CN114374898B - Passive optical network architecture and inter-ONU communication method based on same - Google Patents
Passive optical network architecture and inter-ONU communication method based on same Download PDFInfo
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- H—ELECTRICITY
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- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
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- H—ELECTRICITY
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- H04Q11/00—Selecting arrangements for multiplex systems
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Abstract
In the communication method, the ONU generates an uplink data frame containing uplink user data and target ODN address signaling, and modulates the uplink data frame to a subcarrier pre-allocated by a system by adopting a subcarrier multiplexing technology, after the OLT receives the uplink data, the OLT distributes downlink wavelength for the data according to the address signaling information in the uplink data and transmits the downlink wavelength to the target ODN connected with the OLT, so that the data transmission of each user is only carried out between the OLT and the ONU, the CO is only responsible for transmitting a communication authority control instruction, the downlink communication of the OLT is controlled, the uplink ONU data is not processed any more, the occupation of a storage space caused by the data entering CO between the ONU under the control of the same CO is reduced, and the CO can meet the requirement of more inter-ONU communication of the CO.
Description
Technical Field
The invention belongs to the field of optical communication, relates to a passive optical network technology, and in particular relates to a passive optical network architecture and a communication method based on the architecture.
Background
With the development and progress of technology, everything is interconnected, low delay and high traffic become the characteristics of modern networks. At the same time, with the increasing abundance of teleservice content, users' demands for communication networks have grown year by year. The optical fiber access scheme with the advantages of long distance, high capacity and the like gradually replaces schemes of other access networks such as coaxial cables and the like, and becomes a mature scheme for the optical fiber of the modern access network. The passive optical network (Passive optical network, PON) uses passive devices for the links between the optical line terminal (Optical line terminal, OLT) and the optical network units (Optical networkunit, ONU) of the user, so that the cost of network construction and network operation maintenance is low; the device has small volume, occupies little space of a Central Office (CO), has good service expansibility, can support the advantages of the traditional voice service and the broadband service at the same time, and gradually replaces other access modes to become the main flow technology of the access network.
However, with the development of the internet, the high-speed increase of the number of users and the continuous improvement of the requirements of the users on the network speed and quality are realized, and the traditional PON adopts a time division multiplexing scheme when transmitting data, so that each user can only transmit data in a fixed time slot and is not flexible; with the increase of the number of users, in the existing multipoint network, a plurality of OLTs are controlled under each CO, an optical distribution network (Optical distribution network, ODN) connected with each OLT is connected with a plurality of ONUs, when ONUs connected on different ODNs under the control of the same CO communicate, because of the characteristics of PON structures, users under different OLTs send data to the OLTs in an uplink mode if the users want to communicate, the OLTs upload the data to the COs, the CO issue the data to the corresponding OLTs and issue the data to the corresponding ONUs, which can lead a large amount of data to flow into the COs, if the data can be processed through the improvement scheme without the CO, the data can obviously be more flexible, the data capacity burden of the CO can be obviously reduced, the data storage capacity space of the CO can be saved, and the PON can support the communication demands of more ONUs crossing the CO, and the novel multipoint-to-multipoint PON transmission architecture design with higher speed can be realized.
Disclosure of Invention
In order to solve the technical problems, the invention provides a novel passive optical network architecture for multipoint-to-multipoint inter-ONU communication, so as to meet the requirement of mutual communication between different ONUs connected to the same CO under the condition that communication data does not pass through the CO.
The technical scheme adopted by the invention is as follows: the passive optical network architecture comprises CO, OLT, ODN and ONU, wherein a plurality of OLTs are connected under the CO, the OLTs are in one-to-one correspondence with the ODNs, each OLT is connected with the corresponding ODN, and at least one ONU is connected under each ODN.
As shown in fig. 1, compared with the conventional multipoint-to-multipoint PON architecture, one OLT is used to connect a corresponding one of the ODNs, and the present invention proposes to connect the OLT with a plurality of ODNs respectively, so that the following communication manner can be adopted between ONUs: after the OLT receives the uplink data, the OLT extracts the corresponding data from the uplink data according to the target ODN address signaling information in the received data, and then transmits the extracted data to the corresponding target ODN, and then the downlink data is distributed to the target ONU through the ODN, so that the data transmission only exists between the OLT and the ONU, and the large-flow data is not required to be distributed after passing through the CO, so that the problem that the large-capacity data is uniformly uploaded to the CO to bring the capacity burden of the CO is effectively solved. In addition, the data of each ONU is transmitted after being subjected to frequency division by a subcarrier multiplexing technology, so that the problem that the traditional time division PON architecture is not flexible enough can be further improved.
