CN109155672A - The method and system of passive optical network transmission optical signal - Google Patents

Abstract

This application involves the transmission of the signal of passive optical network more particularly to optical line terminal.The uplink linght that optical line terminal sends optical network unit is ranked up by intensity, determine optical network unit send uplink linght sequence and corresponding resetting time, the leader sequence in optical signal can be effectively reduced, so that optical line terminal can receive more uplink optical signals within the unit time.

Description

Method and system for transmitting optical signal by passive optical network Technical Field

The embodiment of the invention relates to a passive optical network system, in particular to signal transmission of an optical line terminal.

Background

The main components of a passive Optical Network (pon) system include an Optical Line Terminal (OLT), (Optical Line terminal), an Optical Network Unit (ONU), and an Optical splitter connecting the OLT and the ONU. In the PON system, there is a one-to-many optical fiber transmission and access technology between the OLT and the ONUs. The key technology of passive optical network PON application mainly includes: OLT downlink signal adopts continuous broadcast mode and uplink signalThe signal is in a time division multiple access burst mode. For a detailed description of the PON system, see patent documents CN102301670B, CN103248422A, CN103297866B, CN104243092A, orhttps://en.wikipedia.org/wiki/Passive_optical_networkThe contents of which are hereby incorporated by reference into the present application.

For the OLT, a built-in optical module of the OLT receives uplink light with different optical powers, and when the difference between the received optical powers of two adjacent uplink lights is large, the built-in optical module of the OLT needs a long time to establish a threshold level, otherwise, the received signal is converted incorrectly. An improvement is to make it quickly establish the threshold by using a RESET signal RESET in the built-in optical module. However, frequent reset procedures still occupy the uplink bandwidth, which is otherwise tight.

Therefore, a solution that enables the OLT to receive more uplink optical signals per unit time is desired in the industry.

Disclosure of Invention

Embodiments of the present invention provide a method and a system for transmitting an optical signal in a passive optical network, so that an OLT can receive more uplink optical signals in a unit time.

In a first aspect, embodiments of the present invention provide a method for a passive optical network to transmit an optical signal. The optical line terminal acquires the intensity of the uplink optical signals sent by the plurality of optical network units. And the optical line terminal sorts the intensity of the uplink optical signals to determine the sequence of the optical network units for transmitting the uplink optical signals subsequently. And the optical line terminal determines the reset time corresponding to each optical network unit according to the sequencing result. And the optical line terminal sends an instruction to the optical network unit so that the optical network unit sends subsequent uplink optical signals to the optical line terminal according to the sequence and the corresponding reset time. According to the implementation mode, the plurality of optical network units are sequenced according to the intensity of the uplink optical signals, so that the difference of the intensity between different uplink optical signals is effectively reduced, the time required by resetting the optical line terminal is reduced, and the OLT can receive more uplink optical signals in unit time.

In a possible implementation, the above steps can also be performed using other devices, not through the optical line termination.

In a possible implementation manner, the sorting of the intensities of the uplink optical signals by the optical line terminal and the determination of the order in which the optical network units send the uplink optical signals by the optical line terminal may be performed in two steps. The method comprises the steps of firstly sequencing the intensity of uplink optical signals, and then determining the sequence of the optical network units for sending the uplink optical signals and the corresponding reset time of each optical network unit according to the sequencing result.

In one possible implementation, the intensities of the upstream optical signals may be ordered according to decreasing magnitude or decreasing magnitude. The implementation mode reduces the voltage fluctuation caused by the fluctuation of different uplink optical signal intensities in one period, thereby reducing the time required by resetting the optical line terminal.

Further, in a possible implementation, the optical line terminal instructs the optical network units to alternately transmit the upstream optical signals in a sequential order and a reverse order in a plurality of consecutive periods, so as to further reduce the reset time required by the two optical network units between each transmission period.

In one possible implementation manner, the optical line terminal instructs the optical network unit to determine the preamble sequence length of the uplink optical signal according to the corresponding reset time. Because the preamble sequence does not carry data, it is used to cover the reset time of the optical line terminal. If the length of the leader sequence is not enough, the data can not be correctly identified and converted by the optical line terminal; if the length of the preamble sequence is redundant, the data volume transmitted in the uplink optical signal is reduced. The optical network unit determines the length of the preamble sequence of the uplink optical signal according to the corresponding reset time, so that as much valid data as possible is transmitted in the uplink optical signal transmitted at one time. The length of the leader sequence in this application is also referred to as the number of bits of the leader sequence, i.e., how much content is in the leader sequence.

In another possible implementation manner, the optical line terminal determines a preamble sequence length of the uplink optical signal corresponding to the reset time, and instructs the optical network unit to send the uplink optical signal to the optical line terminal according to the preamble sequence length corresponding to the corresponding reset time.

In a possible implementation manner, the optical line terminal may determine a uniform reset time for each optical network unit according to a maximum value of a difference between the sorted two adjacent upstream optical signal strengths. The realization mode ensures that the data sent by each optical line terminal can be correctly received.

In another possible implementation manner, the optical line terminal may determine the reset time corresponding to each optical network unit according to the difference between the sorted strengths of each two adjacent uplink optical signals. The realization mode further improves the quantity of the uplink optical signals which can be received by the OLT in unit time.

