CN108882062B - Passive optical network asymmetric system and management method thereof - Google Patents

Passive optical network asymmetric system and management method thereof Download PDF

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CN108882062B
CN108882062B CN201810532659.XA CN201810532659A CN108882062B CN 108882062 B CN108882062 B CN 108882062B CN 201810532659 A CN201810532659 A CN 201810532659A CN 108882062 B CN108882062 B CN 108882062B
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wavelength
onu
olt
channel
downlink
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CN108882062A (en
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刘静霞
王素椅
侯景元
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Fiberhome Telecommunication Technologies Co Ltd
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Fiberhome Telecommunication Technologies Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
    • H04J14/0241—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
    • H04J14/0242—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
    • H04J14/0254—Optical medium access
    • H04J14/0272—Transmission of OAMP information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q11/0067—Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/0086—Network resource allocation, dimensioning or optimisation

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  • Computer Networks & Wireless Communication (AREA)
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  • Small-Scale Networks (AREA)
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Abstract

A passive optical network asymmetric system and a management method thereof relate to the technical field of passive optical networks, the system comprises an optical line terminal OLT, an optical distribution network ODN and a plurality of optical network units ONU, wherein the plurality of ONU are connected with the OLT through the ODN in a time division multiplexing mode, and the ONU supports an uplink channel with one wavelength and downlink channels with a plurality of wavelengths; the OLT supports an uplink channel with at least one wavelength and a downlink channel with at least two wavelengths; the system improves the downlink bandwidth by increasing the number of the downlink channels, and the uplink bandwidth is kept unchanged or is improved by the speed of the single wavelength channel. On the basis of the system structure, a management method is provided, so that the system can be normally operated and maintained. The invention can reduce the difficulty of increasing the network bandwidth and reduce the cost of increasing the network bandwidth.

Description

Passive optical network asymmetric system and management method thereof
Technical Field
The invention relates to the technical field of passive optical networks, in particular to a passive optical network asymmetric system and a management method thereof.
Background
With the development of 5G mobile communication and the application of new services such as 4K/8K, users have increasingly demanded bandwidth, and a Passive Optical Network (PON) as an Optical access "last kilometer" needs to upgrade bandwidth of an existing PON Network. At present, a PON system mainly comprises an Optical Line Terminal (OLT), an Optical Distribution Network (ODN), and an Optical Network Unit (ONU), where a downlink adopts a broadcast mode and an uplink adopts a Time Division Multiplexing (TDM) mode to transmit signals, and the working wavelengths of the uplink and the downlink are paired, that is, the number of the working wavelengths of the uplink and the downlink is the same.
At present, there are two main ways for upgrading the bandwidth of the PON, one is to increase the number of wavelength channels, and the other is to increase the rate of a single wavelength channel. Increasing the number of the uplink and downlink wavelength channels at the same time undoubtedly requires more wavelength resources. Because dispersion and loss in all wave bands are small, device technology is not improved, and only two wavelength windows exist in an uplink channel suitable for a PON network to carry out data transmission, the difficulty is brought to a transmission and access network system by simultaneously increasing the number of wavelength channels in the uplink and the downlink. In addition, the uplink and downlink wavelength channels are increased at the same time, and the design difficulty of the system and the construction, operation and maintenance cost of the network are increased. The PON network upgrading method for improving the single wavelength channel rate also puts higher requirements on the aspects of bandwidth, isolation and the like of optical devices and electric chips, increases the technical difficulty and development cost of implementation, and the technical maturity of the existing devices is difficult to achieve. Since PON networks are relatively cost sensitive and require sharing with existing ODNs, network economics are also a concern while optical access network bandwidth is upgraded.
Therefore, how to increase the network bandwidth at low cost and perform system management and operation is an urgent problem to be solved.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a passive optical network asymmetric system and a management method thereof.
In order to achieve the above purpose, the present invention adopts a passive optical network asymmetric system, which comprises an optical line terminal OLT, an optical distribution network ODN and a plurality of optical network units ONU, wherein the ONUs are all connected with the OLT through the ODN in a time division multiplexing manner, and the OLT supports at least one uplink wavelength channel and at least two downlink wavelength channels; the ONU supports an uplink wavelength channel and at least one downlink wavelength channel; the system increases the downlink bandwidth by increasing the number of the downlink wavelength channels, and the uplink bandwidth is kept unchanged or is increased by the speed of the single wavelength channel.
