WO2012095024A1

WO2012095024A1 - Method and device for transmitting optical signal, and passive optical network

Info

Publication number: WO2012095024A1
Application number: PCT/CN2012/070342
Authority: WO
Inventors: 何子安; 苏婕; 张德智; 李长垒; 黄新刚
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-01-13
Filing date: 2012-01-13
Publication date: 2012-07-19
Also published as: CN102045610B; CN102045610A

Abstract

Disclosed are a method and a device for transmitting an optical signal, and a passive optical network. The method includes: an ONU receiving a downlink frame from an OLT, wherein the downlink frame is used for indicating status information about a wavelength channel; the ONU determining an idle wavelength channel according to the downlink frame; the ONU carrying out a wavelength registration with the OLT on the idle wavelength channel and transmitting an optical signal after the wavelength registration has succeeded. By means of the present invention, the resource utilization of the optical signal transmission is improved and the registration process is simplified.

Description

The present invention relates to the field of communications, and in particular to an optical signal transmission method and apparatus, and a passive optical network. The Wavelength Division Multiplexing Passive Optical Network (WDM-PON) and the Wavelength Division Multiplexing Time Division Multiplexing Passive Optical Network (WDM-WDM- TDM PON) is a new passive optical network system based on multi-wavelength single-fiber transmission. The working principle is that each end user occupies one wavelength channel separately, and multiple wavelength channels are separated by wavelength division multiplexing. Transmission in the same trunk fiber. Its characteristic is that each end user has exclusive access to a wavelength bandwidth resource. This not only greatly increases the bandwidth provided to individual users, but also fully utilizes the wavelength bandwidth resources of the optical fiber, which greatly expands the total bandwidth of the passive optical network. Although WDM-PON has many advantages, high cost has always been a major difficulty in the development of WDM-P0N. In order to reduce the network construction cost of WDM-P0N, the industry generally recommends the use of the "colorless" ONU scheme, which means that the 0NUs of all users are unified and there is no difference between them. This can significantly reduce the network construction and maintenance costs of WDM-P0N. At present, injection locking FP LD, RS0A and tunable laser are the most important three optical network unit (ONU) implementation schemes, of which tunable laser is the best transmission performance, the simplest one. Since the tunable laser is an active wavelength selective output device compared to the injection-locked FP laser (IL FP LD) and the reflective semiconductor optical amplifier (RS0A), 0LT is required for uniform wavelength initialization. Scheduling and allocation management. For this reason, it has been proposed to set the tunable laser to a fixed wavelength at the time of 0NU initialization, register by the traditional TDM method, and then switch to the different working wavelengths after registration is completed. Can solve the problem of wavelength conflict during 0NU initialization, but 0NU is shipped at the factory or 0NU After the power is cut off, the working wavelength needs to be reset to the unified wavelength for registration, which increases the number of wavelength tuning and wavelength management. Moreover, the registration occupies one user wavelength channel, and the serial registration method also makes the registration process take a long time. In view of the low resource utilization rate of the optical transmission method in the related art and the complicated registration process, an effective solution has not been proposed yet. SUMMARY OF THE INVENTION A primary object of the present invention is to provide an optical signal transmission method and apparatus, and a passive optical network, to at least solve the problem of low resource utilization and complicated registration process of the optical signal transmission method in the related art. According to an aspect of the invention, an optical signal transmission method is provided. The optical signal transmission method according to the present invention includes: ONU reception from an optical line terminal (Optical Line

The downstream frame of the terminal, which is referred to as OLT, wherein the downlink frame carries the state information of the wavelength channel; 0NU adjusts the uplink and downlink working wavelengths to the idle wavelength channel according to the state information of the wavelength channel carried in the downlink frame, and the ONU is adjusted. The ONU is registered with the OLT on the working wavelength channel, and the service is transmitted after the ONU is successfully registered. Preferably, the ONU receives the downlink frame from the OLT, including one of the following: a registration grant frame transmitted on the idle wavelength channel; and a wavelength channel adjustment information frame transmitted on the non-idle wavelength channel. Preferably, before receiving the downlink frame sent by the optical fiber line terminal OLT, the OLT further includes: the OLT generating, according to the status information of the current idle wavelength channel, a wavelength management table that records the current idle wavelength channel information, and loading the wavelength management table information into the The wavelength channel adjustment information frame is sent to all non-idle wavelength channels.

