A ship internal communication system based on a passive optical network

Abstract

The application discloses a ship internal communication system based on a passive optical network and belongs to the technical field of ship internal communication, which comprises an optical line terminal (OLT) arranged on a ship bridge and used for providing a network side interface and performing centralized control, an optical distribution network (ODN) composed of a backbone optical fiber, a passive optical splitter and branch optical fibers and used for distribution and transmission of optical signals, wherein the passive optical splitter is arranged on each deck of the ship and supports a splitting ratio of 1:64 to 1:128. In the application, the passive optical network architecture is introduced to replace the traditional copper cable wiring with optical fibers, the cable weight is reduced by about 90%, the overall load of the ship is significantly reduced, the high splitting ratio of 1:64 to 1:128 is supported by using a single optical fiber, the complex wiring topology in the cabin is greatly simplified, and the ship environment with small space and dense layers is especially suitable.

Description

Technical Field

[0001] This invention belongs to the field of shipboard internal communication technology, specifically a shipboard internal communication system based on a passive optical network. Background Technology

[0002] Passive Optical Network (PON) is a fiber optic access technology that uses a point-to-multipoint topology. Its core feature is that the optical distribution network (ODN) uses only passive optical splitters to distribute and transmit optical signals, eliminating the need for power supplies to intermediate nodes and active electronic devices. This technology supports multiple users with a single optical fiber and has advantages such as high bandwidth, low loss, and resistance to electromagnetic interference. It has been widely used in terrestrial fiber-to-the-home (FTTH) and industrial Ethernet scenarios. With the improvement of ship automation and intelligence, the number of shipborne sensors, monitoring equipment, and control systems has increased significantly, placing higher demands on the bandwidth, reliability, and real-time performance of shipboard communication networks.

[0003] However, existing shipboard internal communication systems generally use copper Ethernet or industrial fieldbuses (such as CAN and Modbus) for cabling, which have several technical drawbacks: First, copper cables are heavy and complex to install, making construction difficult in the confined and densely layered compartments of ships, and significantly increasing the overall load on the ship; second, copper cable transmission is susceptible to interference from the strong electromagnetic environment of the ship's engine room and steering gear room, resulting in significant electromagnetic compatibility issues and making it difficult to guarantee the reliable transmission of critical control commands; third, traditional network topologies have poor scalability, requiring the re-laying of cables and modification of core equipment configuration when adding sensor nodes, leading to high construction costs and long ship downtime; fourth, existing systems cannot meet the deterministic requirements of microsecond-level low-latency transmission for critical operations such as main engine speed regulation and steering gear steering, resulting in insufficient real-time control performance. Therefore, there is an urgent need for an internal communication system suitable for the special environment of ships, possessing high reliability, low latency, and flexible scalability. Summary of the Invention

[0004] The purpose of this invention is to provide a shipboard internal communication system based on a passive optical network to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a shipboard internal communication system based on a passive optical network, comprising:

[0006] Optical line terminal (OLT), deployed on the ship's bridge, is used to provide network-side interfaces and perform centralized control;

[0007] An optical distribution network (ODN) consists of a backbone fiber, passive optical splitters, and branch fibers, and is used for the distribution and transmission of optical signals. The passive optical splitters are deployed on various decks of the ship and support a splitting ratio of 1:64 to 1:128.

[0008] An optical network unit (ONU) is deployed in the engine room, steering gear room and cargo hold area. It is connected to the passive optical splitter through the branch optical fiber and is used to provide a user-side interface and access the shipborne terminal equipment.

[0009] The OLT is connected to the passive optical splitter via the trunk optical fiber, and the passive optical splitter is connected to multiple ONUs via the branch optical fiber, forming a point-to-multipoint tree-shaped physical topology.

[0010] As a further preferred embodiment of this technical solution: the optical line terminal (OLT) includes:

[0011] The Dynamic Bandwidth Allocation (DBA) module is used to allocate transmission time slots to different ONUs according to the service type, which includes at least real-time control commands, video surveillance, and environmental monitoring.