On the basis of the technical scheme, the OLT comprises a first MAC and logic control module, a double-rate filtering module and an OLT optical module;
in a downlink direction, the first MAC and logic control module is configured to perform link control and transmit network-side data to the OLT optical module, where the OLT optical module is configured to convert the data into an optical signal and combine the optical signal with a single-mode optical fiber;
in an uplink direction, the OLT optical module is configured to receive an optical signal from a single-mode fiber, the dual-rate filtering module is configured to perform rate separation on the optical signal from the OLT optical module, and the first MAC and logic control module is configured to transmit the uplink signal separated by the dual-rate filtering module to a network side.
On the basis of the above technical solution, the OLT optical module includes:
the OLT comprises at least two OLT output units, a logic control module and a first MAC and logic control module, wherein the OLT output units are used for receiving downlink signals from the first MAC and logic control module;
the WDM unit is used for combining the downlink signals into a single-mode optical fiber and also used for transmitting the uplink signals from the single-mode optical fiber in a wave-splitting manner;
and the OLT is provided with at least one receiving unit for transmitting the signals from the WDM unit to the double-rate filtering module.
On the basis of the above technical solution, the ONU includes:
at least one ONU receiving unit for receiving the downstream signal from the ODN;
the second MAC and logic control module is used for link control and transmitting the optical signals received by the ONU receiving unit to an upper layer application;
and one ONU output unit in number is used for transmitting the signal from the second MAC and logic control module to the ODN.
On the basis of the above technical solution, at the OLT side, a plurality of downstream wavelength channels and a single upstream wavelength channel are used as an OLT port, and a unique time clock source is adopted and provided to all downstream wavelength channels in the OLT port.
The invention also provides a management method of the passive optical network asymmetric system, which comprises the following steps:
the OLT periodically sends a wavelength declaration message, the wavelength declaration message contains the central wavelengths and channel serial numbers of all downlink wavelength channels in the system, and the ONU records the corresponding channel serial numbers according to the received wavelength declaration message and corrects the central frequency of the receiving wavelength according to the central wavelength in the message;
the OLT sends a bandwidth discovery authorization message to all downlink wavelength channels periodically, the ONU in the non-registration state responds to the bandwidth discovery authorization message to obtain the loop time delay of the corresponding wavelength channel, and the corresponding downlink wavelength channel is set to be in the registration state; the loop delay corresponding to the wavelength channel is the loop delay of one uplink wavelength channel + one downlink wavelength channel in the ONU, and is regarded as the loop delay of one wavelength channel.
On the basis of the technical scheme, all wavelength channels supported by the ONU in the initial state are set to be in a non-registration state; when all wavelength channels of an ONU are in a registration state within a preset time, the ONU enters a working state; otherwise, after the preset time is exceeded, all wavelength channels of the ONU are reset to be in a non-registration state, and the registration process of the ONU is restarted.
On the basis of the technical scheme, when the OLT sends discovery bandwidth authorization messages to all downlink wavelength channel periods, the non-registered ONU receives the discovery bandwidth authorization messages and responds; the registered ONU receives the bandwidth discovery authorization message and does not respond; all wavelength channels of the registered ONU are in a registered state.
On the basis of the technical scheme, the discovery bandwidth authorization message comprises the system time t1 of the OLT, and after the OLT sends the discovery bandwidth authorization message, an uplink discovery window is opened; and the ONU in the non-registration state receives the bandwidth authorization message, extracts the system time t1 of the OLT as the system time of the ONU at the receiving moment, and reports the self-capability message in the windowing time slot of the OLT.
On the basis of the technical scheme, the self capability message comprises the number of downlink wavelength channels supported by the ONU and the channel serial number of the specifically supported downlink wavelength channel; when reporting the self-capability message, the ONU marks the channel serial number of a downlink wavelength channel for receiving the self-capability message; and inserting the ONU system time t2 at the reporting time into the self-capability message as a time table mark.
On the basis of the technical scheme, the OLT receives the self-capability message of the ONU, calculates the loop time delay of the corresponding wavelength channel in the ONU and sends the loop time delay to the ONU; and after receiving the loop delay, the ONU sets the corresponding downlink wavelength channel to be in a registration state.