Preferably, the ONU receives the downlink frame sent by the OLT, including one of the following: When the remote node uses the wavelength division multiplexing demultiplexing device, the ONU uses the wide spectrum optical receiver to receive the OLT to send the registration authorization frame in the idle wavelength channel, where The registration authorization frame indicates that the state of the wavelength channel in which the wavelength channel is located is idle and carries the uplink wavelength value corresponding to the wavelength channel. For the WDM-TDM PON case, the OLT needs to provide a discovery window after sending the registration authorization frame, and the registration is required. The authorization frame informs the ONU. When the remote node uses the optical splitter, the ONU uses the tunable receiver to receive, the OLT sends a registration grant frame on the idle wavelength channel, and transmits the wavelength channel adjustment information frame on the non-idle wavelength channel, where the registration grant frame indicates its location. The status of the wavelength channel is idle. For the WDM-TDM PON, the OLT needs to provide a discovery window after sending the registration authorization frame, and the ONU is notified by the registration authorization frame, and the wavelength channel adjustment information frame carries the current idle wavelength channel information, and Indicates that the state of the wavelength channel in which the ONU is currently located is non-idle; when the remote node uses an optical splitter (or a combination of a wavelength division multiplexing demultiplexer and an optical splitter), the ONU uses an upstream signal optical transmitter ( Tuning the laser) transmitting the local oscillator to the coherent receiver, using the coherent receiver to receive the registration grant frame sent from the OLT on the idle wavelength channel, and adjusting the information frame on the wavelength channel transmitted in the non-idle wavelength channel, where the registration grant frame indicates its location The state of the wavelength channel is idle, or the wavelength channel is adjusted. The information frame carries information about the current idle wavelength channel, and indicates that the state of the wavelength channel in which it is located is not idle. For the WDM-TDM PON case, the OLT needs to provide a discovery window after sending the registration authorization frame, and the registration authorization frame is adopted. Tell the ONU. Preferably, the ONU adjusts the uplink and downlink working wavelengths to the idle wavelength channels according to the state information of the wavelength channel carried by the downlink frame according to the downlink frame, where: when the remote node uses the wavelength division multiplexing demultiplexing device, After receiving the registration authorization frame, the ONU adjusts the uplink transmission wavelength to the uplink wavelength corresponding to the wavelength channel according to the uplink wavelength information included in the registration authorization frame. When the remote node uses the optical splitter, if the ONU receives the registration grant frame, indicating that the wavelength channel of the ONU is the idle wavelength channel, the ONU does not need to adjust the uplink transmit wavelength. When the ONU receives the wavelength channel adjustment information frame, indicating that the wavelength channel of the ONU is a non-idle wavelength channel, the ONU adjusts the idle wavelength channel information carried in the information frame according to the wavelength channel, and adjusts the receiving and transmitting wavelengths to one. On the free wavelength channel. Preferably, the ONU performs ONU registration with the OLT on the idle wavelength channel, and performs service transmission after the ONU is successfully registered. The ONU sends the registration request frame after receiving the registration authorization frame sent by the OLT on the idle wavelength channel; After receiving the registration confirmation frame sent by the OLT, it sends an acknowledgement feedback frame to the OLT and performs service transmission. Preferably, the registration request frame is sent in a burst form. When there are multiple ONUs registered in one idle wavelength channel and the time period of the registration request frame sent by multiple ONUs overlaps, the multiple ONUs wait for random delay. Send the registration request frame again. Preferably, the method further includes: determining, by the ONU, whether the sequence number carried in the registration confirmation frame and the sequence number of the same are the same; if the determination result is yes, sending an acknowledgement feedback frame to the OLT. Preferably, for the WDM-PON, after the OLT successfully receives the registration request frame of an ONU, the OLT changes the state of the wavelength channel in the wavelength management table to be non-idle. For the WDM-TDM PON, when the ONU is in a certain one After the idle wavelength channel is successfully registered, and the idle wavelength channel does not have enough remaining bandwidth available, the OLT modifies the state of the wavelength channel in the wavelength management table to be non-idle. Preferably, for the WDM-PON, if the ONU registration is unsuccessful, or the normal operation occurs, the OLT modifies the wavelength channel state to idle. For WDM-TDM PON, when the state is a non-idle wavelength channel and enough remaining bandwidth is available, the OLT modifies the wavelength channel state to idle. According to another aspect of the present invention, an ONU is provided. The ONU according to the present invention includes: a receiving module, configured to receive a downlink frame from the OLT, wherein the downlink frame is used to indicate status information of the wavelength channel; and the wavelength adjustment module is configured to set, by the ONU, the idle wavelength channel information included in the downlink frame, The working wavelength is adjusted to the idle wavelength channel; the first registration module is configured to perform ONU registration with the OLT on the idle wavelength channel; and the first transmission module is configured to perform optical signal transmission after the ONU is successfully registered. Preferably, the receiving module is configured to receive the downlink frame from the OLT by using one of the following: when the remote node uses the wavelength division multiplexing demultiplexing device, the ONU receives the registration authorization frame from the OLT by using the wide spectrum optical receiver, where The registration authorization frame carries the uplink wavelength information corresponding to the wavelength channel in which it is located: When the remote node uses the optical splitter, the ONU uses the tunable receiver to receive the registration grant frame or the wavelength channel adjustment information frame from the OLT, and register the authorization frame indication. The status of the wavelength channel in which the ONU is currently idle is idle. The wavelength channel adjusts the information frame, carries the information of the current idle wavelength channel, and indicates that the state of the wavelength channel where the ONU is currently located is not idle; or when the remote node uses the optical splitter The ONU sends the local oscillator to the coherent receiver through its uplink transmitter, and uses the coherent receiver to receive the registration grant frame or the wavelength channel adjustment information frame from the OLT. The registration grant frame indicates that the current wavelength channel of the ONU is idle, and the wavelength is idle. The channel adjustment information frame carries the information of the current idle wavelength channel, and indicates the current ONU The state of the wavelength channel is not idle. Preferably, the wavelength adjustment module is configured to adjust the working wavelength to the idle wavelength channel by adjusting state information of the current idle wavelength channel in the information frame according to the wavelength channel. Preferably, the first registration module includes: a registration request frame sending module, configured to send a registration request frame after receiving the registration authorization frame sent by the OLT on the idle wavelength channel; and confirming the sending module, configured to receive the registration sent by the OLT After confirming the frame, an acknowledgment feedback frame is sent to the OLT. According to still another aspect of the present invention, an OLT is also provided. The OLT according to the present invention includes: a sending module, configured to send a downlink frame to the optical network unit ONU, wherein the downlink frame is used to indicate status information of the wavelength channel; and the second registration module is set to be after the ONU adjusts to the idle wavelength channel The ONU is registered with the ONU. The second transmission module is configured to perform service transmission after the ONU is successfully registered. According to yet another aspect of the present invention, a passive optical network is also provided. A passive optical network according to the present invention includes: the ONU described above and the OLT described above. According to the present invention, the ONU receives the downlink frame from the OLT for indicating the status information of the wavelength channel, adjusts the working wavelength to the idle wavelength channel according to the downlink frame, and performs ONU registration on the wavelength channel, thereby solving the related art light. The resource utilization method of the signal transmission method is relatively low and the registration process is complicated, thereby improving the resource utilization of the optical signal transmission and simplifying the registration process. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are set to illustrate,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1 is a flowchart of an optical signal transmission method according to an embodiment of the present invention; FIG. 2 is a flowchart of ONU registration and wavelength assignment according to a preferred embodiment of the present invention; FIG. 3 is a flowchart according to a first embodiment of the present invention. FIG. 4 is a schematic diagram of an ONU and OLT registration information interaction process according to Embodiment 1 of the present invention; FIG. 5 is an ONU use according to Embodiment 2 of the present invention; 2 is a schematic diagram of a WDM-PON system for modulating a laser and a tunable receiver; FIG. 6 is a second schematic diagram of an ONU and OLT registration information exchange process according to Embodiment 2 of the present invention; FIG. 7 is a tunable laser using an ONU according to Embodiment 3 of the present invention; FIG. 8 is a block diagram showing the structure of an ONU according to an embodiment of the present invention; FIG. 9 is a structural block diagram of an OLT according to an embodiment of the present invention; and FIG. 10 is a passive diagram according to an embodiment of the present invention. A block diagram of the optical network. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict. The embodiment provides an optical signal transmission method. FIG. 1 is a flowchart of an optical signal transmission method according to an embodiment of the present invention. As shown in FIG. 1, the method includes steps S102 to S106. Step S102: The ONU receives the downlink frame from the OLT, where the downlink frame carries the state information of the wavelength channel. Step S104: The ONU adjusts the uplink and downlink working wavelengths to the idle wavelength channel according to the wavelength channel information provided by the downlink frame. Step S106 The ONU exchanges ONU registration information with the OLT on the adjusted wavelength channel, and performs service transmission after the ONU is successfully registered. It should be noted that, in this embodiment and the following embodiments, the uplink and downlink wavelengths may have corresponding relationships to reduce the complexity of the configuration. Preferably, the ONU receives the downlink frame sent by the OLT, and includes one of the following two types: a registration authorization frame sent in the idle wavelength channel; and an adjustment information frame sent on the wavelength channel sent in the non-idle wavelength channel. Preferably, before the ONU receives the downlink frame sent by the optical line terminal OLT, the method further includes: the OLT generating a wavelength management table according to the current idle wavelength channel information, recording the current idle wavelength channel information, and loading the wavelength management table information into the wavelength channel adjustment. The information frame is periodically sent to the ONU through all non-idle wavelength channels. Preferably, the process of the ONU receiving the downlink frame sent by the OLT is as follows: When the remote node uses the wavelength division multiplexing demultiplexing device, the ONU uses a wide spectrum optical receiver, and the OLT sends a registration authorization frame in the idle wavelength channel, where, the registration The authorization frame indicates that the state of the wavelength channel in which it is located is idle, and informs the ONU of the upstream wavelength value corresponding to the wavelength channel. For the WDM-TDM PON case, after the OLT sends the registration authorization frame, it also needs to provide a discovery window, and inform the ONU through the registration authorization frame. When the remote node uses the optical splitter, the ONU uses the tunable receiver to receive, the OLT sends a registration grant frame on the idle wavelength channel, and transmits the wavelength channel adjustment information frame on the non-idle wavelength channel, where the registration grant frame indicates the wavelength at which it is located. The status of the channel is idle. For the WDM-TDM PON, the OLT needs to provide a discovery window after sending the registration authorization frame, and inform the ONU through the registration authorization frame. The wavelength channel adjustment information frame carries the current idle wavelength channel information, and indicates that the state of the wavelength channel where the ONU is currently located is not idle; when the remote node uses an optical splitter or a wavelength division multiplexing demultiplexer and an optical splitter, The ONU uses the uplink signal optical transmitter (tunable laser) to transmit the local oscillator to the coherent receiver, the coherent receiver to receive the registration grant frame sent from the OLT in the idle wavelength channel, and the wavelength channel adjustment information frame transmitted in the non-idle wavelength channel. , its The registration authorization frame indicates that the state of the wavelength channel in which it is located is idle. For the WDM-TDM PON case,

