X-Sync: Cross-Technology Clock Synchronization Among Off-the-Shelf Wireless IoT Devices

Rainer Hofmann, David Grubmair, Carlo Alberto Boano, Kay Uwe Römer

Research output: Chapter in Book/Report/Conference proceedingConference paperpeer-review


Clock synchronization in distributed IoT systems is a necessary feature to allow a coherent data collection and event detection. This task is challenging, as today’s IoT systems often consist of heterogeneous wireless devices using incompatible
technologies. Because of this, existing solutions often make use of multi-radio gateways, which allow an indirect synchronization across heterogeneous devices, but increase end-to-end delays and suffer from an increased overhead. In this work, we present X-Sync, a novel approach allowing a direct and bidirectional clock synchronization among off-the-shelf wireless IoT devices with incompatible physical layer. X-Sync leverages cross-technology communication to convey timing information among heterogeneous devices and presents novel techniques to compensate for the inaccuracies in reliably detecting the start of a cross-technology frame. We seamlessly integrate X-Sync into the Contiki-NG operating system and evaluate its performance experimentally on off-the-shelf Bluetooth Low Energy and IEEE 802.15.4 devices, showing that X-Sync achieves a μs-level synchronization accuracy.
Original languageEnglish
Title of host publication46th International Conference on Local Computer Networks (LCN)
Number of pages8
Publication statusPublished - 5 Oct 2021
Event46th IEEE Conference on Local Computer Networks : LCN 2021 - Canada, virtuell, Virtuell, Canada
Duration: 4 Oct 20217 Oct 2021


Conference46th IEEE Conference on Local Computer Networks
Abbreviated titleLCN 2021
Internet address


  • Cross-Technology Communication
  • Clock Synchronization
  • ZigBee
  • BLE
  • IoT
  • IEEE 802.15.4

Fields of Expertise

  • Information, Communication & Computing

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