Mobile telephone location system and method
First Claim
1. A wireless network-based tracking system, comprising:
- an array of fixed antenna sites each including means for receiving and transmitting wireless communication and control channel signals and forming part of a wireless communication network, each antenna site being associated with a predetermined area for wireless connection to portable transceiver units in said predetermined area, and for transmitting and receiving communication and control channel signals to and from portable transceiver units in said predetermined area;
a plurality of agile vector sensor units, each agile vector sensor unit being mounted at a respective one of said fixed antenna sites and including scanning means for scanning said predetermined area over the frequency range of said wireless communication network and detecting reverse communication channel signals of any active transceiver units in the vicinity, analysis receiver means for determining the azimuth of any detected reverse communication channel signals, tracking means for detecting changes in reverse communication channel assignments for each connected call and storing new communication channel assignments, and means for storing an identification code for each active transceiver unit, and the signal strength and azimuth of signals received on the currently assigned communication channel for each transceiver unit connected to the antenna site; and
a monitoring and locating means for locating the approximate position of any active transceiver unit in said network which is currently transmitting over a reverse communication channel, the locating means including means for determining the active antenna site for the selected transceiver unit, means for determining a plurality of neighboring antenna sites to said active antenna site, means for polling the sensor units at said active antenna site and neighboring antenna sites to transmit stored call information from said agile vector sensor units, including signal strength and determined azimuth of reverse communication channel signals received by said antenna sites for at least the selected active transceiver unit to said locating means, and means for determining from said transmitted information a probable x-y coordinate location area in which the selected transceiver unit is located.
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Accused Products
Abstract
A wireless network based location system and method uses an existing wireless communication network to locate the position of any active phone or transceiver unit in the network. The system includes a plurality of agile vector sensor units, one each installed at each antenna site in the network, and a remote central monitoring station to which wireless network users can call for assistance in the event of an emergency. The system is designed to locate a portable phone transceiver unit using the reverse voice channel signal transmitted by the transceiver unit. Each agile vector sensor unit locks onto the reverse voice channel to determine azimuth and signal strength in the reverse voice channel, and also tracks any changes in voice channel by monitoring the forward voice channel. In the event of a voice channel change, the sensor unit tunes to the new voice channel. The azimuth, signal strength, and reverse voice channel information collected is used to track the location of a transceiver unit in real time.
270 Citations
25 Claims
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1. A wireless network-based tracking system, comprising:
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an array of fixed antenna sites each including means for receiving and transmitting wireless communication and control channel signals and forming part of a wireless communication network, each antenna site being associated with a predetermined area for wireless connection to portable transceiver units in said predetermined area, and for transmitting and receiving communication and control channel signals to and from portable transceiver units in said predetermined area; a plurality of agile vector sensor units, each agile vector sensor unit being mounted at a respective one of said fixed antenna sites and including scanning means for scanning said predetermined area over the frequency range of said wireless communication network and detecting reverse communication channel signals of any active transceiver units in the vicinity, analysis receiver means for determining the azimuth of any detected reverse communication channel signals, tracking means for detecting changes in reverse communication channel assignments for each connected call and storing new communication channel assignments, and means for storing an identification code for each active transceiver unit, and the signal strength and azimuth of signals received on the currently assigned communication channel for each transceiver unit connected to the antenna site; and a monitoring and locating means for locating the approximate position of any active transceiver unit in said network which is currently transmitting over a reverse communication channel, the locating means including means for determining the active antenna site for the selected transceiver unit, means for determining a plurality of neighboring antenna sites to said active antenna site, means for polling the sensor units at said active antenna site and neighboring antenna sites to transmit stored call information from said agile vector sensor units, including signal strength and determined azimuth of reverse communication channel signals received by said antenna sites for at least the selected active transceiver unit to said locating means, and means for determining from said transmitted information a probable x-y coordinate location area in which the selected transceiver unit is located. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of locating a transceiver unit, comprising the steps of:
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providing an agile vector sensor unit at each fixed antenna site in a wireless communication network; determining the active antenna site for a selected transceiver unit which is currently in use; determining neighboring antenna sites within a predetermined area of the active antenna site; activating the agile vector sensor units of the active antenna site and neighboring antenna sites to transmit information to a central monitoring station; using the agile vector sensor unit at each of the active and neighboring antenna sites to scan the forward control and communication channels at each antenna site and determine an initial reverse communication channel and any changes in reverse communication channel for the selected transceiver unit; tuning a scanning device of the agile vector sensor unit at the active antenna site to the initial reverse communication channel and any subsequent new communication channels; determining azimuth and signal strength of reverse communication channel signals received from the selected transceiver unit using the agile vector sensor unit at the active antenna site; storing the azimuth, signal strength, and current reverse communication channel of the selected transceiver unit at the agile vector sensor unit of the active antenna site; transmitting a record comprising the azimuth, signal strength, and current reverse communication channel to the central monitoring station at predetermined intervals so that location of a selected transceiver unit may be determined continuously; controlling the agile vector sensor units at each neighboring antenna site to tune into the current reverse communication channel of the selected transceiver unit and determine azimuth and signal strength of the reverse communication channel signal of the selected transceiver unit at each neighboring antenna site; transmitting a record comprising the azimuth and signal strength for the current reverse communication channel at each neighboring antenna site to the central monitoring station at predetermined intervals; re-tuning each of the agile vector sensor units to the new reverse communication channel each time a change in reverse communication channel is detected to determine and collect signal strength and azimuth inforination for the new reverse communication channel; and determining an approximate x and y coordinate position from the azimuth and signal strength information received from the activated agile vector sensor units. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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Specification