[0012] The priority scheduling unit is used to allocate high-priority time slots for real-time control commands and low-priority time slots for video surveillance and environmental monitoring, so as to achieve microsecond-level low-latency transmission of control commands.

[0013] As a further preferred embodiment of this technical solution: the Dynamic Bandwidth Allocation (DBA) module controls the transmission delay of the corresponding time slot to within 50 microseconds by identifying the control command feature code in the service flow;

[0014] As a further preferred embodiment of this technical solution: the optical network unit (ONU) includes:

[0015] The protocol conversion module is used to transparently convert Ethernet frames into industrial fieldbus protocol frames, wherein the industrial fieldbus protocol includes at least the CANopen protocol and the Modbus protocol.

[0016] A multi-protocol interface unit is used to connect to shipborne sensor equipment, which includes at least a rudder angle sensor, a temperature sensor, and a pressure sensor.

[0017] As a further preferred embodiment of this technical solution: the protocol conversion module includes:

[0018] The frame parsing unit is used to parse Ethernet frames from the PON side and extract payload data;

[0019] A protocol encapsulation unit is used to re-encapsulate the payload data according to the target industrial protocol format.

[0020] The transparent mapping unit is used to maintain the integrity of the original data content without modifying the protocol semantics.

[0021] As a further preferred embodiment of this technical solution: the passive optical splitter in the optical distribution network (ODN) is a completely passive device that does not require external power supply and heat dissipation device, and the backbone fiber and branch fiber are made of bending resistant single-mode fiber to meet the wiring requirements of the narrow space in the ship cabin.

[0022] As a further preferred embodiment of this technical solution: the tree-shaped physical topology is a loop-free design, and the optical line terminal (OLT) distinguishes different optical network units (ONUs) through logical link identifiers (LLIDs).

[0023] As a further preferred embodiment of this technical solution, the system further includes:

[0024] The network management module, integrated into the optical line terminal (OLT), is used for remote configuration, fault monitoring, and online upgrade of the optical network unit (ONU);

[0025] The optical power monitoring unit is used to monitor the optical power attenuation status of each optical link in the optical distribution network (ODN) in real time and issue an alarm when there is an abnormality.

[0026] As a further preferred embodiment of this technical solution: the optical network unit (ONU) adopts an industrial-grade protection design with a protection level of not less than IP67 and an operating temperature range of -40℃ to +85℃ to adapt to the harsh environment of ships with high humidity, high salt spray and vibration shock.

[0027] As a further preferred embodiment of this technical solution, the system expansion method is as follows: when adding a new shipborne sensor node, it is only necessary to deploy a new optical network unit (ONU) in a nearby location and connect it to the existing passive optical splitter through a branch optical fiber, without the need to re-lay the trunk optical fiber or modify the optical line terminal (OLT) configuration.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. In this invention, by introducing a passive optical network architecture, optical fiber is used to completely replace traditional copper cable wiring, reducing cable weight by about 90% and significantly reducing the overall load on the ship. At the same time, the single optical fiber supports a high split ratio of 1:64 to 1:128, which greatly simplifies the complex wiring topology in the ship's cabin, making it particularly suitable for the confined space and densely layered ship environment.

[0030] 2. In this invention, the optical distribution network (ODN) adopts a completely passive optical splitter, which does not require power supply and heat dissipation devices, completely eliminating the potential for failure of intermediate nodes and achieving maintenance-free operation. In addition, optical fiber transmission is naturally immune to electromagnetic interference (EMI) and electromagnetic pulse (EMP), which fundamentally solves the problem that communication signals are easily interfered with in strong electromagnetic environments such as ship engine rooms and steering gear rooms, and ensures the long-term stability and reliability of communication links.

[0031] 3. In this invention, the Dynamic Bandwidth Allocation (DBA) module and priority scheduling unit built into the Optical Line Terminal (OLT) can identify control command signature codes and allocate high-priority time slots for real-time control commands, keeping end-to-end transmission latency within 50 microseconds. This fully meets the deterministic low-latency requirements for critical operations such as ship main engine speed regulation and steering gear steering. At the same time, the tree-shaped physical topology adopts a loop-free design, distinguishing different optical network units (ONUs) through Logical Link Identifiers (LLIDs), effectively avoiding broadcast storms and improving network security. Combined with the optical power monitoring unit to detect link attenuation in real time and issue alarms, and the network management module to remotely configure, monitor faults, and upgrade ONUs online, the operational reliability and management convenience of the ship's internal communication system are significantly improved.

