CN107181989A - Passive optical network - Google Patents

Abstract

The invention discloses a passive optical network system, which is based on a serial port communication protocol and a system transparent transmission serial port protocol. The passive optical network system includes: a passive optical network ODN, a plurality of terminal equipment ONU and a central office equipment OLT. The passive optical network ODN includes optical fibers and passive optical splitters; the user-side communication interface of multiple terminal equipment ONUs is a serial port, which supports Uart data transparent transmission, and multiple terminal equipment ONUs use low-speed optical modules; and the central office equipment OLT uses low-speed optical modules. module, and the network side interface of the central office equipment OLT supports Uart data transparent transmission, the central office equipment OLT sends downlink data to the passive optical network ODN through optical fibers or receives uplink data from multiple terminal equipment ONUs on the user side. Wherein, the input ports of the passive optical splitter are connected to the central office equipment OLT through optical fibers, and the multiple output ports of the passive optical splitter are respectively connected to multiple terminal equipment ONUs through optical fibers. Thereby, the passive optical network system of the present invention saves cost, reduces power consumption, and has a flexible networking mode.

Description

Passive Optical Network System

technical field

The invention relates to the technical field of optical fiber communication, in particular to a passive optical network system.

Background technique

RS232/422/485 bus has the advantages of simple structure, high communication rate, convenient networking, etc. It is an important communication mode of industrial field bus. Due to the harsh working environment of most automation equipment, they are easily affected by various electromagnetic interferences. Cables are used as transmission media, and the communication reliability is not high. At the same time, the transmission distance of cables is limited, and long-distance transmission of tens of kilometers cannot be realized. Using optical fiber as the transmission medium solves the problems of electromagnetic interference and long-distance transmission of serial data. There are three ways of serial optical fiber networking: serial optical modem, industrial Ethernet and EPON passive optical network.

(1) The serial port optical modem completes the conversion from serial port to optical fiber, and realizes the long-distance transparent transmission of RS232/422/485 serial data through optical fiber. The serial optical modem is generally a "point-to-point" networking method, or multiple serial optical modems are combined into one device to support the "star" networking mode. For more complex networks, the "serial" networking mode is adopted. The common point of the three methods is that each optical fiber needs a pair of serial optical modems.

(2) The networking methods of the industrial Ethernet and serial optical modem solutions are exactly the same, and they are also "point-to-point", "star" or "serial" networking methods; The data is encapsulated in Ethernet frame and transmitted with TCP/IP protocol. The advantage of this is that the network transmits not only serial port data, but also other high-bandwidth Ethernet data.

(3) A typical EPON (Ethernet Passive Optical Network) system consists of OLT, ONU, and ODN. The central office equipment OLT is placed in the central computer room; the terminal equipment ONU is placed near the user equipment end; ODN is an optical distribution network, including passive optical splitters and optical fibers, connecting OLT and ONU equipment to realize point-to-multipoint network transmission. EPON technology is designed according to the high bandwidth requirements of telecom operators, and has been successfully commercialized in large-scale in the field of FTTC/FTTB/FTTH. In recent years, it has been widely used in the field of power automation. Encapsulate into Ethernet frame and transmit to OLT equipment. Different from the high bandwidth requirements of telecom operators, power applications have extremely high requirements on the cost and power consumption of EPON technology.

Through the research on the existing technical solutions, it is easy to conclude that the existing solutions have the following disadvantages: (1) For the serial port optical modem and industrial Ethernet solutions, each optical fiber needs a pair of optical modules, which is not suitable for high cost and power consumption. Complex networking methods such as "tree type" and "series" networking methods increase system failure points and maintenance costs, and power access in industrial environments is also a problem. (2) For EPON application solutions in electric power, since EPON technology is customized for high-bandwidth business requirements, the application bandwidth utilization rate in power systems is extremely low, and the pursuit of high bandwidth has brought about an increase in cost and power consumption, which does not meet power business need. (3) When the EPON system is connected to the Uart interface, the Uart data is encapsulated into an Ethernet data frame. For the RS232/422/485 business with a very small amount of business data, a large number of "frame headers", " Frame tail", "fill" and other bytes, the network transmission efficiency is very low

The information disclosed in this Background section is only for enhancing the understanding of the general background of the present invention and should not be taken as an acknowledgment or any form of suggestion that the information constitutes the prior art that is already known to those skilled in the art.

Contents of the invention

The purpose of the present invention is to provide a passive optical network system, which can not only realize the point-to-multipoint transmission of serial data through the passive optical network, but also meet the service requirements of low cost and low power consumption.

