Positioning using observer-based time-of-arrival measurements

Disclosed are implementations that include a method, performed by a network control device, including sending a first instruction to a first device to send a first measurement signal, and sending a second instruction to a second device to receive the first measurement signal. Following receipt of a first acknowledgement signal from the target mobile device, the first and second devices change their roles so the second device sends, and the first device receives, a second measurement signal, and the first and second devices receive a second acknowledgement signal from the target device. Position of the target device is determined based on timing measurements associated with the first and second measurement signals, the first and second acknowledgement signals, and on known positions of the first and second devices. Another network device is selected to perform additional measurements upon a determination that a desired accuracy of the position determined was not achieved.