[0032] 4. In this invention, by setting a protocol conversion module in the optical network unit (ONU), Ethernet frames are transparently converted into industrial fieldbus protocol frames such as CANopen and Modbus. Seamless access can be achieved without modifying the original sensor equipment, and it is fully compatible with the existing shipboard fieldbus equipment. When a new monitoring node is needed, only a new ONU needs to be deployed nearby and connected to the existing passive optical splitter through a branch optical fiber. There is no need to lay the trunk optical fiber again or modify the OLT configuration. It supports plug-and-play expansion and greatly reduces the construction cost and downtime of the ship's communication system transformation. Attached Figure Description

[0033] Figure 1 This is a flowchart of a shipboard internal communication system based on a passive optical network according to the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1:

[0036] Please see Figure 1As shown, the present invention provides a shipboard internal communication system based on a passive optical network;

[0037] Application Background: A bulk carrier with a total length of 200 meters and a deadweight of 30,000 tons, designed to solve the technical problems of complex wiring, sensitivity to electromagnetic interference, poor scalability, and difficulty in meeting the requirements of low-latency transmission of real-time control commands in traditional ship internal communication systems.

[0038] Optical line terminal (OLT), deployed on the ship's bridge, is used to provide network-side interfaces and perform centralized control;

[0039] An optical distribution network (ODN) consists of a backbone fiber, passive optical splitters, and branch fibers, and is used for the distribution and transmission of optical signals. The passive optical splitters are deployed on various decks of the ship and support a splitting ratio of 1:64 to 1:128.

[0040] An optical network unit (ONU) is deployed in the engine room, steering gear room and cargo hold area. It is connected to the passive optical splitter through the branch optical fiber and is used to provide a user-side interface and access the shipborne terminal equipment.

[0041] The OLT is connected to the passive optical splitter via the trunk optical fiber, and the passive optical splitter is connected to multiple ONUs via the branch optical fiber, forming a point-to-multipoint tree-shaped physical topology.

[0042] Further details: OLT deployment: An OLT device is deployed in the control cabinet of the ship's bridge. The OLT provides a standard uplink network side interface (such as GE or 10GE optical port) for interconnection with the ship's integrated navigation system, automatic identification system (AIS) and external satellite communication system. As the core of the entire PON network, the OLT performs registration, ranging, dynamic bandwidth allocation and centralized control management of all ONUs.

[0043] ODN Deployment: The ODN consists of one trunk fiber and three passive optical splitters, which are deployed on decks A, B, and C respectively. The trunk fiber is a bend-resistant single-mode fiber, laid along the ship's cable channel from the bridge to the installation points of the optical splitters on each deck. Each optical splitter uses a fully passive optical power distribution device with a splitting ratio of 1:64, requiring no power supply or heat dissipation device. The input port of the optical splitter is connected to the trunk fiber, and the output port is connected to the branch fiber.

[0044] ONU Deployment: A total of 15 ONU devices were deployed, including:

[0045] Three ONUs are deployed in the engine compartment area, which are respectively connected to the main engine speed sensor, exhaust temperature sensor and fuel pressure sensor;

[0046] Two ONUs are deployed in the steering gear room, connecting the steering angle feedback sensor and the hydraulic oil temperature sensor;

[0047] Four ONUs are deployed in the cargo hold area, connecting the cargo hold smoke detectors and the hatch status sensors;

[0048] The remaining ONUs are reserved for future expansion;

[0049] All ONUs are equipped with industrial-grade protective housings with an IP67 protection rating, an operating temperature range of -40℃ to +85℃, and are reinforced for vibration and shock resistance.

[0050] Topology: The OLT is connected to the passive optical splitters on each deck via the backbone fiber. Each optical splitter is then connected to multiple ONUs via branch optical fibers, forming a typical point-to-multipoint tree physical topology. This topology is a loop-free design. The OLT distinguishes different terminals by assigning a unique Logical Link Identifier (LLID) to each ONU to avoid data conflicts.