The communication architecture between different ONUs under the control of the same CO provided by the invention is divided into two types, namely: a communication architecture between different ONUs connected in the same ODN, and a communication architecture between different ODNs. These two architectures will be described separately below.
A method for mutual communication between ONU users connected to the same ODN, now assuming that ONU1 wants to communicate with ONU2, the communication scheme has the following steps:
step S1-1, ONU1 generates uplink user data and target ODN address signaling to form an uplink data frame, modulates the uplink data frame onto an uplink data transmission frequency band pre-allocated to ONU1 by a subcarrier multiplexing technology, and transmits the modulated data through an uplink signal transmitter positioned in ONU1 after intensity modulation and transmits the modulated data to an ODN1 through an optical fiber;
step S1-2, the ODN1 couples the data of all uplink users connected with the ODN into one path of optical signals through a coupler, and the optical signals are transmitted to the OLT1 through optical fibers;
s1-3, an uplink signal receiver positioned on the OLT1 receives the optical signals in the S1-2, recovers uplink data, gathers and stores the uplink data of each user, and waits for a CO transmission instruction;
step S1-4, the CO transmits a communication authority instruction to the OLT1, and after the OLT1 receives the CO communication permission instruction, the ONU1 data in the step S1-3 are packaged and sent to a downlink signal transmitter connected with the ODN1 in the OLT1;
step S1-5, corresponding downstream signal transmitters in the OLT1 allocate downstream data transmission wavelength lambda for downstream data according to ODN1 address signaling d1 Modulating ONU1 data in the step S1-4 onto a corresponding downlink data transmission frequency band, modulating the modulated data through intensity to form a path of optical signal and transmitting the path of optical signal, and transmitting downlink data onto the ODN1 through an optical fiber connected with the ODN 1;
step S1-6, a coupler in the ODN1 couples the downlink optical signal from the OLT1 and the downlink optical signals from other OLTs into one path of optical signal;
the optical signals in the step S1-7 and the step S1-6 are transmitted to all users connected to the ODN1 in a broadcasting mode through another coupler in the ODN 1;
and step S1-8, after the ONU2 receives the data in the step S1-7, a downlink signal receiver positioned in the ONU2 automatically filters out the data of the ONU1 and recovers the data.
In step S1-1, each ONU generates respective data and ODN signaling information indicating a destination address and forms an uplink data frame, where the uplink data frame is modulated by using a carrier. Before modulation, the system will design the center frequency f of its sub-carrier transmitting data for each ONU separately k And a fixed bandwidth B, leaving a guard interval Δf between each carrier for modulation of each ONU data. First carrier center frequency f 1 Given by the system, carrier center frequency f of other ONUs k Can be represented by formula f k ＝f k-1 +b/2+Δf, where k=2, …, M represents the number of ONUs connected to ODN 1.
After the system pre-allocates sub-carriers and bandwidths for each user, the uplink data transmitter of each ONU modulates each user data onto the pre-allocated frequency band of the system according to the sub-carrier multiplexing technology, and the implementation process is shown in fig. 5, and includes the following steps:
step 5-1, the original bit sequences of the users are respectively according to M k Order quadrature amplitudeModulation (Quadrature amplitude modulation, QAM) grouping and mapping one-to-one to form complex QAM symbol data having I-and Q-paths, where k=1, 2, …, M represents the number of ONUs connected to ODN 1;
and 5-2, after QAM symbols are obtained through the method 5-1, respectively carrying out shaping filtering on complex QAM symbols containing I paths and Q paths, wherein the shaping filtering can be realized through a root raised cosine roll-off filter, and the expression of the impulse response of the root raised cosine roll-off filter of the kth user is as follows:
wherein T is k For the kth user QAM symbol length, alpha k For the kth user roll-off factor, k=1, 2, …, M represents the number of ONUs connected to ODN 1;
step 5-3, data R of I, Q paths of QAM symbols obtained in step 5-2 respectively k And I k At a sampling rate of F s Resampling to obtain a baseband signal;
step 5-4, respectively performing digital up-conversion on I, Q paths of data according to the carrier frequency allocated to each user by the system, wherein the carrier frequency multiplied by the I path is f k The cosine signal of the carrier frequency is multiplied by the Q path to be f k To obtain intermediate frequency signals s of I path and Q path respectively kI Sum s kQ ：
After obtaining two paths of intermediate frequency signals in step 5-5, the two paths of signals can be directly and correspondingly added to obtain a transmitting signal s due to the characteristics that the intensity modulation/direct detection system cannot process complex numbers and sine and cosine mutual orthogonality and mutual noninterference k ；
Step 5-6, transmitting signal s k And forming an optical signal after the digital-to-analog converter and the intensity modulation.
