WO2018171595A1

WO2018171595A1 - Data transmission method and optical line terminal

Info

Publication number: WO2018171595A1
Application number: PCT/CN2018/079697
Authority: WO
Inventors: 陆建鑫; 郭勇
Original assignee: 中兴通讯股份有限公司
Priority date: 2017-03-21
Filing date: 2018-03-21
Publication date: 2018-09-27
Also published as: CN108632682A; CN108632682B; CN114945116A

Abstract

The present disclosure provides a data transmission method and an optical line terminal. The data transmission method comprises: when a burst uplink signal exists, sending the burst uplink signal to a system side module by means of an optical module; and when the burst uplink signal does not exist, sending an idle signal to the system side module by means of the optical module.

Description

Data transmission method and optical line terminal

Technical field

The present disclosure relates to the field of data communications, and more particularly to data transmission methods and optical line terminations.

Background technique

The optical access network is an important part of the next generation network and a major direction for the development of optical communication technology in the future. As the "nerve end" of the network architecture, the optical access network has great application prospects, and its broadband service is also growing.

In recent years, the construction of optical access networks has developed rapidly in countries around the world. With the implementation of the “light into copper” strategy, passive optical networks (PONs) have been deployed on a large scale. PON is a point-to-multipoint (P2MP) fiber access technology, which consists of an optical line terminal (OLT) on the central office side, an optical network unit (ONU) on the user side, and an optical distribution network (ODN). As users' demand for bandwidth continues to grow and technology matures, PON systems with 1G bandwidth begin to upgrade to 10G PON systems, even to higher-speed single-wavelength 25G PON systems and four-wavelength 100G PON systems.

The increase of the rate of the 25G/100G PON system is more and more challenging for the OLT design. In particular, the burst uplink data signal of the PON puts higher requirements on the OLT as the receiving end. After receiving the upstream optical signal, the optical module below 10G is directly sent to the medium access control (PON MAC) of the system through the burst mode transimpedance amplifier and the burst mode limiting amplifier. The PON MAC generally has a built-in burst mode clock data recovery (BCDR) function to recover (restore) the upstream optical signal. To facilitate maintenance, PON OLT optical modules are generally pluggable. When the data signal rate is increased above 25G, this scheme will make the connection between the optical module and the PON MAC difficult. As the symbol width becomes smaller, the bandwidth increases, and the connection transmission bandwidth is limited, so that the symbol edge is limited. And cause more errors.

Public content

The present disclosure provides a communication method between a high-speed pluggable PON OLT optical module and a system, provides a stable and reliable transmission connection scheme, and simplifies PON MAC chip design.

As an aspect of the present disclosure, a data transmission method is provided for use in an optical line terminal, where the optical line terminal includes an optical module and a system side module, and the data transmission method includes: when there is a burst uplink signal, The optical module sends the burst uplink signal to the system side module; and when there is no burst uplink signal, the optical module sends an idle signal to the system side module.

As another aspect of the present disclosure, an optical line terminal is provided, where the optical line terminal includes an optical module and a system side module, and when there is a burst uplink signal, the optical module sends the burst uplink signal to The system side module sends the idle signal to the system side module when there is no burst uplink signal.

DRAWINGS

The drawings in the following description of the embodiments of the present invention are intended to provide a further understanding of the present disclosure, which is used to explain the present disclosure, and is not intended to limit the scope of the disclosure.

FIG. 1 is a flowchart of a data transmission method according to an embodiment of the present disclosure;

2 is a schematic structural diagram of an optical line terminal according to an embodiment of the present disclosure;

3 is a schematic structural diagram of another structure of an optical line terminal according to an embodiment of the present disclosure;

4 is a schematic diagram of an insertion feature code.

detailed description

In order to facilitate the understanding of those skilled in the art, the present disclosure is further described below in conjunction with the accompanying drawings, which are not intended to limit the scope of the disclosure. It should be noted that the embodiments of the present disclosure and various modes in the embodiments may be combined with each other without conflict.

