System for automatically determining cell transmitter parameters to facilitate the location of wireless devices

• US 7,974,640 B2
• Filed: 07/30/2010
• Issued: 07/05/2011
• Est. Priority Date: 12/01/2006
• Status: Expired due to Fees

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Anderson, Robert J.
• Primary Examiner(s): Cordero; Marivelisse Santiago
• Assistant Examiner(s): Choo; Munsoon
• Application Number:
  US12/847,419
• Publication Number:
  US 20100304763A1
• Time in Patent Office: 340 Days
• Field of Search: 455/404.2, 4554561-4565
• US Class Current: 455/456.5
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Several techniques for locating wireless devices involve the Mobile Stations (MS) making measurements of the signals transmitted by geographically distributed base stations within a wireless network. If some key site information is known about these transmitters, such as the transmitter location, transmit signal power, signal propagation, and transmit signal timing, measurements of these transmit signals by a MS can be used to determine the position of the MS. An automatic method to detect transmitters, identify key transmitter information, and utilize the base station transmit signals to perform location is presented. In addition, this method facilitates the use of cell site transmit signals that are part of multiple wireless networks.

Claims

1. A system for automatically determining cell transmitter parameters to facilitate the location of wireless devices, comprising:

a location processing node;

a first wireless device, wherein said first wireless device is configured to communicate with said location processing node via a communications link, and to make scanning measurements of signals from one or more geographically distributed transmitters, wherein said first wireless device is further configured to assist the location processing node in determining key transmitter information by receiving and measuring characteristics of said signals and providing information about said characteristics via the communications link to said location processing node; and

a server configured to communicate with a second wireless device, and to cause said second wireless device to make signal measurements of signals from one or more transmitters and to provide measurement information to said location processing node;

wherein said characteristics measured by said first wireless device are useful, in combination with characteristics measured by other wireless devices, to determine the key transmitter information; and

wherein said key transmitter information includes cell identification information, cell transmitter location information, and cell transmitter signal timing information.

2. A system as recited in claim 1, wherein said location processing node is configured to use information automatically determined by said first wireless device to determine key transmitter information concerning base station transmitters.

3. A system as recited in claim 1, wherein said key transmitter information includes cell transmitter position information, and the system is configured such that, once a set of cell transmitter positions is established, these positions are assumed to be correct in the future and are not solved for on a frequent basis, and wherein the system periodically checks for new cell identification information and determines coordinates for new cell transmitters.

4. A system as recited in claim 1, wherein at least one transmitter of said one or more geographically distributed transmitters is part of a first wireless communications network and a least one transmitter is part of a second wireless communications network, and wherein said first wireless device is configured to scan and report cell transmitter information for cell transmitters of two different wireless communications networks.

5. A system as recited in claim 1, wherein said server is configured to communicate via a user plane data channel with said first wireless device, and wherein said first wireless device is configured to provide measurement information via the data channel to said location processing node.

6. A system as recited in claim 1, wherein said key transmitter information includes cell identification information including at least one member of the group consisting of Cell ID, frequency channel, base station identity code, Cell Global Identity, and Base Station ID.

7. A system as recited in claim 1, wherein said signal measurements made by said second wireless device include at least one member of the group consisting of relative signal timing, absolute signal timing, and received power level.

8. A system as recited in claim 1, wherein said location processing node is programmed to compute a location solution based upon time difference measurements.

9. A system as recited in claim 1, wherein said location processing node is programmed to compute a location solution using said measurements and previously known information to solve for unknown information.

10. A system as recited in claim 1, wherein said location processing node is programmed to limit a portion of a location solution to a geographic region, and to then later combine the data from various regions to simplify solution of unknown data.

11. A method for locating a mobile wireless device, comprising:

instructing a first wireless device to communicate with a location processing node via a communications link, and to make scanning measurements of signals from one or more geographically distributed transmitters, and further instructing said first wireless device to assist the location processing node in determining key transmitter information by receiving and measuring characteristics of said signals and providing information about said characteristics via the communications link to said location processing node, wherein said characteristics are useful to determine the key transmitter information;

instructing a second wireless device to make signal measurements of signals from one or more transmitters and to provide measurement information to said location processing node; and

at the location processing node, using said key transmitter information and said measurement information to determine the geographic location of said wireless device to be located;

wherein said key transmitter information includes cell identification information, cell transmitter position information, and cell transmitter signal timing information; and

wherein the method further comprises periodically checking for new cell identification information and determining the coordinates for cell transmitters associated with new cell identification information.

12. A method as recited by claim 11, wherein the method is performed such that, once a set of cell transmitter positions is established, these positions are assumed to be correct in the future and are not solved for on a frequent basis.

13. A method as recited by claim 11, wherein the method is performed with at least one transmitter of a first wireless communications network and a least one transmitter of a second wireless communications network.

14. A method as recited by claim 11, wherein communications between said first wireless device and said location processing node are conducted via a user plane data channel.

15. A method as recited by claim 11, wherein said key transmitter information includes cell identification information, cell transmitter location information, and cell transmitter signal timing information.

16. A system for automatically determining cell transmitter parameters to facilitate the location of wireless devices, comprising:

a location processing node;

a first wireless device, wherein said first wireless device is configured to communicate with said location processing node via a communications link, and to make scanning measurements of signals from one or more geographically distributed transmitters, wherein said first wireless device is further configured to assist the location processing node in determining key transmitter information by receiving and measuring characteristics of said signals and providing information about said characteristics via the communications link to said location processing node; and

a server configured to communicate with a second wireless device to be located, and to cause said second wireless device to make signal measurements of signals from one or more transmitters and to provide measurement information to said location processing node;

wherein said characteristics measured by said first wireless device are useful, in combination with characteristics measured by other wireless devices, to determine the key transmitter information; and

wherein said location processing node is programmed to;

compute an error function based on known and unknown information, and to solve for the unknown information by minimizing the error function;

compute the error of each of the measurements as a function of the unknown information; and

compute the square error of each of the measurements based on the unknown information, and to weight the square error of each of the measurements based on the quality of the measurement, and to sum the weighted errors to create an error value which is a function of the unknown data, and to solve for the unknown data by minimizing the error function.

17. A system as recited in claim 16, wherein said location processing node is further programmed to mark data values as known once determined, and to use the known values to simplify the solution of unknown information.

18. A system as recited in claim 17, wherein the known information includes previously determined transmitter position information, timing of a transmitter known to be synchronous with respect to a common timing source, positions of fixed receivers, and positions of mobile receivers.