Mobile-based positioning using assistance data provided by onboard micro-bsa

A mobile device, comprising:

• a processor;
• a receiver in communication with the processor;
• and
• a memory including program code executable by the processor for estimating position of the mobile device, the program code including:
• code receiving, from a network server, observed time difference of arrival (OTDOA) assistance data for a first plurality of cells, the OTDOA assistance data included within a base station almanac (BSA) accessible to the network server;
• code for storing, within the memory, the OTDOA assistance data as a first micro-BSA;
• code for determining an initial position estimate for the mobile device based upon time difference of arrival (TDOA) measurements associated with an initial subset of the first plurality of cells and initial OTDOA assistance data corresponding to the initial subset of the first plurality of cells wherein the initial OTDOA assistance data is generated by the micro-BSA based upon an initial seed estimate;
• and
• code for determining an improved position estimate for the mobile device based upon TDOA measurements associated with an additional subset of the first plurality of cells and improved OTDOA assistance data corresponding to the additional subset of the first plurality of cells wherein the improved OTDOA assistance data is generated by the micro-BSA based upon the initial position estimate.

A method performed in a mobile device for estimating position of the mobile device, the method comprising:

• receiving, from a network server, first observed time difference of arrival (OTDOA) assistance data for a first plurality of cells and second OTDOA assistance data for a second plurality of cells from a base station almanac (BSA) accessible to the network server, the first plurality of cells corresponding to a first geographic area and the second plurality of cells corresponding to a second geographic area different from the first geographic area wherein the second plurality of cells includes at least one cell not included within the first plurality of cells;
• storing, within a memory of the mobile device, the first OTDOA assistance data as a first micro-BSA and the second OTDOA assistance data as a second micro-BSA;
• determining, without receiving additional OTDOA assistance data from the network server, a first position estimate for the mobile device based upon first time difference of arrival (TDOA) measurements associated with a subset of the first plurality of cells and first OTDOA assistance data corresponding to the subset of the first plurality of cells, the first OTDOA assistance data being generated by the first micro-BSA based upon a prior position estimate;
• and
• determining, without receiving additional OTDOA assistance data from the network server, a second position estimate for the mobile device based upon second time difference of arrival (TDOA) measurements associated with a subset of the second plurality of cells and second OTDOA assistance data corresponding to the subset of the second plurality of cells, the second OTDOA assistance data being generated by the second micro-BSA based upon the first position estimate.