A distance-bounding concept for bilateral IEEE 802.15.4 communication

In this paper a concept for bounding the operation range of IEEE 802.15.4 based wireless sensors is introduced. The distance-bounding is based on a signal round-trip time of flight measurement. For the round-trip time of flight measurement two essential problems have to be solved: on the one hand the time of arrival estimation and on the other hand precise clock synchronization. In our novel approach both challenges were solved by utilizing the preamble and start of frame delimiter (SFD) signal that is available in every IEEE 802.15.4 data package. Based on a Wiener optimal filter applied to the demodulated received IEEE 802.15.4 packet the time of arrival is estimated. The frequency offset is estimated based on the residual frequency of the undemodulated received signal. Exemplary indoor measurements with a system based on a TI CC2430 ZigBEE-Chip prove that the introduced concept allows for a distance-bounding accuracy of approx. 1 m in indoor scenarios with moderate multipath distortions.