| Summary: | 碩士 === 中華大學 === 資訊工程學系碩士在職專班 === 101 === Telecommunications network switching technology is rapidly converted from the circuit-switched to packet-switched technology. In circuit-switched networks TDM (Time-Division Multiplexing, TDM) is used to achieve accurate frequency synchronization. In packet-switched networks high QoS (Quality of Service, QoS) and MSAN (Multi-Service Access Node) depend on frequency synchronization in the backhaul networks. Ethernet is a main technology of packet-switching networks. Whether carrier-grade synchronization quality can be provided to wireless base stations and remote access platforms via Ethernet is a key consideration to build an Ethernet backhaul network.
In traditional circuit-switched networks the Network Time Protocol (NTP) is used for frequency synchronization. The reference oscillators in the remote network equipment such as street cabinet access platforms and wireless base stations are driven by the servo control circuits to retrieve synchronous signals. In the past T1/E1 TDM provides a dedicated circuit-switched line, but the use of NTP in Ethernet has become a problem because Ethernet is basically a type of non-deterministic networks. To solve this problem, IEEE 1588 Precision Time Protocol (PTP) is devised to synchronize the remote network equipment in Ethernet. But even using PTP, the precision is still a problem. How to improve the precision of PTP has become a research topic.
No matter which synchronization technology is adopted by common carriers, the frequency synchronization issue in Ethernet networks must be resolved as Long Term Evolution (LTE) market has become more popular and the number of users and data quantity continue to rise. To respond this problem, ITU-T (International Telecommunication Unit - Telecommunication Standardization Sector) specified the Synchronous Ethernet (Sync-E) standard. In this thesis, we present how a system of carrier-grade Ethernet system can be constructed based on Sync-E. The Clock synchronization can be archived through the network physical layer.
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