Method and apparatus for enhanced 911 location using power control in a wireless system

• US 20030210186A1
• Filed: 06/06/2003
• Published: 11/13/2003
• Est. Priority Date: 01/21/2000
• Status: Active Grant

• Current Assignee: AT&T Mobility II LLC (AT&T, Inc.)
• Original Assignee: AT&T Wireless Services Incorporated (AT&T, Inc.)
• Inventors: Winters, Jack Harriman, Sollenberger, Nelson Ray
• Granted Patent: US 6,972,717 B2
• Time in Patent Office: Days
• US Class Current: 342/387
• CPC Class Codes: G01S 2205/06 Emergency
• CPC Class Codes: G01S 5/019 Energy consumption
• CPC Class Codes: G01S 5/02 using radio waves using satellite radio beacon systems for determining position G01S19/00
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 76/50 for emergency connections
• CPC Class Codes: H04W 8/18 Processing of user or subscriber data, e.g. subscribed services, user preferences or user profiles; Transfer of user or subscriber data

Abstract

A method of locating a mobile telephone includes steps of receiving, transmitting, increasing and determining. In the receiving step, a first base station receives a call from a mobile telephone, the call including a dialed number and a TDMA signal. In the transmitting step, the base station transmits a control message to the mobile telephone when the dialed number meets a predetermined criterion, such as being 911. The control message instructs the mobile telephone to transmit the TDMA signal at a maximum power. In the increasing step, the mobile telephone increases the TDMA signal to maximum power in response to the control message. Then in the determining step, location information for the mobile telephone is determined based on at least one characteristic of the TDMA signal received at at least one of the first base station and other base stations. In an alternate embodiment, the method is practiced in a mobile telephone and the power level is automatically increased in response to the dialed number meeting a predetermined criterion.

Claims

1. A method of locating a mobile telephone, comprising the steps of:

receiving at a base station a call from a mobile telephone, the call including a dialed number and a TDMA signal;

transmitting from the base station to the mobile telephone a control message, in response to the dialed number meeting a predetermined criterion, the control message instructing the mobile telephone to transmit the TDMA signal at a maximum power;

increasing the TDMA signal to maximum power in response to the control message; and

determining location information for the mobile telephone based on at least one characteristic of the TDMA signal received at the base station.

2. The method according to claim 1, wherein the at least one characteristic of the TDMA signal is the time of arrival of a portion of the TDMA signal.

3. The method according to claim 1, wherein the at least one characteristic of the TDMA signal is the angle of arrival of the TDMA signal.

4. The method according to claim 1, further comprising:

receiving a MIN from the mobile telephone;

querying a user profile database with the MIN to determine whether the location function should be invoked; and

invoking location function based on the query.

5. The method according to claim 1, further comprising:

receiving a dialed number from the mobile telephone; and

invoking the location function when the dialed number meets a predetermined criterion.

6. The method according to claim 1, further comprising:

completing the call to the dialed number.

7. The method according to claim 6, further comprising:

providing the location information to a recipient of the call.

8. The method according to claim 7, further comprising:

providing the location information to a geographic information system for displaying the location information on a map.

9. A method of locating a mobile telephone comprising the steps of:

receiving at a base station a signal from a mobile telephone;

invoking a location function in response to the signal;

determining whether the mobile telephone should increase transmit power for location determination;

transmitting from the base station to the mobile telephone a control message instructing the mobile telephone to transmit a TDMA signal at an increased power level based on the determining;

receiving at at least one of a plurality of base stations the TDMA signal transmitted at the increased power level; and

calculating a location of mobile telephone based on the TDMA signal received at at least one of the plurality of base stations.

10. The method according to claim 9, wherein the determining step is performed based on the time of arrival of the TDMA signal at at least one of the plurality of base stations.

11. The method according to claim 9, wherein the determining step is performed based on the angle of arrival of the TDMA signal at at least one of the plurality of base stations.

12. The method according to claim 9, further comprising:

receiving a MIN from the mobile telephone;

querying a user profile database with the MIN to determine whether the location function should be invoked; and

invoking location function based on the query.

13. The method according to claim 9, further comprising:

receiving a dialed number from the mobile telephone; and

invoking the location function when the dialed number meets a predetermined criterion.

14. A method of locating a mobile telephone, comprising the steps of:

determining whether a dialed number triggers a location function;

initiating a mobile telephone call to the dialed number; and

transmitting known data to a mobile telephone system over a TDMA channel for location determination at increased power level when the location function is determined to be triggered.

15. The method according to claim 14, further comprising:

receiving location data from the mobile telephone system; and

displaying the location data on the mobile telephone.

16. The method according to claim 14, further comprising:

decreasing the power level after location determination.

17. An apparatus for locating a mobile telephone, comprising:

a plurality of base stations communicating TDMA signals with a mobile telephone;

a mobile switching center, coupled with the plurality of base stations, the mobile switching center a) receiving from one of the plurality of base stations a call that includes a dialed number the mobile telephone, b) determining whether the dialed number invokes a location function, and c) sending an instruction to the mobile telephone via one of the plurality of base stations to increase transmission power when the location function is invoked; and

a location processor, coupled with the plurality of base stations and the mobile switching center, the location processor determining the location of the mobile telephone based on the TDMA signals received from the mobile telephone via at least one of the plurality of base stations at the increased power level.

18. The apparatus according to claim 17, further comprising:

a geographic information system, coupled with the location processor, the geographic information system receiving the location from the location processor and plotting the location on a map.

19. The apparatus according to claim 17, further comprising:

a public switched telephone network, coupled to the mobile switching center, for transmitting a call to a destination telephone corresponding to the dialed number.

20. The apparatus according to claim 17, wherein the mobile switching center further determines whether the call invokes the location function based on a mobile identification number received from the mobile telephone.