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JP-7855151-B2 - Optical network termination device

JP7855151B2JP 7855151 B2JP7855151 B2JP 7855151B2JP-7855151-B2

Inventors

  • 村上 謙

Assignees

  • 三菱電機株式会社

Dates

Publication Date
20260507
Application Date
20231019

Claims (5)

  1. An optical signal transmission unit that transmits the optical signal to the station-side equipment when it receives a transmission permission, which is permission to transmit an optical signal, An optical output control unit that grants the optical signal transmission unit permission to transmit the optical signal at a time allocated by the station-side equipment in order to transmit the optical signal, A fault detection unit monitors the transmission permission and the transmission status of the optical signal, and when it detects an abnormal light emission state, it issues a transmission permission invalidation instruction, which is an instruction to invalidate the transmission permission, to the optical signal transmission unit and the switch unit . The system includes a switch unit that cuts off the power supplied to the optical signal transmission unit when the instruction to invalidate the transmission permission is given , The optical line termination device is characterized in that the optical signal transmission unit stops transmitting the optical signal when power is cut off by the switch unit, or stops transmitting the optical signal even if it has been granted permission to transmit when it receives the instruction to invalidate the transmission permission.
  2. The optical output control unit outputs an optical output permission signal indicating permission to transmit to the optical signal transmission unit. The optical signal transmission unit outputs an optical output status signal to the fault detection unit, which indicates whether or not it is outputting the optical signal as the transmission status. The optical circuit termination device according to claim 1, characterized in that the fault detection unit monitors the optical output permission signal and the optical output status signal, and detects the abnormal light emission state when the optical signal transmission unit has been outputting the optical signal for a predetermined time or longer.
  3. The system further includes a signal processing unit that, when the abnormal light emission state is detected, notifies the station-side device via the optical output control unit of information indicating that the abnormal light emission state has been detected. The optical line termination device according to claim 1 or 2, characterized in that the fault detection unit gives the instruction to invalidate the transmission permission to the optical signal transmission unit after the notification of the information has been made.
  4. The system further includes a signal processing unit that, in accordance with instructions from the station-side equipment, restarts the transmission of the optical signal by the optical signal transmission unit, which has stopped transmitting the optical signal in accordance with the instruction to invalidate the transmission permission, When the fault detection unit detects the abnormal light emission state, it stores information indicating that the abnormal light emission state has been detected. The optical circuit termination device according to claim 1 or 2, characterized in that the signal processing unit does not restart the transmission of the optical signal by the optical signal transmission unit, even if instructed by the station-side device, while information indicating that the abnormal light emission state has been detected is being held.
  5. The optical line termination device according to claim 4, characterized in that the fault detection unit stops retaining information indicating that the abnormal light emission state has been detected when the power to the optical line termination device is turned on after it has been turned off.

Description

This disclosure relates to an optical network terminal. In a Passive Optical Network (PON) system, uplink data is transmitted using Time Division Multiplexing (TDMA). The Optical Line Terminal (OLT), a central office device, allocates a data transmission time grant to each Optical Network Unit (ONU). The ONU emits light during the time allocated by the OLT to transmit uplink data. Here, the OLT determines the allocation time so that the time allocated to each ONU does not overlap. As a result, only one ONU can emit light and transmit data at a time. If an ONU malfunctions and emits light outside of its allocated time, the uplink data signals of non-malfunctioning ONUs will be overwhelmed. If the illumination continues for a predetermined period of time or longer (hereinafter referred to as "abnormal illumination state"), it will affect the communication of all ONUs under the OLT. In the conventional ONU described in Patent Document 1, when the fault detection unit detects an abnormal light emission state, it controls the power supply Disable signal to shut off the power to the optical module transmitter via the optical module power supply unit. As a result, the optical module transmitter stops emitting light. Japanese Patent Publication No. 2011-29883 (paragraphs 0018-0032, Figure 2) This is a block diagram that schematically shows the overall configuration of the PON system according to Embodiment 1.This is a block diagram schematically showing the main components of the ONU according to Embodiment 1.This is a first time chart showing the optical output Enable signal or optical output status signal, the transmit permission invalid signal, the supplied power, and the optical output in Embodiment 1.This is a second time chart showing the optical output Enable signal or optical output status signal, the transmit permission invalid signal, the supplied power, and the optical output in Embodiment 1.This is a third time chart showing the optical output Enable signal or optical output status signal, the transmit enable invalid signal, the supplied power, and the optical output in Embodiment 1.This is a block diagram schematically showing the main components of the ONU in Embodiment 2.This is a block diagram schematically showing the configuration of the upstream queue control unit in Embodiment 2.This is a time chart showing the optical output Enable signal or optical output status signal, the transmit permission invalid signal, the supplied power, and the optical output in Embodiment 2.This is a block diagram schematically showing the main components of the ONU in Embodiment 3. Embodiment 1. Figure 1 is a block diagram schematically showing the overall configuration of the PON system 100 according to Embodiment 1. The PON system 100 comprises an OLT 110, which is a central office-side device, and an ONU 120, which is a subscriber-side termination device or optical line termination device. The OLT 110 and the ONU 120 are connected via the optical fiber 101 and the optical coupler 102. Although Figure 1 shows multiple ONUs 120, the PON system 100 only needs to be equipped with at least one ONU 120. Terminal 103 is connected to ONU 120. Uplink data signals are transmitted from terminal 103 and sent to network 104 via ONU 120 and OLT 110. Figure 2 is a block diagram schematically showing the main components of the ONU 120 according to Embodiment 1. In Embodiment 1, the main components of the ONU 120 include a PON MAC (Media Access Control) 130 as a control unit, an optical module 140 as an optical communication interface, and an FET switch 150. The PON MAC130 comprises an optical output control unit 131, an upstream queue control unit 132, and a fault detection unit 133. The optical output control unit 131 grants the optical module 140 a transmit permission, which is permission to transmit an optical signal, at the time allocated by the OLT 110 for transmitting the optical signal. For example, the optical output control unit 131 provides the optical module 140 with an optical output Enable signal (also called an optical output permission signal), which is a signal that permits optical output. The upstream queue control unit 132 stores the upstream data signal from terminal 103 in a queue and performs queue control for transmission to OLT 110. The fault detection unit 133 monitors the transmission permission and the transmission status of the optical signal, and if it detects an abnormal light emission state, it gives the optical module 140 a transmission permission invalidation instruction, which is an instruction to invalidate the transmission permission. For example, the fault detection unit 133 monitors the optical output Enable signal output from the optical output control unit 131 and the optical output status signal output from the optical module 140. The fault detection unit 133 monitors the optical output Enable signal and the optical output status signal, and if it detects a fault, it outputs a transmission