Multi-hop synchronization and timeslot distribution method for IEEE 802.15.4 based positioning networks

One of the important aspects in wireless sensor networks is an energy efficient communication protocol to allow battery powered devices with a lifetime of several of years. The most important step therefor is to maximize the time the network nodes staying in power down modes. The possibility to measure distances with an easy-to-use and low cost phase difference of arrival method between network nodes enables an accurate positioning of these nodes. Because this technology needs additional requirements on synchronization and channel access, this paper describes a centralized multi-hop beaconing protocol to synchronize all the devices and to schedule the guaranteed timeslots for the ranging procedures. This yields to an increase of time in power down mode and an increase of the maximum rate of distance measurements per second. Measurements were made at the implemented system at company ZIGPOS GmbH.

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