CN115209245A

CN115209245A - Data transmission method, optical line terminal, optical network unit and communication system

Info

Publication number: CN115209245A
Application number: CN202210043535.1A
Authority: CN
Inventors: 景磊
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-04-02
Filing date: 2022-01-14
Publication date: 2022-10-18

Abstract

The application discloses a data transmission method, an optical line terminal, an optical network unit and a communication system, and relates to the technical field of optical networks. The OLT can determine a downlink time window and an uplink time window according to the data transmission bandwidth requirement and the distance between the OLT and the ONU; sending the superframe structure to an optical network unit; the superframe structure includes: information of a downlink time window and information of an uplink time window; sending a first data packet to the ONU in a downlink time window; a second data packet is received from the ONU in the upstream time window. According to the data transmission method, the optical line terminal is in discontinuous transmission when transmitting data in a downlink mode, and the method can be suitable for optical transceiving components with a transmitter and a receiver separated from each other, and can also be suitable for an optical device with the transmitter and the receiver integrated.

Description

Data transmission method, optical line terminal, optical network unit and communication system

The present application claims priority from chinese patent application having application number 202110362179.5 and application name of "a data transmission method, an optical line terminal, an optical network unit and a communication system" filed on 04/02/2021, which is incorporated herein by reference in its entirety.

Technical Field

The present application relates to the field of optical network technologies, and in particular, to a data transmission method, an optical line terminal, an optical network unit, and a communication system.

Background

When a video is monitored by using a camera of a Passive Optical Network (PON) to perform video return, a plurality of cameras are connected to an Optical Line Terminal (OLT) through an Optical Distribution Network (ODN), and each camera is equivalent to an Optical Network Unit (ONU). The OLT provides a network-side interface for the PON system, which may be connected to one or more ODNs. The ONU provides a user side interface for the PON system and is connected with the ODN. The ODN is a network composed of optical fibers and passive optical splitting devices, and is used to connect the OLT device and the ONU device, and to distribute or multiplex data signals between the OLT and the ONU. In the PON system, transmitting a data signal from the OLT to the ONU is called downstream; conversely, the transmission of data signals from an ONU to the OLT is referred to as upstream.

The downlink OLT transmitter continuously transmits data by adopting light with the wavelength of 1550nm, and the ONU identifies useful data and discards useless data after receiving all downlink data. And the upstream ONU transmits data in different time slots at 1310nm according to the instruction of the OLT. The optical transceiver component utilizes the beam splitter to couple the light with two different wavelengths to the same optical fiber, so as to realize point-to-multipoint optical communication.

The optical transceiver module suitable for the data transmission mode can couple signals of different uplink and downlink light paths to optical fibers by using a beam splitter as shown in fig. 1, the circuit connection is complex, and in addition, a transmitter and a receiver of the optical transceiver module shown in fig. 1 are realized by 2 different optical devices, so that the manufacturing cost is high, and the cost is not saved.

With the development of the optical transceiver module, there is a proposal that a transmitter and a receiver are realized by the same optical device, so as to save cost, however, the improved optical transceiver module cannot simultaneously transmit and receive uplink and downlink, so the above data transmission method cannot be applied to the improved optical transceiver module.

Disclosure of Invention

The embodiment of the application provides a data transmission method, an optical line terminal, an optical network unit and a communication system, so that the optical line terminal transmits data discontinuously, and the method can be suitable for an optical transceiver module with a transmitter and a receiver separated, and can also be suitable for an optical device with a transmitter and a receiver integrated.

In a first aspect, an embodiment of the present application provides a data transmission method, which is applied to an OLT, and when the method is executed, the OLT may determine a downlink time window and an uplink time window according to a data transmission bandwidth requirement and a distance between the OLT and an ONU; then sending the superframe structure to the ONU; the superframe structure includes: information of the downlink time window and information of the uplink time window; sending a first data packet to the ONU in the downstream time window; receiving a second data packet from the ONU in the upstream time window.