After the OLT sends the registration authorization frame, it also needs to provide a discovery window, and inform the ONU through the registration authorization frame. Or the wavelength channel adjustment information frame carries the information of the current idle wavelength channel, and indicates that the state of the wavelength channel in which it is located is not idle. Preferably, the process of adjusting the ONU to an idle wavelength channel according to the downlink frame is as follows: When the remote node uses the wavelength division multiplexing demultiplexing device, after the ONU receives the registration authorization frame, according to the uplink wavelength included in the registration authorization frame. Information, adjusting the uplink transmit wavelength to the upstream wavelength value corresponding to the wavelength channel. When the remote node uses an optical splitter, the ONU must be able to choose to receive a downstream wavelength (implemented with a tunable receiver or tunable filter) and choose to transmit an upstream wavelength (implemented with a tunable laser). The wavelengths have a one-to-one correspondence. If the ONU receives a registration authorization frame, indicating that the wavelength channel of the ONU is the idle wavelength channel, the ONU does not need to adjust the uplink transmission wavelength. When the ONU receives the wavelength channel adjustment information frame, indicating that the wavelength channel of the ONU is a non-idle wavelength channel, the ONU adjusts the idle wavelength channel information carried in the information frame according to the wavelength channel, and adjusts the receiving and transmitting wavelengths to one. On the free wavelength channel. Preferably, the ONU performs ONU registration with the OLT on the idle wavelength channel, and performs service transmission after the ONU is successfully registered. The ONU sends the registration request frame after receiving the registration authorization frame sent by the OLT on the idle wavelength channel; After receiving the registration confirmation frame sent by the OLT, it sends an acknowledgement feedback frame to the OLT and performs service transmission. Preferably, the registration request frame is sent in a burst format. When an idle wavelength channel has multiple ONUs simultaneously registered and the time period of the registration request frame sent by multiple ONUs reaches the OLT overlaps, multiple ONUs wait for a random delay. The registration request frame is sent again. Preferably, the method further includes: determining, by the ONU, whether the sequence number carried in the registration confirmation frame and the sequence number of the same are the same; if the determination result is yes, sending an acknowledgement feedback frame to the OLT. Preferably, for the WDM-PON, after the OLT successfully receives the registration request frame of an ONU, the OLT modifies the state of the wavelength channel in the wavelength management table to be non-idle. For the WDM-TDM PON, after the ONU registers successfully in an idle wavelength channel, if the idle wavelength channel does not have enough remaining bandwidth available, the OLT modifies the state of the wavelength channel in the wavelength management table to be non-idle. Preferably, for the WDM-PON, the status is a non-idle wavelength channel. If the ONU registration is unsuccessful, or the normal operation is dropped, the OLT changes the wavelength channel status to idle. For WDM-TDM PON, When the state is a non-idle wavelength channel and sufficient remaining bandwidth is available, the OLT modifies the wavelength channel state to idle. Embodiment 1 This embodiment provides a WDM-PON ONU initialization and wavelength allocation method suitable for a tunable laser. This embodiment combines the above-mentioned embodiments and the preferred embodiments thereof. The method includes the following steps: Step 1: An optical network unit (OCU) is powered on, and waits for receiving downlink signals. Optical Line Terminal (OLT) The OLT has a built-in wavelength management table that contains the currently idle wavelength channel information. Each wavelength channel contains a pair of corresponding uplink and downlink wavelengths. The OLT sends two types of downlink frames to the newly accessed ONU: a registration grant frame and a wavelength channel adjustment information frame. Based on the received downlink frame, the ONU makes necessary adjustments to the transmit wavelength of the tunable transmitter to operate in the idle wavelength channel. Step 2: The ONU and the OLT perform registration information exchange on the idle wavelength channel, complete the ONU registration process, and perform necessary updates on the wavelength management table information. Step 3: After the ONU registration is completed, the ONU and the OLT start normal service communication. Preferably, in step 1, if the remote node uses a wavelength division multiplexing demultiplexing device and the ONU uses a wide spectrum optical receiver, the ONU starts to receive the registration grant frame corresponding to the wavelength channel, if the tunable laser Already in this wavelength channel, there is no need to adjust the wavelength. Otherwise, the ONU needs to adjust the tunable laser to the corresponding upstream wavelength. Preferably, in step 1, if the remote node uses the optical splitter and the ONU uses the tunable receiver, the ONU may initially receive the registration grant frame, and the ONU does not need to adjust the working wavelength of the tunable laser. It may also be a wavelength channel adjustment information frame, which contains the currently idle wavelength channel information. Based on this information, the ONU adjusts the tunable laser emission wavelength and the tunable receiver reception wavelength to an idle wavelength channel. Preferably, in step 1, if the remote node uses an optical splitter (or a wavelength division multiplexing demultiplexer and an optical splitter) and the ONU uses a coherent receiver, the initially tunable laser of the ONU is only coherent The receiver emits light, while the ONU itself does not output light. This can be done by adding an optical switch to the output of the tunable laser or by an external modulator. If the ONU initially receives the registration grant frame, the ONU does not need to adjust the working wavelength of the tunable laser. If it is a wavelength channel adjustment information frame, the frame contains the currently idle wavelength channel information. Based on this information, the ONU adjusts the tunable laser emission wavelength to the idle wavelength channel, but still only emits light to the coherent receiver. Preferably, since there may be multiple ONUs registered simultaneously in one idle wavelength channel, in step 2, the uplink frame sent by the tunable receiver must be in burst form. Preferably, since there may be multiple ONUs registered in an idle wavelength channel, in step 2, after receiving the registration authorization frame, all ONUs send a registration request frame to the OLT, if multiple registration request frames arrive at the OLT. If the time conflicts, the request frame is invalid. After the ONU sends a registration request frame, a waiting time elapses. If the registration confirmation frame is not received, the registration request frame is sent again after a random delay. Preferably, since there may be multiple ONUs simultaneously registered in an idle wavelength channel, in step 2, only the SN corresponding to the received registration confirmation frame matches the SN of the SN, and the acknowledgment feedback frame is sent to the OLT, and the registration is performed. After receiving the registration confirmation frame, the ONU that does not match the SN in the frame returns to the new access state and continues to wait for the downlink frame sent by the OLT. Embodiment 2 This embodiment provides an ONU registration and wavelength allocation method. FIG. 2 is a flowchart of ONU registration and wavelength allocation according to a preferred embodiment of the present invention. As shown in FIG. 2, the method includes steps S202 to S214. Step S202: The ONU is powered on, waiting to receive the downlink signal. The OLT has a built-in wavelength management table, which includes current idle wavelength channel information, and each wavelength channel includes a pair of corresponding uplink and downlink wavelengths. The OLT sends two types of downlink frames to the newly accessed ONU: a registration grant frame and a wavelength channel adjustment information frame. Step S204: Whether the ONU receives the wavelength channel adjustment information frame. If the result of the determination is YES, step S206 is performed, otherwise, step S208 is performed. Step S206: The ONU adjusts the uplink and downlink working wavelengths to the idle wavelength channel. Step S208: The ONU determines whether the transmit wavelength is consistent with the uplink wavelength value indicated in the registration grant frame. If the step S210 is not performed, if the step S212 is performed. Step S210: The ONU adjusts the uplink transmission wavelength to the uplink wavelength value indicated by the registration authorization frame. Step S212: The ONU performs registration information exchange with the OLT, completes the ONU registration process, and performs necessary updating on the wavelength management table. Step S214: The ONU performs normal service communication with the OLT by using the allocated wavelength channel. Embodiment 1 This embodiment provides an optical signal transmission method of a WDM-P0N using a tunable laser and a wide spectrum receiver, and FIG. 3 is a directional laser and a wide spectrum receiver using an ONU according to an embodiment of the present invention. Schematic diagram of WDM-PON system, as shown in Figure 3, the WDM-PON system uses a wavelength division multiplexing demultiplexing device (Mux/Dmux) at the remote node (RN node) to separate the downstream wavelengths of different channels from the backbone fibers. To the corresponding branch fiber, or to converge the upstream optical signals incident on different branch fibers to the backbone fiber transmission. Thereby, the wavelength routing of the uplink and downlink signals is realized. FIG. 4 is a first schematic diagram of an ONU and OLT registration information interaction process according to an embodiment of the present invention. As shown in FIG. 4, the method includes the following steps. Step S402: The OLT periodically sends a registration authorization frame to the idle wavelength channel. Step S404: The unregistered ONU receives the registration authorization frame corresponding to an idle wavelength channel sent by the OLT. If the tunable laser has already operated in the wavelength channel, the wavelength does not need to be adjusted. Otherwise, the ONU needs to adjust the tunable laser to the corresponding Wavelength channel. Step S406: After receiving the registration authorization frame, the ONU sends a registration request frame to the OLT, and reports its own SN number. Step S408: After receiving the registration request frame, the OLT sends a registration confirmation frame to the ONU to notify the ONU to send the start time of the uplink signal. For the WDM-PON system, the current wavelength channel status is changed to non-idle. Step S410: After receiving the registration confirmation frame, the ONU sends an acknowledgement feedback frame to the OLT. Step S412: After receiving the acknowledgment feedback frame, the OLT changes the state of the wavelength management table, completes the ONU registration and the wavelength allocation process, and the ONU and the OLT start normal service communication. It should be noted that, since the multi-wavelength downlink signal sent by the OLT reaches the ONU side, it has been filtered, and only the downlink optical signal of the single wavelength channel is used. Therefore, the ONU only needs to receive the downlink optical signal by using a common wide spectrum receiver. Moreover, due to the system architecture, the unregistered ONU does not receive the normal service frame of the registered ONU, and there are no multiple ONUs registered through one wavelength channel at the same time. The ONU registration process is relatively simple. For the WDM-TDM PON system, the OLT informs the ONU when sending the registration grant frame and the registration acknowledgement frame, and provides a time window for receiving the uplink frame. Embodiment 2 The present embodiment provides a method for wavelength allocation of an ONU using a tunable laser and a tunable receiver WDM-PON. This embodiment is based on a split-mode ODN network WDM-PON networking mode, and FIG. 5 is implemented according to the present invention. A schematic diagram of a WDM-PON system in which an ONU uses a tunable laser and a tunable receiver is shown in FIG. 5, because the ODN network cannot divide the multi-wavelength downlink signal transmitted by the OLT into each ONU by wavelength. Therefore, on the ONU side, a wavelength tunable receiver, that is, an optical receiver with a wavelength filtering function, is required. The characteristic of the networking mode is that the ONU can receive downlink signals sent to other ONUs in the same WDM-PON network, but cannot receive more than one downlink signal at the same time. Since the ONU initially operates randomly on a certain wavelength channel, it may receive a registration grant frame or a wavelength channel adjustment information frame. And there may be cases where multiple ONUs compete for the same idle wavelength channel. FIG. 6 is a schematic diagram 2 of an ONU and OLT registration information interaction process according to an embodiment of the present invention. As shown in FIG. 6, the method includes: Step 1: The ONU is powered on, operates randomly in a certain wavelength channel, and waits to receive a downlink signal. The OLT periodically sends a registration grant frame to the idle wavelength channel, and sends a wavelength channel adjustment information frame to the occupied wavelength channel. The wavelength channel adjustment information frame includes the current idle wavelength channel information. If the ONU receives the registration authorization frame, the wavelength channel of the ONU is the idle wavelength channel. The ONU does not need to adjust the working wavelength of the tunable laser and the tunable receiver. If the ONU receives the wavelength channel adjustment information frame. , indicating that the wavelength channel currently occupied by the ONU is occupied, and the ONU should adjust the tunable laser emission wavelength and the tunable receiver receiving wavelength to the corresponding wavelength channel. Step 2: The ONU and the OLT perform registration information exchange on the idle wavelength channel to complete the registration process. Since there may be multiple ONUs registered simultaneously in an idle wavelength channel, in step 2, in addition, since there may be multiple ONUs simultaneously registered in an idle wavelength channel, the registration protocol frame sent by the tunable receiver must be It is a sudden form. After all the ONUs receive the registration authorization frame, the registration request frame is sent to the OLT. If the time when multiple registration request frames arrive at the OLT conflicts, the request frame is invalid, and the ONU waits for a waiting time after sending the registration request frame. After receiving the registration confirmation frame, after a random delay, the registration request frame is sent again. After the OLT successfully receives the registration request frame, it sends a registration confirmation frame corresponding to the received SN to the wavelength channel. Only after the received registration confirmation frame matches its own SN, the acknowledgment feedback frame is sent to the OLT. After receiving the registration confirmation frame, the ONU that does not match the SN in the registration confirmation frame returns to the initial state and continues to wait for the downlink frame sent by the OLT. . Embodiment 3 This embodiment provides a method for wavelength allocation of an ONU using a WDM-PON of a tunable laser and a coherent receiver. In this embodiment, a WDM-PON system using a coherent receiver is adopted, and the system can implement the same. An ultra-dense WDM-PON system with a track spacing of several GHz. The use of coherent detection technology can not only make a qualitative leap in the number of users, but also significantly improve the receiving sensitivity, thereby increasing the coverage of access network users. 7 is a schematic diagram of a WDM-PON system in which an ONU uses a tunable laser and a coherent receiver according to an embodiment of the present invention. As shown in FIG. 7, a WDM-PON ONU based on a coherent reception technique is internally composed of three parts, a tunable laser. , external modulator and coherent receiver, the upstream signal is generated by the light emitted by the tunable laser after being loaded by the external modulator. The coherent receiver receives the downlink signal of multiple wavelengths, and performs the difference frequency with the unmodulated local oscillator optical signal generated by the tunable laser, and then filters out a corresponding downlink signal through the spectrum filter. This process is coherent detection. process. It can be seen from the principle of coherent detection that the premise of the coherent receiver to receive the signal must have local oscillator, which is characteristic of the coherent receiver different from the ordinary receiver. The ONU registration process of the WDM-PON system based on the coherent receiver and the tunable laser in this embodiment is similar to that in the fourth embodiment, except that in step 1, the tunable laser of the ONU initially emits light only to the coherent receiver, and the ONU It does not output light itself. This can be done by adding an optical switch to the output of the tunable laser or by an external modulator. The ONU may initially receive the registration grant frame, and the ONU does not need to adjust the working wavelength of the tunable laser. It may also be a normal service frame, and the normal service frame contains wavelength channel status information. The ONU adjusts the tunable laser emission wavelength to the idle wavelength channel based on the wavelength channel information, but still only emits light to the coherent receiver. The second and third steps of registration are the same as in the fourth embodiment. Embodiment 4 This embodiment provides an optical signal transmission method for a WDM-TDM-PON in which an ONU uses a tunable laser and a wide-spectrum receiver. The WDM-PON system uses wavelength division multiplexing at a remote node (RN node). The demultiplexing device (Mux/Dmux) divides the downstream wavelengths of the different channels from the backbone fibers to the corresponding branch fibers, or aggregates the upstream optical signals incident on the different branch fibers to the backbone fibers for transmission. Thereby, the wavelength routing of the uplink and downlink signals is realized. Each branch fiber is connected to multiple ONUs through an optical splitter. The ONUs connected under each optical splitter use the same pair of uplink and downlink wavelengths to communicate with the OLT through time division multiplexing. The wavelength allocation phase includes the following steps: Step 1: The OLT periodically sends a registration authorization frame through each downlink wavelength channel with idle bandwidth (idle).