In the scheme of mutual communication between ONUs in the same ODN, in step S1-3, each OLT includes multiple sets of transceiver units for receiving uplink data from the ODN and transmitting downlink data to the ODN. Each set of transceiver unit comprises an uplink signal receiver and a downlink signal transmitter, after the uplink optical signal reaches the OLT, the uplink optical signal is transmitted to the uplink signal receiver located in the OLT, and each user signal is received and recovered, where the process of recovering the signal by the receiver is shown in fig. 5, and the steps are as follows:
step 5-7, obtaining a digital signal y by the optical signal through a photoelectric detector and an analog-to-digital converter k ；
Step 5-8, receiving the signal y k After down-conversion, two paths of I and Q recovery signals are obtained respectively;
step 5-9, resampling the two paths of signals obtained in the step 5-8 respectively;
step 5-10, respectively carrying out matched filtering on the two paths of signals obtained in the step 5-9;
and 5-11, equalizing the two paths of recovery signals obtained in the step 5-10 to obtain QAM symbols.
And 5-12, performing QAM demapping on the QAM signals obtained in the step 5-11 to obtain original bit sequences of all users.
In step S1-4, the CO does not all receive the data received by the OLT, but after the OLT receives the uplink data, a control instruction is sent to the OLT according to the actual need, to control whether the OLT has authority to send data to the target ODN. The information quantity required by the control instruction is far smaller than the data quantity of the uplink data frames of each user, so that most of storage capacity can be saved for the CO, and the user transmission requirements among more ONU crossing the CO can be supported.
In step S1-5, after OLT1 receives the permission command of CO communication, the downstream transmitter module allocates a corresponding downstream transmission wavelength λ to the target ODN1 information according to the target ODN1 information in the data d1 The OLT1 then packages the data from the ONU1 together with other downstream data to be transmitted, according to steps 5-1 to 5-6 shown in fig. 5, including: m is performed on the original bit sequence k Mapping, shaping filtering and resampling the baseband signal by the order QAM, and processing the baseband signalAnd carrying out digital up-conversion and IQ (in-phase/quadrature-phase) two paths of superposition to obtain a transmitting signal, and then forming a path of optical signal after digital-to-analog converter and intensity modulation. Here, each OLT allocates different downlink transmission wavelengths λ to the downlink data according to different ODN address signaling received in the uplink data dj 。
Then, the downstream data from the OLT1 is multiplexed with downstream data from other OLTs in steps S1-6, so as to form a path of optical signal for transmission to the ONU.
In step S1-8, the downstream signal receiver located in ONU2 filters the received data to obtain information from ONU1, and processes the information, where the processing steps are the same as steps 5-7 to 5-12 shown in fig. 5, and the method includes: the optical signal obtains a receiving signal through a photoelectric detector and an analog-to-digital converter, a QAM symbol is obtained after down-conversion, resampling, matched filtering and equalization of the receiving signal, and the original bit sequence of each user can be recovered by demapping the obtained QAM signal, so that the communication process is completed.
A method for mutual communication between ONUs connected in different ODNs, let us now assume that ONU1 wants to communicate with ONU2, as shown in fig. 4, the communication procedure is as follows:
step S2-1, ONU1 generates uplink user data and target ODN2 address signaling to form an uplink data frame, modulates the uplink data frame onto an uplink data transmission frequency band pre-allocated to ONU1 by a subcarrier multiplexing technology, and transmits the modulated data through an uplink signal transmitter positioned in ONU1 after intensity modulation and transmits the modulated data to an ODN1 through an optical fiber;
step S2-2, the ODN1 couples the data of the uplink user into one path of optical signal through a coupler, and transmits the optical signal to the OLT1 through an optical fiber;
s2-3, an uplink signal receiver positioned on the OLT1 receives the optical signals in the S2-2, recovers uplink data, gathers and stores the uplink data of each user, and waits for a CO transmission instruction;
step S2-4, the CO transmits a communication authority instruction to the OLT1, and after the OLT1 receives the CO communication permission instruction, the ONU1 data in the step S2-3 are packaged and sent to a downlink signal transmitter connected with the ODN2 in the OLT1;
step S2-5, corresponding downstream signal receiver in OLT1 allocates downstream data transmission wavelength lambda for downstream data according to ODN2 address signaling d2 Modulating the data in the step S2-4 onto a corresponding downlink data transmission frequency band, modulating the modulated data through intensity to form a path of optical signal, transmitting the path of optical signal, and transmitting downlink data onto the ODN2 through an optical fiber connected with the ODN 2;
step S2-6, coupling the optical signal from the OLT1 and the downlink optical signal of the OLT2 into one path of optical signal by a coupler in the ODN 2;
step S2-7, after the optical signals in step S2-6 pass through the coupler in the ODN2, the optical signals are transmitted to all users connected to the ODN2 in a broadcasting mode;
and step S2-8, after the ONU2 receives the data in the step S2-7, a downlink signal receiver positioned in the ONU2 automatically filters out the data of the ONU1 and recovers the data.