In the present application, data transmission may be performed between the OLT and the ONU in a point-to-point communication manner, or in a point-to-multipoint communication manner. The OLT determines an uplink time window and a downlink time window according to the distance between the OLT and the ONU and the bandwidth condition required by uplink and downlink transmission data. And then the OLT informs the ONU of the information of the uplink time window and the information of the downlink time window through a superframe structure, sends a downlink data packet, namely a first data packet, in the downlink time window, and receives an uplink data packet, namely a second data packet, from the ONU in the uplink time window. The method can be suitable for the optical transceiving components with the transmitter and the receiver separated, and can also be suitable for the optical device with the transmitter and the receiver integrated. In addition, the method can be applied to scenes that the transmission of uplink and downlink data is not matched, such as a video return scene (a large amount of uplink data and a small amount of downlink data exist in the video return scene), the situation that the transmission resources are wasted due to continuous transmission of the downlink data is avoided, and in addition, the consumption of the electric quantity of equipment can be reduced under the situation that the downlink data is continuously transmitted. In the case where the power consumption of the device is small, the usage time that can be supported by the device is also increased appropriately.

In an alternative manner, the superframe structure includes a plurality; the plurality of superframe structures are transmitted at a first periodicity.

It should be noted that the superframe structure may be transmitted according to a fixed period, for example, 125 μ uS. The superframe structure is sent according to a fixed period, so that the superframe structure can be ensured to be timely notified to different ONUs, and the condition that the information of the OLT and the ONUs is not synchronous is avoided.

In an optional manner, the superframe structure further includes: super frame head; the superframe header is sent by broadcasting.

In the embodiment of the application, the superframe header can be notified to more ONUs through broadcast transmission, and a plurality of ONUs can receive the superframe header from the OLT.

In an alternative mode, the super-frame header includes: synchronization information, frame number information, and Dynamic Bandwidth Allocation (DBA) of next N superframe structures; said N is greater than or equal to 1; the DBA includes: identification information of one or more ONUs, uplink and downlink data transmission indication information and position information of data transmission.

It should be noted that the next N superframe structures can be understood as a certain superframe structure after the current superframe structure, for example, the current superframe structure is a 3 rd superframe structure, and assuming that N is 3, the superframe header can carry DBA of a 6 th (3 + 3) superframe structure. Wherein the DBA comprises: the identification information of one or more optical network units, the uplink and downlink data transmission indication information and the data transmission position information are used, so that the ONU can know which ONU needs to receive the downlink data packet or which ONU needs to send the uplink data according to the DBA. The frame number information in the superframe structure can record the several superframe structures sent by the olt, so that the ONU can better learn about the operations performed in different superframe structures. The synchronization information in the superframe structure may synchronize partial information of the last superframe structure so that the ONU may know the timing relationship of the received superframe structure and other superframe structures.

In an optional manner, the uplink and downlink data transmission indication information is identified by a type value; if the type value is 1, one or more ONUs in the DBA perform uplink data transmission; and if the type value is 0, one or more ONUs in the DBA perform downlink data transmission.

In an alternative mode, the first data packet and the second data packet have a time interval; the time interval is greater than the uplink and downlink data transmission switching time.

It should be noted that, in the present application, uplink and downlink data may be transmitted through the same data transmission channel, so that, in order to avoid transmission collision during data transmission, a time interval exists between an uplink data packet (i.e., a first data packet) and a downlink data packet (i.e., a second data packet).

In a second aspect, an embodiment of the present application provides a data transmission method, which is applied to an ONU, where in execution of the method, the ONU may first receive a superframe structure from an OLT; the superframe structure includes: information of the downlink time window and information of the uplink time window; then, receiving a first data packet from the OLT in the downlink time window; and sending a second data packet to the OLT in the uplink time window.

In the present application, data transmission may be performed between the OLT and the ONUs in a point-to-point communication manner, or in a point-to-multipoint communication manner. The OLT determines an uplink time window and a downlink time window according to the distance between the OLT and the ONU and the bandwidth condition required by uplink and downlink transmission data. And then the OLT informs the ONU of the information of the uplink time window and the information of the downlink time window through a superframe structure, sends a downlink data packet, namely a first data packet, in the downlink time window, and receives an uplink data packet, namely a second data packet, from the ONU in the uplink time window. The method can be suitable for the optical transceiving component with the separated transmitter and receiver, and can also be suitable for the optical device with the integrated transmitter and receiver. In addition, the method can be applied to the scene that the transmission of the uplink and downlink data is not matched, such as the scene of video return (the scene of video return has a large amount of uplink data and a small amount of downlink data), the condition that the transmission resource is wasted due to continuous transmission of the downlink data is avoided, and in addition, the consumption of the electric quantity of equipment can be reduced under the condition that the downlink data is continuously transmitted. In the case where the power consumption of the device is small, the usage time that can be supported by the device is also increased appropriately.