On the basis of the above technical solution, in the ONU, the method for calculating the loop delay of the wavelength channel includes: and the OLT records the OLT system time t3 of the received ONU self capability message, extracts the ONU system time t2 from the ONU self capability message, and calculates the loop delay of the corresponding wavelength channel in the ONU through t3-t 2.
On the basis of the above technical solution, the process of the ONU correcting the wavelength center frequency according to the received wavelength announcement message includes: the ONU sets a channel serial number corresponding to the central wavelength of the system according to the wavelength declaration message received by the downlink wavelength channel and stores the channel serial number as system wavelength information; when the wavelength declaration message is received again, comparing whether the wavelength declaration message is consistent with the previously stored system wavelength information, and if so, not processing the wavelength declaration message; if not, the wavelength information of the local system is updated by the latest wavelength declaration message.
The invention has the beneficial effects that:
1. the invention improves the bandwidth by increasing the wavelength channel in the downlink direction, and the uplink direction can keep the original system unchanged or can upgrade the speed of the original wavelength; or the OLT supports multiple uplink wavelengths, but the ONU supports different single uplink wavelengths to improve the bandwidth, thereby reducing the difficulty of improving the network bandwidth and reducing the cost of improving the network bandwidth.
2. The invention can be completely compatible with the existing system structure, provides higher downlink system bandwidth for users, makes the downlink wavelength resource of the ONU more flexible, can realize flexible configuration of services under one or more downlink channels, and provides possibility of multiple service. In the uplink direction, according to the user requirement, the system supports the user side equipment with the existing bandwidth uplink and also supports the user equipment with the higher-speed uplink bandwidth.
3. In the passive optical network asymmetric system, the OLT is provided with a plurality of wavelength channels in the downlink direction, and one or more wavelength channels in the uplink direction can be provided; when a plurality of uplink direction wavelength channels are provided, the passive optical network asymmetric optical network system can be regarded as simple superposition of a plurality of passive optical network asymmetric systems, and the application scene is wide.
Drawings
Fig. 1 is a schematic diagram of an asymmetric system of a passive optical network according to a third embodiment of the present invention;
fig. 2 is a schematic diagram of an asymmetric passive optical network system according to a fourth embodiment of the present invention;
fig. 3 is a management flowchart of a seventh embodiment of the asymmetric passive optical network system according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
First embodiment
The invention relates to a passive optical network asymmetric system which comprises an OLT, an ODN and a plurality of ONUs, wherein the ONUs are connected with the OLT through the ODN in a time division multiplexing mode. The OLT supports at least one uplink wavelength channel and at least two downlink wavelength channels; an ONU supports one upstream wavelength channel and also supports at least one downstream wavelength channel.
In the downlink direction, the OLT synthesizes a plurality of wavelengths into a single-mode optical fiber in a wavelength division multiplexing mode; in the uplink direction, the OLT supports the original uplink wavelength channel. The system improves the downlink bandwidth by increasing the number of the downlink channels, and the uplink bandwidth can be kept unchanged or improved by the speed of the single wavelength channel.
Furthermore, at the OLT side, a plurality of downstream wavelength channels and a single upstream wavelength channel are used as an OLT port, a unique time clock source is adopted, and the time clock source is provided for all the downstream wavelength channels in the OLT port, so that the uniqueness of the system time is ensured. The time clock source can be generated locally by the system or introduced by an external network.
Second embodiment
On the basis of the first embodiment, the OLT includes a first Media Access Control (MAC) and logic Control module, a Dual-rate filter (Dual-rate filter) module, and an OLT optical module, where the first MAC and logic Control module is configured to complete a link Control function. The principle of the double-rate filtering module is as follows: the signals with different rates are separated out by synchronizing the different rates, because the rate interval of the passive optical network is larger at present, such as 1G and 10G, or 2.5G and 10G, which is easy to be realized by a filter.
In the downlink direction, the first MAC and logic control module is used for transmitting the network side data to the OLT optical module; the OLT optical module is used for converting network side data into optical signals, combining the optical signals on a single mode optical fiber, and transmitting the optical signals to the user side equipment ONU through the ODN.
