System and method for locating WiMAX or LTE subscriber stations
A system and method for estimating a location of a subscriber station receiving a first signal from a first base station and receiving a second signal from a second base station where the first and second base stations are nodes in a WiMAX or LTE network. A message may be received from the subscriber station containing first and second information, and a range ring determined from the first base station using the first information. A location hyperbola may be determined using the second information wherein the location hyperbola has the first and second base stations as foci. A location of the subscriber station may be estimated using the range ring and the location hyperbola.
1. A method for estimating a location of a subscriber station operating in a wireless network, comprising the steps of:
(a) transmitting from a network location device to a first base station a request for network measurement data;
(b) transmitting from said first base station to said subscriber station a message to trigger said subscriber station to scan said wireless network;
(c) transmitting from said subscriber station to said first base station a scanning result message containing information characterizing said first base station and a second base station;
(d) transmitting from said first base station to said network location device information from said scanning result message; and
(e) estimating at said network location device a location for said subscriber station based at least on said information from said scanning result message.
2. The method of claim 1 wherein said scanning result message includes a round trip time delay, a relative delay, a carrier to interference noise ratio, and a received signal strength indicator.
3. The method of claim 1 wherein the step of estimating a location for said subscriber station includes:
(i) determining a range ring from said first base station;
(ii) determining a location hyperbola having said first and said second base stations as foci; and
(iii) estimating a location of said subscriber station using said range ring and said location hyperbola.
4. The method of claim 1 wherein signals sent from said first and second base stations are synchronized to a common timing standard.
5. The method of claim 1 wherein said subscriber station is an Assisted-Global Positioning System (“A-GPS”) enabled subscriber station, and wherein a timing offset between said first and second signals is determined from said subscriber station message.
6. The method of claim 1 wherein plural additional subscriber stations are operating in said wireless network with each reporting their Global Positioning System (“GPS”) locations and subscriber station measurements to said network to thereby allow said network to determine synchronization between said base stations.
7. A system for estimating a location of a subscriber station operating in a wireless network, comprising:
(a) a network location device including a first transmitter for transmitting to a first base station a request for network measurement data;
(b) said first base station including a second transmitter to transmit to said subscriber station a message to trigger said subscriber station to scan said wireless network;
(c) said subscriber station including a third transmitter to transmit to said first base station a scanning result message containing information characterizing said first base station and a second base station;
(d) said first base station including a fourth transmitter to transmit to said network location device information from said scanning result message; and
(e) circuitry for estimating at said network location device a location for said subscriber station based at least on said information from said scanning result message.
8. The system of claim 7 wherein said scanning result message includes a round trip time delay, a relative delay, a carrier to interference noise ratio, and a received signal strength indicator.
9. The system of claim 7 wherein said circuitry for estimating a location for said subscriber station includes:
(i) circuitry for determining a range ring from said first base station;
(ii) circuitry for determining a location hyperbola having said first and said second base stations as foci; and
(iii) circuitry for estimating a location of said subscriber station using said range ring and said location hyperbola.
10. The system of claim 7 wherein said second transmitter and said fourth transmitter are the same.
11. The system of claim 7 wherein signals sent from said first and second base stations are synchronized to a common timing standard.
12. The system of claim 7 wherein said wireless network is a World Interoperability Microwave Access or Long Term Evolution network.
13. The system of claim 12 wherein said World Interoperability Microwave Access or Long Term Evolution network includes a Network Synchronization Unit (“NSU”) wherein said NSU is synchronized to a timing standard and located at a predetermined location.
14. The system of claim 13 wherein said World Interoperability Microwave Access or Long Term Evolution network includes a predetermined number N base stations and a predetermined number M NSUs wherein
N>1 and N>M.
15. The system of claim 7 wherein said subscriber station is an Assisted-Global Positioning System (“A-GPS”) enabled subscriber station, and wherein a timing offset between said first and second signals is determined from said subscriber station message.
16. The system of claim 7 wherein plural additional subscriber stations are operating in said wireless network with each reporting their Global Positioning System (“GPS”) locations and subscriber station measurements to said network to thereby allow said network to determine synchronization between said base stations.