Software Defined Radio Development of Accurate Time Synchronization for Industrial WLAN Systems

In this paper, we propose a hardware development of a high accuracy Precision Time Protocol (PTP) on Software Defined Radio (SDR) for Industrial WLAN systems. To increase the throughput of the transmission system, we propose a low overhead 3-frames exchange PTP instead of 4-frames transmission as IEEE 1588 PTP protocol. Besides, our hardware-software co-design of the full SoC MAC-PHY can select the PTP timestamp point to remove the random transmission jitters caused by higher layers and the imbalanced timing made by the rugged hardware designs between master and slave. In previous work, the PTP synchronization has been evaluated on the M820-ZYNQ platform with Dummy PHY. In this paper, the proposed PTP system is developed on the SDR platform with real PHY. The SDR platform can reduce the processing delay between software and hardware compared to the previous platform. The result of our demonstration experiments shows that an oscilloscope captures the time synchronization of the proposed system in high accuracy with the nano-second level, which is less than 200 ns.