In an alternative manner, the superframe structure includes a plurality; the plurality of superframe structures are transmitted at a first cycle; receiving a superframe structure from an optical line terminal, comprising: and the ONU receives the superframe structure according to the first period.

In an optional manner, the superframe structure further includes: super frame head; the superframe header is sent by broadcasting. In an alternative mode, the super-frame header includes: synchronizing information, frame number information and next N DBAs of the superframe structure; the N is greater than or equal to 1; the DBA includes: identification information of one or more ONUs, uplink and downlink data transmission indication information and position information of data transmission.

In an optional manner, the optical network unit may determine that the identity of the ONU is the same as the identity of the ONU in the DBA, and receive the first data packet according to the downstream data transmission indication information.

In a third aspect, an embodiment of the present application provides an optical line terminal, including: a processing unit and a transceiver unit;

the processing unit is used for determining a downlink time window and an uplink time window according to the data transmission bandwidth requirement and the distance between the optical line terminal OLT and the optical network unit ONU; a transceiver unit, configured to send a superframe structure to the onu; the superframe structure includes: information of the downlink time window and information of the uplink time window; and, in the downstream time window, sending a first data packet to the ONU; receiving a second data packet from the ONU in the upstream time window.

In an alternative mode, the super-frame header includes: synchronizing information, frame number information and next N DBAs of the superframe structure; said N is greater than or equal to 1; the DBA includes: identification information of one or more ONUs, uplink and downlink data transmission indication information and position information of data transmission.

In a fourth aspect, an embodiment of the present application provides an optical network unit, including: a transceiving unit and a processing unit;

the receiving and sending unit is used for receiving a superframe structure from an optical line terminal OLT; the superframe structure includes: information of the downlink time window and information of the uplink time window; a processing unit, configured to receive a first data packet from the OLT in the downlink time window; and sending a second data packet to the OLT in the uplink time window.

In an alternative manner, the superframe structure includes a plurality; the plurality of superframe structures are transmitted at a first cycle; the transceiver unit is configured to receive the superframe structure according to the first period.

In an alternative mode, the super-frame header includes: synchronizing information, frame number information and next N DBAs of the superframe structure; the N is greater than or equal to 1; the DBA includes: identification information of one or more ONUs, uplink and downlink data transmission indication information and position information of data transmission.

In an optional manner, the uplink and downlink data transmission indication information is identified by a value of a type; if the value of the type is 1, one or more ONUs in the DBA perform uplink data transmission; and if the type value is 0, one or more ONUs in the DBA perform downlink data transmission.

In an optional mode, the processing unit is configured to:

and determining that the identification of the ONU is the same as the identification of the ONU in the DBA, and receiving the first data packet according to the downlink data transmission indication information.

In a fifth aspect, an embodiment of the present application provides an optical line terminal, including: a processor and a memory;

the memory for storing a computer program;

the processor is configured to execute the computer program stored in the memory to cause the optical line terminal to perform the method according to the first aspect.

In a sixth aspect, an embodiment of the present application provides an optical network unit, including: a processor and a memory;

the memory for storing a computer program;

the processor is configured to execute the computer program stored in the memory to cause the optical network unit to perform the method according to the second aspect.

In a seventh aspect, an embodiment of the present application provides a communication system, where the communication system includes the optical line terminal according to the third aspect and the optical network unit according to the fourth aspect.

In an eighth aspect, embodiments of the present application provide a computer-readable storage medium storing instructions that, when executed, cause a computer to perform the method of the first or second aspect.

These and other aspects of the present application will be more readily apparent from the following description of the embodiments.