In a possible implementation manner, after receiving the uplink optical signal of each optical network unit, the optical line terminal may obtain the uplink optical signal strength of each optical network unit through detection. In this implementation manner, the uplink optical signal strength of each optical network unit is obtained in real time, which has higher accuracy.

In another possible implementation, the optical line terminal may read the upstream optical signal strength corresponding to each optical network unit from the storage module. Further, the corresponding relationship between the uplink optical signal strength in the storage module and each optical network unit may be stored in the storage module after being detected by the optical line terminal, or may be directly input into the storage module from the outside. In the implementation mode, the optical line terminal has the capability of quick response and is easy to install and replace.

In a possible implementation manner, the olt may periodically detect the received uplink optical signal strength of each onu, compare the received uplink optical signal strength with the stored uplink optical signal strength data, and when an inconsistency or a newly added onu uplink optical signal strength is found, sort the uplink optical signal strengths again to determine the order and the reset time for the onu to send the uplink optical signals.

In another possible implementation manner, the olt may also detect the received uplink optical signal strength of each onu in real time, compare the detected uplink optical signal strength with stored uplink optical signal strength data, and sort the uplink optical signal strengths again to determine the order and the reset time for the onu to send the uplink optical signals when the inconsistency or the newly added onu uplink optical signal strength is found.

In a second aspect, in combination with the foregoing technical solutions, an embodiment of the present invention provides a method for transmitting an optical signal, including:

the optical line terminal acquires a first intensity of a first uplink optical signal sent by a first optical network unit;

the optical line terminal acquires a second intensity of a second uplink optical signal sent by a second optical network unit, wherein the second intensity is not equal to the first intensity;

the optical line terminal determines the order of the first optical network unit sending the third uplink optical signal and the corresponding reset time by referring to the first intensity and the second intensity;

the optical line terminal determines the order of sending the fourth uplink optical signal by the second optical network unit and the corresponding reset time by referring to the first intensity and the second intensity;

the optical line terminal sends an instruction to the first optical network unit and the second optical network unit, so that the first optical network unit learns the sequence of sending the third uplink optical signal and the corresponding reset time, and the second optical network unit learns the sequence of sending the fourth uplink optical signal and the corresponding reset time.

Alternatively, in a possible implementation manner, the optical line terminal determines, with reference to the first intensity and the second intensity, an order in which the first optical network unit sends the third uplink optical signal and a corresponding reset time, and an order in which the second optical network unit sends the fourth uplink optical signal and a corresponding reset time. Two of the steps identified in various implementations of the invention may be combined in one step.

Alternatively, in a possible implementation manner, the optical line terminal determines, by referring to the first strength and the second strength, a first sequence number and a corresponding first reset time for the first optical network unit to send the third uplink optical signal. And the optical line terminal determines a second sequence number and a corresponding second reset time of a fourth uplink optical signal sent by the second optical network unit by referring to the first intensity and the second intensity. The sequence number is directly determined, and storage and transmission are facilitated.

In one possible implementation, the optical line terminal sends an indication to the first optical network unit and the second optical network unit. And the first optical network unit receives the indication and sends a third uplink optical signal to the optical line terminal by referring to the first sequence number and the first reset time. And the second optical network unit receives the indication and sends a fourth uplink optical signal to the optical line terminal by referring to the second sequence number and the second reset time.

In another possible implementation manner, the optical line terminal determines, by referring to the first strength and the second strength, a first sequence number and a corresponding first reset time for the first optical network unit to send the third uplink optical signal, and a second sequence number and a corresponding second reset time for the second optical network unit to send the fourth uplink optical signal.

Alternatively, in a possible implementation manner, the optical line terminal sends a first indication to the first optical network unit with reference to the first sequence number and the first reset time. And the optical line terminal sends a second indication to the second optical network unit by referring to the second sequence number and the second reset time. And the first optical network unit receives the first indication and sends the third uplink optical signal. And the second optical network unit receives the second indication and sends the fourth uplink optical signal.

In a third aspect, an embodiment of the present invention provides an optical line terminal. The optical line terminal has the function of realizing the method. The functions may be implemented by hardware, or may be implemented by hardware executing corresponding software, where the hardware or software includes one or more modules corresponding to the functions, and the modules may be hardware and/or software.

In one possible implementation, the optical line terminal includes:

the signal transmission module is used for receiving an uplink optical signal from the optical network unit and sending downlink light to the optical network unit;

the detection module is used for detecting the strength of an uplink optical signal sent by an optical network unit and received by an optical line terminal;

the sorting module is used for sorting the strength of the uplink optical signals sent by each optical network unit to determine the sequence of the uplink optical signals sent by each optical network unit, and sending the sending sequence to the optical network unit in downlink light through the signal transmission module;

the reset time determining module is used for determining the reset time of each optical network unit according to the sequencing result of the uplink optical signal strength and sending the reset time to the optical network units in downlink light through the signal transmission module; and

and the storage module is used for storing the sequence and the reset time.

