Mitsubishi Denki Kabushiki Kaisha

Yoshihiro Asashiba

Toshikazu Yoshida

Hiroaki Mukai

Seiji Kozaki

Hiroshi Ichibangase

Michiya Takemoto

Mitsuyoshi Iwasaki

Takamasa Suzuki

Tetsuya Yokotani

Ryusuke Kawate

Eiichi Horiuchi

Minoru Akita

Mitsuru Tsuchida

A passive optical network including: a parent station OLT (optical line terminal); and a plurality of child stations ONU (optical network terminating unit), wherein the parent station and the plurality of child stations transmit an upstream frame and a downstream frame to each other, and the parent station includes means for generating a maintenance signal indicating failure at a mini slot, corresponding to each of the plurality of child stations, on a basis of a receiving state of a signal at the mini slot sent from each of the plurality of child stations.

Control system using a mini slot signal in a passive optical network

A primary station equipment unit transmits, to a secondary station equipment unit, a message transmission enable signal granting transmission of a PST message from the secondary station equipment unit, when a predetermined period of time defined for transmission elapses after the primary station equipment unit transmitted a downstream PST message in a redundancy switching process corresponding to the secondary station equipment unit.

Optical multi-branch communication system

According to an aspect of this invention, dynamic bandwidth assignment (DBA) can be performed without interrupting communication of a regular cell and interfering with communication between child stations. In a passive optical network including a parent station and a plurality of child stations, a maintenance signal for a mini slot signal is provided. Each of the child stations sends a corresponding maintenance signal if necessary, and the parent station controls state transition by using the maintenance signal concerning on the mini slot signal for each of the child stations. By controlling the state transition, the dynamic bandwidth assignment can be performed.

An OLTsequentially allocates transmission permission of a packet on an upstream transmission line to a plurality of ONUsregistered, and performs packet communication in a simplified method with control by using a first timer for detecting a packet signal and a second timer for controlling transmission permission time, in order to transmit an IP packet of variable length without mounting a function of complex processing for analyzing an upstream packet in the OLT

Packet transmission system, packet transmission method, packet transmission program, and recording medium on which the recorded program is recorded

A dynamic bandwidth assignment system includes a network unit for carrying out cell slot assignment, and a network termination for transmitting cells to the network unit by means of cell slots assigned by the network unit. When the number of consecutive valid cells the network unit receives from the network terminations exceeds a predetermined threshold value, the network unit increases the number of the cell slots to be assigned to the network termination. The system can solve a problem of a conventional system in that it is unavoidable that a cell transfer delay and a bursting tendency of cells are statistically increased.

Dynamic bandwidth assignment system and dynamic bandwidth assignment method capable of reducing cell transmission delay

An optical distribution network system includes an OLT; a plurality of ONUs; a first optical network and a second optical network, one of which connects the OLT with the plurality of ONUs; and a bandwidth controller. The bandwidth controller apportions the plurality of ONUs between the first optical network and the second optical network, assigns a predetermined transmission bandwidth to each of the plurality of ONUs, and accepts a bandwidth change of the transmission bandwidth. It solves a problem of a conventional optical distribution network system in that the maximum bandwidth available by DBA (dynamic bandwidth assignment) is equal to the total transmission bandwidth of working side minus the sum total of the minimum cell rates of the ONUs, and hence it cannot secure a large usable bandwidth for DBA, when congestion of bandwidth increase takes place among the plurality of ONUs.

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Tokyo, Japan

Yoshihiro Asashiba