Multi-Channel Distance Measurement With IEEE 802.15.4 (ZigBee) Devices

The addition of positioning capabilities to low-cost communications such as IEEE 802.15.4 compliant (ZigBee) networks can open up interesting markets, in particular if existing hardware and standard communications packets can be used for this purpose. High-precision localization requires large transmission bandwidths and thus the use of multiple frequency-channels. In the presence of oscillator frequency uncertainty the coherent synthesis of individual measurements poses a challenge. This paper proposes a particular frequency-hopping and signal processing scheme by which most transmitter and receiver frequency-errors can be eliminated in signal processing. Measurements show that high precision distance estimation with errors down to a few cm can be achieved.