A TDOA positioning system that employs a calculated initial location of a wireless network device can be implemented to minimize sensitivity to the initial location of the wireless network device. For each pair of a plurality of reference network devices, the wireless network device can determine a distance difference between itself and the pair of the plurality of reference network devices based, at least in part, on round trip transit times between the wireless network device and the plurality of reference network devices. The initial location of the wireless network device can be calculated based on a location of each of the plurality of reference network devices. A location of the wireless network device can be estimated based on the calculated initial location of the wireless network device, the distance differences, and the location of each of the plurality of reference network devices.