Nippon Telegraph and Telephone Corporation

Shinji Matsuoka

Yoshihiko Uematsu

Masahito Tomizawa

Akira Hirano

Takafumi Tanaka

Yoshiaki Sone

Akihiro Kadohata

A frequency assignment method for selecting a frequency width used on a route connecting between a start point and an end point when the start point and the end point of an optical signal are supplied in a photonic network including an optical node that includes an optical switch for switching the optical signal without electrically terminating the optical signal is disclosed. The frequency assignment method includes steps of: obtaining a correlation amount of use state of wavelength or frequency between adjacent links by referring to a route calculation result; determining a fixed frequency width or variable frequency width to be set for a communication route based on the correlation amount; and assigning the fixed frequency width or the variable frequency width on the route.

Frequency assignment method and apparatus

In a trunk transmission network for transmitting information signals between nodes via paths, flexible path operation is achieved by setting up paths between source nodes and destination nodes after pre-classifying paths into a higher service class in which any loss of information occurring in that path is made good restored; and a lower service class which permits loss of information to occur in the path. The flexible operation is further achieved by arranging for each node, when it acts as a source node, to recognize the service class of the information signal it is sending to a destination node, and to select a path corresponding to that service class.

Trunk transmission network

In a trunk transmission network for transmitting information signals between nodes via paths, flexible path operation is achieved by setting up paths between source nodes and destination nodes after pre-classifying paths into a higher service class in which any loss of information occurring in that path is restored, and a lower service class which permits loss of information to occur in the path. The flexible operation is further achieved by arranging for each node, when it acts as a source node, to recognize the service class of the information signal it is sending to a destination node, and to select a path corresponding to that service class.

The invention has the object of offering a channel-selection-type demultiplexing circuit which is capable of interchanging the time slots of demultiplexed signals when demultiplexing ultra-high-speed multi-channel multiplexed signal stream without expanding the scale of the circuits, and does not require the scale of the circuits to be expanded even if the speed of the transmission path increases. The invention is a channel-selection-type demultiplexing circuit capable of demultiplexing signals to a desired output port during bit demultiplexing, instead of simply demultiplexing the bits as in conventional devices, which performs bit demultiplexing based on a frequency division clock after selecting the bit signals to be demultiplexed to the desired output port from the N-channel multiplexed signal stream based on channel selection information.

Channel-selection-type demultiplexing circuit

A pointer processor for use in an SDH/SONET transmission system, realizing a proper VC path management. A pointer interpreter constantly monitors 3X pairs of H1 and H2 bytes to contain a prescribed maximum size pointer AU-4-Xc that can possibly be received by the pointer processor, to obtain and hold an inside AU-size map indicating an occupation state of AU pointers on 3X pairs of H1 and H2 bytes, while generating and holding an assigned AU-size map indicating an assigned state of AU pointers on 3X pairs of H1 and H2 bytes according to an externally set AU pointer size, and compares these two AU-size maps. For a part of map where the inside AU-size map coincides with the assigned AU-size map, the pointer interpreter carries out size-fixed pointer interpretations in pointer sizes specified by the assigned AU-size map, and the pointer generator generates transmission pointers in forms of normal pointers or AISs in the pointer sizes specified by the assigned AU-size map according to the size-fixed pointer interpretations. For a part of map where the inside AU-size map does not coincide with the assigned AU-size map, the pointer generator generates AISs in the pointer sizes specified by the assigned AU-size map as the transmission pointers.

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Yokosuka, Japan

Shinji Matsuoka