Time synchronization method for passive optical network, device and system

Abstract

A method for time synchronization on a passive optical network is disclosed, including: an optical line terminal OLT receives clock information sent by a first optical network unit ONU; the optical line terminal adjusts local time of the optical line terminal according to the clock information, to implement clock synchronization between the optical line terminal and the first optical network unit; the optical line terminal sends the clock information to a second optical network unit, to implement clock synchronization between the second optical network unit and the optical line terminal. The OLT in an embodiment of the present invention obtains clock information from an ONU on a PON; the OLT transmits the clock information to other ONUs; the OLT does not need to obtain clock signals from an upper network and the clock information does not need to be transmitted in a multi-level mode over a packet network; therefore, the precision of ToD can be greatly increased.

Description

technical field [0001] The invention relates to the communication field, in particular to a time synchronization method, device and system of a passive optical network. Background technique [0002] Passive Optical Network (PON) technology is a point-to-multipoint optical access technology. Such as figure 1 As shown, a PON network usually consists of an optical line terminal (OLT) 12, an optical splitter 14, an optical network unit (ONU) 16, and an optical fiber connected to this device. The optical splitter connects each ONU through a separate branch fiber. In the downstream direction, the optical splitter realizes the light splitting function, and sends the downstream optical signal of the OLT12 to all ONU16 through the branch optical fiber; Send it to OLT12 through the backbone optical fiber. [0003] In order to ensure that the optical signals sent by each ONU arrive at the OLT at the same time, the existing PON is usually implemented by ToD (Time of Day, time and da...

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Problems solved by technology

The inventors found that in practical applications, individual ONUs in some PON networks have their own high-precision time sources. If the OLT still obtains ToD from a certain time source in the core network, it needs to be transmitted in multiple stages through the packet network, resulting in the accuracy of ToD reduce

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