In a fourth aspect, an embodiment of the present invention provides a passive optical network system, which utilizes the optical line and the terminal and the transmission method implemented above. The passive optical network system comprises an optical line terminal, an optical splitter and a plurality of optical network units. The optical line terminal and the optical network unit are connected through an optical splitter. The optical line terminal has the function of realizing the intelligent sequencing. The functions may be implemented by hardware, or may be implemented by hardware executing corresponding software, where the hardware or software includes one or more modules corresponding to the functions, and the modules may be hardware and/or software.

In one possible implementation, a passive optical network system includes:

a plurality of optical network units;

an optical splitter; and

the optical line terminal is connected with the optical network unit through the optical splitter and comprises:

a signal transmission unit for receiving the upstream optical signal transmitted from the optical network unit and transmitting the downstream optical signal to the optical network unit,

a processor for sequencing the intensity of the uplink optical signals to determine the order in which the optical network units transmit the uplink optical signals and the reset time corresponding to each optical network unit, and transmitting the order and the reset time to the optical network units, an

The memory is used for storing the sequence and the reset time corresponding to each optical network unit;

and the optical network unit sends an uplink optical signal to the optical line terminal according to the sequence and the reset time indicated by the optical line terminal.

Through the scheme, the embodiment of the invention can flexibly identify the intensity of the uplink optical signals, so that the uplink optical signals are sequentially and circularly sequenced according to the intensity. Therefore, the light intensity difference during the switching of adjacent uplink optical signals can be reduced, the direct-current voltage threshold value is quickly established, and the Preamble sequence bit of each sequence is reduced, so that the OLT can receive more uplink optical signals in unit time.

Drawings

Fig. 1 is a schematic diagram of a passive optical network PON system provided in accordance with one possible embodiment of the present invention;

fig. 2 is a schematic diagram of an optical receiving circuit of an optical module built in an optical line terminal OLT according to one possible embodiment of the present invention;

fig. 3 is a schematic diagram illustrating a change of a voltage amplitude signal of an optical signal received by an optical line terminal OLT according to one possible embodiment of the present invention;

fig. 4 is a flowchart of a method for transmitting an optical signal in a passive optical network PON system according to one possible embodiment of the present invention;

fig. 5 is a schematic diagram illustrating a variation of a voltage amplitude signal of an optical signal received by an optical line terminal OLT according to one possible embodiment of the present invention;

fig. 6 is a schematic structural diagram of a passive optical network PON system according to one possible embodiment of the present invention;

figure 7 is a block schematic diagram of a part of the structure of an optical line termination OLT according to one possible embodiment of the present invention;

figure 8 is a block schematic diagram of a part of the structure of an optical line termination OLT according to another possible embodiment of the present invention;

fig. 9 is a flowchart of a method for transmitting an optical signal in a passive optical network PON system according to one possible embodiment of the present invention;

fig. 10 is a flowchart of a method for transmitting an optical signal in a passive optical network PON system according to another possible embodiment of the present invention;

fig. 11 is a flowchart of a method for transmitting an optical signal in a passive optical network PON system according to another possible embodiment of the present invention;

fig. 12 is a flowchart of a method for transmitting an optical signal in a passive optical network PON system according to another possible embodiment of the present invention;

figure 13 is an architecture diagram of an optical line termination OLT provided in accordance with one possible embodiment of the present invention.

Detailed Description

Fig. 1 is a schematic diagram of a passive optical network PON system according to one possible embodiment of the present invention. As shown in fig. 1, in one possible embodiment, the PON system comprises an optical line termination OLT 10, a plurality of optical network units ONU 20 and an optical splitter 30. The OLT 10 is connected to an optical splitter 30. The optical splitter 30 is connected to a plurality of ONUs 20. The optical signal transmitted from the ONU 20 to the OLT 10 via the optical splitter 30 is an upstream optical signal, and the optical signal received from the OLT 10 by the ONU 20 via the optical splitter 30 is a downstream optical signal. The plurality of ONUs 20 transmit the upstream light to the OLT 10 in a time division multiple access burst manner, that is, the plurality of ONUs 20 sequentially transmit the upstream light to the OLT 10 in one cycle.

The use of "upstream light" to refer to "upstream optical signals" in some places in the present application does not impede the understanding of those skilled in the art, consistent with the spirit of the invention.

In the embodiment of fig. 1, ONUs 20 are identified by numbers 1 through 3, respectively, which is not intended to represent a requirement that ONUs 20 be identical devices. ONU 20 may be the same or different devices, including ont (optical Network terminal) and the like.

Fig. 2 is a schematic diagram of an optical transceiver circuit of an optical module built in an optical line terminal OLT 10 according to one possible embodiment of the present invention. As shown in fig. 2, for the OLT 10, when receiving the upstream light of each ONU 20, the built-in optical module is reset at the start position of the upstream light, so that the energy storage capacitor C2 is charged and discharged quickly, and the purpose of quickly establishing the threshold level is achieved.