In the uplink direction, the OLT optical module is used for receiving optical signals from the ONU through a single-mode optical fiber; the dual-rate filtering module is used for performing rate separation on signals from the OLT optical module, namely, separating the ONU uplink signals with the existing rate from the uplink signals with the higher rate. The first MAC and logic control module is used for transmitting the uplink signals separated by the double-rate filtering module to a network side.
The third embodiment:
as shown in fig. 1, in this embodiment, the OLT includes a first MAC and logic control module, a double-rate filtering module, and an OLT optical module, and the connection relationship and function of each module are the same as those in the second embodiment.
More specifically, the OLT optical module includes a WDM (Wavelength Division Multiplexing) unit, one OLT receiving unit, and two OLT output units, and in other embodiments, the OLT may also be a plurality of OLT output units.
The ONU comprises a second MAC and logic control module for controlling the link, an ONU output unit and at least one ONU receiving unit. By the difference of the number of the ONU receiving units, the ONU downstream direction can support a single wavelength channel and also can support a multi-wavelength channel. In this embodiment, two ONUs supporting a single wavelength channel and one ONU supporting two wavelength channels are included.
In the downlink direction, the OLT output unit is configured to receive a downlink signal from the first MAC and logic control module. The WDM unit is used for transmitting the downstream signal waves from different OLT output units to a single-mode optical fiber and transmitting the downstream signal waves to the ONU through the ODN. And each ONU receives the optical signal of the wavelength channel thereof through the ONU receiving unit and transmits the optical signal to the upper application layer through the second MAC and logic control module to finish the transmission of the downlink data.
In the uplink direction, the user data passes through the second MAC and logic control module of each ONU to complete the link control function, is transmitted to the ODN through the ONU output unit, and is transmitted to the WDM unit through the single mode fiber. The WDM unit transmits the uplink signal to the double-rate filtering module through the OLT receiving unit for rate separation, and then the uplink signal is transmitted to the network side through the first MAC and logic control module.
As shown in fig. 1, specifically, the number of OLT receiving units of the OLT optical module is 1, which corresponds to the uplink wavelength λ of the system; two OLT output units are respectively an OLT output unit 1 and an OLT output unit 2 which respectively correspond to the downlink wavelength lambda of the system1And downstream wavelength lambda2. Among a plurality of ONUs (ONU1, ONU2, … …, ONUn), ONU1 supports downstream wavelength λ1Channel, ONU2, supporting downstream wavelength λ2Channel, ONUn, supporting downstream wavelength λ1And downstream wavelength lambda2Two wavelength channels. In this embodiment, the wavelength λ is 1270nm, the wavelength λ1At 1490nm and a wavelength λ2Is 1577 nm.
The fourth embodiment:
as shown in fig. 2, in this embodiment, the OLT optical module includes a WDM unit, two OLT receiving units, and two OLT output units, and in other embodiments, the OLT optical module may further include a plurality of OLT receiving units and a plurality of OLT output units. Specifically, the two OLT receiving units are an OLT receiving unit 1 and an OLT receiving unit 2, which respectively send the downlink wavelength λ1And downstream wavelength lambda2. The two OLT receiving units are respectively an OLT receiving unit 1 and an OLT receiving unit 2 which respectively receive the upstream wavelength lambdaaAnd downstream wavelength lambdab。
The ONU comprises a second MAC and logic control module for controlling the link, an ONU output unit and at least one ONU receiving unit. Specifically, ONU1, ONU2, ONU3, and ONU4 each include an ONU output unit and an ONU reception unit. The ONU1 supports the downstream wavelength lambda1Channel and upstream wavelength lambdaaA channel; ONU2 supports downstream wavelength lambda2Channel and upgoing waveLong lambdaaA channel; ONU3 supports downstream wavelength lambda1Channel and upstream wavelength lambdabA channel; ONU4 supports downstream wavelength lambda2Channel and upstream wavelength lambdabA channel. ONUn supports downlink wavelength lambda1And downstream wavelength lambda2Two wavelength channels supporting an upstream wavelength lambdabA channel. In this embodiment, the wavelength λa1270nm, wavelength lambdab1310nm, wavelength lambda1At 1490nm and a wavelength λ2Is 1577 nm.
