Time synchronization method, equipment and system

Abstract

The invention discloses a time synchronization method. The time synchronization method comprises the following steps that: an OLT sends a synchronous message to a base station through an ONU; after receiving the synchronous message sent by the OLT, the ONU carries a first timestamp in the synchronous message and forwards the synchronous message to the base station; the first timestamp is the local time of the ONU itself, which is recorded when the synchronous message is forwarded; after receiving the synchronous message forwarded by the ONU, the base station sends a delay request message to the OLT through the ONU; after receiving the delay request message sent by the base station, the ONU carries a fourth timestamp in the delay request message and forwards the delay request message to the OLT; the fourth timestamp is the local time of the ONU itself, which is recorded when the delay request message is received; and, after receiving the delay request message forwarded by the ONU, the OLT carries the fourth timestamp in a delay response message and sends the delay response message to the base station. The invention further discloses a time synchronization method for the OLT, a time synchronization method for the ONU, the OLT, the ONU and a time synchronization system.

Description

technical field [0001] The present invention relates to time synchronization technology in the field of wireless communication, in particular to a time synchronization method, device and system. Background technique [0002] Passive Optical Network (PON) is a pure media network, which avoids the electromagnetic interference and lightning effects of external equipment, reduces the failure rate of lines and external equipment, improves system reliability, and saves maintenance costs. The types of PON are mainly divided into Gigabit Passive Optical Network (GPON) and Ethernet Passive Optical Network (EPON). Optical Distribution Node (ODN) and Optical Network Unit (Optical Network Unit, ONU). PON generally adopts a tree topology structure, such as figure 1 As shown, the OLT and the ODN are connected, multiple ONUs are hung under the ODN, the downlink data between the OLT and the ONU is broadcasted, the uplink data uses the channel through time division multiplexing, and the OL...

AI Technical Summary

Problems solved by technology

[0005] In the prior art, the OLT, as the slave clock Slave, interacts with the upper-level clock source device to implement time synchronization through PTP message interaction, and the ONU adopts ITU-TG.984 or IEEE802.1AS to achieve time synchronization with the OLT; Interacting PTP packets with the lower-level clock source device to achieve time synchronization. Because the PTP packets are truncated on the PON, some attribute parameters obtained by the OLT from the PTP packets of the upper-level clock source device cannot be transmitted to the ONU, resulting in The incoherence of the PTP protocol

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