Referring to FIG. 1 , the present disclosure provides a data transmission method, which is applied to an optical line terminal, where the optical line terminal includes an optical module and a system side module, and the data transmission method includes: Step 100, in a burst uplink signal The optical module sends the burst uplink signal to the system side module. In step 200, when there is no burst uplink signal, the optical module sends an idle signal to the system side module.

In some embodiments, when there is no burst uplink signal, the optical module sends the idle signal to the system side module, where the optical module detects the received signal to obtain a detection signal; When the no-burst uplink signal is indicated, the optical module sends an idle signal to the system-side module.

In some embodiments, when the optical module sends the idle signal to the system side module, the optical module generates a zero-crossing indication signal according to the received signal, specifically, the The optical module detects a zero-crossing signal of the received signal, and sets the zero-crossing indication signal to be valid when the zero-crossing signal exceeds a preset threshold; when the zero-crossing indication signal is valid, The optical module sends an idle signal to the system side module.

In some embodiments, the idle signal is a signal with better pattern balance, and the pattern balance can be set within a predetermined range, for example, between 0.3 and 0.7, and the idle signal can be preset. The periodic signal can also be set to other signals, as long as it is set to maintain the AC signal between the optical module and the system side module (ie, to avoid clock loss between the optical module and the system side module). For example, the idle signal can be set to an alternate code stream signal of 0 and 1.

By inserting the idle signal during idle time, the AC frequency signal is maintained between the optical module and the PON MAC during the uplink burst, so that the clock of the PON MAC as the receiving end does not lose lock, and does not need to receive the uplink data signal every time. The system data (including clock data) is restored first, which improves the reliability of the system transmission. The system side no longer needs complex burst mode clock data recovery function, which simplifies the design of the PON MAC chip.

In some implementations, in order to solve the problem that the connection between the optical module and the PON MAC is difficult and the bit error rate is increased when the data signal rate is increased to 25 G or more, the BCDR function needs to be added to both the optical module and the system side, thereby improving signal quality. To reduce the bit error rate, however, the BCDR function is added to both the optical module and the system side. The preamble requirement for signal transmission is more demanding. When receiving the burst uplink signal, the optical module and the system side are required to execute the burst mode clock data. Recovery features increase the complexity of the system design.

In the embodiment of the present disclosure, by inserting an idle signal when there is no uplink data signal (ie, uplink idle, no burst uplink signal), the system side receives the quasi-continuous signal, so the system side MAC does not need the BCDR function. This simplifies the design of the PON MAC chip.

In the embodiment of the present disclosure, when forwarding the uplink data signal of the low rate channel, the optical module may select to send the uplink data signal of the low rate channel to the system side module through the high rate channel.

By transmitting the uplink data signal of the low rate channel to the system side module through the high rate channel, only one data transmission channel needs to be set between the optical module and the system side module, and the data transmission channel has a high transmission rate and various rates. The data signals can be transmitted through the data transmission channel, which simplifies system design and improves data transmission reliability.

The low rate data signals can be matched (mapped) to the high rate channels in a number of ways.

In the case where the high rate is an integer multiple of the low rate, a repeated code stream may be used, for example, an 8-bit or 10-bit data slice is repeated an integer multiple, and then the next data slice is transmitted. If the high rate is not an integer multiple of the low rate, you need to consider other mapping methods. You only need to make the agreement at both ends of the communication.

The following is described in conjunction with a specific example. The transmission rate of the high-rate channel is 20 Gbit/s, and the rate of the low-rate channel is 10 Gbit/s. When the optical module transmits the data signal of the low-rate channel, each data slice is repeatedly transmitted twice, and the system-side module receives the data. When the data signal is known, the data signal is a data signal with a rate of 10 Gbit/s, and then a piece of data is forwarded, and duplicate pieces of data are discarded.