(Also known as the discovery of the authorization frame), the frame contains the upstream wavelength information corresponding to the current wavelength channel, and provides an ONU discovery window. Step 2: The unregistered ONU receives the registration authorization frame sent by the OLT. If the tunable laser has been working on the upstream wavelength indicated by the registration authorization frame, the tunable laser does not need to adjust the wavelength. Otherwise, the ONU needs to adjust the tunable laser to Corresponding upstream wavelength channel. The registration process includes the following steps: Step 1: The ONU sends a registration request frame to the OLT through the discovery window provided by the OLT through the corresponding upstream wavelength channel, and reports its own SN number information. Step 2: After receiving the registration request frame, the OLT sends a registration confirmation frame to the ONU, assigns an ONU ID to the ONU, and provides a receiving window. Step 3: After receiving the registration confirmation frame, the ONU sends an acknowledgement feedback frame to the OLT in the receiving window provided by the OLT. Step 4: After receiving the acknowledgement feedback frame, the OLT completes the ONU registration and wavelength assignment process, and the ONU and the OLT start normal service communication. If the wavelength channel of the newly registered ONU is full, change the wavelength management table status. It should be noted that, since the multi-wavelength downlink signal sent by the OLT reaches the ONU side, it has been filtered, and only the downlink optical signal of the single wavelength channel is used. Therefore, the ONU only needs to receive the downlink optical signal by using a common wide spectrum receiver. Embodiment 5 This embodiment provides a method for wavelength allocation of an ONU using a tunable laser and a tunable receiver WDM-TDM-PON. This embodiment is based on an ODN network networking mode in the form of a Splitter, because the ODN network cannot The multi-wavelength downlink signal transmitted by the OLT is divided into wavelengths by each ONU. Therefore, on the ONU side, a wavelength tunable receiver, that is, an optical receiver with a wavelength filtering function, is required. The characteristic of this networking mode is that the ONU cannot receive downlink signals of more than one wavelength at the same time. Since the ONU initially receives the downlink signal of any wavelength channel at random, and this channel may have no free bandwidth, a wavelength channel initialization process is also required.