In step S2-1, each ONU generates respective data and ODN signaling information indicating a destination address and forms an uplink data frame, where the uplink data frame is modulated by using a carrier. Before modulation, the system will design the center frequency f of its sub-carrier transmitting data for each ONU separately k And a fixed bandwidth B, leaving a guard interval Δf between each carrier for modulation of each ONU data. First carrier center frequency f 1 Given by the system, carrier center frequency f of other ONUs k Can be represented by formula f k ＝f k-1 +b/2+Δf, where k=2, …, M.
After the system pre-allocates subcarriers and bandwidths for each user, the uplink data transmitter of each ONU modulates each user data onto the frequency band pre-allocated by the system according to the subcarrier multiplexing technology, and the implementation process is the same as steps 5-1 to 5-6 shown in fig. 5, and includes: m is performed on the original bit sequence k The baseband signal obtained by the mapping of the order QAM, the shaping filtering and the resampling is subjected to digital up-conversion and IQ two-way superposition to obtain a transmitting signal, and one-way light is formed after the digital-to-analog converter and the intensity modulationA signal.
In step S2-3, the upstream signal receiver in each OLT is configured to receive the upstream data from the corresponding ODN, and the upstream signal receiver located in the OLT receives and recovers each user signal. The receiver recovery signal process is the same as steps 5-7 to 5-12 shown in fig. 5, and includes: the optical signal obtains a receiving signal through a photoelectric detector and an analog-to-digital converter, a QAM symbol is obtained after down-conversion, resampling, matched filtering and equalization of the receiving signal, and the original bit sequence of each user can be recovered by demapping the obtained QAM signal.
In step S2-5, after the OLT1 receives the permission command for CO communication, the downstream transmitter module allocates a corresponding downstream transmission wavelength λ to the downstream data according to the target ODN2 information in the upstream data d2 Data is generated according to steps 5-1 to 5-6 shown in fig. 5, and a downstream optical signal is formed by intensity modulation. Similarly, each OLT allocates different downstream transmission wavelengths λ to downstream data according to different ODN address signaling received in the upstream data dj Where j=1, 2, …, N. Meanwhile, in order to ensure that the downlink data from the OLT1 can be multiplexed with the downlink data from the OLT2 in step S2-6 under the condition that the normal downlink transmission data of the OLT2 is not affected, so that a path of data flow to the ONU is formed for transmission, and when the downlink data is modulated by the downlink signal transmitter in the OLT1, the frequency band range in which the normal downlink data of the OLT2 is located is avoided, and the downlink data is modulated on a higher frequency band with less influence on the data transmission.
Then, the downstream data from the OLT1 is multiplexed with the downstream data from the OLT2 in step S2-6 to form a data stream for transmission to the ONU.
In step S2-8, the downstream signal receiver located in ONU2 filters the received data to obtain information from ONU1, and processes the information, where the processing steps are the same as steps 5-7 to 5-12 shown in fig. 5, and the method includes: the optical signal obtains a receiving signal through a photoelectric detector and an analog-to-digital converter, a QAM symbol is obtained after down-conversion, resampling, matched filtering and equalization of the receiving signal, and the original bit sequence of each user can be recovered by demapping the obtained QAM signal, so that the whole communication process is completed.
The CO will continue to detect data transmissions throughout the transmission. The data of each ONU cannot be uploaded to the CO, but the downstream transmission between the OLT and the ONU is affected by the permission instruction issued by the CO to the OLT. When the ONU is hijacked or unauthorized abnormal data transmission is initiated, the CO prevents the OLT from receiving data or prevents the OLT from distributing data downwards after detecting the abnormality.
Compared with the prior art, the invention has the following beneficial effects:
the invention controls the data transmission of communication between ONUs under the same CO control between the OLT and the ONUs, can save CO storage space, and the saved part of storage space can be used for meeting the data transmission requirement between the ONUs crossing the CO, thereby realizing the access of more users and higher transmission rate.