In the downstream direction, the OLT output unit 1 and the OLT output unit 2 are both configured to receive a downstream signal from the first MAC and logic control module. The WDM unit is used for transmitting the downstream signal waves from different OLT output units to a single-mode optical fiber and transmitting the downstream signal waves to the ONU through the ODN. And each ONU receives the optical signal of the wavelength channel thereof through the ONU receiving unit and transmits the optical signal to the upper application layer through the second MAC and logic control module of each ONU so as to complete the transmission of the downlink data.
In the uplink direction, the data of the user passes through the second MAC and logic control module of each ONU to complete the link control function, is transmitted to the ODN through the ONU output unit of the same ONU, and is transmitted to the WDM unit through the single mode fiber. The WDM unit is used for branching the uplink signals to respective receiving modules, transmitting the uplink signals to the double-rate filtering module for rate separation through the OLT receiving unit 1 and the OLT receiving unit 2, and transmitting the uplink signals to the network side through the first MAC and logic control module.
Fifth embodiment:
a management method of a passive optical network asymmetric system comprises the following steps:
the OLT periodically sends system channel information and broadcasts the wavelength and sequence number information of the system channel to all user equipment. And the ONU receives the system channel information and confirms the channel serial number supported by the ONU. The system channel information is a series of messages, including a wavelength declaration message, where the wavelength declaration message includes center wavelengths and channel numbers of all downlink wavelength channels in the system. All the supported wavelength channels of the ONU in the initial state are set to be in a non-registration state, the ONU records the serial number of the corresponding downlink wavelength channel according to the received wavelength declaration message, and corrects the central frequency of the receiving wavelength according to the central wavelength in the message.
And the OLT sends a bandwidth discovery authorization message to all downlink wavelength channel periods, and the system time of the OLT is contained in the bandwidth discovery authorization message. For the ONU supporting the multi-wavelength downlink channel, the registered state and the unregistered state are independent for the downlink wavelength channel supported by each wavelength channel, only the downlink wavelength channel in the unregistered state responds to the discovery bandwidth authorization message of the OLT, and the downlink wavelength channel in the registered state does not respond to the discovery bandwidth authorization message of the OLT after receiving the discovery bandwidth authorization message. The ONU in the unregistered state responds to the discovery bandwidth authorization packet, obtains a loop Time delay (RTT) of a corresponding wavelength channel in the ONU, and sets the corresponding downstream wavelength channel to be in the registered state according to the Round Trip Time (RTT). The loop delay of the wavelength channel in the ONU refers to the loop delay of one uplink wavelength channel + one corresponding downlink wavelength channel in the ONU, and is used as the loop delay of one wavelength channel in the ONU.
Sixth embodiment:
this embodiment is substantially the same as the fourth embodiment, and more specifically: all downlink wavelength channels in the passive optical network asymmetric system periodically send discovery bandwidth authorization messages, and the OLT opens an uplink discovery window.
And when the ONU in the non-registered state receives the bandwidth discovery authorization message, the OLT system time t1 is extracted from the bandwidth discovery authorization message and is used as the system time of the ONU at the moment of receiving. Because the system time of all downstream wavelength channels within the system are homologous, the OLT system time it receives from multiple wavelength channels is consistent even for ONUs supporting multiple wavelength downstream channels. And in a windowing time slot appointed by the OLT, the ONU reports a self-capability message, the ONU system time t2 at the sending moment is used as a time table mark to be inserted into the self-capability message, the self-capability message comprises the number of downlink wavelength channels supported by the ONU and the specifically supported downlink channel serial number, and the self-capability message is marked to receive the downlink wavelength channel serial number.
And the OLT receives the self-capability message of the ONU, calculates the loop time delay of the corresponding wavelength channel in the ONU, and sends the calculated loop time delay to the ONU in the form of a message. For the ONU supporting a single wavelength channel, since there is only one uplink wavelength channel and one downlink wavelength channel, the calculated loop delay of the wavelength channel is the loop delay of the ONU. For an ONU supporting multiple wavelength channels, since there are multiple downstream wavelength channels, there are multiple situations for one upstream wavelength channel + one corresponding downstream wavelength channel. The calculated loop delay at this time is the loop delay of a wavelength channel formed by the downlink wavelength channel and the uplink wavelength channel marked in the ONU self-capability message. And, for the ONU with multiple wavelength channels, the loop delay of the ONU includes the loop delays of all the wavelength channels in the ONU. And the ONU receives the loop delay message from the OLT, and sets the state of the downlink wavelength channel in the wavelength channel as a registration state according to the loop delay of the corresponding wavelength channel.