The ONU wavelength assignment and registration process is as follows: Step 1 (wavelength assignment process): The ONU is powered on, and operates randomly in a certain wavelength channel, waiting to receive the downlink signal. The OLT periodically sends a registration grant frame on a wavelength channel with idle bandwidth to provide a discovery window. The wavelength channel adjustment information frame with the wavelength channel status is periodically sent to the wavelength channel without the idle bandwidth, and the ONU is notified that the current channel has no free bandwidth, so that it switches the working wavelength to the wavelength channel with the idle bandwidth. If the ONU receives the registration authorization frame, the wavelength channel of the ONU is the idle wavelength channel. The ONU does not need to adjust the working wavelength of the tunable laser and the tunable receiver. If the ONU receives the wavelength channel adjustment information frame. , indicating that the wavelength channel currently in the ONU has no free bandwidth, then the ONU needs to receive according to The idle bandwidth wavelength channel information in the frame adjusts the tunable laser transmit wavelength and the tunable receiver receive wavelength to a wavelength channel having an idle bandwidth. Step 2 (Registration process): The ONU and the OLT perform registration information exchange on the wavelength channel with idle bandwidth to complete the registration process. The process is the same as the ONU registration process of Embodiment 6. This embodiment provides an ONU, and FIG. 8 is a structural block diagram of an ONU according to an embodiment of the present invention.

