Modified transmission method for improving accuracy for E-911 calls

• US 6,519,465 B2
• Filed: 07/16/2001
• Issued: 02/11/2003
• Est. Priority Date: 01/08/1999
• Status: Expired due to Term

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Sheehan, Joseph W., Stilp, Louis A., Anderson, Robert J.
• Primary Examiner(s): Le, Thanh Cong
• Application Number:
  US09/907,028
• Publication Number:
  US 20010046870A1
• Time in Patent Office: 575 Days
• Field of Search: 455/422, 455/403, 455/404, 455/450, 455/455, 455/62, 455/63, 455/67.1, 455/428, 455/424, 455/115, 455/522, 455/69, 455/70, 370/321, 370/318
• US Class Current: 455/456.1
• CPC Class Codes: G01S 1/026 of associated receivers
• CPC Class Codes: G01S 2205/006 for emergency situations
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• 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 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• 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 76/50 for emergency connections

Abstract

The accuracy of the location estimate of a Wireless Location System is dependent, in part, upon both the transmitted power of the wireless transmitter and the length in time of the transmission from the wireless transmitter. In general, higher power transmissions and transmissions of greater transmission length can be located with better accuracy by the Wireless Location System than lower power and shorter transmissions. Wireless communications systems generally limit the transmit power and transmission length of wireless transmitters in order to minimize interference within the communications system and to maximize the potential capacity of the system. The inventive method disclosed herein meets the conflicting needs of both systems by enabling the wireless communications system to minimize transmit power and length while enabling improved location accuracy for certain types of calls, such as wireless 9-1-1 calls. The method comprises the following steps: a wireless transmitter receives normal transmission parameters from a base station; the user of the wireless transmitter initiates a call on the wireless transmitter by dialing a sequence of digits and pressing “SEND” or “YES”; a processor within the wireless transmitter compares the dialed sequence of digits with one or more trigger events stored within the wireless transmitter; if the dialed sequence of digits does not match the trigger event, then the wireless transmitter uses the normal transmission parameters in making the call; and if the dialed sequence of digits matches the trigger event, then the wireless transmitter uses a modified transmission sequence.

Claims

1. A wireless transmitter adapted to transmit a modified transmission sequence to facilitate location by a Wireless Location System, wherein the modified transmission sequence comprises a message sent from the wireless transmitter using transmission parameters different from the normal transmission parameters broadcast on a forward control channel by base stations in a wireless communications system;

and wherein the wireless transmitter is programmed to perform the following functions;

receiving the normal transmission parameters from a base station;

initiating a call when a user of the wireless transmitter dials a sequence of digits and presses a predefined button;

comparing the dialed sequence of digits with one or more trigger events stored within the wireless transmitter;

using the normal transmission parameters in making the call if the dialed sequence of digits do not match the trigger event; and

using the modified transmission sequence if the dialed sequence of digits matches the trigger event.

2. A wireless transmitter adapted to transmit a modified transmission sequence to facilitate location by a Wireless Location System, wherein the modified transmission sequence comprises a message sent from the wireless transmitter using transmission parameters different from the normal transmission parameters broadcast on a forward control channel by base stations in a wireless communications system;

and wherein the modified transmission sequence comprises the wireless transmitter transmitting an additional predetermined number of access probes after the base station has acknowledged receipt of the access probes to the wireless transmitter.

3. A wireless transmitter adapted to transmit a modified transmission sequence to facilitate location by a Wireless Location System, wherein the modified transmission sequence comprises a message sent from the wireless transmitter using transmission parameters different from the normal transmission parameters broadcast on a forward control channel by base stations in a wireless communications system;

and wherein the modified transmission sequence comprises the wireless transmitter including at least one additional field in the transmitted message even if the additional field is not requested in the normal parameters broadcast on forward channels by the base station.