And when all wavelength channels of the ONU are in a registration state within the preset time, the ONU enters a working state, transmits uplink service data in a time slot specified by the OLT, and simultaneously can also receive downlink service data of a downlink channel. Otherwise, after the preset time is exceeded, even if one wavelength channel is not in the registration state, all wavelength channels of the ONU need to be reset to be in the non-registration state, and the registration management process of the ONU is restarted.
Seventh embodiment:
as shown in fig. 3, on the basis of the fifth embodiment, the method for managing an asymmetric passive optical network system specifically includes the following steps:
and S101, periodically sending wavelength declaration messages by the OLT in all the downlink wavelength channels in a broadcasting mode, wherein the wavelength declaration messages comprise the number of all the downlink wavelength channels in the system, the central wavelength of the downlink wavelength channels and the corresponding channel serial numbers. Referring to fig. 1 and the third embodiment, there are two downlink wavelength channels in the corresponding wavelength declaration message, where one wavelength channel has a serial number of 1 and a center wavelength of 1490 nm; the other wavelength channel has the serial number of 2 and the central wavelength of 1577 nm.
And S102, all wavelength channels supported by the ONU in the initial state are in a non-registration state. And the ONU receives the wavelength declaration message sent by the supported channel, extracts the system wavelength information, records the corresponding channel serial number, and corrects the self receiving wavelength central frequency according to the central wavelength in the message.
For example: referring to fig. 1, ONU1 receives the wavelength announcement message sent by channel number 1, and locally at ONU1, ONU1 checks the optical module of ONU1 to make it have the highest receiving sensitivity in the 1490nm wavelength range, with respect to 1490nm as channel number 1. The ONUn supports two downlink wavelength channels, and can receive the wavelength declaration message sent by the channel serial number 1 and the wavelength declaration message sent by the channel serial number 2. Because the wavelength declaration message is the same in all wavelength channels in the system, the ONUn receives the wavelength declaration message according to the downlink wavelength channel, sets a channel serial number corresponding to the central wavelength of the system, and stores the channel serial number as the system wavelength information. For example: the ONUn sets the central wavelength of its own system 1490nm as channel number 1, the central wavelength of its own system 1577nm as channel number 2, and at the same time, the ONUn calibrates its own optical module.
For the wavelength declaration message received again, comparing whether the wavelength declaration message is consistent with the previously stored system wavelength information, and if so, not processing the wavelength declaration message; if not, updating the wavelength information of the local system by using the latest wavelength declaration message.
And S103, the OLT sends discovery bandwidth authorization messages to all downlink wavelength channel periods, all ONUs accessed to the wavelength channel are notified, the OLT marks the system time t1 of the OLT at the moment of sending the discovery bandwidth authorization messages, and time slots in which the ONUs can send uplink messages.
S104, the ONU receives a bandwidth discovery authorization message in a broadcast mode, firstly detects whether system wavelength information exists locally or not, and a corresponding wavelength channel is in a non-registration state, if so, the method enters S105; if not, the process is not carried out, and the flow is ended.
And S105, the ONU in the non-registered state receives the bandwidth discovery authorization message, extracts the system time t1 of the OLT as the system time of the ONU at the receiving moment, and reports the self-capability message in the windowing time slot of the OLT.
Taking ONUn as an example to describe the processing procedure, ONUn receives a discovery bandwidth authorization message from a downlink wavelength channel with sequence number j, assuming that j is 1. ONUn checks localStored system wavelength information corresponding to wavelength lambda1If the channel has a serial number of 1 and the wavelength channel with the serial number of 1 is in the unregistered state, the ONUn extracts the OLT system time t1 in the discovery bandwidth authorization message, and sets the OLT system time t1 as the system time of the ONU. And the ONUn sends a self-capability message of the ONUn in a time slot specified by the discovery bandwidth authorization message, and the OLT calculates the loop delay passing through the wavelength channel by using the self-capability message. The self-capability message content comprises the number of wavelength channel serial numbers supported by the ONU and the corresponding channel serial numbers, the ONUn supports two wavelength channels of lambda 1 and lambda 2, and the corresponding channel serial numbers are 1 and 2. The message response marked in the self-capability message is a discovery bandwidth authorization message sent by a channel serial number 1, and the ONU system time t2 at the sending time is inserted in the self-capability message.
