Patent ID: 7286624

Claim:
A positioning system, comprising: a plurality of devices, each device including: a transceiver for exchanging RF signals with the other of the plurality of devices; the transceiver periodically receiving a message from each other device of the plurality of devices during time slots assigned to the other devices; local clock for generating a local clock signal; receiver logic for determining a time of arrival, relative to the local clock signal, of the message from each of the other devices; transmitter logic for periodically transmitting messages to the other devices during a time slot assigned to said device, each transmitted message including information representing the determined time of arrival for at least one of the other devices; wherein the received message from each other device includes information representing a time of arrival at the other device of a respective message transmitted by said device; at least one of the devices further including ranging logic for determining a respective range to each of a plurality of the other devices, said determined respective range to a respective device of the other devices being determined as function of the determined time of arrival of the message from the other device and the time of arrival information in the message from the other device.