Method and system for mobile station location
A system and method for locating mobile stations in a wireless communication system such as a cellular system based on at least one received wireless signal and a database of geographical information.
1. A method of estimating an accuracy of a range measurement comprising:
determining an intersection point from a plurality of received wireless signal rays;
partitioning said rays into clusters;
determining an average delay time and a received signal power for each said cluster based on said received wireless signal rays;
determining an expected accuracy and an accuracy function based on said average delay time and said received signal power, where said accuracy function comprises directional properties of said cluster and properties of the receiver for receiving said wireless signal rays; and
presenting an estimated range measurement accuracy based on said expected accuracy and said accuracy function.
2. The method of claim 1 , further comprising using a time difference of arrival technique to determine said expected accuracy and said accuracy function.
3. The method of claim 1 , further comprising using one or more of time of arrival techniques and angle of arrival techniques to determine said expected accuracy and said accuracy function.
4. The method of claim 1 , wherein said expected accuracy comprises a probability within a predefined error.
5. The method of claim 1 , wherein determining of said expected accuracy and said accuracy function is further based on ray tracing techniques, where said ray tracing techniques comprise one or more of determining a dominant ray signal strength estimation, a ray angle of arrival calculation and using multiple rays to apply statistical methods for estimation.
6. The method of claim 5 , wherein said ray tracing techniques comprise a calculation based on a property of an antenna.
7. The method of claim 1 , wherein determining of said expected accuracy and said accuracy function is further based on use of a predetermined prediction database comprising information about signals.
8. The method of claim 1 , wherein determining of said expected accuracy and said accuracy function is further based on use of one or more of a predetermined radio frequency database and a geographical database.
9. The method of claim 1 , further comprising determining said expected accuracy and said accuracy function using said received wireless signal rays to determine a channel delay spread, wherein said channel delay spread is based on one or more of an average delay of said received wireless signal rays, a partial power of said received wireless signal rays and a statistical distribution of a received signal amplitude.
10. The method of claim 1 , wherein partitioning of said rays into clusters is according to a sensor resolution.
11. The method of claim 10 , wherein said location management unit determines an estimation of an accuracy of a range measurement based on a distribution function of at least one parameter of said cluster.
12. A system comprising:
a plurality of receivers to receive respective instances of a plurality of wireless signal rays;
a plurality of location measurement units associated with said plurality of receivers to determine properties of received wireless signals rays;
a location manager, comprising a processor and a memory, the processor to:
partition said rays into clusters,
determine an average delay time and a received signal power for each said cluster based on said received wireless signal rays;
determine an expected accuracy and an accuracy function based on said average delay time and said received signal power, wherein said accuracy function comprises directional properties of said cluster and properties of the receiver for receiving said wireless signal rays; and
present an estimated range measurement accuracy based on said expected accuracy and said accuracy function.
13. The system of claim 12 , wherein the processor uses a time difference of arrival technique to determine said expected accuracy and said accuracy function.
14. The system of claim 12 , wherein the processor uses one or more of time of arrival techniques and angle of arrival techniques to determine said expected accuracy and said accuracy function.
15. The system of claim 12 , wherein said expected accuracy comprises a probability within a predefined error.
16. The system of claim 12 , wherein the processor is to determine said expected accuracy and said accuracy function based on ray tracing techniques, where said ray tracing techniques comprise one or more of determining a dominant ray signal strength estimation, a ray angle of arrival calculation and using multiple rays to apply statistical methods for estimation.
17. The system of claim 16 , wherein determining of said expected accuracy and said accuracy function is further based on ray tracing techniques, where said ray tracing techniques comprise one or more of determining a dominant ray signal strength estimation, a ray angle of arrival calculation and using multiple rays to apply statistical methods for estimation.
18. The system of claim 16 , wherein said ray tracing techniques comprise a calculation based on a property of an antenna.
19. The system of claim 12 , wherein the processor is to determine said expected accuracy and said accuracy function based on use of a predetermined prediction database comprising information about signals.