And S106, after receiving the ONU self-capability message, the OLT records the OLT system time t3 of receiving the self-capability message, extracts the downlink wavelength channel serial number 1 and the ONU system time t2 in the self-capability message, calculates the loop time delay of the corresponding wavelength channel through t3-t2, and sends the loop time delay message to the corresponding ONUn in the corresponding downlink wavelength channel (channel serial number 1). The loop delay corresponding to the wavelength channel refers to a loop delay of one uplink wavelength channel + one corresponding downlink wavelength channel in the ONU, for example, in the ONUn, the uplink wavelength channel + the downlink wavelength channel supporting the wavelength λ 1 has a loop delay of one wavelength channel; similarly, the uplink wavelength channel + the downlink wavelength channel supporting the wavelength λ 2 in the ONUn also has a loop delay of one wavelength channel; the loop delay of the two wavelength channels is the loop delay of the ONUn.
And S107, receiving the loop delay message by the ONUn through the downlink wavelength channel (channel serial number 1), storing the value of the loop delay, setting the downlink wavelength channel with the channel serial number 1 to be in a registration state, and synchronously starting a timer T1.
S108, checking whether all wavelength channels supported by the ONU are in a registration state within the time set by the timer T1, and if not, entering S109; if yes, the process proceeds to S110.
And S109, setting all wavelength channels of the ONU to be in an unregistered state, and turning to S102.
And S110, closing the timer T1, and enabling the ONU to enter a working state and normally receive and transmit uplink data and downlink data.
In the above embodiments, the number of OLT receiving units in the OLT optical module is not limited to one or two, and may also be multiple, and when there are multiple OLT receiving units, the principle remains unchanged.
The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention. Those not described in detail in this specification are within the skill of the art.

Claims (13)

1. A passive optical network asymmetric system comprises an Optical Line Terminal (OLT), an Optical Distribution Network (ODN) and a plurality of Optical Network Units (ONU), wherein the ONUs are all connected with the OLT through the ODN in a time division multiplexing mode, and the passive optical network asymmetric system is characterized in that:
the OLT supports at least one uplink wavelength channel and at least two downlink wavelength channels;
the ONU supports an uplink wavelength channel and at least one downlink wavelength channel;
the system increases the downlink bandwidth by increasing the number of the downlink wavelength channels, and the uplink bandwidth is kept unchanged or is increased by the speed of the single wavelength channel;
meanwhile, the wavelengths of the uplink wavelength channels and/or the downlink wavelength channels supported by at least two ONUs in the ONUs are different, and at least one ONU supports two downlink wavelength channels.
2. The passive optical network asymmetric system as recited in claim 1, wherein:
the OLT comprises a first MAC and logic control module, a double-rate filtering module and an OLT optical module;
in a downlink direction, the first MAC and logic control module is configured to perform link control and transmit network-side data to the OLT optical module, where the OLT optical module is configured to convert the data into an optical signal and combine the optical signal with a single-mode optical fiber;
in an uplink direction, the OLT optical module is configured to receive an optical signal from a single-mode fiber, the dual-rate filtering module is configured to perform rate separation on the optical signal from the OLT optical module, and the first MAC and logic control module is configured to transmit the uplink signal separated by the dual-rate filtering module to a network side.
3. The passive optical network asymmetric system as defined in claim 2, wherein the OLT optical module comprises:
the OLT comprises at least two OLT output units, a logic control module and a first MAC and logic control module, wherein the OLT output units are used for receiving downlink signals from the first MAC and logic control module;
the WDM unit is used for combining the downlink signals into a single-mode optical fiber and also used for transmitting the uplink signals from the single-mode optical fiber in a wave-splitting manner;
and the OLT is provided with at least one receiving unit for transmitting the signals from the WDM unit to the double-rate filtering module.