Drawings
Fig. 1 is a schematic diagram of a reference model of a multipoint-to-multipoint PON system according to the present invention;
fig. 2 is a schematic diagram of a communication architecture between ONUs connected to the same ODN in the present invention;
fig. 3 is an upstream data frame structure of each ONU in the present invention;
fig. 4 is a schematic diagram of a communication architecture between ONUs connected to different ODNs in the present invention;
fig. 5 is a diagram showing steps of processing a digital signal of a transceiver in the data transmission process according to the present invention.
Detailed Description
The present invention will be described in detail with reference to the following examples and the accompanying drawings to help those skilled in the art to better understand the inventive concept of the present invention, but the scope of the claims of the present invention is not limited to the following examples, and it should be understood that those skilled in the art should not make any other embodiments without departing from the inventive concept of the present invention.
Example 1
As shown in fig. 2, the present invention provides a method for inter-communication between ONU users connected to the same ODN, so as to solve the problem of inter-communication between ONUs connected to the same ODN. Let us now assume that ONU1 wants to communicate with ONU2 as follows:
the system designs the center frequency f of the sub-carrier of the transmission data for the ONU1 connected with the ODN1 1 The data transmission bandwidth B and other carriers are provided with a protection interval delta f for modulation of ONU1 data; if other ONUs connected to the ODN1 also need to transmit information, the center frequency f of the carrier wave of the other ONUs k Can be represented by formula f k ＝f k-1 +b/2+Δf, where k=2, …, M.
After the system pre-allocates subcarriers and bandwidths for each user, the ONU1 generates ODN signaling indicating the destination address and its own data, so as to form an uplink data frame as shown in fig. 3, and the uplink signal transmitter modulates the uplink data frame to a corresponding frequency band and transmits the uplink data frame by subcarrier multiplexing technology according to the pre-allocated subcarriers and bandwidths, and the implementation process is shown in steps 5-1 to 5-6 in fig. 5, and the specific process is as follows:
the original bit sequence is M 1 The order QAM carries out grouping and one-to-one mapping to form complex QAM symbol data with I paths and Q paths; and after the QAM symbols are obtained, respectively carrying out shaping filtering on the complex QAM symbols containing the I path and the Q path. The shaping filtering may be implemented by a root raised cosine roll off filter. The root raised cosine roll off filter impulse response of ONU1 is expressed as follows:
wherein T is 1 For QAM symbol length, α 1 Is a roll-off factor;
after passing through the shaping filter, I, Q paths of data R of QAM symbols are obtained respectively 1 And I 1 At a sampling rate of F s And (4) resampling to obtain a baseband signal, and then respectively carrying out digital up-conversion on I, Q paths of data according to the carrier frequency allocated to the ONU1 by the system. Wherein the I-path multiplied by carrier frequency is f 1 The cosine signal of the carrier frequency is multiplied by the Q path to be f 1 To obtain intermediate frequency signals s of I path and Q path respectively 1I Sum s 1Q ：
After obtaining two paths of intermediate frequency signals, the intensity modulation/direct detection system can not process complex numbers and the characteristics of quadrature and noninterference of sine and cosine, and can directly add the two paths of signals respectively and correspondingly to obtain a transmitting signal s 1 Transmitting a signal s 1 And forming a path of optical signal after the digital-analog converter and the intensity modulation, and transmitting the optical signal to the ODN1 through an optical fiber.
The ODN1 couples the data of the uplink user into one path of optical signal through the coupler, and transmits the optical signal to the OLT1 through the optical fiber.
The OLT1 includes a plurality of transceiver units for receiving uplink data from the ODN and transmitting downlink data to the ODN. Each transceiver unit contains an uplink signal receiver and a downlink signal transmitter. After the uplink optical signal reaches the OLT, the uplink optical signal is transmitted to an uplink signal receiver located in the OLT, and each user signal is received and recovered. The data receiving process is shown in steps 5-7 to 5-12 in fig. 5, and the specific process is as follows:
the optical signal is passed through photoelectric detector and analog-digital converter to obtain digital signal y 1 After that, the received signal y 1 And performing down-conversion to obtain two paths of I and Q recovery signals respectively. And then re-sampling and matched filtering are respectively carried out on the two paths of signals to obtain baseband signals, then equalization is carried out on the two paths of obtained baseband signals to obtain QAM symbols, and finally QAM demapping is carried out on the obtained QAM signals to obtain an original bit sequence of the ONU 1. The OLT1 gathers and stores the recovered uplink data, and waits for a CO communication instruction.
In the transmission process, the CO does not all receive the data received by the OLT1, but after the OLT1 receives the uplink data, a control instruction is sent to the OLT1 according to actual needs, so as to control whether the OLT1 has permission to perform downlink data transmission.
