver to transmit the initiate ranging request message to the mobile station and to receive the ranging frame from the mobile station.

26. The system of claim 25 wherein the mobile station is currently associated with the serving base station, and

wherein the serving base station grants the uplink time-slot to the mobile station for use when transmitting the ranging frame, and

wherein the processing circuitry generates a first uplink time-difference of arrival (U-TDOA) parameter from a timing advance and the first and the second timing adjustments.

27. The system of claim 26 wherein the non-serving base station reserves an uplink time-slot for receipt of the ranging frame from the mobile station in response to being informed by the serving base station, the uplink time-slot being selected based on a time indicated by the ranging frame parameters provided by the serving base station.

28. A machine-accessible medium that provides instructions, which when accessed, cause a machine to perform operations to determine current location information of a mobile station, the operations comprising:

informing a non-serving base station of ranging frame parameters for the mobile station to use when transmitting a ranging frame;

sending an initiate ranging message to the mobile station, the mobile station responsively transmitting the ranging frame within a granted uplink time-slot in accordance with the ranging frame parameters;

determining a first timing adjustment from receipt of the ranging frame from the mobile station within the granted uplink time-slot; and

receiving a second timing adjustment from the non-serving base station, the second timing adjustment being determined by the non-serving base station based on receipt of the ranging frame from the mobile station.

29. The machine-accessible medium of claim 28 wherein the mobile station is currently associated with a serving base station, and

wherein the instructions, when further accessed cause the machine to perform operations comprising:

granting the uplink time-slot to the mobile station for use when transmitting the ranging frame; and

generating a first uplink time-difference of arrival (U-TDOA) parameter from a timing advance and the first and the second timing adjustments.

30. The machine-accessible medium of claim 29 wherein the non-serving base station reserves an uplink time-slot for receipt of the ranging frame from the mobile station in response to being informed by the serving base station, the uplink time-slot being selected based on a time indicated by the ranging frame parameters provided by the serving base station.