Research And Implementation Of Time Synchronization On High-end Router

Clock synchronization technology is one of the key technologies in the construction of IP Radio Access Network. Clock synchronization includes frequency synchronization and time synchronization, in wireless network, frequency division multiplexing modes such as WCDMA only need to guarantee the synchronization of frequency, while the time division multiplexing modes such as TD-SCDMA needs support both. Currently, there only IEEE1588v2 protocol support time synchronization in clock synchronization technologys that IP RAN supports. What’s more,China Mobile make sure of the requirement that the core and convergence access devices must support the IEEE1588v2 protocol in the construction of IP RAN.IEEE1588v2 also called precision time protocol, the protocol defines the specification to complete high precision time synchronization and the principle of the message interaction in network. It is mainly used for solving the problem about high costs and the lack of precision. At present, the main scheme to solve the time synchronization problem in the construction of wireless network is install GPS receiver on the base station node, by acquiring satellite time to finish time synchronization between the access equipment. But the GPS scheme has disadvantages, such as large difficulty in construction, high cost and low reliability. The IEEE1588v2 protocol not only can provide the same level time synchronization accuracy relative to GPS, but also can overcome the shortcomings of GPS.In this paper, the IEEE1588v2 protocol is used to complete the time synchronization on the high-end router which work on the core layer of IP RAN. It is proved that the proposed scheme can replace the GPS synchronization scheme. In this paper, the key points of the IEEE1588v2 protocol are studied, including the concept of protocol, message type and format, clock working mode, data set and state machine in synchronization mechanism.The clock function module of the high-end router is divided into two parts, the main control board and the service board, respectively introduced in the third and fourth chapter. In this paper, the frequency synchronization is implemented by synchronous Ethernet and the time synchronization is completed by the IEEE1588v2 protocol.The realize of two technologies both needs the software and hardware support, the background of the project mainly based on the network processor that support 1588v2 protocol and 10 GE Ethernet interface card that support Ethernet synchronization function, the sending and receiving of the PTP message and the acquisition of the time stamp is implemented on the NP chip, and the recovery of the clock signal and up sent the signal is implemented on Ethernet interface card.The primary work of this thesis includes the development of Ethernet interface card, time synchronization function encode and system network test, ultimately complete the time synchronization in the equipment and between the master to slave devices. Referring to the IP RAN time test specification, the network test is carried out, the accuracy analysis of the test results is given, and verify the feasibility of the time synchronization of the proposed scheme. At last, puts forward the deficiency and the prospect of the future of this paper.