After the OLT1 receives the permission instruction of CO communication, its downstream signal transmitter receives the upstream data from ONU1 according to the OLT1The corresponding downlink transmission wavelength lambda is allocated to the address information of the medium target ODN1 d1 . Then, the downstream signal transmitter packages the data from the ONU1 together with other downstream data to be transmitted, modulates the data to different frequency bands according to the location of the data sink and forms a downstream optical signal by intensity modulation according to steps 5-1 to 5-6 shown in fig. 5. And then the downlink data from the OLT1 and the downlink data from other OLTs are multiplexed at the ODN1 through a coupler to form a path of optical signal, and the path of optical signal is transmitted to all users connected to the ODN1 in a broadcasting mode. After receiving the broadcast data, the downstream signal receiver located in ONU2 automatically filters the data from ONU1 and recovers it according to steps 5-7 to 5-12 shown in fig. 5, thus completing the whole communication process.
Example two
As shown in fig. 4, this embodiment provides a method for mutual communication between ONUs connected in different ODNs under the same CO control. Let us now assume that ONU1 wants to communicate with ONU2 as follows:
the system designs the center frequency f of the subcarrier of the transmission data for the ONU1 connected to the ODN1 1 The data transmission bandwidth B and other carriers are provided with a protection interval delta f for modulation of ONU1 data; if other ONUs connected to the ODN1 also need to transmit information, the center frequency f of the carrier wave of the other ONUs k Can be represented by formula f k ＝f k-1 +b/2+Δf, where k=2, …, M.
After the system pre-allocates subcarriers and bandwidths for each user, the ONU1 generates ODN signaling indicating the destination address and its own data, so as to form an uplink data frame as shown in fig. 3, and the uplink signal transmitter modulates the uplink data frame to a corresponding frequency band and transmits the uplink data frame by subcarrier multiplexing technology according to the pre-allocated subcarriers and bandwidths, and the implementation process is shown in steps 5-1 to 5-6 in fig. 5, and the specific process is as follows:
the original bit sequence is M 1 The order QAM carries out grouping and one-to-one mapping to form complex QAM symbol data with I paths and Q paths;
after QAM symbols are obtained, respectively carrying out shaping filtering on complex QAM symbols containing I paths and Q paths;
after passing through the shaping filter, I, Q paths of data R of QAM symbols are obtained respectively 1 And I 1 At a sampling rate of F s Resampling to obtain a baseband signal;
then according to the carrier frequency allocated to ONU1 by the system, respectively implementing digital up-conversion to I, Q paths of data, wherein the carrier frequency multiplied by I path is f 1 The cosine signal of the carrier frequency is multiplied by the Q path to be f 1 To obtain intermediate frequency signals s of I path and Q path respectively 1I Sum s 1Q ；
After obtaining two paths of intermediate frequency signals, the intensity modulation/direct detection system can not process complex numbers and the characteristics of quadrature and noninterference of sine and cosine, and can directly add the two paths of signals respectively and correspondingly to obtain a transmitting signal s 1 Transmitting a signal s 1 And forming a path of optical signal after the digital-analog converter and the intensity modulation, and transmitting the optical signal to the ODN1 through an optical fiber.
The ODN1 couples the data of the uplink user into one path of optical signal through the coupler, and transmits the optical signal to the OLT1 through the optical fiber.
The OLT1 includes a plurality of transceiver units, and the transceiver units are configured to receive uplink data from the ODN and transmit downlink data to the ODN. Each transceiver unit contains an uplink signal receiver and a downlink signal transmitter. After the uplink optical signal reaches the OLT, the uplink optical signal is transmitted to an uplink signal receiver located in the OLT, and each user signal is received and recovered. The signal receiving process is shown in steps 5-7 to 5-12 in fig. 5, and the specific process is as follows:
the optical signal is passed through photoelectric detector and analog-digital converter to obtain digital signal y 1 After that, the received signal y 1 And performing down-conversion to obtain two paths of I and Q recovery signals respectively. And then re-sampling and matched filtering are respectively carried out on the two paths of signals to obtain baseband signals, then equalization is carried out on the two paths of obtained baseband signals to obtain QAM symbols, and finally QAM demapping is carried out on the obtained QAM signals to obtain an original bit sequence of the ONU 1. The OLT1 gathers and stores the recovered uplink data, and waits for a CO communication instruction.
In the transmission process, the CO does not all receive the data received by the OLT1, but after the OLT1 receives the uplink data, a control instruction is sent to the OLT1 according to actual needs, so as to control whether the OLT1 has permission to perform downlink data transmission.
