Positioning system

Abstract

There is disclosed a method of managing a database of positioning data, the positioning data including electromagnetic signal source data for use by a positioning system, and the method comprising: receiving signal data relating to signals received from a plurality of electromagnetic signal sources; associating an appropriate one of a plurality of zone identifiers with each of the electromagnetic signal sources, each zone identifier being associated with a respective geographical zone; selecting a subset of the plurality of electromagnetic signal sources in dependence on their associated zone identifiers; processing the signal data relating to the subset of the plurality of electromagnetic signal sources to compute position estimates of the electromagnetic signal sources; and updating the database of electromagnetic signal source data in dependence on the computed position estimates.

1 . A method of managing a database of positioning data, the positioning data including electromagnetic signal source data for use by a positioning system, and the method comprising:
 receiving signal data relating to signals received by user devices from a plurality of electromagnetic signal sources;   associating each of the electromagnetic signal sources with an appropriate geographical region selected from a plurality of geographical regions;   selecting a subset of the plurality of electromagnetic signal sources in dependence on their associated geographical regions;   processing the signal data relating to the subset of the plurality of electromagnetic signal sources to compute position estimates of the electromagnetic signal sources; and   updating the database of electromagnetic signal source data in dependence on the computed position estimates.   
     
     
         2 . A method according to  claim 1 , wherein selecting a subset of signal sources comprises selecting signal sources associated with geographical regions that have a relatively poor coverage in the database. 
     
     
         3 . A method according to  claim 1 , wherein the electromagnetic signal source data relating to the selected subset of signal sources is updated before the electromagnetic signal source data relating to the non-selected signal sources. 
     
     
         4 . A method according to  claim 1 , further comprising processing the selected subset of signal sources substantially in real-time and/or on demand. 
     
     
         5 . A method according to  claim 1 , further comprising processing the non-selected signal sources on a periodic basis, as a batch job and/or when a processing load falls below a threshold amount. 
     
     
         6 . A method according to  claim 1 , further comprising assigning a priority to each of the signal sources, and processing the signal sources substantially in order of said priority. 
     
     
         7 . A method according to  claim 1 , wherein updating the database comprises at least one of: updating a database entry and adding a database entry. 
     
     
         8 . A method according to  claim 1 , wherein whilst the device is in continuous communication with an electromagnetic signal source of the subset of electromagnetic signal sources, the method comprises: estimating the position of the device using an estimate of the position of the said electromagnetic signal source from the database prior to the step of updating the database of electromagnetic signal source data; obtaining an updated estimate of the position of the said electromagnetic signal source; and estimating an updated position of the device using the updated estimate of the position of the said electromagnetic signal source. 
     
     
         9 . A method according to  claim 8  wherein the step of obtaining an updated estimate of the position of the electromagnetic signal source comprises obtaining an updated estimate of the position of the electromagnetic signal source from the database after the step of updating the database has been performed. 
     
     
         10 . A method according to  claim 8  further comprising outputting the position and the updated position to a user whilst the device is in continuous communication with the said electromagnetic signal source. 
     
     
         11 . A method according to  claim 1 , wherein each electromagnetic signal source has a zone code assigned to it, a first zone code being associated with a subset of signal sources having substantially the highest level of accuracy of position estimation, a second zone code being associated with zones of signal sources whose position estimates depend on position estimates associated with a zone of the first zone code. 
     
     
         12 . A method of managing a database of positioning data, the positioning data including electromagnetic signal source data for use by a positioning system, and the method comprising:
 receiving signal data relating to signals received from a plurality of electromagnetic signal sources;   associating an appropriate one of a plurality of zone codes with each of the electromagnetic signal sources, each zone code being associated with a respective geographical zone, and wherein the zone codes comprise a first zone code associated with a subset of signal sources having substantially the highest level of accuracy of position estimation, and a second zone code associated with zones of signal sources whose position estimates depend on position estimates associated with electromagnetic signal source associated with the first zone code;   processing the signal data to compute position estimates of the electromagnetic signal sources; and   updating the database of electromagnetic signal source data in dependence on the computed position estimates.   
     
     
         13 . A method according to  claim 11 , wherein processing the signal data further comprises identifying connections between zones, and processing relevant portions of the electromagnetic signal source data to re-estimate the position of relevant signal sources and optionally to recalculate zone codes of relevant zones. 
     
     
         14 . A method according to  claim 13 , wherein re-estimating the position of relevant signal sources includes processing portions of said signal data relating to signals received from said relevant signal sources at a plurality of different locations. 
     
     
         15 . A method according to  claim 14 , wherein said signal data, relating to signals received at a plurality of different locations, is a combination of a plurality of signal data transmissions received from a respective plurality of devices. 
     
     
         16 . A method according to  claim 14 , further comprising modelling the plurality of different locations as points on a path in the vicinity of said relevant zones. 
     
     
         17 . A method according to  claim 14 , wherein at least some adjacent zones of electromagnetic signal sources associated with different zone codes differ in terms of altitude. 
     
     
         18 . A method according to  claim 1 , further comprising:
 receiving local signal data relating to signals received at a user device from a plurality of electromagnetic signal sources local to the user device;   processing the local signal data in dependence on the electromagnetic signal source data to generate an estimate of the position of the user device; and   outputting the estimate of the position of the user device.   
     
     
         19 . A method according to  claim 1 , wherein the database is a local database that is at least a partial copy of a master database. 
     
     
         20 . A method according to  claim 19 , further comprising synchronizing the local database and the master database.