For the case where the high rate is not an integer multiple of the low rate, other mapping methods may be employed. Specifically, the feature code may be inserted before the data slice, the start position of the data slice is identified by the feature code, and then filled by the idle code, thereby mapping the low-rate data slice to the high-rate channel. Three mapping modes are specifically described below.

Manner 1: When the optical module receives the data slice of the low rate channel, the first feature code is inserted before the data slice, and then sent to the system side module through the high rate channel.

Manner 2: When the optical module receives the data slice of the low rate channel, insert the first feature code before the data slice, insert the second feature code after the data slice, and then send the signal to the system side module through the high rate channel; The start position of the data piece may be identified by the first feature code, and the end position of the data piece may be identified by the second feature code. Since the size of the data piece is fixed, only the first feature may be adopted. The code identifies the starting position of the piece of data.

Manner 3: When the optical module receives the data slice of the low rate channel, insert the first feature code before the data slice, insert the second feature code and the idle code after the data slice, and then send the system to the system through the high rate channel. Side module.

In some embodiments, the optical module in an embodiment of the present disclosure includes a burst mode clock data recovery unit that recovers a received signal, the burst mode clock data The source of the reference clock of the recovery unit includes any one of the following methods: a reference clock provided by the reference oscillator inside the optical module; a reference clock extracted by the optical module from the received signal; and a reference provided by the system directly to the optical module clock.

Based on the same or similar concepts as the above embodiments, an embodiment of the present disclosure further provides an optical line terminal (OLT). Referring to FIG. 2, the OLT includes an optical module 10 and a system side module, and the system side module includes a PON. MAC 20.

The optical module 10 includes a BCDR unit 11, a control unit 12, an adaptation unit 13, an output unit 14, and a clock unit 15, and the optical module 10 may further include a signal amplification unit (not shown).

After receiving the signal sent by the ONU, the OLT first amplifies the signal through a burst mode transimpedance amplifier and a burst mode limiting amplifier to form a reference signal.

The BCDR unit 11 is configured to receive a reference signal amplified by a burst mode transimpedance amplifier and a burst mode limiting amplifier, and recover the reference signal.

Further, the BCDR unit 11 receives the reference clock transmitted by the clock unit 15, and generates a zero-crossing indication signal based on the recovered signal, and transmits the zero-crossing indication signal to the control unit 12.

Specifically, the BCDR unit 11 detects a zero-crossing signal of the recovered signal, and sets the zero-crossing indication signal to be valid when the zero-crossing signal exceeds a preset threshold.

The control unit 12 receives the detection signal obtained by detecting the signal received by the optical module 10 and the zero-crossing indication signal, and instructs the adaptation unit 13 to output an uplink data signal according to the detection signal and the zero-crossing indication signal. Still output an idle signal.

Specifically, when the detection signal indicates that there is no burst uplink signal, or when the zero-crossing indication signal is valid, the adaptation unit 13 inserts an idle signal, and in other cases, forwards the burst recovered by the BCDR unit 11. Send an upstream signal.

The adaptation unit 13 is configured to receive the indication signal sent by the control unit 12, and send the idle signal or the burst uplink signal recovered by the BCDR unit 11 to the output unit 14 according to the indication signal.

The output unit 14 outputs the data signal output from the adaptation unit 13.

The clock unit 15 is for providing a reference clock, and in the embodiment of the present disclosure, the source of the reference clock provided by the clock unit 15 includes any one of the following: a reference clock provided by a reference oscillator inside the optical module (for example, The clock unit 15 is a reference oscillator); the reference clock extracted by the optical module from the received signal; the system directly adjusts the reference clock provided to the optical module.

On the basis of the OLT shown in FIG. 2, the embodiment of the present disclosure further provides another OLT. As shown in FIG. 3, the PON MAC unit 20 sends a rate indication signal to the BCDR unit 11 in the optical module 10. The BCDR unit 11 restores the received data signal by the rate indication signal, so that the transmission rate is not required to be parsed each time the data signal transmitted by the ONU is received, and the uplink data signal can be recovered (restored) more quickly.

