Method for realizing clock synchronization between optical line terminal (OLT) and optical network unit (ONU) in Ethernet-based passive optical network (EPON) system
A clock synchronization, system clock technology, applied in time division multiplexing systems, electrical components, multiplexing communications, etc., to achieve the effect of reducing impact, avoiding uncertainty, and high quality of service
Active Publication Date: 2012-04-11
FENGHUO COMM SCI & TECH CO LTD
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[0010] For the defects existing in the prior art, the purpose of the present invention is to provide a kind of method that realizes clock synchronization between OLT and ONU in EPON system, the technical problem to be solved is how to fundamentally solve the clock between ONU and OLT Synchronization issues, thus providing better service quality for the ONU side
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[0033] The present invention will be further described in detail below with reference to the accompanying drawings.
[0034] The invention relates to a method for realizing clock synchronization between an OLT and an ONU in an EPON system. The EPON system topological structure includes: an optical network central office OLT and an optical network unit ONU, and the optical network central office OLT and the optical network unit ONU respectively pass through optical fibers Connect with optical branch network ODN, such as figure 1 As shown, this system topology is known in the art. The network is a tree topology. If the ONU and OLT clocks are synchronized, higher-quality voice and data communication can be completed between the OLT and the ONU, and synchronized clock signals can be provided for users at the same time.
[0035] The invention solves the problem of clock synchronization between the ONU and the OLT by adding hardware circuits on the EPON upper connection disk on the...
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The invention relates to a method for realizing clock synchronization between an optical line terminal (OLT) and an optical network unit (ONU) in an Ethernet-based passive optical network (EPON) system. An external clock on the local side is accessed into a time division multiplexing (TDM) chassis on the local side; the TDM chassis on the local side extracts a clock as a system clock and forwards an Ethernet packet to an EPON wire clamping chassis in the OLT on the local side of an optical network through a main control chassis on the local side; the Ethernet packet reaches the ONU through an optical fiber, and the ONU side extracts 125-MHZ frequency clock from a PON chip, sends the 125-MHZ frequency clock to a phase locked loop (PLL) to generate 19.44-MHZ frequency clock and sends the 19.44-MHZ frequency clock to the TDM chassis on the ONU side, so the clock synchronization between the OLT and the ONU is realized. By the clock synchronization method, high-precision clock transmission between the ONU side and the OLT is realized through hardware, uncertainty of software dynamic adjustment is avoided, influence on a grouping network is reduced, a high-precision synchronous clock signal is supplied to a user on the ONU side, and TDM service with higher service quality is supplied to the ONU side in the EPON system.
Description
technical field [0001] The present invention relates to clock synchronization between OLT and ONU in Ethernet passive optical network EPON, in particular to a method for realizing clock synchronization between OLT and ONU in EPON system. The OLT is the Optical Line Terminal, and the ONU is the Optical Networks Unit. Background technique [0002] Optical fiber communication has been favored by people since its appearance due to its advantages of large capacity, high speed, and little influence by electromagnetic interference. At present, high-speed optical fiber transmission technology has been widely used in various backbone networks. Ethernet Passive Optical Network (EPON) has become the preferred solution for relevant operators because of its low cost and time-sharing to provide users with high-performance access, providing necessary conditions for people to travel in the world of information. Nowadays, more and more video services and interactive services, such as video...
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IPC IPC(8): H04J3/06
Inventor 易涛张前进王瑞波
Owner FENGHUO COMM SCI & TECH CO LTD