Specifically, when receiving the uplink burst light signal, the current flowing through the PD/APD diode will change proportionally, and the output side of the transconductance amplifier (TIA) will generate a voltage value corresponding to the light intensity, which will charge the capacitance at the LN-pin of 149 CL. Due to the voltage hysteresis characteristic generated by the capacitor charging, a voltage difference is generated between the LN + and the LN-, the light intensity of the uplink light sent by the same ONU 20 is stable, and at this time, the 149CL amplifier can normally reflect the light signal value. When the difference between the intensities of the upstream lights sent by two adjacent ONUs is large, for example, the intensity of the second upstream light is smaller than that of the previous upstream light, when the second upstream light comes, the voltage at C2 will be larger than the voltage at LN + pin, resulting in that the amplifier 149CL erroneously determines the first logic 1 signals bit as logic 0. After several uplink light bits, the discharge of C2 reduces the dc threshold, and the voltage amplifier 149CL can normally output the data of the second uplink light. Similarly, if the intensity of the two adjacent upstream lights is the second stronger than the first one, it may happen that C2 is charged too slowly, so that the dc threshold rises too slowly, resulting in a data conversion error of the optical signal of the second ONU 20 in the first few bits.

In order to prevent data conversion errors, a switch switching path is added, and in the starting stage of each sequence, a RESET control mode is adopted to manually control the opening of two switch devices M5 and M6 when uplink light of different ONUs is switched, so that the rapid discharging of the uplink light to C2 in strong light and weak light cutting or the rapid charging of C2 in weak light and strong light cutting can be realized.

FIG. 3 reflects the voltage change of LN + and LN-when the light is weakened by strong light. From the LN-voltage, immediately after the second sequence comes, the LN-voltage signal has a slow-down process due to the presence of the RESET signal, and the amplifier 149CL cannot correctly convert the optical signal data to the back end. After the reset is completed, the establishment of the dc threshold is completed, and a relatively stable value is reached, and at this time, the amplifier 149CL can correctly convert the data.

As can be seen from fig. 3, in the resetting process, the ONU 20 can only send the Preamble without Data, and after the resetting process is finished, the Delimiter is used to inform that Payload/Data needs to be sent next. Therefore, in the case that the Payload/Data of the Data in the uplink light transmitted each time is not changed, the longer the reset time is, the more Preamble sequences need to be transmitted by the ONU 20, and thus, the longer the transmission time is required. In particular, the larger the difference between adjacent optical powers, the longer the reset time is required. In the PON system, one OLT 10 device is usually connected to several tens of ONU 20 devices at the same time, and the upstream communication uses a time division multiple access burst method, which requires a plurality of resets. It can be seen that reducing the reset time enables more ONUs 20 to send upstream light within the same Guard time Guard.

The embodiment of the invention reduces the reset time, thereby improving the efficiency of transmitting optical signals in the PON system.

Fig. 4 is a flowchart of a method for transmitting an optical signal in a passive optical network PON system according to one possible embodiment of the present invention. As shown in fig. 4, the method includes the following steps.

Step 100, begin.

Step 101, the OLT acquires the upstream optical power of each ONU.

Errors in the production and installation processes, or the use of different types of ONU devices, or signal attenuation caused by different quality and length of the connection optical cable may cause inconsistency of the upstream optical power of each ONU. The OLT acquires the uplink light intensity of each ONU, so that the corresponding relation between the uplink light intensity and each ONU is established.

In a possible embodiment, after receiving the upstream light of each ONU, the OLT may obtain the upstream light intensity of each ONU by detecting. Various detection methods in the prior art may be incorporated into embodiments of the present invention, such as CN 100505592C. Further, the OLT may store the detected light intensity and the correspondence with the ONUs in the storage module. The storage module may be built in the OLT or be an external storage device.

In another possible embodiment, the OLT may read the upstream optical power corresponding to each ONU from the storage module. Further, the corresponding relationship between the upstream light intensity in the storage module and each ONU may be stored in the storage module after being detected by the OLT, or may be directly input into the storage module from the outside.

In one possible implementation, the OLT acquires the upstream optical power of each ONU by detection. The OLT may first test the optical intensity of the ONU and then instruct the ONU to transmit the upstream light containing data. The OLT may also directly receive upstream light including data sent by the ONU, and determine the optical intensity of the ONU while receiving the data. Further, each ONU may be first assigned a longer RESET time to avoid data conversion errors.

And 102, the OLT determines the sending sequence of the ONU according to the intensity sequence of the uplink light.

The result of sorting the upstream light by intensity may be from small to large, or from large to small, or from small to large and from large to small. The result of the sorting can be embodied in one period or can be embodied in a plurality of periods in a circulating way. The cycle in the plurality of periods can be sequentially cycled or reversely cycled. As shown in fig. 1, for example, if the uplink light intensities respectively come from ONU 2, ONU 3, and ONU 1 from small to large, the order may be ONU 2, ONU 3, and ONU 1, that is, the uplink light intensities are ordered from small to large; the optical network units can also be ONU 1, ONU 3 and ONU 2, namely the ascending light intensity is sequenced from big to small; the optical network units can also be ONU 2, ONU 3, ONU 1, ONU 2, ONU 3 and ONU 1, namely, the ascending light intensity is sequenced from small to large and is added in sequence for repeating; the optical network unit can also be ONU 2, ONU 3, ONU 1, ONU 1, ONU 3, ONU 2, that is, the ascending light intensity is sequenced from small to large and repeated in a reverse order.

In one possible embodiment, the OLT intensity-sorts the upstream light and determines the order of sending the ONUs in two steps.