As shown in FIG. 8, the ONU includes: a receiving module 82, a wavelength adjusting module 84, a first registration module 86, and a first transmitting module 88. The foregoing structure is described in detail below: The receiving module 82 is configured to receive a downlink frame from the OLT. The downlink frame is used to indicate the status information of the wavelength channel. The wavelength adjustment module 84 is connected to the receiving module 82, and is configured to adjust the working wavelength to idle according to the wavelength channel information carried by the ONU according to the downlink frame received by the receiving module 82. The first registration module 86 is connected to the wavelength adjustment module block 84 and configured to perform ONU registration with the OLT on the idle wavelength channel adjusted by the wavelength adjustment module 84. The first transmission module 88 is connected to the first registration module. 86. Set to perform service transmission after the ONU registration of the registration module 86 is successful. Preferably, the receiving module 82 is configured to receive the downlink frame from the OLT by using one of the following: When the remote node uses the wavelength division multiplexing demultiplexing device, the ONU uses the wide spectrum optical receiver to receive the OLT to send the registration in the idle wavelength channel. An authorization frame, where the registration authorization frame indicates that the state of the wavelength channel in which the channel is located is idle, and carries the uplink wavelength value corresponding to the wavelength channel. For the WDM-TDM PON, the OLT needs to provide a discovery window after sending the registration authorization frame. And inform the ONU through the registration authorization frame. When the remote node uses the optical splitter, the ONU uses the tunable receiver to receive, the OLT sends a registration grant frame on the idle wavelength channel, and transmits the wavelength channel adjustment information frame on the non-idle wavelength channel, where the registration grant frame indicates its location. The status of the wavelength channel is idle. For the WDM-TDM PON, the OLT needs to provide a discovery window after sending the registration authorization frame, and the ONU is notified by the registration authorization frame, and the wavelength channel adjustment information frame carries the current idle wavelength channel information, and Indicates that the state of the wavelength channel in which the ONU is currently located is non-idle; when the remote node uses an optical splitter (or a combination of a wavelength division multiplexing demultiplexer and an optical splitter), the ONU uses an upstream signal optical transmitter ( Tuning the laser) transmitting the local oscillator to the coherent receiver, using the coherent receiver to receive the registration grant frame sent from the OLT on the idle wavelength channel, and adjusting the information frame on the wavelength channel transmitted in the non-idle wavelength channel, where the registration grant frame indicates its location The state of the wavelength channel is idle, or the wavelength channel adjustment information frame carries the current idle wave. Information channel, and indicates the state in which it is non-wavelength channel is idle, the case for the WDM-TDM PON, the OLT transmits registration grant frame further need to provide a discovery window, and inform through which the ONU registration grant frame. Preferably, the wavelength adjustment module 84 is configured to adjust the information of the wavelength channel in the information frame according to the wavelength channel, and adjust the working wavelength to the idle wavelength channel. Preferably, the first registration module includes: a registration request frame sending module, configured to send a registration request frame after receiving the registration authorization frame sent by the OLT on the idle wavelength channel; and confirming the feedback frame sending module, and setting the sending to the OLT After registering the confirmation frame, an acknowledgment feedback frame is sent to the OLT. Preferably, the first transmission module includes: after the ONU completes registration, performing service frame transmission with the OLT. The present embodiment provides an OLT. FIG. 9 is a structural block diagram of an ONU according to an embodiment of the present invention. As shown in FIG. 9, the OLT includes: a sending module 102, a second registration module 104, and a second transmission module 106. The second module is configured to send the downlink frame to the optical network unit ONU, where the downlink frame is used to indicate the status information of the wavelength channel, and the second registration module 104 is set to the ONU in an idle state. On the wavelength channel, the registration information is exchanged with the ONU. The second transmission module 106 is configured to perform service frame transmission after the ONU is successfully registered. This embodiment provides a passive optical network. FIG. 10 is a structural block diagram of a passive optical network according to an embodiment of the present invention. As shown in FIG. 10, the passive optical network includes an ONU 2 and a P OLT 4, wherein the ONU The specific structure of FIG. 2 is shown in FIG. 8. The structure of the OLT 4 is as shown in FIG. 9, and details are not described herein again. With the above embodiments, an optical signal transmission method, a device, and a passive optical network are provided. The method receives, by the ONU, a downlink frame that carries the state information of the wavelength channel and is provided by the OLT according to the wavelength channel information provided by the downlink frame. The uplink and downlink working wavelengths are adjusted to an idle wavelength channel, and registration is performed on the wavelength channel, thereby solving the problem that the resource utilization ratio of the optical signal transmission method in the related art is relatively low and the registration process is complicated, thereby achieving the improvement of the light. Resource utilization of signal transmission and streamline the registration process. With the present invention, it is not necessary to initially set the tunable laser to a uniform wavelength, which increases the flexibility of the system, and can realize simultaneous ONU registration of multiple wavelength channels in parallel. Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device and, in some cases, may be different from the order herein. The steps shown or described are performed, or they are separately fabricated into individual integrated circuit modules, or a plurality of modules or steps are fabricated as a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software. The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

