Research On The End-to-End One-Way-Delay Measurement Technology Of Communication Network

With social requirements of information technology being much higher, the scale of communication network is expanding rapidly for information transportation. It is very important to measure the performance of network for better operations and maintenances. Although it is not a critical attribute for general communication services, the End-to-End (E2E) One-Way-Delay (OWD) plays an important role in carrying the information of relay protection of power systems. Requirements include the path delay constraint and the symmetry of bidirectional delays. The research on the measurement technology of E2E OWD can provide important technical foundation for the network quality evaluation of delay-sensitive services deploying.This thesis focuses on the E2E OWD measurement technology of communication network. First of all, the thesis introduces the ASON technology and the advantages if it is brought into real-time control services; then the network measurement technology is introduced, and the time synchronization problem during the OWD measurement is studied. Combined with the requirements of practical applications, a measurement method of OWD based on the external time relay is proposed. The measurement method chooses GPS clock as external reference clock, through a time relay device called Clock-Bridge to synchronize the clock of Operating-Terminal, so that the clocks of the measurement devices at both ends will be synchronized. Besides, in order to improve the reliability of the method, the time-out trigger mechanism is taken to deal with line interruption and congestion of network, and the fallback mechanism is taken to deal with transmission errors of data.In this thesis, the prototype of measurement system based on the above method is designed. The module structures of Clock-Bridge and Operating-Terminal are designed, and the function of each is specified. The system takes activation mechanism to avoid invalid measurements; meanwhile, the event-triggering mechanism is taken to get hardware timestamps, so that the measurement results can be accuracy. Besides, the logic procedures of Clock-Bridge and Operating-Terminal are proposed after the feasibility analysis.