Precise time of flight measurements in IEEE 802.11 networks by cross-correlating the sampled signal with a continuous Barker code

Wireless LAN devices can be used for two-way time of arrival (TOA) measurements even with off-the-shelf hardware that has only a measurement resolution of 1 µs. However, to get a good locating and tracking performance the send and arrival times as well as the durations of IEEE 802.11 MAC packets must be measured precisely. In this paper, we calculate a cross-correlation between the received and sampled signal and a time continuous Barker code sequence to determine the TOA. Our adaptive sampling offset algorithm helps to efficiently obtain a subsample resolution. We implemented our algorithm and an IEEE 802.11 receiver as a Software-Defined-Radio (SDR) program. In our experiments, the algorithm needs fewer observations in comparison to previously published approaches that measure the time of flight between two WLAN devices.

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