Method for providing two-way optical timed channel on optical transport network (OTN)

Abstract

The invention provides a method for realizing timed distribution in an optical transport network (OTN). The method comprises the following steps of: on the basis of the wavelength of an optical supervisory channel (OSC) used in the OTN, configuring a two-way communication channel on an optical fibre, wherein optical signals having a first wavelength and a second wavelength respectively adjacent to the central wavelength of the OSC are configured on each optical fibre, so that data is transmitted in two directions; performing OSC duplex communication in a first two-way communication channel at the position of an optical switching / multiplexing node, and performing optical timed channel (OTC) duplex communication in a second two-way communication channel; and regenerating signals in the OTC through a line amplifier (ILA), so that timed signals in the OTC are transparently transmitted.

Description

technical field [0001] The present invention generally relates to the field of wired communication, and more specifically, relates to a method for providing a bidirectional optical timing channel on an Optical Transport Network (OTN) to simultaneously transmit frequency information and time information. Background technique [0002] Traditional network synchronization depends on the precise distribution of frequencies, and evolved wireless networks (eg, TD-LTE) require precise time and phase distributions. Currently, the IEEE1588V2 protocol (PTP) is commonly used to implement timing synchronization functions with sub-microsecond range precision. In order to simplify the network structure and reduce operation consumption, the primary reference clock (PRTC) is suggested to be arranged at the top of the OTN network. So time / phase is distributed over OTN from the main reference clock to the backhaul network. [0003] In order to realize precise time / phase transmission on the O...

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Problems solved by technology

[0005] But there are two sources affecting the end-to-end (End-to-End) PTP performance in the OTN network

The first source is the link asymmetry between the master and slave clocks, which, if not measured and compensated for, can easily lead to timing errors with half the value of the link asymmetry

However, link asymmetry is common in OTN and not easily measured

The second source is when time nodes are cascaded along the timing path, the synchronization performance will be degraded or the network size will be limited due to the accumulated noise

[0014] Solution A has the following disadvantages: OSC needs to be terminated and processed at each node, and each node also terminates the timing signal and acts as a timing node

[0016] Option B has the disadvantage that for system and network management, the OSC needs to be terminated and processed on each node, which also terminates the timing signal and acts as a timing node

Obviously, there is a problem of accuracy in this method, because the chromatic dispersion coefficient of the optical fiber is not a unique value, and the OSC wavelength in practical applications is not the central wavelength, OSC is a sparse wavelength division multiplexing (Coarse WavelengthDivision Multiplexing, CWDM) channel, which allows + / -7.5nm offset from center wavelength)

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