In addition, the PON MAC unit 20 can also transmit a rate indication signal to the adaptation unit 13 so that the adaptation unit 13 can insert and output a suitable uplink signal.

In addition, when the rate indication signal indicates the low-rate transmission of the uplink signal, the adaptation unit 13 maps the low-rate data slice to the high-rate channel in an agreed manner, for example, mapping the low-rate data slice to the high rate in one of the following three manners. aisle.

Manner 1: The adapting unit 13 inserts the first feature code before the data piece.

Manner 2: The adapting unit 13 inserts a first feature code before the data piece, and inserts a second feature code after the data piece.

Manner 3: The adapting unit 13 inserts a first feature code before the data slice, and inserts a second feature code and an idle code after the data slice.

The following is described in conjunction with a specific example.

As shown in FIG. 4, when the adaptation unit 13 receives the low-speed data slice A, the signature 1 is inserted before the low-speed data slice A, and then the signature 1 and the low-speed data slice A are transmitted on the high-speed channel, after the data transmission is completed. Inserting the feature code 2 and the idle code after the low-speed data slice A, and transmitting the feature code 2 and the idle code. When the adaptation unit 13 receives the low-speed data slice B, the feature code 1 is inserted before the low-speed data slice B, Then, the signature 1 and the low-speed data slice B are transmitted on the high-speed channel. After the data transmission ends, the signature 2 and the idle code are inserted after the low-speed data slice B, and the signature 2 and the idle code are transmitted. The feature code 1 and the feature code 2 are predetermined codes that can be distinguished from ordinary data signals and can be identified.

When the PON MAC receives the data signal and searches for "Signature 1", it can determine the starting position of the data slice, thereby recovering (restoring) the low-speed data signal stream.

The "unit" and "module" in the present disclosure may be implemented by software, hardware or a combination thereof, which may be, for example, a processor.

Embodiments of the present disclosure also provide a computer storage medium storing a computer program for performing a data transmission method of an embodiment of the present disclosure.

It should be noted that the above-mentioned embodiments are only for the convenience of those skilled in the art, and are not intended to limit the scope of the disclosure, and the features disclosed in the above embodiments may be combined in any combination without departing from the disclosure. Any obvious substitutions and improvements made to the present disclosure by those skilled in the art are considered to fall within the scope of the present disclosure.

Claims

A data transmission method is applied to an optical line terminal, where the optical line terminal includes an optical module and a system side module, and the data transmission method includes the following steps:

When there is a burst uplink signal, the optical module sends the burst uplink signal to the system side module;

When there is no burst uplink signal, the optical module sends an idle signal to the system side module.
The data transmission method according to claim 1, wherein the step of the optical module transmitting the idle signal to the system side module when there is no burst uplink signal comprises:

The optical module detects the received signal to obtain a detection signal;

When the detection signal indicates that there is no burst uplink signal, the optical module sends an idle signal to the system side module.
The data transmission method according to claim 1, wherein the step of the optical module transmitting the idle signal to the system side module when there is no burst uplink signal comprises:

The optical module generates a zero-crossing indication signal according to the received signal, where the optical module detects a zero-crossing signal of the received signal, and the zero-connected signal when the zero-crossing signal exceeds a preset threshold The indication signal is set to be valid;

When the zero-indication signal is valid, the optical module sends an idle signal to the system-side module.
The data transmission method according to claim 1, wherein the optical module transmits the uplink data signal of the low rate channel to the system side module through the high rate channel when forwarding the uplink data signal of the low rate channel.
The data transmission method according to claim 4, wherein the uplink data signal of the low rate channel is transmitted to the system side module through the high rate channel in any of the following manners:

When receiving the data slice of the low rate channel, the optical module inserts the first feature code before the data slice, and then sends the first feature code to the system side module through the high rate channel;

When receiving the data slice of the low rate channel, the optical module inserts a first feature code before the data slice, inserts a second feature code after the data slice, and then sends the second feature code to the system side module through a high rate channel. ;

