Localization of a mobile device

A method of determining a location of a mobile device based on a first location estimation performed using a first location system, the first location system comprising a first network of wireless reference nodes, and the method comprising:

• obtaining an initial estimate of the location of the mobile device based on a second location estimation coarser than the first location estimation;
• using the initial estimate to select a subset of the reference nodes of the first network, the subset being selected based on being within a defined vicinity of the location of the mobile device as determined from the initial estimate;
• and
• from amongst a database of respective assistance data for each of the reference nodes of the first network stored on a server of the first location system, selectively providing the respective assistance data for each of said subset of wireless reference nodes to a localization module on the mobile device, for the mobile device to calculate a finer estimate of the location of the mobile device, the finer estimate being calculated to a finer degree than the initial estimate, by performing the first location estimation based on signals communicated between the mobile device and some or all of said subset of reference nodes, and on the respective assistance data for said some or all of the subset of reference nodes.

A computer program product for assisting in determining a location of a mobile device based on a first location estimation performed using a first location system, the first location system comprising a first network of wireless reference nodes, and the computer program product comprising code embodied on a computer readable medium and/or being downloadable therefrom, configured so as when executed to perform operations of:

• obtaining an initial estimate of the location of the mobile device based on a second location estimation coarser than the first location estimation;
• using the initial estimate to select a subset of the reference nodes of the first network, the subset being selected based on being within a defined vicinity of the location of the mobile device as determined from the initial estimate;
• and
• from amongst a database of respective assistance data for each of the wireless reference nodes of the first network stored on a server of the first location system, selectively providing the respective assistance data for each of said subset of wireless reference nodes to a localization module on the mobile device, for the mobile device to calculate a finer estimate of the location of the mobile device, the finer estimate being calculated to a finer degree than the initial estimate, by performing the first location estimation based on signals communicated between the mobile device and some or all of said subset of reference nodes, and on the respective assistance data for said some or all of the subset of reference nodes.