Method and system for determining the position of a device in a light based positioning system using locally stored maps

A mobile device for determining position using a light-based positioning system, the mobile device comprising:

• an approximate location determination module configured to determine an approximate location of the mobile device using geo-location information not derived from visible light received at the mobile device;
• a network interface for receiving, from a remote server, when the mobile device is at a location remote from the remote server, a map data structure of positions of a plurality of asynchronous light sources at a location corresponding to the approximately location of the mobile device;
• an image sensor for receiving an identifier broadcast from one of the asynchronous light sources of the plurality of asynchronous light sources, wherein (i) the identifier identifies the asynchronous light source, and (ii) the identifier corresponds to a pattern of distortions within an image acquired by the image sensor, the pattern of distortions being related to a modulation frequency of modulated light emitted by an asynchronous light source;
• and
• a position determination module configured to match the identifier to the asynchronous light source stored by the map data structure and determine the position of the mobile device by setting the position of the mobile device to the position of the asynchronous light source stored by the map data structure.