6. A wireless transmitter as recited in claim 3, wherein the additional field is an Authentication field.

7. A wireless transmitter as recited in claim 3, wherein the additional field is a Serial Number field.

8. A wireless transmitter as recited in claim 3, wherein the additional field is a Mobile Assisted Channel Allocation Report field.

4. A wireless transmitter adapted to transmit a modified transmission sequence to facilitate location by a Wireless Location System, wherein the modified transmission sequence comprises a message sent from the wireless transmitter using transmission parameters different from the normal transmission parameters broadcast on a forward control channel by base stations in a wireless communications system;

and wherein the modified transmission sequence comprises the wireless transmitter following a transmitted message with one or more repeated registration messages.

5. A wireless transmitter adapted to transmit a modified transmission sequence to facilitate location by a Wireless Location System, wherein the modified transmission sequence comprises a message sent from the wireless transmitter using transmission parameters different from the normal transmission parameters broadcast on a forward control channel by base stations in a wireless communications system;

and wherein the modified transmission sequence comprises the wireless transmitter following a transmitted message transmitted on a first one of a plurality of channels with one or more repeated registration messages transmitted on a second one of the plurality of channels.

9. A wireless transmitter as recited in claim 5, wherein the one or more repeated registration messages are of the normal length determined from the transmission parameters broadcast on the forward channels by the base station.

10. A wireless transmitter as recited in claim 5, wherein the one or more repeated registration messages are modified to a longer length by including additional fields.

11. A wireless transmitter as recited in claim 5, wherein the one or more repeated registration messages are of the normal length determined from the transmission parameters broadcast on the forward channels by the base station.

12. A wireless transmitter as recited in claim 5, wherein the second one of a plurality of channels is selected to be one in use by a second base station within listening range of the wireless transmitter and for which the wireless transmitter can receive the forward control channel broadcast by that second base station.

13. A wireless transmitter as recited in claim 5, wherein the second one of a plurality of channels is selected to be one for which the wireless transmitter can detect no forward control channel activity by any base station.

14. A wireless transmitter adapted to transmit a modified transmission sequence to facilitate location by a Wireless Location System, wherein the modified transmission sequence comprises a message sent from the wireless transmitter using transmission parameters different from the normal transmission parameters broadcast on a forward control channel by base stations in a wireless communications system;

and wherein the trigger events are broadcast by a wireless communications system for receipt by a plurality of wireless transmitters.

15. A wireless transmitter adapted to transmit a modified transmission sequence to facilitate location by a Wireless Location System, wherein the modified transmission sequence comprises a message sent from the wireless transmitter using transmission parameters different from the normal transmission parameters broadcast on a forward control channel by base stations in a wireless communications system;

and wherein the actions to be taken during the modified transmission sequence are preprogrammed and permanently stored in the wireless transmitter.

16. A wireless transmitter adapted to transmit a modified transmission sequence to facilitate location by a Wireless Location System, wherein the modified transmission sequence comprises a message sent from the wireless transmitter using transmission parameters different from the normal transmission parameters broadcast on a forward control channel by base stations in a wireless communications system;

and wherein the actions to be taken during the modified transmission sequence are programmed by the user into the wireless transmitter.

17. A wireless transmitter adapted to transmit a modified transmission sequence to facilitate location by a Wireless Location System, wherein the modified transmission sequence comprises a message sent from the wireless transmitter using transmission parameters different from the normal transmission parameters broadcast on a forward control channel by base stations in a wireless communications system;

and wherein the actions to be taken during the modified transmission sequence are broadcast by the wireless communications system for receipt by all wireless transmitters.

18. A wireless transmitter adapted to transmit a modified transmission sequence to facilitate location by a Wireless Location System, wherein the modified transmission sequence comprises a message sent from the wireless transmitter using transmission parameters different from the normal transmission parameters broadcast on a forward control channel by base stations in a wireless communications system;

and wherein the trigger event includes the dialed digits “

9-1-1”

.