Method and apparatus to select an optimum site and/or sector to provide geo-location data
View Patent ↗A system and method selects secondary base stations to task that provide geo-location information used to geo-locate a mobile station. A network overlay location system may be co-located at base station sites of a wireless communications network. The location measurement units of the network overlay system provide location information of the mobile station, which may be determined via one or more geo-location techniques, for example: time of arrival (TOA), time difference of arrival (TDOA), uplink time difference of arrival (UTDOA), angle of arrival (AOA), signal power, radio fingerprinting etc. Selecting secondary base stations to task using various selection criteria may provide optimum results when geo-locating a mobile station.
1. A method of geo-locating a mobile station in a geographic area serviced by a plurality of base station sites co-located with location measurement units (LMUs), the method comprising:
selecting a reference position within a communication coverage area of a first site;
selecting at least one secondary site according to a function of the reference position;
selecting at least one secondary sector of the at least one selected secondary site to task based on a function of the reference position; and,
tasking the at least one secondary sector to obtain location information of the mobile station;
further comprising:
calculating a cost function to determine which secondary site has the minimum total cost, and flagging that site as no longer considered an available candidate site,
wherein the cost function is: COST=W(DMS_BS F)+[BL−BMS_BS];
where W is a weighting factor that controls the relative cost between distance and bearing costs, DMS_BS is the distance from the mobile station reference position to the base station in kilometers, F is an exponent representing the distance cost penalty for a distance inside a cutoff radius measured from the MS reference position, BL is a look direction bearing angle, and BMS_BS is a bearing angle measured from the mobile station to the base station.
2. A method of geo-locating a mobile station in a geographic area serviced by a plurality of base station sites co-located with location measurement units (LMUs), the method comprising:
selecting a reference position within a communication coverage area of a first site: selecting at least one secondary site according to a function of the reference position;
selecting at least one secondary sector of the at least one selected secondary site to task based on a function of the reference position; and,
tasking the at least one secondary sector to obtain location information of the mobile station;
further comprising:
calculating a cost function to determine which secondary site has the minimum total cost, and flagging that site as no longer considered an available candidate site,
wherein the cost function is: COST=(W*DMS_BS+C)+[BL−BMS_BS];
where W is a weighting factor that controls the relative cost between distance and bearing angle costs, DMS_BS is the distance from the mobile station reference position to the base station in kilometers, C is a constant term equal to the distance cost evaluated at the distance cutoff radius, BL is a look direction bearing angle, and BMS_BS is a bearing angle measured from the mobile station to the base station.
3. A method of geo-locating a mobile station in a geographic area serviced by a plurality of base station sites co-located with location measurement units (LMUs), the method comprising:
selecting a reference position within a communication coverage area of a first site;
selecting at least one secondary site according to a function of the reference position;
selecting at least one secondary sector of the at least one selected secondary site to task based on a function of the reference position; and
tasking the at least one secondary sector to obtain location information of the mobile station;
further comprising:
calculating a cost to determine an available candidate site,
wherein the cost is a function of W, DMS_BS, F, BL and BMS_BS;
where W is a weighting factor that controls the relative cost between distance and bearing costs, DMS_BS is the distance from the mobile station reference position to the base station in kilometers, F represents the distance cost penalty for a distance inside a cutoff radius measured from the MS reference position, BL is a look direction bearing angle, and BMS_BS is a bearing angle measured from the mobile station to the base station.
4. A method of geo-locating a mobile station in a geographic area serviced by a plurality of base station sites co-located with location measurement units (LMUs), the method comprising:
selecting a reference position within a communication coverage area of a first site;
selecting at least one secondary site according to a function of the reference position;
selecting at least one secondary sector of the at least one selected secondary site to task based on a function of the reference position; and
tasking the at least one secondary sector to obtain location information of the mobile station;
further comprising:
calculating a cost to determine an available candidate site,
wherein the cost is a function of W, DMS_BS, C, BL and BMS_BS;
where W is a weighting factor that controls the relative cost between distance and bearing angle costs, DMS_BS is the distance from the mobile station reference position to the base station in kilometers, C is a constant term equal to the distance cost evaluated at the distance cutoff radius, BL is a look direction bearing angle, and BMS_BS is a bearing angle measured from the mobile station to the base station.