Method of and system for estimating position

Abstract

A method of estimating the position of a user device is provided. The user device is initially in electronic communication with a positioning system controller through a communication network. The method comprises determining that a user device meets one or more proximity criteria with respect to an offline region where electronic communication between the user device and the positioning system controller, through the communication network, is expected to meet one or more failure criteria. Responsive thereto and in advance of the user device entering the said offline region, the positioning system controller transmitting local positioning data to the user device, the local positioning data comprising data concerning electromagnetic signal sources in the said offline region. The user device subsequently estimates its position whilst it is within the offline region by measuring signal data from a plurality of electromagnetic signal sources and processing the measured signal data and the local positioning data. The method may be used by, for example, a smartphone to estimate its position.

What is claimed is: 
     
         1 . A method of estimating the position of a user device, the method comprising: determining that a user device is offline such that it does not communicate with a positioning system controller through a communication network, the user device having initially been in electronic communication with the positioning system controller through the communication network, and responsive thereto subsequently estimating the position of the user device using captured data from one or more sensors of the user device. 
     
     
         2 . The method according to  claim 1  wherein the said one or more sensors comprise any one or more of: accelerometer; compass; altimeter. 
     
     
         3 . The method according to  claim 1  wherein the said one or more sensors comprise an accelerometer configured to calculate the number of steps taken by a user carrying the device. 
     
     
         4 . The method according to  claim 1  wherein the said one or more sensors comprise a compass configured to measure a direction of movement of the user device. 
     
     
         5 . The method according to  claim 1  further comprising: determining a direction of movement of the device; determining a distance travelled by the device; and combining the direction and distance to provide a motion vector representing a movement of the device. 
     
     
         6 . The method according to  claim 5  further comprising combining the said motion vector with a previously known position of the device to determine an updated estimate of position of device. 
     
     
         7 . The method according to  claim 1  further comprising, in advance of the user device going offline, a positioning system controller transmitting local positioning data to the user device, the local positioning data comprising data concerning one or more electromagnetic signal sources, and the user device subsequently estimating its position whilst it is offline by measuring signal data from a plurality of electromagnetic signal sources and processing the measured signal data and the local positioning data. 
     
     
         8 . The method according to  claim 1  further comprising the user device measuring and logging data detected by the user device from electromagnetic signal sources when the user device is offline. 
     
     
         9 . The method according to  claim 1  further comprising the user device measuring and logging its own position when it is offline. 
     
     
         10 . The method according to  claim 1  further comprising the user device gathering data while it is offline; and processing the gathered data to improve the accuracy of local positioning data. 
     
     
         11 . The method according to  claim 10  wherein the data gathered by the user device when it is offline comprises any one or more of the following: the MAC addresses of one or more electromagnetic signal sources; the type and model of one or more electromagnetic signal sources; transmitted and received powers from one or more electromagnetic signal sources; a period of time since an arbitrary start point; the number of steps taken by a user; directional data from a compass provided onboard the user device; and/or manually entered check-in data. 
     
     
         12 . The method according to  claim 1  further comprising associating electromagnetic signal data received by the user device when it is offline with the determined position of the user device when it received that data. 
     
     
         13 . The method according to  claim 12  further comprising transmitting the electromagnetic signal data and position data to a positioning system controller when it is subsequently online. 
     
     
         14 . The method according to  claim 13  further comprising the controller generating a path based on the electromagnetic signal data and the position data. 
     
     
         15 . The method according to  claim 14  further comprising the controller generating path data specifying electromagnetic signal data that would be expected to be received from one or more electromagnetic signal sources along the path. 
     
     
         16 . The method according to  claim 13  further comprising the positioning system controller determining the positions of one or more of the said electromagnetic signal sources using the signal data and the positioning data. 
     
     
         17 . A method of estimating the position of a user device, the method comprising: determining that a user device is offline such that it does not communicate with a positioning system controller through a communication network, the user device having initially been in electronic communication with the positioning system controller through the communication network, and responsive thereto subsequently estimating the position of the user device using captured data from one or more sensors of the user device; associating electromagnetic signal data received by the user device when it is offline with the determined position of the user device when it received that data; transmitting the electromagnetic signal data and position data to a positioning system controller when the user device is subsequently online; and generating a path based on the electromagnetic signal data and the position data. 
     
     
         18 . The method according to  claim 17  further comprising: determining that second and further user devices are offline and responsive thereto estimating the positions of second and further user devices using captured data from one or more sensors of the respective user devices; associating electromagnetic signal data received by the respective second and further user devices when they are offline with the determined positions of the respective user devices when they received that data; transmitting the electromagnetic signal data and position data to a positioning system controller when the second and further user devices are subsequently online; and improving the accuracy of existing paths based on the electromagnetic signal data and position data received from the said second and further user devices.