1. An optical signal transmission method, comprising:

The optical network unit ONU receives the downlink frame from the optical fiber line terminal OLT, where the downlink frame carries state information of the wavelength channel;

The ONU adjusts the uplink and downlink working wavelengths to the idle wavelength channel according to the state information of the wavelength channel carried in the downlink frame.

The ONU performs ONU registration with the OLT on the adjusted wavelength channel, and performs service transmission after the ONU is successfully registered.

2. The method according to claim 1, wherein the ONU receives a downlink frame from the OLT and includes one of the following:

A registration grant frame sent on an idle wavelength channel; a wavelength channel transmitted on a non-idle wavelength channel adjusts the information frame.

3. The method according to claim 1, wherein before the ONU receives the downlink frame from the OLT, the method further includes:

The OLT generates a wavelength management table that records status information of the current idle wavelength channel according to status information of the current idle wavelength channel, and loads the wavelength management table information into the wavelength channel adjustment information frame, and passes all non-idle wavelengths. The channel is sent to the ONU.

4. The method according to claim 1, wherein the ONU receives a downlink frame from the OLT and includes one of the following:

When the remote node uses the wavelength division multiplexing demultiplexing device, the ONU receives the registration authorization frame sent by the OLT in the idle wavelength channel by using the wide spectrum optical receiver, where the registration authorization frame indicates the wavelength at which the registration authority is located The status of the channel is idle and carries the uplink wavelength value corresponding to the wavelength channel. In the case of the WDM-TDM PON, the OLT further provides a discovery window after sending the registration authorization frame:

When the remote node uses an optical splitter, the ONU uses a tunable receiver to receive a registration grant frame sent by the OLT in an idle wavelength channel, and adjusts an information frame in a wavelength channel sent by the non-idle wavelength channel, where The registration authorization frame indicates that the state of the wavelength channel in which the wavelength channel is located is idle, and the wavelength channel adjustment information frame carries state information of the current idle wavelength channel, and indicates the ONU The status of the current wavelength channel is non-idle. In the case of the WDM-TDM PON, the OLT also provides a discovery window after sending the registration authorization frame.

