Fujitsu Corporation

Ryuichi Moriya

Koji Takeguchi

Nobuhiro Rikitake

Hirotaka Morita

Hideki Matsui

Yasuyuki Mitsumori

Naoya Okada

Kenichi Yajima

Tsuyoshi Ohigawa

Ken Mizukura

A transmission device includes: a code generator configured to generate delay measurement information; an insertion unit configured to sequentially insert the delay measurement information generated by the code generator, in each of delay measurement signals in a plurality of frames, and to sequentially transmit the plurality of frames sequentially inserted with the delay measurement information to a counterpart device on a transmission path whose path delay time is to be measured; and a detector configured to receive a plurality of frames transmitted from the counterpart device and to detect the delay measurement information included in each of delay measurement signals in the plurality of received frames.

Transmission device, transmission network system, and path delay measuring method

In order to increase the efficiency of large-capacity transmission, the continuity of divided signals generated by dividing a multiplexed signal is maintained and the original large-capacity multiplexed signal is restored. A signal dividing section divides a multiplexed signal to generate a plurality of divided signals in the STS or STM transmission interface format. A guarantee information adding section adds guarantee information for guaranteeing the continuity of the divided signals to each of the divided signals to generate transmission signals. A signal sending section sends the transmission signals via a transmission line in the transmission interface format. A signal receiving section receives the transmission signals. A signal restoring section restores the multiplexed signal by constructing the divided signals on the basis of the guarantee information.

Transmission system

Proposed is an optical clock distribution system in the WDM network, which particularly relates to a system to control clock synchronization between optical transmission devices constituting an optical communication network. The optical clock distribution system includes an optical clock generator converting a clock signal of PRC (Primary Reference Clock) level into an optical clock signal having a wavelength &#x3bb;a wavelength multiplexer wavelength-multiplexing the optical clock signal having wavelength &#x3bb;together with other optical wavelength data; and a wavelength-demultiplexer provided in a unit of the network, wavelength-demultiplexing the optical clock signal having wavelength &#x3bb;wherein the other optical wavelength data are processed in the unit of the network using the wavelength-demultiplexed optical clock signal having wavelength &#x3bb;as a reference clock.

Optical clock signal distribution system in WDM network

A network synchronization controller and method for effectively preventing a timing loop from happening in a synchronous network. A clock status message controller, disposed in each network element on the network, produces and sends clock status messages which are each composed of clock quality data and synchronization control data. The clock quality data indicates the quality level of a clock signal that each network element supplies to its neighboring network elements. The synchronization control data contains information to be used to make the network synchronized with a single reference timing source. A clock selector chooses one of the clock signals received from other network elements, based on the clock status messages received along with the clock signals.

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Kawasaki, Japan

Ryuichi Moriya