Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An OLT 1 sequentially allocates transmission permission of a packet on an upstream transmission line to a plurality of ONUs 2 registered, 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 1.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An OLT 1 sequentially allocates transmission permission of a packet on an upstream transmission line to a plurality of ONUs 2 registered, 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 1.

Abstract: A primary station equipment unit 51 transmits, to a secondary station equipment unit 52, a message transmission enable signal granting transmission of a PST message from the secondary station equipment unit 52, when a predetermined period of time defined for transmission elapses after the primary station equipment unit 51 transmitted a downstream PST message in a redundancy switching process corresponding to the secondary station equipment unit 52.

Abstract: 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.

Abstract: An optical distribution network system includes an optical line termination and a plurality of optical network units. The optical line termination monitors a system switching request transmitted from each of the optical network units, and controls the switching between the working side and the standby side system of the optical network unit. It can solve a problem of a conventional system in that if the working side an optical network unit fails, and when its standby side is normal, even if the standby side of the other optical network units has a failure, they are switched from the working side to the standby side, thereby worsening the total system operation.

Abstract: 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.

Abstract: A slot allocation among child station devices is determined in a communication control device, and slot allocation information is sent as a downward signal to the child station devices. In each child station device, upwards packets are inserted into slots of an upward signal according to the slot allocation information, and the upward signal is sent from the child station devices to the communication control device. In the communication control device, it is checked whether or not upward packets exist in slots of the upward signal. Also, one child station device relating to slots of the upward signal currently received is identified according to a preset delay time for each child station device and a current time, the number of slots allowed for the identified child station device is detected according to the slot allocation information.

Abstract: 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.