When the remote node uses one of the following: a combination of the optical splitter, a wavelength division multiplexing demultiplexer, and an optical splitter, the ONU uses an uplink signal optical transmitter to transmit the local oscillator to the coherent receiver And receiving, by the coherent receiver, a registration grant frame sent by the OLT in an idle wavelength channel, and adjusting a information frame in a wavelength channel sent by the non-idle wavelength channel, where the registration authorization frame indicates a state of a wavelength channel in which the register is located For the idle, the wavelength channel adjustment information frame carries the information of the current idle wavelength channel, and indicates that the state of the wavelength channel in which the wavelength channel is located is not idle. In the case of the WDM-TDM PON, the OLT sends the registration authorization frame. A discovery window is also available.

The method according to claim 4, wherein the ONU adjusts the uplink and downlink working wavelengths to the idle wavelength channels according to the state information of the wavelength channel carried by the downlink frame, including:

When the remote node uses the wavelength division multiplexing demultiplexing device, after the ONU receives the registration authorization frame, the uplink transmission wavelength is adjusted to the uplink wavelength corresponding to the wavelength channel according to the uplink wavelength information included in the registration authorization frame. value.

When the remote node uses the optical splitter, the ONU receives the registration grant frame, and the ONU cancels the adjustment of the uplink transmit wavelength; when the ONU receives the wavelength channel adjustment information frame, the ONU according to the wavelength The channel adjusts the status information of the idle wavelength channel carried in the information frame, and adjusts the working wavelengths of the uplink and the downlink to the idle wavelength channel.

The method according to claim 1, wherein the ONU performs ONU registration with the OLT on the idle wavelength channel, and performs service transmission after the ONU is successfully registered, including:

After receiving the registration authorization frame sent by the OLT on the idle wavelength channel, the ONU sends a registration request frame;

After receiving the registration confirmation frame sent by the OLT, the ONU sends an acknowledgement feedback frame to the OLT, and performs service transmission.

The method according to any one of claims 1 to 6, wherein

The registration request frame is sent in a burst form;

When the idle wavelength channel has multiple ONUs simultaneously registered, and the time period of the registration request frame sent by the multiple ONUs to the OLT overlaps, the multiple ONUs wait for a random delay and then send the registration again. Request frame.

The method according to any one of claims 1 to 6, further comprising: The OLT carries data of a channel state in which the current idle wavelength channel is idle in the wavelength management table in the registration confirmation frame.

9. The method according to claim 8, further comprising:

The ONU determines whether the serial number carried in the registration confirmation frame and its own serial number are the same;

If the result of the determination is yes, an acknowledgment feedback frame is sent to the OLT.

The method according to any one of claims 1 to 6, wherein for the WDM-PON system, the idle wavelength channel is an unused wavelength channel; for a WDM-TDM PON system, the idle wavelength channel is present A wavelength channel of a spare time slot bandwidth, the non-idle wavelength channel being a wavelength channel other than the idle wavelength channel.

11. The method according to claim 1, further comprising:

For the WDM-PON, after the OLT successfully receives the registration request frame sent by the ONU, the OLT changes the state of the wavelength channel in the wavelength management table to be non-idle;

For the WDM-TDM PON, after the ONU is successfully registered in an idle wavelength channel, if the idle wavelength channel has no remaining bandwidth available, the OLT changes the state of the wavelength channel in the wavelength management table to be non-idle.

For the WDM-PON, the status is a non-idle wavelength channel. If the ONU registration is unsuccessful, or the line is dropped, the OLT changes the wavelength channel status to idle. For a WDM-TDM PON, when the state is a non-idle wavelength channel and there is sufficient remaining bandwidth, the OLT modifies the wavelength channel state to idle.

12. An optical network unit ONU, comprising:

a receiving module, configured to receive a downlink frame from the optical fiber line terminal OLT, where the downlink frame carries status information of the wavelength channel;

The wavelength adjustment module is configured to adjust the working wavelength to the idle wavelength channel according to the wavelength channel information carried by the downlink frame;

a first registration module, configured to perform ONU registration with the OLT on the idle wavelength channel;

The first transmission module is configured to perform service transmission after the ONU is successfully registered. The ONU according to claim 12, wherein The receiving module is configured to receive a downlink frame from the OLT by using one of: when the remote node uses a wavelength division multiplexing demultiplexing device, the ONU uses the wide spectrum optical receiver to receive the OLT in idle state a registration authorization frame sent by the wavelength channel, where the registration authorization frame indicates that the state of the wavelength channel in which the wavelength channel is located is idle, and carries the uplink wavelength value corresponding to the wavelength channel, and in the case of the WDM-TDM PON, the OLT sends The registration authorization frame further provides a discovery window: when the remote node uses the optical splitter, the ONU receives the tunable receiver, and the OLT registers the authorized grant frame in the idle wavelength channel. The wavelength channel adjustment information frame sent by the non-idle wavelength channel, wherein the registration authorization frame indicates that the state of the wavelength channel in which the wavelength is located is idle, and the wavelength channel adjustment information frame carries state information of the current idle wavelength channel, and the indication information The state of the wavelength channel in which the ONU is currently located is non-idle. In the case of the WDM-TDM PON, the OLT also provides a registration frame after sending the registration authorization frame. Discovery window

14. The ONU according to claim 13, wherein

The wavelength adjustment module is configured to adjust the operating wavelength to the idle wavelength channel by adjusting state information of the wavelength channel in the information frame according to the wavelength channel.

The ONU of claim 13, wherein the first registration module comprises:

a registration request frame sending module, configured to send a registration request frame after receiving the registration authorization frame sent by the OLT on the idle wavelength channel;

The acknowledgment transmitting module is configured to send an acknowledgment feedback frame to the OLT after receiving the registration confirmation frame sent by the OLT.

16. An optical line termination OLT, comprising: a sending module, configured to send a downlink frame to the optical network unit ONU, where the downlink frame is used to indicate status information of the wavelength channel;

a second registration module, configured to perform ONU registration with the ONU after the idle wavelength channel adjusted by the ONU;

The second transmission module is configured to perform service transmission after the ONU is successfully registered.

17. A passive optical network, comprising:

The optical network unit ONU according to any one of claims 12 to 15 and the optical fiber line terminal OLT according to claim 16.