In order to achieve the above object, the present invention provides a passive optical network system, which is based on the serial port communication protocol and the system transparent transmission serial port protocol. The passive optical network system includes: a passive optical network ODN, a plurality of terminal equipment ONU and a local Equipment OLT. The passive optical network ODN includes optical fibers and passive optical splitters; the user-side communication interface of multiple terminal equipment ONUs is a serial port, which supports Uart data transparent transmission, and multiple terminal equipment ONUs use low-speed optical modules; and the central office equipment OLT uses low-speed optical modules. module, and the network side interface of the central office equipment OLT supports Uart data transparent transmission, the central office equipment OLT sends downlink data to the passive optical network ODN through optical fibers or receives uplink data from multiple terminal equipment ONUs on the user side. Among them, the input port of the passive optical splitter is connected to the central office equipment OLT through optical fibers, and the multiple output ports of the passive optical splitter are respectively connected to multiple terminal equipment ONUs through optical fibers, and the data in the passive optical network system is in the form of The original frame format is transmitted without encapsulation.

Preferably, in the above technical solution, the low-speed optical modules of the plurality of terminal equipment ONUs and the low-speed optical modules of the central office equipment OLT are all 2M low-speed optical modules.

Preferably, in the above technical solution, sending downlink data adopts broadcast mode, and receives uplink data adopts time division multiple access mode.

Preferably, in the above technical solution, the passive optical splitter supports a maximum splitting ratio of 1:512.

Preferably, in the above technical solution, the workflow of sending downlink data includes: within the working time window of the downlink data, the central office equipment OLT pushes the downlink data to a plurality of terminal equipment ONUs using a passive optical splitter, and the multiple terminal equipment ONUs Both open the receiving circuit, receive the downlink data and forward it from the serial port; during the sleep time window of the downlink data, the central office equipment OLT does not forward the downlink data, and multiple terminal equipment ONUs turn off the receiving circuit.

Preferably, in the above technical solution, the workflow for sending the uplink data includes: dividing the uplink time of the uplink data into multiple time slices, and each terminal equipment ONU obtains time slices of equal length; each terminal equipment ONU can only Send uplink data to the central office equipment OLT in its own time slice, and transmit only one uplink data to the central office equipment OLT through optical fiber in each time slice; each terminal equipment ONU is outside its own time slice, and the terminal equipment ONU closes the sending circuit.

Compared with the prior art, the present invention has the following beneficial effects: the passive optical network system of the present invention has the following beneficial effects compared with the serial port optical modem and the industrial Ethernet scheme: (1) the passive optical network mode saves Reduces the number of backbone fiber resources and optical modules, reduces cost and power consumption; (2) Flexible networking mode, more suitable for complex network environment of industrial bus; (3) Reduces system failure points, increases reliability, and reduces maintenance cost. Compared with the EPON scheme, the passive optical network system of the present invention has the following beneficial effects: (1) The passive optical network system adopts 2M low-speed optical modules, which saves costs and reduces power consumption. (2) Due to the high receiving sensitivity of the 2M low-speed optical module, the transmission distance is longer and the splitting ratio is larger.

Description of drawings

Fig. 1 is a topological diagram of a passive optical network system according to the present invention.

Fig. 2 is a schematic diagram of a workflow of downlink data in a passive optical network system according to the present invention.

Fig. 3 is a schematic diagram of a workflow of uplink data in a passive optical network system according to the present invention.

detailed description

The specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations thereof such as "includes" or "includes" and the like will be understood to include the stated elements or constituents, and not Other elements or other components are not excluded.

As shown in Figures 1 to 3, a passive optical network system according to a specific embodiment of the present invention is based on a serial port communication protocol and a system transparent transmission serial port protocol, and the communication system of the passive optical network system is point-to-multipoint The communication system of the passive optical network system includes: passive optical network ODN, multiple terminal equipment ONU and central office equipment OLT. The passive optical network ODN includes optical fibers and passive optical splitters; the user-side communication interface of multiple terminal equipment ONUs is a serial port, which supports Uart (Universal Asynchronous Receiver/Transmitter) data transparent transmission, and multiple terminal equipment ONUs use 2M low-speed optical modules, and the cost And the power consumption is lower, the receiving sensitivity is better, the terminal equipment ONU can exist in two forms as a communication module or an independent collector; and the central office equipment OLT adopts a 2M low-speed optical module, and the network side interface of the central office equipment OLT supports Uart data Transparent transmission, the central office equipment OLT sends downlink data to the passive optical network ODN through optical fibers or receives uplink data from multiple terminal equipment ONUs on the user side. Among them, the input port of the passive optical splitter is connected to the central office equipment OLT through optical fibers, and the multiple output ports of the passive optical splitter are respectively connected to multiple terminal equipment ONUs through optical fibers, and the data in the passive optical network system is in the form of The original frame format is transmitted without encapsulation.

Preferably, the high-density central office equipment OLT supports up to 96 PON ports, and the central office equipment OLT can exist as a communication module of a business equipment, thereby providing a higher degree of equipment integration; the passive optical splitter supports a maximum of 1:512 Split ratio.

Preferably, sending downlink data adopts a broadcast mode, and receiving uplink data adopts a time division multiple access mode.