As shown in fig. 5, the ONU transmits the upstream light to the OLT according to the sorting result of the upstream light intensities, so that the difference between the upstream light intensities transmitted by the ONUs is reduced, thereby shortening the time required for resetting the RESET, and reducing the number of bits of the Preamble sequence in the upstream light signal transmitted by the ONU, thereby allowing more ONUs to transmit the upstream light in unit time, and transmitting more Data Payload/Data.

In other words, the OLT is RESET regardless of whether the difference in upstream light intensity is positive or negative, so the RESET time is related to the absolute value of the difference between the upstream light intensities. When the intensity of the uplink light sent by the ONU is arranged according to the intensity, the RESET time is required to be minimum compared with the time when the intensity is irregularly fluctuated, namely

For example, let ONU 1, ONU 2, and ONU 3 have upstream light intensity values of 4, 1, and 3, respectively. If the uplink light is sent by number instead of being sorted by size, the light intensity difference values corresponding to two times of RESET among the three uplink lights are respectively 4-1-3 and |1-3| -2. On the other hand, if the upstream lights are transmitted in the order of the smaller to the larger ordering results, that is, the order of ONU 2, ONU 3, and ONU 1, the light intensity difference corresponding to two times of RESET between the three upstream lights is |1-3| ═ 2 and |3-4| ═ 1, respectively, so that the RESET time is shortened. Therefore, when the number of devices is further increased, the scheme for determining the sending sequence of the ONU according to the upstream optical intensity provided by the embodiment of the present invention can effectively reduce the RESET time, so that the ONU can reduce the sent Preamble sequence Preamble, and the OLT can receive more upstream optical signals in unit time.

And 103, the OLT determines the RESET time of the ONU according to the sequencing result of the upstream light intensity of the ONU.

In a possible implementation, the OLT determines a uniform RESET time for each ONU according to the sequencing result of the upstream optical power. Specifically, the OLT determines the RESET time according to the maximum value of the difference value between two sequenced adjacent upstream light intensities, and then informs each ONU of the unified RESET time. In this embodiment, the RESET time determined according to the maximum value of the upstream light intensity difference ensures that data in the upstream light sent by each ONU can be effectively identified and converted, thereby avoiding a conversion error.

In another possible implementation, the OLT determines a corresponding RESET time for each ONU according to the sorting result of the upstream optical power. Specifically, the OLT determines the RESET time of each ONU according to the difference between the sorted light intensities of each two adjacent upstream lights, and then notifies the RESET time corresponding to each ONU. In other words, the upstream optical power has a shorter RESET time than the ONU with the smaller change of the previous ONU, and the upstream optical power has a longer RESET time than the ONU with the larger change of the previous ONU. In this embodiment, the ONU may determine the Preamble sequence Preamble that needs to be sent according to the requirement of the actual RESET, so that the OLT can receive more uplink optical signals in a unit time.

In one possible embodiment, the OLT may store the sequencing result and the RESET time in the memory module. When the OLT is restarted after being replaced or powered off, the steps do not need to be repeatedly executed.

In a possible embodiment, the storage module stores light intensity data corresponding to different ONU devices in advance, and the light intensity data may be from factory settings or data analysis within a period of time. The reset time may be directly allocated to the ONU.

And step 104, the OLT instructs the ONU to send the uplink light according to the sequencing result and the RESET time.

The ONU can determine the length of a Preamble sequence Preamble which needs to be sent according to the RESET time sent by the OLT, and then sends uplink light to the OLT according to the sequence indicated by the OLT. The Preamble sequence Preamble does not carry data and is used to cover the RESET time, so as to avoid conversion errors of the early transmission data at the OLT.

In a possible implementation, the OLT may also directly determine and indicate the length of the Preamble sequence Preamble that the ONU needs to send.

In a possible embodiment, the detection and sequencing of the light intensity may not be performed by the OLT device, for example, by an optical splitter, or by interposing a detection and/or sequencing device between the OLT and the ONU.

In a possible embodiment, the OLT may instruct the ONUs to transmit the upstream light in sequence, or may exhaust the transmission time for one or more cycles for each ONU device and then instruct the time for transmitting the upstream light to the ONUs. In this embodiment, the ONU determines the length of the Preamble sequence to be transmitted according to the transmission time.

In the embodiment of the invention, the intensity of the uplink light sent by the ONU is intelligently detected by the built-in optical module of the OLT in a time division multiple access sequence period, and the uplink sequences of all the ONUs are sequentially arranged from large to small according to the intensity. The voltage profiles of LN + and LN-for this embodiment are shown in FIG. 5. Therefore, the uplink optical sequences sent by the plurality of ONUs are sequentially arranged according to the light intensity, so that the light intensity difference of adjacent optical sequences is reduced, the required RESET RESET control time is shorter, and the LN-can reach a threshold value more quickly.

After the required reset time is shortened, the Preamble of each sequence, namely the bit required by the Preamble sequence, can be reduced, the total time occupied by the uplink light of each corresponding ONU can be shortened, and when the Guard time is unchanged, the OLT can receive more uplink optical signals in unit time.