Drawings

Fig. 1 shows a schematic structural diagram of an optical transceiver module;

fig. 2 is a schematic diagram illustrating a topology of an optical communication system provided in an embodiment of the present application;

fig. 3 is a schematic flowchart illustrating a data transmission method according to an embodiment of the present application;

fig. 4 is a diagram illustrating a superframe structure provided by an embodiment of the present application;

fig. 5 is a diagram illustrating a superframe structure provided by an embodiment of the present application;

fig. 6 is a schematic diagram illustrating a structure of a data packet provided in an embodiment of the present application;

fig. 7A is a schematic diagram illustrating a system architecture of a peer-to-peer communication system according to an embodiment of the present application;

fig. 7B is a schematic diagram illustrating a system architecture of a point-to-multipoint communication system provided by an embodiment of the present application;

fig. 8 illustrates a system architecture of another communication system provided by an embodiment of the present application;

fig. 9 is a schematic diagram illustrating a communication scenario provided by an embodiment of the present application;

fig. 10 is a schematic diagram illustrating another communication scenario provided by an embodiment of the present application;

fig. 11 is a flowchart illustrating a registration method provided in an embodiment of the present application;

fig. 12 is a schematic structural diagram of a communication device provided in an embodiment of the present application;

fig. 13 shows a schematic structural diagram of a communication device provided in an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more clear, the present application will be further described in detail with reference to the accompanying drawings. The particular methods of operation in the method embodiments may also be applied in device embodiments or system embodiments. In the description of the present application, the term "plurality" means two or more unless otherwise specified.

The embodiment of the application can be applied to an optical communication system, and the optical communication system can be a PON system. The PON system may be a COMBO networking system. For example, an evolved user of a 10gigabit-capable passive optical network (10G PON) needs to consider a smooth transition from GPON to 10GPON, and thus a practical application environment of a 10GPON system is a COMBO network of GPON and 10 GPON.

In the embodiment of the present application, the COMBO networking may be a networking of a GPON and a 10GPON (denoted as GPON &10GPON COMBO), or a networking of an EPON and a 10GEPON (denoted as EPON &10GEPON COMBO). COMBO networking may also be a combination of any of a variety of PON systems. For example, the PON system in a COMBO networking may also be a time and wavelength division multiplexing passive optical network (TWDM-PON), a ten gigabit-capable passive optical network (XG-PON) system, or a ten gigabit-capable symmetric passive optical network (XGs-PON) system, as well as various systems evolving in the future.

The following describes an architecture of an optical communication system to which the embodiments of the present application can be applied. An optical communication system includes an OLT and a plurality of ONUs, which may also be referred to as Optical Network Terminals (ONTs). For example, if an ONU directly provides a user port function, such as an ethernet user port for internet access of a Personal Computer (PC), the ONU may be called an ONT.

In the embodiment of the present application, an ONU is taken as an example for description. The OLT communicates with a plurality of ONUs respectively, the optical communication system can also comprise an ODN, and the plurality of ONUs can be connected to a PON port of the same OLT through the ODN. Other network devices, such as user terminals, servers, mobile base stations, etc., may also be included in the optical communication system. As shown in fig. 2, an optical communication system topology is illustratively described. In the topology shown in fig. 2, the communication devices can be divided into a "user side" and a "network side" according to the connection relationship of the communication devices. For a user terminal, such as a PC, terminating a service, the network topology shown in fig. 2 includes: in an optical communication system, a communication direction from an OLT to an ONU is called downstream, and a communication direction from the ONU to the OLT is called upstream.

It should be noted that, the ONU and the OLT generally perform data transmission through an optical transceiver module, and a conventional optical transceiver module includes a transceiver and a receiver as shown in fig. 1, when the optical transceiver module is working, a downstream OLT transmitter continuously transmits data by using light with a wavelength of 1550nm, and the ONU identifies useful data after receiving all downstream data and discards useless data. And the upstream ONU transmits data in different time slots at 1310nm according to the instruction of the OLT. However, in an application scenario of video backhaul, generally, the OLT sends less downstream data to the ONU, and on the contrary, the ONU sends a large amount of video data back to the OLT.

Fig. 3 shows a data transmission method, which needs OLT and ONU interaction to implement, and in actual application, the number of ONUs is not limited, but this application only uses 2 ONUs, that is, ONU1 and ONU2. May be performed with reference to the following steps:

step 301: and the OLT determines a downlink time window and an uplink time window according to the data transmission bandwidth requirement and the distance between the OLT and the ONU.

It should be noted that the bandwidths required for the upstream transmission and the downstream transmission of data may not be the same, and the distances between the OLT and the different ONUs may also be different. For example, the uplink transmission bandwidth is 20Mbps, the downlink transmission bandwidth is 1mbps, the distance between the onuu 1 and the OLT is 100 meters, the distance between the ONU2 and the OLT is 120 meters, and the ONU1 and the ONU2 are deployed in the same cell, so that the OLT can perform data processing (data analysis, weighting calculation, and the like, which is not specifically limited herein) with reference to the requirement of the normal bandwidth for uplink and downlink data transmission in the cell and the distance between the OLT and each ONU, and determine the time window for uplink transmission and the time window for downlink data transmission.

