The Design And Implementation Of The Synchronous Ethernet System Oriented To OTU2Service

The Optical Transport Network (OTN) equipments in the transmission network are applied more and more widely in recent years, along with the OTN technology becomes more and more mature. The carrying business of network has been diversified and complicated. The OTN transmission equipments are not only required to transmit packets in order to adapt to the IP development, but also to provide support for various business systems. At the same time, the demand of time synchronization is increasingly high for wireless network with the development of Time Division-Synchronization Code Division Multiple Access (TD-SCMDA)/Time Division-Long Term Evolution (TD-LTE). Because of the difficulty of the addressing, maintenance, cable laying, at the same time with the high cost of security and installation, the existing Global Position System (GPS) satellite system is not a good choice. A time synchronization scheme base on ground of high precision becomes a big demand. To address this need, IEEE introduced1588v2international standard at the end of2008. The1588v2applicated in the field of telecommunications is a brand-new technology, and the stable and reliable deployment and operation is still the focus of the research.IEEE1588puts forward a packet synchronization technology, which the synchronization related time information is encapsulated in the Precision Time Protocol (PTP) message. It still uses the original data transmission link of Ethernet, without the need for additional clock link, which makes the construction of the network connections simplify. Following this standard to plan and design of network system, we realize the entire system of the subtle level time synchronization, which can effectively solve the problem of real-time distributed system without increasing the network load and network cost.The IEEE1588v2is currently in research and development from multiple communication equipment manufacturers, and has been widely applied in the Packet Transport Network (PTN). In this paper, after deeply studied the1588v2standard and OTN standard, we propose a new synchronization functional design oriented to the OTN frame. This design becomes the hard-core of the time synchronous Ethernet system on the OTN traffic board.In this paper, we complete the analysis of principle, simulation and verification on board using Field Programmable Gate Array (FPGA). In the direction of the line side, FPGA logic circuit inserts the PTP message into the overhead of OTN frame structure Optical Channel Transport Unit (OTU2), and extracts the PTP message from OTU2overhead in the direction of the line side. In this case, we complete the timing synchronization function and realize the precise time synchronization transmission network.