Fujitsu Corporation

Kazuhiro Uchida

Toshinori Koyanagi

Setsuo Abiru

Katsuhiko Hirashima

Toshiyuki Sakai

Kazuya Ryu

Shinichi Fujiyoshi

Tamotsu Matsuo

Kenji Miura

Yoshimi Toyoda

Takashi Monzawa

Mitsuharu Wakayoshi

Jun Asato

Masamichi Kasa

Hideki Shiono

Tateo Shimaru

Kenichi Abe

Kiyotaka Shikata

Masaharu Matsumoto

Susumu Tominaga

Kanna Okamura

Takamitsu Shirai

Michihiko Goto

Manabu Tomiyasu

Shigeharu Murakami

Toshimi Kida

Masahiko Iwakiri

Masashi Shibata

Miho Kawai

A communication device capable of restraining the packet transmission efficiency from lowering. An address storing unit extracts, from uplink packets, the addresses of terminals connected to sub-units and registers the addresses in an address management table. An address extracting unit extracts the address of a destination terminal included in a downlink packet output from a layer 2 switch, and an address determining unit determines whether or not the address of the destination terminal is registered in the address management table. In accordance with the result of the determination, a packet output unit outputs the downlink packet to a corresponding coupler.

Host unit in a passive optical network

In an optical transmission method and device of a point-multipoint type, whether or not identification information of an optical network unit designated is received within a fixed phase tolerance for a transmission enabling phase designated to optical network units on multipoint sides is determined. When it is determined that no identification information of the optical network unit designated is received and identification information of any optical network unit is received up to a transmission enabling phase subsequently designated, a transmission stop command is transmitted to the optical network unit whose identification information is received. Also, when abnormality is detected in transmitted data from the optical network unit designated or any optical network unit within a transmission enabling duration designated for the transmission enabling phase designated to the optical network units, a transmission enabling duration reducing command is transmitted to the optical network unit or all of the optical network units respectively. Thereafter, when the identification information of the optical network unit designated is received within a fixed phase tolerance for the transmission enabling phase designated to the optical network units and identification information of another optical network unit is also received up to a transmission enabling phase subsequently designated, a transmission stop command to the other optical network unit and a command for restoring the transmission enabling duration for the optical network unit and all of the optical network units are transmitted.

Optical transmission method and device

A method of communicating through a passive optical network (PON) that improves the efficiency of the network with low cost child apparatuses having only simple functions. A parent apparatus provides the child apparatuses with a multi-frame standard signal, and a child apparatus transfers asynchronous information as a frame of variable length, as it is, at a time delayed from the multi-frame standard signal by a time period designated by the parent apparatus. Since the asynchronous information does not need to be divided into pieces to which a frame header is attached, the efficiency of the uplink channel is increased.

Method of transferring frames of variable length for a passive optical network that improves network efficiency and simplifies child apparatus

An optical network unit and an optical line terminal which efficiently control the data receiving and dechurning processes in a passive optical network. In a churning parameter memory subsystem, a first memory bank stores churning parameters that are currently used, while a second memory bank stores updates made to the churning parameters. Under the control of the churning parameter memory subsystem, those first and second memory banks change their roles with each other at a churning key updating time point. A data dechurning unit receives a data stream consisting of a plurality of frames and dechurns the information contained in the data stream, according to the stored churning parameters. When an update is done to the parameters in a certain frame, the data dechurning unit makes the update effective at the next frame, thus starting data dechurning operations from the next frame.

Optical network unit and optical line terminal

In a communication system comprising a network unit and a plurality of subscriber units connected to the network unit, the network unit generates a message in which validity of transmission grant information is set for the subscriber units, and suspends a transmission of polling information to allocate a transmission grant to the subscriber units by using the transmission grant information for a fixed time in consideration of a processing time of the subscriber units from a time when the message has been completely transmitted. Also, when a disconnection state of an inputted cell from the subscriber units is detected, the network unit may suspend an input disconnection detecting operation for a fixed time from a time when the message and the polling information have been completely transmitted. Furthermore, a switchover of an input disconnection detection/transmission grant information may be suspended by mutually exchanging messages.

Communication system

An optical line terminal which sends and receives messages or data to/from optical network units (ONUs) connected thereto. A cyclic message monitor produces a trigger signal, for use in a PLOAM grant generator, at certain intervals in harmonization with upstream messages that a specific optical network unit regularly transmits. A downstream message monitor watches outgoing downstream messages to detect a certain message requesting an ONU to return a response, and it triggers the PLOAM grant generator if such a message is detected. An upstream message monitor detects an upstream message whose identification code indicates that the sending ONU has no information to return. If such an upstream message is found, it limits the issuance of PLOAM grants to that optical network unit. The PLOAM grant generator produces PLOAM grants which permit ONUs to transmit their messages, and sends them out through a PLOAM cell transmitter.

Optical line terminal

In a homo-code continuity proof testing device for testing with test data including a predetermined homo-code continuity proof test pattern, a testing device on a transmitting side synchronizes the test data in the form of a frame, including a predetermined test pattern, a data synchronous pattern, an error detecting pattern, and preferably a frame synchronous pattern for testing a homo-code continuity proof strength, with a predetermined clock, to be transmitted. A tested device on a receiving side extracts a clock included in the test data, detects the data synchronous pattern, the error detecting pattern, and the frame synchronous pattern in synchronization with the extracted clock, and determines a homo-code continuity proof test by the detection/undetection of each pattern.

Homo-code continuity proof testing device

Growing community of inventors

Fukuoka, Japan

Kazuhiro Uchida