After the OLT1 receives the permission instruction of the CO communication, the downlink signal transmitter allocates a corresponding downlink transmission wavelength lambda for the uplink data according to the target ODN2 information in the uplink data d2 Data are generated according to the steps 5-1 to 5-6 shown in fig. 5, and the downlink optical signal is formed by intensity modulation. Meanwhile, in order to ensure that the downlink data from the OLT1 can be multiplexed with the downlink data from the OLT2 under the condition that the normal downlink transmission of the OLT2 is not affected, a path of data stream is formed to transmit to the ONU, and when the downlink data is modulated by the downlink signal transmitter in the OLT1, the frequency band range in which the normal downlink data of the OLT2 is located is avoided, and the downlink data is modulated on a higher frequency band with less influence on the data transmission. Then, the downstream data from the OLT1 is multiplexed with the downstream data from the OLT2 at the ODN2 by a coupler to form a path of optical signal, and the data is transmitted to all the users connected to the ODN2 in a broadcast manner. Finally, the downstream signal receiver located in ONU2 filters the received data to obtain the information from ONU1, and then receives the signal according to steps 5-7 to 5-12 in fig. 5, specifically: the optical signal obtains a receiving signal through a photoelectric detector and an analog-to-digital converter, a QAM symbol is obtained after down-conversion, resampling, matched filtering and equalization of the receiving signal, and the original bit sequence of each user can be recovered by demapping the obtained QAM signal, so that the whole communication process is completed.
The present invention is not limited to the above-described embodiments, and according to the above-described matters, the present invention may be modified, replaced or altered in various equivalent ways without departing from the basic technical spirit of the present invention, all falling within the scope of the present invention, according to the general technical knowledge and conventional means in the art.
Claims (4)
1. An inter-ONU communication method of a passive optical network architecture, wherein the passive optical network architecture comprises CO, OLT, ODN and ONUs, a plurality of OLTs are connected under the CO, the OLTs are in one-to-one correspondence with the ODNs, each OLT is connected with the corresponding ODN, at least one ONU is connected under each ODN, and at least one OLT is connected with at least one other ODN besides the ODN corresponding to the OLT; the method is characterized by comprising the following steps of:
after receiving the uplink data, the OLT extracts corresponding data from the uplink data according to the target ODN address signaling information in the received data and then transmits the extracted corresponding data to the corresponding target ODN, and the downlink data is then distributed to the target ONU through the ODN;
specifically, if ONU1 and ONU2 are connected under ODN1, OLT1 is an OLT corresponding to ODN1, and designs a center frequency and a bandwidth of a subcarrier for transmitting data for each ONU, and a protection interval is reserved between each carrier, and a communication process between ONU1 and ONU2 connected under the same ODN is as follows:
step S1-1, ONU1 generates uplink user data and target ODN address signaling to form an uplink data frame, modulates the uplink data frame onto an uplink data transmission frequency band pre-allocated to ONU1 by a subcarrier multiplexing technology, and transmits the modulated data through an uplink signal transmitter positioned in ONU1 after intensity modulation and transmits the modulated data to an ODN1 through an optical fiber;
step S1-2, the ODN1 couples the data of all uplink users connected with the ODN into one path of optical signals through a coupler, and the optical signals are transmitted to the OLT1 through optical fibers;
s1-3, an uplink signal receiver positioned on the OLT1 receives the optical signals in S1-2, recovers uplink data, stores the recovered data and waits for a CO transmission instruction;
step S1-4, the CO transmits a command of communication authority to the OLT1, and after the OLT1 receives the command of CO permission for communication, the data of the ONU1 in the step S1-3 are packaged and sent to a downlink signal transmitter connected with the ODN1 in the OLT1;
step S1-5, corresponding downstream signal transmitters in the OLT1 allocate downstream data transmission wavelength lambda for downstream data according to ODN1 address signaling d1 Modulating ONU1 data in the step S1-4 onto a corresponding downlink data transmission frequency band, modulating the modulated data through intensity to form a path of optical signal, transmitting the path of optical signal, and connecting with ODN1Downlink data is sent to the ODN1 through the optical fiber;
step S1-6, a coupler in the ODN1 couples the downlink optical signal from the OLT1 and the downlink optical signals from other OLTs into one path of optical signal;
the optical signals in the step S1-7 and the step S1-6 are transmitted to all users connected to the ODN1 in a broadcasting mode through another coupler in the ODN 1;
and step S1-8, after the ONU2 receives the data in the step S1-7, a downlink signal receiver positioned in the ONU2 automatically filters out the data of the ONU1 and recovers the data.
