Estimating Locations of Mobile Devices in a Wireless Tracking System

A system for determining an estimated location of a mobile device in a wireless tracking system, the wireless tracking system comprising a first mobile device, a second mobile device and multiple stationary devices at known locations, the system comprising:

• an input port
• to receive a first radio measurement indicative of a first propagation path length of radio frequency radiation between the first mobile device and the multiple stationary devices, and
• to receive sensor data indicative of the movement of the first mobile device, wherein the sensor data is of a type different to the radio measurement;
• and
• a processor
• to determine a historical location of the first mobile device based on the first radio measurement and the sensor data,
• to determine error data indicative of a difference between a historical radio measurement associated with the historical location and the historical location,
• to store the error data associated with the historical location on a data store,
• to receive a second radio measurement indicative of a second propagation path length of radio frequency radiation between a second mobile device and the multiple stationary devices, and
• to determine an estimated location of the second mobile device based on the second radio measurement and the stored error data.

A method for determining an estimated location of a mobile device as performed by a location server in a wireless tracking system, the wireless tracking system comprising a first mobile device, a second mobile device and multiple stationary devices at known locations, the method comprising:

• receiving a first radio measurement indicative of a first propagation path length of radio frequency radiation between the first mobile device and the multiple stationary devices;
• receiving sensor data indicative of the movement of the first mobile device, wherein the sensor data is of a type different to the radio measurement;
• determining a historical location of the first mobile device based on the first radio measurement and the sensor data;
• determining error data indicative of a difference between a historical radio measurement associated with the historical location and the historical location;
• sending the error data associated with the historical location to a second mobile device to allow the second mobile device to determine an estimated location of the second mobile device based on the error data and a second radio measurement indicative of a second propagation path length of radio frequency radiation between the second mobile device and the multiple stationary devices.

A location server for determining an estimated location of a mobile device in a wireless tracking system, the wireless tracking system comprising a first mobile device, a second mobile device and multiple stationary devices at known locations,

• the location server comprising:
• an input port
• to receive a first radio measurement indicative of a first propagation path length of radio frequency radiation between the first mobile device and the multiple stationary devices, and
• to receive sensor data indicative of the movement of the first mobile device, wherein the sensor data is of a type different to the radio measurement;
• a processor
• to determine a historical location of the first mobile device based on the first radio measurement and the sensor data,
• to determine error data indicative of a difference between a historical radio measurement associated with the historical location and the historical location;
• and
• an output port to send the error data associated with the historical location to a second mobile device to allow the second mobile device to determine an estimated location of the second mobile device based on the error data and a second radio measurement indicative of a second propagation path length of radio frequency radiation between the second mobile device and the multiple stationary devices.

A method for determining an estimated location of a second mobile device as performed by the second mobile device in a wireless tracking system, the wireless tracking system comprising a first mobile device, the second mobile device and multiple stationary devices at known locations, the method comprising:

• receiving error data associated with a historical location of a first device, the error data being indicative of a difference between a historical radio measurement associated with the historical location indicative of a first propagation path length of radio frequency radiation between the first mobile device and the multiple stationary devices and the historical location of the first mobile device determined based on the first radio measurement and sensor data indicative of the movement of the first mobile device, wherein the sensor data is of a type different to the radio measurement;
• receiving a second radio measurement indicative of a second propagation path length of radio frequency radiation between a second mobile device and the multiple stationary devices;
• and
• determining an estimated location of the second mobile device based on the second radio measurement and the received error data.

A second mobile device for determining an estimated location of the second mobile device in a wireless tracking system, the wireless tracking system comprising a first mobile device, the second mobile device and multiple stationary devices at known locations, the second mobile device comprising:

• a first input port to receive error data associated with a historical location of a first device, the error data being indicative of a difference between a historical radio measurement associated with the historical location indicative of a first propagation path length of radio frequency radiation between the first mobile device and the multiple stationary devices and the historical location of the first mobile device determined based on the first radio measurement and sensor data indicative of the movement of the first mobile device, wherein the sensor data is of a type different to the radio measurement;
• a second input port to receive a second radio measurement indicative of a second propagation path length of radio frequency radiation between a second mobile device and the multiple stationary devices;
• and
• a processor to determine an estimated location of the second mobile device based on the second radio measurement and the received error data.