[0051] The workflow is as follows:

[0052] When the bridge issues commands such as ship steering and main engine speed adjustment, the OLT first identifies the command data packet. Then, the Dynamic Bandwidth Allocation (DBA) module and priority scheduling unit immediately place the command in a high-priority channel and allocate the nearest transmission time slot. Ordinary services such as video monitoring or temperature data are placed in a low-priority channel. Ultimately, the entire transmission time from the OLT to the target ONU for control commands does not exceed 50 microseconds, ensuring the real-time performance of critical ship control commands. At the same time, transparent conversion of heterogeneous fieldbus protocols is achieved. Specifically, sensors in areas such as the engine room and steering gear room mostly use CANopen or Modbus protocols, while the PON network transmits Ethernet frames. Then, the ONU's built-in protocol conversion module completes the translation between the two protocols. The two translations are as follows: Downlink: The Ethernet frame sent by the OLT is unpacked, the valid data is extracted, and it is repackaged into CANopen / Modbus format and sent to the sensor. Uplink: The CANopen / Modbus data sent by the sensor is encapsulated into Ethernet frames without modification and sent to the OLT. Thus, the entire process does not change the original data content, ensuring data authenticity and integrity, and there is no need to replace the original sensors.

[0053] The optical power monitoring unit checks the signal strength of each optical fiber link in real time. If the optical power of a branch optical fiber drops beyond the threshold due to bending or dirty connectors, the system immediately sends an alarm to the bridge and indicates which link is faulty. As a result, the crew can quickly find and locate optical fiber problems without having to go to the engine room or cargo hold.

[0054] Meanwhile, when a ship needs to add new monitoring nodes, the expansion steps are as follows:

[0055] A new ONU is deployed near the ballast water treatment room. This ONU is then connected to an idle output port of the existing passive optical splitter on this deck via a new branch optical fiber. The physical connection is completed without any operation. The OLT identifies the new ONU through an automatic discovery mechanism and the serial number acquisition and registration process defined by the PON protocol, and assigns it a new LLID and bandwidth configuration. The entire process does not require laying new trunk optical fiber, replacing or modifying OLT hardware, or interrupting existing communication services, achieving true plug-and-play expansion. This significantly reduces the construction cost of the ship's communication system upgrade and the ship's downtime.

[0056] Example 2

[0057] This embodiment is basically the same as Embodiment 1, except that the passive optical splitter adopts a 1:128 splitting ratio and is applied to a very large liquefied natural gas carrier. The DBA module of the OLT can still control the end-to-end delay of the control command within 50 microseconds through a more refined time slot allocation algorithm. At the same time, the backbone fiber in the ODN adopts a dual-path redundant backup design. When the primary fiber is broken due to an accident, the OLT and ONU automatically switch to the backup fiber with a switching time of less than 50 milliseconds, which further improves the reliability of the system.

[0058] Example 3

[0059] This embodiment provides a network management method for a ship's internal communication system, based on the system described in Embodiment 1. The network management module performs the following steps:

[0060] Initialization phase: The OLT periodically sends a discovery gate message. After receiving the message, the newly connected ONU sends a registration request, which includes its own sequence number. After the OLT confirms the request, it assigns an LLID to the ONU and measures its logical distance.

[0061] During operation: The network management module collects the status parameters of each ONU in real time. The parameters include: operating temperature, power supply voltage, optical module transmit and receive power, packet loss rate, and bit error rate. When any parameter exceeds the preset threshold, the module automatically triggers a remote restart or reduces the bandwidth limit of the ONU to control heat generation.

[0062] Upgrade phase: The network management module distributes the new firmware in blocks to the designated ONU via the OMCI protocol. After receiving the firmware, the ONU verifies its integrity and automatically flashes and restarts the firmware. No on-site operation is required throughout the entire process.