2. The method of inter-ONU communication according to claim 1, wherein,
the ONU1 is connected under the ODN1, the ONU2 is connected under the ODN2, the OLT1 is the OLT corresponding to the ODN1, the OLT2 is the OLT corresponding to the ODN2, the OLT1 is connected with the ODN1 and the ODN2, the central frequency and the bandwidth of the subcarrier for transmitting data are designed for each ONU, a protection interval is reserved between each carrier, and the communication process between the ONU1 and the ONU2 connected under different ODNs is as follows:
step S2-1, ONU1 generates uplink user data and target ODN address signaling to form an uplink data frame, modulates the uplink data frame onto an uplink data transmission frequency band pre-allocated to ONU1 by a subcarrier multiplexing technology, and transmits the modulated data through an uplink signal transmitter positioned in ONU1 after intensity modulation and transmits the modulated data to an ODN1 through an optical fiber;
step S2-2, the ODN1 couples the data of the uplink user into one path of optical signal through a coupler, and transmits the optical signal to the OLT1 through an optical fiber;
s2-3, an uplink signal receiver positioned on the OLT1 receives the optical signals in the S2-2, recovers uplink data, gathers and stores the uplink data of each user, and waits for a CO transmission instruction;
step S2-4, the CO transmits a communication authority instruction to the OLT1, and after the OLT1 receives the CO communication permission instruction, the ONU1 data in the step S2-3 are packaged and sent to a downlink signal transmitter connected with the ODN2 in the OLT1;
step S2-5, corresponding downstream signal transmitter in OLT1According to ODN2 address signaling, downlink data transmission wavelength lambda is allocated for downlink data d2 Modulating ONU1 data in the step S2-4 onto a corresponding downlink data transmission frequency band, modulating the modulated data through intensity to form a path of optical signal and transmitting the path of optical signal, and transmitting downlink data onto the ODN2 through an optical fiber connected with the ODN 2;
step S2-6, coupling the optical signal from the OLT1 and the downlink optical signal of the OLT2 into one path of optical signal by a coupler in the ODN 2;
step S2-7, after the optical signals in step S2-6 pass through another coupler in the ODN2, the optical signals are transmitted to all users connected to the ODN2 in a broadcasting mode;
and step S2-8, after the ONU2 receives the data in the step S2-7, a downlink signal receiver positioned in the ONU2 automatically filters out the data of the ONU1 and recovers the data.
3. The inter-ONU communication method according to claim 1 or 2, wherein after obtaining the CO communication authority command, the OLT1 allocates different downlink transmission wavelengths λ to the downlink data according to the received target ODN address signaling in the uplink data dj The method comprises the steps of carrying out a first treatment on the surface of the In addition, in order to ensure that the downlink data from the OLT1 does not affect the normal downlink transmission data of the OLT where the target ODN is located, when the downlink data is modulated by the downlink signal transmitter in the OLT1, the frequency band range where the normal downlink data of the OLT where the target ODN is located is avoided, and the downlink data is modulated on a higher frequency band with less influence on data transmission.
4. An inter-ONU communication method according to claim 1 or 2, characterized in that the signal transmitter processes the following:
step 5-1, the original bit sequences of the users are respectively according to M k The method comprises the steps of grouping and mapping the order QAMs into complex QAM symbol data with I paths and Q paths one by one, wherein k=1, 2, …, M and M represent the number of ONUs connected with the ODN 1;
step 5-2, after the QAM symbols are obtained in the step 5-1, respectively carrying out shaping filtering on the complex QAM symbols containing the I path and the Q path;
step 5-3, for the QAM symbols obtained in step 5-2 respectivelyI, Q way data R of (2) k And I k At a sampling rate of F s Resampling to obtain a baseband signal;
step 5-4, respectively carrying out digital up-conversion on I, Q paths of data according to carrier frequencies allocated to each user by the system to obtain an intermediate frequency signal s of an I path kI And Q-path intermediate frequency signal s kQ ；
Step 5-5, the two paths of signals in step 5-4 are respectively and correspondingly added to obtain a transmitting signal s k ；
Step 5-6, transmitting signal s k Forming a path of optical signal after digital-to-analog converter and intensity modulation;
the processing procedure of the signal receiver is as follows:
step 5-7, obtaining a digital signal y by the optical signal through a photoelectric detector and an analog-to-digital converter k ；
Step 5-8, receiving the signal y k After down-conversion, two paths of I and Q recovery signals are obtained respectively;
step 5-9, resampling the two paths of signals obtained in the step 5-8 respectively;
step 5-10, respectively carrying out matched filtering on the two paths of signals obtained in the step 5-9;
step 5-11, equalizing the two paths of recovery signals obtained in the step 5-10 to obtain QAM symbols;
and 5-12, performing QAM demapping on the signals in the step 5-11 to obtain original bit sequences of all users.
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