Step 302: the OLT sends a superframe structure to the ONU1; the superframe structure includes: information of downlink time windows and information of uplink time windows. Accordingly, the ONU1 receives the superframe structure from the optical line termination OLT. The OLT also sends the superframe structure to ONU2. Accordingly, the ONU2 receives the superframe structure from the optical line termination OLT.

In an optional embodiment, the superframe structure further includes: a super-frame header; the superframe header is sent by broadcast. The super frame header may be sent to more ONUs by broadcast, and multiple ONUs may all receive the super frame header from the OLT, that is, as shown in step 302, the OLT may send the super frame structure to multiple ONUs.

It should be noted that the OLT sends the information of the upstream time window and the downstream time window to the ONUs, so that the ONUs can know which time window receives the downstream data and which time window sends the upstream data, and the manner can ensure the ordered transmission of the upstream data and the downstream data.

In an alternative embodiment, the OLT may send multiple superframe structures, where the superframe structures are sent according to a first period, and accordingly, the ONU needs to receive the superframe structures according to the first period. As shown in fig. 4, after the nth superframe structure is transmitted, the (N + 1) th superframe structure is transmitted with a first period, e.g., 125us being the first period. It should be noted that the superframe structure is sent according to a fixed period, which can ensure that the superframe structure is timely notified to different ONUs, and avoid the occurrence of the condition that the information of the OLT and the ONUs is not synchronous.

Step 303A: the OLT sends a first data packet, i.e. a downstream data packet, to the ONU1 within the downstream time window. Accordingly, ONU1 receives the first packet from the OLT.

Step 303B: the OLT sends a first data packet to ONU2 within the downlink time window. Accordingly, ONU2 receives the first packet from the OLT.

Since the ONU1 and the ONU2 work independently, whether to send the second data packet or not, and there is no association between the two ONUs, both ONUs may send the second data packet in the uplink time window, and other ONUs may also send the second data packet in the uplink time window. Next, only the ONU1 will transmit the second packet, that is, the upstream packet, to the OLT.

Step 304: the ONU1 sends a second data packet to the OLT in the uplink time window. Accordingly, the OLLT receives the second packet from ONU 1.

In the application, the OLT determines the uplink time window and the downlink time window according to the distance between the OLT and the ONU and the bandwidth condition required by uplink and downlink transmission data. And then the OLT informs the ONU of the information of the uplink time window and the information of the downlink time window through a superframe structure, sends a downlink data packet, namely a first data packet, in the downlink time window, and receives an uplink data packet, namely a second data packet, from the ONU in the uplink time window. The method can be suitable for the optical transceiving components with the transmitter and the receiver separated, and can also be suitable for the optical device with the transmitter and the receiver integrated. In addition, the method can be applied to scenes that the transmission of uplink and downlink data is not matched, such as a video return scene (a large amount of uplink data and a small amount of downlink data exist in the video return scene), the situation that the transmission resources are wasted due to continuous transmission of the downlink data is avoided, and in addition, the consumption of the electric quantity of equipment can be reduced under the situation that the downlink data is continuously transmitted. In the case of low power consumption of the device, the supportable use time of the device is also increased appropriately. In an alternative embodiment, the superframe header includes: synchronizing information, frame number information and DBAs of next N superframe structures; wherein N is greater than or equal to 1. The next N superframe structures can be understood as a certain superframe structure after the current superframe structure, and if the current superframe structure is a 3 rd superframe structure, assuming that N is 3, the superframe header can carry DBA of a 6 th (3 + 3) superframe structure; if N is 1, the superframe header may carry DBA of superframe structure 4 (3 + 1). Wherein the DBA includes: the identification information of one or more optical network units, the uplink and downlink data transmission indication information and the data transmission position information are provided, so that the ONU can know which ONU needs to receive a downlink data packet or which ONU needs to send uplink data according to the DBA. The frame number information in the superframe structure can record the several superframe structures sent by the optical line terminal, so that the ONU can better learn the operations performed in different superframe structures. The synchronization information in the superframe structure may synchronize partial information of the last superframe structure so that the ONU may know the timing relationship of the received superframe structure and other superframe structures.