In one possible embodiment, the OLT instructs the ONUs to alternately transmit upstream light in sequential and reverse order in successive cycles to further reduce the RESET time required by the ONUs between each transmission cycle. One cycle referred to herein is one time in which a plurality of ONU devices sequentially transmit upstream light.

Specifically, in order to ensure that the situation of excessive light intensity difference does not exist during cyclic switching of each period, the uplink light sequences are sequentially and cyclically sequenced from strong to weak → from weak to strong → from strong to weak according to the period, so that the excessive light intensity difference does not occur whenever, the number of the leader sequences bits is less, and the duration is shorter. For example, the ONU 2, ONU 3, ONU 1, ONU 3, and ONU 2 are exemplified above. Through the circulation of the light intensity from small to large and then from large to small, the severe change of switching from the ONU with the maximum light intensity to the ONU with the minimum light intensity is avoided during the switching of two periods, and the reset time is shortened.

In one possible implementation, the OLT periodically detects the upstream optical power of each ONU.

When an ONU device is newly added or replaced, an uplink optical sequence is correspondingly added or the light intensity sequence is changed. The OLT in this embodiment may automatically and periodically detect the intensity of all the upstream lights, and therefore, even if such a change occurs, the OLT may re-order all the upstream lights according to a predetermined light intensity rule. I.e. it is ensured that all the upstream light is sequenced in order of light intensity as shown in fig. 5.

Specifically, the OLT may periodically compare the received uplink light intensity of each ONU with the data in the storage module, and when an inconsistency or a newly added ONU uplink light intensity is found, sort the ONU devices again and determine the reset time.

In another possible implementation, the OLT may also compare the received uplink light intensity of each ONU with the data in the storage module in real time, and when it is found that there is an inconsistency or a newly added ONU uplink light intensity, sort the ONU devices again and determine the reset time.

Fig. 6 is a schematic structural diagram of a passive optical network PON system according to one possible embodiment of the present invention. As shown in fig. 6, the OLT 10 is connected to a plurality of ONUs 20 via an optical splitter 30. The OLT 10 comprises a signal transmission unit 11, a processor 12 and a memory 13.

The signal transmission unit 11 is configured to receive the upstream light transmitted from the ONU 20 and transmit the downstream light to the ONU 20.

The processor 12 is configured to sort the intensities of the upstream lights sent by the ONUs 20 to determine an order in which the ONUs 20 send the upstream lights and a reset time corresponding to each ONU 20, and send a sorting result and the reset time to the ONUs 20.

The memory 13 is configured to store a result of the processor 12 sorting the ONUs 20 according to the transmitted upstream light intensity and a reset time corresponding to each ONU 20.

The ONU 20 transmits upstream light to the OLT according to the sequence and reset time instructed by the OLT 10.

Figure 7 is a block schematic diagram of a part of the structure of an optical line termination OLT according to one possible embodiment of the present invention. As shown in fig. 7, the OLT includes a signal transmission module 14, a detection module 15, a sorting module 16, a reset time determination module 17, and a storage module 18.

The signal transmission module 14 is configured to receive the upstream light from the ONU and transmit the downstream light to the ONU.

The detection module 15 is configured to detect the upstream optical power sent by the ONU and received by the OLT.

The sorting module 16 is configured to sort the upstream optical intensities sent by each ONU, and send the sorting results to the ONUs in the downstream optical through the signal transmission module 14.

The reset time determining module 17 is configured to determine the reset time of each ONU device according to the result of the upstream light intensity sorting, and send the reset time to the ONU in the downstream light through the signal transmission module 14.

The storage module 18 is used for storing the sorting result of the sorting module 16 and the reset time determined by the reset time determination module 17.

In one possible embodiment, the sorting module 16 sorts the intensity of the upstream light according to a small to large or a large to small order.

In a possible embodiment, the sorting module 16 instructs the optical network units ONU to send upstream light alternately in sequential and reverse order in consecutive periods.

In a possible embodiment, the reset time determination module 17 instructs the optical network unit ONU to determine the preamble sequence length of the upstream light according to the corresponding reset time.

In a possible embodiment, the reset time determination module determines 17 a preamble sequence length of the upstream light corresponding to the corresponding reset time, and the reset time determination module 17 instructs the optical network unit ONU to send the upstream light to the optical line terminal OLT according to the preamble sequence length.

In a possible embodiment, the reset time determining module 17 determines a uniform reset time for each optical network unit ONU according to the maximum value of the difference between the intensities of the two sequenced adjacent upstream lights.

In a possible embodiment, the reset time determining module 17 determines the reset time corresponding to each optical network unit ONU according to the difference between the sorted adjacent upstream light intensities.

In a possible embodiment, the detection module 15 stores the detected and obtained intensity of the upstream light of each ONU in the storage module 18.

In a possible embodiment, the detecting module 15 periodically detects the intensity of the received upstream light of each ONU, compares the detected intensity with the stored upstream light intensity data, and when an inconsistency or a new increase is found, the sorting module 16 sorts the intensity of the upstream light again to determine the order in which the ONU sends the upstream light, and the reset time determining module 17 determines the reset time.