4. The passive optical network asymmetric system of claim 3, wherein the ONU comprises:
at least one ONU receiving unit for receiving the downstream signal from the ODN;
the second MAC and logic control module is used for link control and transmitting the optical signals received by the ONU receiving unit to an upper layer application;
and one ONU output unit in number is used for transmitting the signal from the second MAC and logic control module to the ODN.
5. The passive optical network asymmetric system as recited in claim 1, wherein: at the OLT side, a plurality of downstream wavelength channels and a single upstream wavelength channel are used as an OLT port, a unique time clock source is adopted, and the time clock source is provided for all the downstream wavelength channels in the OLT port.
6. A method for managing an asymmetric passive optical network system according to claim 1, comprising:
the OLT periodically sends a wavelength declaration message, the wavelength declaration message contains the central wavelengths and channel serial numbers of all downlink wavelength channels in the system, and the ONU records the corresponding channel serial numbers according to the received wavelength declaration message and corrects the central frequency of the receiving wavelength according to the central wavelength in the message;
the OLT sends a bandwidth discovery authorization message to all downlink wavelength channels periodically, the ONU in the non-registration state responds to the bandwidth discovery authorization message to obtain the loop time delay of the corresponding wavelength channel, and the corresponding downlink wavelength channel is set to be in the registration state; the loop delay corresponding to the wavelength channel is the loop delay of one uplink wavelength channel + one downlink wavelength channel in the ONU, and is regarded as the loop delay of one wavelength channel.
7. The method for managing an asymmetric system of a passive optical network as claimed in claim 6, wherein: all the supported wavelength channels of the ONU in the initial state are set to be in a non-registration state;
when all wavelength channels of an ONU are in a registration state within a preset time, the ONU enters a working state;
otherwise, after the preset time is exceeded, all wavelength channels of the ONU are reset to be in a non-registration state, and the registration process of the ONU is restarted.
8. The method for managing an asymmetric system of a passive optical network as claimed in claim 6, wherein: when the OLT sends discovery bandwidth authorization messages to all downlink wavelength channel periods, the non-registered ONU receives the discovery bandwidth authorization messages and responds; the registered ONU receives the bandwidth discovery authorization message and does not respond;
all wavelength channels of the registered ONU are in a registered state.
9. The method for managing an asymmetric system of a passive optical network as claimed in claim 8, wherein: the discovery bandwidth authorization message comprises the system time t1 of the OLT, and after the OLT sends the discovery bandwidth authorization message, an uplink discovery window is opened;
and the ONU in the non-registration state receives the bandwidth authorization message, extracts the system time t1 of the OLT as the system time of the ONU at the receiving moment, and reports the self-capability message in the windowing time slot of the OLT.
10. The method for managing an asymmetric system of a passive optical network as claimed in claim 9, wherein: the self-capability message comprises the number of downlink wavelength channels supported by the ONU and the channel serial number of the specifically supported downlink wavelength channel;
when reporting the self-capability message, the ONU marks the channel serial number of a downlink wavelength channel for receiving the self-capability message; and inserting the ONU system time t2 at the reporting time into the self-capability message as a time table mark.
11. The method for managing an asymmetric system of a passive optical network as claimed in claim 10, wherein: the OLT receives the self-capability message of the ONU, calculates the loop time delay of a corresponding wavelength channel in the ONU and sends the loop time delay to the ONU;
and after receiving the loop delay, the ONU sets the corresponding downlink wavelength channel to be in a registration state.
12. The method for managing the asymmetric system of the passive optical network according to claim 11, wherein in the ONU, the method for calculating the loop delay of the wavelength channel comprises: and the OLT records the OLT system time t3 of the received ONU self capability message, extracts the ONU system time t2 from the ONU self capability message, and calculates the loop delay of the corresponding wavelength channel in the ONU through t3-t 2.
13. The method for managing the asymmetric system of the passive optical network according to claim 6, wherein the process of the ONU correcting the wavelength center frequency according to the received wavelength announcement message includes: the ONU sets a channel serial number corresponding to the central wavelength of the system according to the wavelength declaration message received by the downlink wavelength channel and stores the channel serial number as system wavelength information; when the wavelength declaration message is received again, comparing whether the wavelength declaration message is consistent with the previously stored system wavelength information, and if so, not processing the wavelength declaration message; if not, the wavelength information of the local system is updated by the latest wavelength declaration message.
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