Preferably, the workflow for sending downlink data includes: within the working time window of downlink data, the central office equipment OLT pushes the downlink data to multiple terminal equipment ONUs using a passive optical splitter, and multiple terminal equipment ONUs open the receiving circuit, Receive the downlink data and forward it from the serial port; during the sleep time window of the downlink data, the central office equipment OLT does not forward the downlink data, and multiple terminal equipment ONUs turn off the receiving circuit.

Preferably, the workflow for sending the uplink data includes: dividing the uplink time of the uplink data into multiple time slices, and each terminal equipment ONU obtains time slices of equal length; each terminal equipment ONU can only Send upstream data to the central office equipment OLT, and transmit only one upstream data stream to the central office equipment OLT through the optical fiber in each time slice, avoiding the conflict between the upstream data streams of the terminal equipment ONU, and will not cause data loss; each The terminal equipment ONU is out of its own time slice, and the terminal equipment ONU closes the transmission circuit, thereby reducing power consumption.

In practical application, the present invention can be widely applied to remote communication of meter reading systems such as electric meters, water meters, and gas meters, and can also be applied to industrial field bus networks of automation control systems such as Internet of Things, industrial and mining, transportation, and buildings. The source optical network system of the present invention is based on the serial port communication protocol and the system transparent transmission serial port protocol, without any data encapsulation, the communication system is a point-to-multipoint communication system, and its central office equipment OLT and terminal equipment ONU use 2M low-speed optical modules , The 2M rate can meet the bandwidth requirements of serial port data. Compared with the standard 1000M high-speed optical module, the cost and power consumption are lower, and the receiving sensitivity is better, and the passive optical splitter supports a maximum splitting ratio of 1:512.

In summary, the passive optical network system of the present invention has the following beneficial effects compared with the serial port optical modem and industrial Ethernet solutions: (1) the passive optical network mode saves the number of backbone optical fiber resources and optical modules, The cost and power consumption are reduced; (2) The networking mode is flexible, which is more suitable for the complex network environment of the industrial bus; (3) The failure points of the system are reduced, the reliability is increased, and the maintenance cost is reduced. Compared with the EPON scheme, the passive optical network system of the present invention has the following beneficial effects: (1) The passive optical network system adopts 2M low-speed optical modules, which saves costs and reduces power consumption. (2) Due to the high receiving sensitivity of the 2M low-speed optical module, the transmission distance is longer and the splitting ratio is larger.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling others skilled in the art to make and use various exemplary embodiments of the invention, as well as various Choose and change. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims (6)

1. a kind of passive optical network, it is based on serial communication protocol and system transparent transmission serial port protocol, it is characterised in that described Passive optical network is included：

EPON ODN, it includes optical fiber and passive optical splitters；

Multiple terminal devices ONU, its user side communication interface is serial ports, supports Uart data penetration transmissions, and the multiple terminal is set Standby ONU uses low speed optical module；And

Local side apparatus OLT, it uses low speed optical module, and the Network Side Interface of the local side apparatus OLT supports that Uart data are saturating Pass, the local side apparatus OLT sends downlink data to the EPON ODN by the optical fiber or receives to come from user side The multiple terminal device ONU upstream data；

Wherein, the input port of the passive optical splitters is connected by the optical fiber with the local side apparatus OLT, and described passive Multiple output ports of optical splitter are connected by the optical fiber with the multiple terminal device ONU respectively, and

Data in wherein described passive optical network are transmitted without being packaged with original frame format.

2. passive optical network according to claim 1, it is characterised in that the multiple terminal device ONU's is described Low speed optical module and the local side apparatus OLT low speed optical module are 2M low speed optical modules.

3. passive optical network according to claim 1, it is characterised in that it is using broadcast to send the downlink data Pattern, it is to use time division multiple acess pattern to receive the upstream data.

4. passive optical network according to claim 1, it is characterised in that the passive optical splitters maximum supports 1: 512 splitting ratios.

5. passive optical network according to claim 3, it is characterised in that send the workflow of the downlink data Comprising：

In the working time window of the downlink data, under the local side apparatus OLT will be described using the passive optical splitters Row data are pushed to the multiple terminal device ONU, and the multiple terminal device ONU opens receiving circuit, under reception is described Row data are simultaneously forwarded from the serial ports；With

In the dormancy time window of the downlink data, the local side apparatus OLT is without forwarding the downlink data, and institute State multiple terminal devices ONU and all close receiving circuit.

6. passive optical network according to claim 3, it is characterised in that send the workflow of the upstream data Comprising：

The upstream time of the upstream data is divided into multiple timeslices, each terminal device ONU obtains equal length The timeslice；

Each terminal device ONU can only be described to local side apparatus OLT transmissions in the one's own timeslice Upstream data, and a upstream data is only transmitted to the local side apparatus by the optical fiber in each timeslice OLT；With

Each terminal device ONU is outside the timeslice of oneself, and the terminal device ONU closes transtation mission circuit.