When the optical module receives the data slice of the low rate channel, insert the first feature code before the data slice, insert the second feature code and the idle code after the data slice, and then send the message to the System side module.
The data transmission method according to claim 1, wherein said optical module comprises a burst mode clock data recovery unit, said burst mode clock data recovery unit recovers said received signal, said burst mode clock data The source of the reference clock of the recovery unit includes any one of the following methods: a reference clock provided by the reference oscillator inside the optical module; a reference clock extracted by the optical module from the received signal; and a reference provided by the system directly to the optical module clock.
An optical line terminal includes an optical module and a system side module, wherein

When there is a burst uplink signal, the optical module sends the burst uplink signal to the system side module;

When there is no burst uplink signal, the optical module sends an idle signal to the system side module.
The optical line terminal according to claim 7, wherein said optical module comprises a control unit, an adaptation unit, and an output unit, and wherein said optical module transmits an idle signal to said system when there is no burst uplink signal Side modules include:

The control unit receives a detection signal obtained by detecting a signal received by the optical module;

When the detection signal indicates that there is no burst uplink signal, the control unit instructs the adaptation unit to insert an idle signal and transmit it to the output unit;

The output unit transmits the idle signal to the system side module.
The optical line terminal according to claim 8, wherein the optical module further comprises a burst mode clock recovery unit, and the burst mode clock recovery unit recovers a signal received by the optical module,

When the detection signal indicates that there is a burst uplink signal, the control unit instructs the adaptation unit to forward the burst uplink signal recovered by the burst mode clock recovery unit to the output unit, and the output unit The burst uplink signal is sent to the system side module.
The optical line terminal according to claim 7, wherein said optical module comprises a burst mode clock data recovery unit, a control unit, an adaptation unit, and an output unit, and wherein said optical module is in the absence of a burst uplink signal Sending the idle signal to the system side module includes:

The burst mode clock recovery unit recovers the signal received by the optical module, generates a zero-crossing indication signal according to the recovered signal, and sends the zero-crossing indication signal to the control unit, where the burst The burst mode clock recovery unit detects the zero-crossing signal of the recovered signal, and sets the zero-crossing indication signal to be valid when the zero-crossing signal exceeds a preset threshold;

When the zero-indication signal is valid, the control unit instructs the adaptation unit to insert an idle signal and transmit it to the output unit;

The output unit transmits the idle signal to the system side module.
The optical line terminal according to claim 10, wherein, when the zero-indication signal is invalid, the control unit instructs the adaptation unit to forward the burst uplink signal recovered by the burst mode clock recovery unit to The output unit sends the burst uplink signal to the system side module.
The optical line terminal according to claim 7, wherein the optical module transmits the uplink data signal of the low rate channel to the system side module through the high rate channel when forwarding the uplink data signal of the low rate channel.
The optical line terminal according to claim 12, wherein the uplink data signal of the low rate channel is transmitted to the system side module through the high rate channel in any of the following manners:

When receiving the data slice of the low rate channel, the optical module inserts the first feature code before the data slice, and then sends the first feature code to the system side module through the high rate channel;

When receiving the data slice of the low rate channel, the optical module inserts a first feature code before the data slice, inserts a second feature code after the data slice, and then sends the second feature code to the system side module through a high rate channel. ;

When the optical module receives the data slice of the low rate channel, insert the first feature code before the data slice, insert the second feature code and the idle code after the data slice, and then send the message to the System side module.
The optical line terminal according to claim 7, wherein the optical module comprises a burst mode clock recovery unit, and a source of the reference clock of the burst mode clock recovery unit comprises any one of the following: an optical module internal The reference clock provided by the reference oscillator; the reference clock extracted by the optical module from the received signal; the system directly adjusts the reference clock provided to the optical module.
A computer storage medium storing a computer program for performing the data transmission method according to any one of claims 1 to 6.