[0063] Conclusion: Through the above management methods, this system realizes remote operation and maintenance of the entire life cycle of the ship's internal communication nodes, which is particularly suitable for harsh environments such as the engine room and cargo hold where personnel cannot stay for long periods of time.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A shipboard internal communication system based on a passive optical network, characterized in that, include: Optical line terminal (OLT), deployed on the ship's bridge, is used to provide network-side interfaces and perform centralized control; An optical distribution network (ODN) consists of a backbone fiber, passive optical splitters, and branch fibers, and is used for the distribution and transmission of optical signals. The passive optical splitters are deployed on various decks of the ship and support a splitting ratio of 1:64 to 1:

128. An optical network unit (ONU) is deployed in the engine room, steering gear room and cargo hold area. It is connected to the passive optical splitter through the branch optical fiber and is used to provide a user-side interface and access the shipborne terminal equipment. The OLT is connected to the passive optical splitter via the trunk optical fiber, and the passive optical splitter is connected to multiple ONUs via the branch optical fibers, forming a point-to-multipoint tree-shaped physical topology.

2. The shipboard internal communication system based on a passive optical network according to claim 1, characterized in that: The optical line terminal (OLT) includes: The Dynamic Bandwidth Allocation (DBA) module is used to allocate transmission time slots to different ONUs according to the service type, which includes at least real-time control commands, video surveillance, and environmental monitoring. The priority scheduling unit is used to allocate high-priority time slots for real-time control commands and low-priority time slots for video surveillance and environmental monitoring, so as to achieve microsecond-level low-latency transmission of control commands.

3. The shipboard internal communication system based on a passive optical network according to claim 2, characterized in that: The Dynamic Bandwidth Allocation (DBA) module controls the transmission delay of the corresponding time slot to within 50 microseconds by identifying the control command signature codes in the service flow.

4. A shipboard internal communication system based on a passive optical network according to claim 1, characterized in that: The optical network unit (ONU) includes: The protocol conversion module is used to transparently convert Ethernet frames into industrial fieldbus protocol frames, wherein the industrial fieldbus protocol includes at least the CANopen protocol and the Modbus protocol. A multi-protocol interface unit is used to connect to shipborne sensor equipment, which includes at least a rudder angle sensor, a temperature sensor, and a pressure sensor.

5. A shipboard internal communication system based on a passive optical network according to claim 4, characterized in that: The protocol conversion module includes: The frame parsing unit is used to parse Ethernet frames from the PON side and extract payload data; A protocol encapsulation unit is used to re-encapsulate the payload data according to the target industrial protocol format. The transparent mapping unit is used to maintain the integrity of the original data content without modifying the protocol semantics.

6. A shipboard internal communication system based on a passive optical network according to claim 1, characterized in that: The passive optical splitter in the optical distribution network (ODN) is a completely passive device that requires no external power supply or heat dissipation device, and the backbone fiber and branch fiber are made of bending resistant single-mode fiber to meet the wiring requirements of the narrow space in the ship cabin.

7. A shipboard internal communication system based on a passive optical network according to claim 1, characterized in that: The tree-shaped physical topology is a loop-free design, and the optical line terminal (OLT) distinguishes different optical network units (ONUs) through logical link identifiers (LLIDs).

8. A shipboard internal communication system based on a passive optical network according to any one of claims 1 to 7, characterized in that: The system also includes: The network management module, integrated into the optical line terminal (OLT), is used for remote configuration, fault monitoring, and online upgrade of the optical network unit (ONU); The optical power monitoring unit is used to monitor the optical power attenuation status of each optical link in the optical distribution network (ODN) in real time and issue an alarm when there is an abnormality.

9. A shipboard internal communication system based on a passive optical network according to claim 1, characterized in that: The optical network unit (ONU) adopts an industrial-grade protection design with a protection level of no less than IP67 and an operating temperature range of -40℃ to +85℃ to adapt to the harsh environment of ships with high humidity, high salt spray and vibration impact.

10. The closed-loop ecological marine system device according to claim 1, characterized in that: The system expansion method is as follows: when adding a new shipborne sensor node, it is only necessary to deploy a new optical network unit (ONU) in a nearby location and connect it to the existing passive optical splitter through a branch optical fiber, without having to re-lay the trunk optical fiber or modify the optical line terminal (OLT) configuration.

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