Method and System for Enhancing a Location Server Reference Database Through Round-Trip Time (RTT) Measurements

Abstract

A mobile device in a cellular communication network collects round-trip time (RTT) measurements for a single active cell. The collected RTT measurements are transmitted to a location server. The location server uses the transmitted RTT measurements to calculate a GNSS position of the single active cell. One or more of the transmitted RTT measurements are taken by the mobile device, and/or are collected from other mobile devices in the single active cell. The transmitted RTT measurements are collected at different GNSS fixes in the same single active cell. The mobile device location stamps the collected RTT measurements using corresponding GNSS fixes, and transmits to the location server using a NML. The location server calculates the GNSS position of the single active cell using location stamped RTT measurements in the received NMLR to refine an associated reference database periodically or aperiodically.

1 . A method of processing signals, the method comprising:
 performing by a mobile communication device:
 collecting round trip time (RTT) measurements for an active cell associated with the mobile communication device; and 
 transmitting the collected RTT measurements to a location server, wherein the RTT measurements collected for the active cell are used by the location server to calculate a GNSS location of the active cell. 
   
     
     
         2 . The method according to  claim 1 , wherein the step of collecting comprises:
 collecting three or more RTT measurements taken by one or more other mobile communication devices in the active cell.   
     
     
         3 . The method according to  claim 2 , wherein the step of collecting the three or more RTT measurements comprises:
 collecting the one or more of the three or more RTT measurements from the one or more other mobile devices associated with the active cell.   
     
     
         4 . The method according to  claim 1 , wherein the step of collecting comprises:
 collecting each of the RTT measurements at a different GNSS fix in the active cell.   
     
     
         5 . The method according to  claim 4 , further comprising:
 location stamping each of the collected RTT measurements using a corresponding GNSS fix in the active cell associated with the mobile communication device.   
     
     
         6 . The method according to  claim 5 , further comprising:
 transmitting the location stamped RTT measurements to the location server.   
     
     
         7 . The method according to  claim 1 , further comprising:
 selecting the active cell from a set of active cells associated with the mobile communication device.   
     
     
         8 . A mobile communication device, comprising:
 a cellular radio module configured to collect round trip time (RTT) measurements for an active cell associated with the mobile communication device, wherein the RTT measurements comprise RTT measurements for one or more other mobile devices; and   a processor configured to direct the cellular radio module to collect the RTT measurements and transmit the collected RTT measurements to a location server for use in calculating a GNSS location of the active cell.   
     
     
         9 . The mobile communication device of  claim 8 , further comprising:
 a GNSS radio module configured to receive GNSS satellite broadcast signals and calculate a GNSS fix of the mobile communication device corresponding to one of the RTT measurements.   
     
     
         10 . The mobile communication device of  claim 9 , wherein the processor is further configured to location stamp each of the RTT measurements using the corresponding GNSS fix and transmit the location stamped RTT measurements to the location server. 
     
     
         11 . The mobile communication device of  claim 9 , wherein the processor is further configured to direct the GNSS radio module to collect each of the RTT measurements at a different GNSS fix in the associated active cell. 
     
     
         12 . The mobile communication device of  claim 8 , wherein the RTT measurements comprise three or more RTT measurements. 
     
     
         13 . The mobile communication device of  claim 12 , wherein the processor is further configured to direct the cellular radio module collect at least one of the three or more RTT measurements from at least one other mobile communication device in the active cell. 
     
     
         14 . The mobile communication device of  claim 12 , wherein the processor is further configured to direct the cellular radio module to collect the at least one of the three or more RTT measurements from the at least one other mobile communication device associated with the active cell. 
     
     
         15 . A method comprising:
 receiving at a location server round trip time (RTT) measurements collected by at least one mobile communication device for an active cell associated with the mobile communication device;   calculating at the location server a GNSS position of the active cell using the received RTT measurements; and   updating location information for the active cell in an associated reference database using the calculated GNSS position of the active cell.   
     
     
         16 . The method of  claim 15 , wherein the step of updating further comprises refining the reference database associated with the location server. 
     
     
         17 . The method of  claim 15 , wherein the step of receiving further comprises receiving three or more RTT measurements from the at least one mobile communication device. 
     
     
         18 . The method of  claim 15 , wherein the step of receiving further comprises receiving location stamped RTT measurements from the at least one mobile communication device. 
     
     
         19 . The method of  claim 18 , wherein the step of receiving further comprises receiving the location stamped RTT measurements from the at least one mobile communication device in the active cell. 
     
     
         20 . The method of  claim 18 , wherein the step of receiving further comprises receiving the location stamped RTT measurements from the at least one mobile communication device associated with the active cell.