In a possible embodiment, the detecting module 15 detects the intensity of the received upstream light of each ONU, compares the detected intensity with the stored upstream light intensity data, and when the detected intensity is inconsistent or increased, the sorting module 16 sorts the intensity of the upstream light again to determine the order of sending the upstream light by the ONU, and the reset time determining module 17 determines the reset time.

Fig. 8 is a block diagram of a partial structure of an optical line terminal OLT according to another possible embodiment of the present invention. As shown in fig. 8, unlike the embodiment shown in fig. 7, the present embodiment further includes a transmission order determining module 19, configured to determine an order in which the ONU transmits subsequent upstream light according to the result of the ordering by the ordering module 16, and transmit the order to the ONU in the downstream light through the signal transmission module 14.

Fig. 9 is a flowchart of a method for transmitting an optical signal in a passive optical network PON system according to one possible embodiment of the present invention. As shown in fig. 9, after sorting the uplink optical signal strengths of the ONUs 1 and 2, the OLT determines the transmission sequence and the reset time, and transmits the transmission sequence and the reset time to the ONUs to instruct the ONUs 1 to transmit the uplink optical signal secondly and the ONUs 2 to transmit the uplink optical signal firstly.

Fig. 10 is a flowchart of a method for transmitting an optical signal in a passive optical network PON system according to another possible embodiment of the present invention. As shown in fig. 10, after the OLT sequences the uplink optical signal strengths of the ONUs 1 and 2, the sending sequence and the resetting time are determined, the preamble sequence length is further determined, and the sending sequence and the preamble sequence length are sent to the ONUs, which instructs the ONU 1 to send the uplink optical signal for the second time and the ONU 2 to send the uplink optical signal for the first time.

Fig. 11 is a flowchart of a method for transmitting an optical signal in a passive optical network PON system according to another possible embodiment of the present invention. As shown in fig. 11, after the OLT sequences the uplink optical signal strengths of the ONUs 1 and 2, the OLT determines the transmission sequence number and the reset time, and transmits the transmission sequence number and the reset time to the ONUs, so as to instruct the ONUs 1 to transmit the uplink optical signal for the second time and the ONUs 2 to transmit the uplink optical signal for the first time.

Fig. 12 is a flowchart of a method for transmitting an optical signal in a passive optical network PON system according to another possible embodiment of the present invention. As shown in fig. 12, after the OLT sorts the upstream optical signal strengths of the ONUs 1 and 2, the OLT determines the transmission sequence and the reset time, and transmits the transmission time to the ONUs to instruct the ONUs 1 to transmit the upstream optical signal secondly and the ONUs 2 to transmit the upstream optical signal firstly.

Figure 13 is an architecture diagram of an optical line termination OLT provided in accordance with one possible embodiment of the present invention. As shown in fig. 13, the OLT includes a receiver, a transmitter, a processor, and a memory distributed on a communication bus. The memory has stored therein program code and applications.

In one possible implementation, the ONU and/or the optical splitter may also have an architecture as shown in fig. 13.

From the above description of the embodiments, it is clear to those skilled in the art that the present invention can be implemented by hardware, firmware, or a combination thereof. When implemented in software, the functions described above may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. Taking this as an example but not limiting: computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Furthermore, the method is simple. Any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, a server, or other remote source using a coaxial cable, a fiber optic cable, a twisted pair, a Digital Subscriber Line (DSL), or a wireless technology such as infrared, radio, and microwave, the coaxial cable, the fiber optic cable, the twisted pair, the DSL, or the wireless technology such as infrared, radio, and microwave are included in the fixation of the medium. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy Disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

In short, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (17)

1. A method of transmitting an optical signal, comprising:

   the optical line terminal acquires a first intensity of a first uplink optical signal sent by a first optical network unit;

   the optical line terminal acquires a second intensity of a second uplink optical signal sent by a second optical network unit, wherein the second intensity is not equal to the first intensity;

   the optical line terminal determines the order of sending the third uplink optical signal by the first optical network unit and the corresponding reset time by referring to the first intensity and the second intensity;

   the optical line terminal determines the order of sending fourth uplink optical signals by the second optical network unit and the corresponding reset time by referring to the first intensity and the second intensity;

