Dual mode uplink/downlink location measurement and multi-protocol location measurement

A method of locating a mobile device, the method comprising:

• determining at each of at least two measurement units times of arrival of an uplink signal from the mobile device;
• determining at the at least two measurement units times of arrival of downlink signals from each of at least two base stations;
• receiving from the mobile device time of arrival determinations for the downlink signals from the at least two base stations;
• and
• computing a location of the mobile device based on the determined times of arrival.

A system for determining the location of a mobile device comprising:

• an uplink processor to implement an uplink location algorithm;
• a downlink processor to implement a downlink location algorithm;
• at least three base stations, located at known locations, to communicate with the mobile device;
• and
• at least three measurement units, having an uplink mode and a downlink mode,
• wherein, in the uplink mode, each of the measurement units determines a time of arrival of an uplink signal that originated from the mobile device and reports the determined time of arrival to the uplink processor, and the uplink processor determines the location of the mobile device using the uplink location algorithm based on the times of arrival reported to the uplink processor by the measurement units, and
• wherein, in the downlink mode, the mobile device determines times of arrival of downlink signals arriving from each of the at least three base stations and reports the determined times of arrival to the downlink processor, the measurement units collectively determine a time of arrival of downlink signals that originated from each of the at least three base stations and report the determined times of arrival to the downlink processor, and the downlink processor determines the location of the mobile device using the downlink location algorithm based on the times of arrival reported to the downlink processor by the mobile device and by the measurement units.