RFClock: Timing, Phase and Frequency Synchronization for Distributed Wireless Networks

  • 13 Jan, 2022
Emerging applications like distributed coordinated beamforming (DCB), intelligent reflector arrays, and networked robotic devices will transform wireless applications. However, for systems-centric work on these topics, the research community must first overcome the hurdle of implementing fine-grained, over-the-air timing synchronization, which is critical for any coordinated operation. To address this gap, this paper presents an open-source design and implementation of `RFClock’ that provides timing, frequency and phase synchronization for software defined radios (SDRs). By utilizing a leader-follower architecture, RFClock-leader allows follower clocks to synchronize with mean offset under $0.107$Hz, and then corrects the time/phase alignment to be within a $5$ns deviation. RFClock is designed to operate in generalized environments: as standalone unit, it generates a 10MHz/1PPS signal reference suitable for most commercial-off-the-shelf (COTS) SDRs today; it does not require custom protocol-specific headers or messaging; and it is robust to interference through a frequency-agile operation.

Fig. 1: Network architecture showing the distributed timing enabled by RFClock.


Fig. 2: RFClock follower evaluation board. The board dimensions are 13cm x 7.5cm. Total weight is 35g.

Download design files:
This work is licensed under Apache License 2.0 . Please use below links to download PCB design files to build RFClock follower hardware:

RFClock front-end design
RFClock custom UWB part
RFClock tunable filter
RFClock full version 1
RFClock full version 2

These hardwares were used for the paper "RFClock: Timing, Phase and Frequency Synchronization for Distributed Wireless Networks". Please use this link to download the paper.

Conference version:
K. Alemdar, D. Varshey, S. Mohanti, U. Muncuk, K. Chowdhury, "RFClock: Timing, Phase and Frequency Synchronization for Distributed Wireless Networks,” ACM International Conference on Mobile Computing and Networking (MobiCom 2021), New Orleans, LA, USA, 2021.