   the optical line terminal sends an instruction to the first optical network unit and the second optical network unit, so that the first optical network unit learns the sequence of sending the third uplink optical signal and the corresponding reset time, and the second optical network unit learns the sequence of sending the fourth uplink optical signal and the corresponding reset time.
2. The method of claim 1, wherein the first and second intensities are ordered by the optical line termination according to a small to large order, or a large to small order.
3. The method of claim 2, wherein the order in which the first optical network unit transmits the third upstream optical signals and the order in which the second optical network unit transmits the fourth upstream optical signals are such that upstream optical signals are transmitted alternately in successive periods.
4. The method according to any of claims 1-3, further comprising the optical line terminal instructing the first optical network unit and the second optical network unit to determine a first preamble sequence length of the third upstream optical signal and a second preamble sequence length of the fourth upstream optical signal according to the corresponding reset times.
5. The method according to any of claims 1 to 3, further comprising determining, by the optical line terminal, that the third upstream optical signal corresponds to a first preamble sequence length of the corresponding reset time and the fourth upstream optical signal corresponds to a second preamble sequence length of the corresponding reset time, and instructing, by the optical line terminal, the first optical network unit and the second optical network unit to send the third upstream optical signal and the fourth upstream optical signal to the optical line terminal according to the first preamble sequence length and the second preamble sequence length.
6. The method according to any of claims 1-5, wherein the first intensity and the second intensity are obtained by the optical line terminal through detection.
7. The method of any of claims 1-5, wherein the first intensity and the second intensity are read by the optical line terminal from a storage module.
8. The method according to claim 7, further comprising the olt periodically detecting a third strength of the received third uplink optical signal and a fourth strength of the received fourth uplink optical signal, comparing the detected third strength and fourth strength with the stored first strength and second strength, when the detected first strength and second strength are inconsistent or newly added, the olt determining, with reference to the third strength and the fourth strength, an order in which the first onu transmits a fifth uplink optical signal and a corresponding reset time, and the olt determining, with reference to the third strength and the fourth strength, an order in which the second onu transmits a sixth uplink optical signal and a corresponding reset time.
9. The method according to claim 7, further comprising the olt detecting a third intensity of the received third uplink optical signal and a fourth intensity of the received fourth uplink optical signal in real time, comparing the detected third intensity and the stored fourth intensity with the stored first intensity and the stored second intensity, when the detected third intensity and the stored second intensity are inconsistent or newly added, the olt determining, with reference to the third intensity and the fourth intensity, an order in which the first onu transmits a fifth uplink optical signal and a corresponding reset time, and the olt determining, with reference to the third intensity and the fourth intensity, an order in which the second onu transmits a sixth uplink optical signal and a corresponding reset time.
10. A passive optical network system, comprising:

    a plurality of optical network units;

    an optical splitter; and

    the optical line terminal is connected with the plurality of optical network units through the optical splitter and comprises:

    a signal transmission unit for receiving the upstream optical signal transmitted from the optical network unit and transmitting downstream light to the plurality of optical network units,

    a processor for sequencing the intensity of the uplink optical signals to determine an order in which the plurality of optical network units transmit subsequent uplink optical signals and reset times corresponding to the plurality of optical network units, and transmitting the order and the reset times to the plurality of optical network units, and

    a memory for storing the order and the reset times corresponding to the plurality of optical network units;

    wherein the plurality of optical network units send the subsequent uplink optical signal to the optical line terminal according to the sequence indicated by the optical line terminal and the reset time.
11. An optical line terminal comprising:

    the optical network unit comprises a signal transmission module, a signal receiving module and a signal processing module, wherein the signal transmission module is used for receiving an uplink optical signal from the optical network unit and sending downlink light to the optical network unit;

    a detection module, configured to detect the intensity of the uplink optical signal sent by the optical network unit and received by the optical line terminal;

    a sorting module, configured to sort the intensity of the uplink optical signal sent by each optical network unit to determine a sequence in which each optical network unit sends a subsequent uplink optical signal, and send the sequence in the downlink optical to the optical network unit through the signal transmission module;

    a reset time determining module, configured to determine the reset time of each optical network unit according to the result of the sorting of the intensities of the uplink optical signals, and send the reset time in downlink light to the optical network units through a signal transmission module; and

    and the storage module is used for storing the sequence and the reset time.
12. A method of transmitting an optical signal, comprising:

    a first optical network unit sends a first uplink optical signal to an optical line terminal with a first intensity;

    the first optical network unit sends a second uplink optical signal to the optical line terminal at a second intensity;

    the optical line terminal determines a first sequence number and corresponding first reset time of a third uplink optical signal sent by the first optical network unit by referring to the first intensity and the second intensity;

    the optical line terminal determines a second sequence number and corresponding second reset time of a fourth uplink optical signal sent by the second optical network unit by referring to the first intensity and the second intensity;

    the optical line terminal sends an instruction to the first optical network unit and the second optical network unit;

    the first optical network unit receives the indication and sends the third uplink optical signal to the optical line terminal by referring to the first sequence number and the first reset time;

    and the second optical network unit receives the indication and sends the fourth uplink optical signal to the optical line terminal by referring to the second sequence number and the second reset time.
13. A method of transmitting an optical signal, comprising:

    a first optical network unit sends a first uplink optical signal to an optical line terminal with a first intensity;

    the first optical network unit sends a second uplink optical signal to the optical line terminal at a second intensity;

    the optical line terminal determines a first sequence number and corresponding first reset time of a third uplink optical signal sent by the first optical network unit by referring to the first intensity and the second intensity;

    the optical line terminal determines a second sequence number and corresponding second reset time of a fourth uplink optical signal sent by the second optical network unit by referring to the first intensity and the second intensity;

    the optical line terminal sends a first indication to the first optical network unit by referring to the first sequence number and the first reset time;

    the optical line terminal sends a second indication to the second optical network unit by referring to the second sequence number and the second reset time;

    the first optical network unit receives the first indication and sends the third uplink optical signal;

    and the second optical network unit receives the second indication and sends the fourth uplink optical signal.
14. An optical line terminal comprising a plurality of modules for performing the method of claim 1.
15. An optical line terminal comprising a plurality of modules for performing the method of claim 12.
16. A computer program product configured to perform the method of claim 1.
17. Computer program product configured to perform the method of claim 12.