The DBA includes: identification information of one or more ONUs, uplink and downlink data transmission indication information and position information of data transmission. Correspondingly, the ONU determines whether the identification of the ONU is the same as the identification of the ONU in the DBA, and receives the first data packet according to the downlink data transmission indication information if the identification of the ONU is the same as the identification of the ONU in the DBA. In an optional embodiment, the uplink and downlink data transmission indication information may be identified by a value of a type (type); if the value of the type is 1, one or more ONUs in the DBA carry out uplink data transmission; if the value of the type is 0, one or more ONUs in the DBA carry out downlink data transmission. As shown in fig. 5, the nth superframe header includes: the synchronization information, the frame number information, and the DBA of the next 1 superframe structure (i.e., the DBA of the second superframe structure), the identification information of the ONU included in the DBA of the N +1 superframe structure is indicated by AlloclID, the uplink and downlink transmission indication information is indicated by type (type), and the location information of the data transmission is indicated by Start and End, as shown in the superframe structure in fig. 5, it is displayed that AlloclID is ONU1, start is 100 and End is 200, and the value of type (type) is 1, indicating that ONU1 needs to send an uplink data packet to the OLT in rows 100 to 200 after receiving the second superframe structure. The AlloclID is ONU2, the Start is 300 and the End is 400, and the value of the type (type) is 0, indicating that ONU2 needs to receive downlink packets in rows 300 to 400 after receiving the second superframe structure.

In an alternative embodiment, since the uplink data and the downlink data are not transmitted simultaneously, there is a time interval between the first data packet and the second data packet, and the time interval is usually greater than the uplink data transmission switching time. The first data packet and the second data packet are burst data packets, and the number of the first data packet and the number of the second data packet are specifically determined according to the DBA, which is not specifically limited herein, and the number of the first data packet and the number of the second data packet may be the same in a superframe structure, but the number of the first data packet may also be less than the data of the second data packet, or the number of the first data packet is greater than the data of the second data packet, and the specific number of the first data packet and the second data packet is determined according to the actual transmission requirement of the data.

Fig. 6 shows that the data information that may be included in the first packet or the second packet mainly includes a preamble (preamble), a delimiter), a payload (payload), and an end (end) part, where the preamble is used for fast recovery of data, the delimiter is used for defining the range of the packet, the payload is used for carrying useful data information, and the end indicates the end of the packet by fixed 1 or 2 bytes.

The data transmission method provided by the present application is described next with reference to different communication scenarios and different optical transceiver components. Fig. 7A illustrates a system architecture for point-to-point communication, including: the optical fiber distribution frame comprises a convergence switch, an access switch, an OLT, an Optical Distribution Frame (ODF), a plurality of ONUs and a plurality of cameras (IPC), wherein optical transceiving components are arranged in the components of the OLT and the ONUs. Under the system architecture shown in fig. 7A, it is assumed that the requirement index is shown in table 1 during data transmission, that is, during data transmission, it is required to ensure that the mainstream splitting ratio is 1:32, or 1:64. the maximum transmission distance, i.e. the distance between the OLT and the ONU, needs to be less than 20km. The transmission delay needs to be less than 10mS, the bandwidth required by each camera when returning the uplink data is 20Mbps, and the bandwidth required by each camera when receiving the downlink data is less than 1Mbps. The OLT can determine the uplink time window information and the downlink time window information according to the requirement index so as to meet the requirement of the requirement index as far as possible during data transmission.

TABLE 1

Under the system architecture of fig. 7A, by using the data transmission method provided in the present application, both uplink and downlink use discontinuous data packets for data transmission, and the achievable effect is shown in table 2, where table 2 is only schematically described and is not particularly limited. Table 2 illustrates two different cases, where the time for uplink and downlink handover is 10uS and 50uS, respectively, and the time delay is 10mS. With a delay of 10mS, uplink and downlink 20, each slot may occupy 476uS. When the actual bandwidth is calculated, a Feedforward Error Correction (FEC) rate is required to be multiplied, that is, 0.87, when the transceiving switching time is 10uS, the actually-working bandwidth is 4G bps, 200 cameras can be supported to transmit back uplink data, and when the transceiving switching time is 50uS, the actually-working bandwidth is 3.7G bps, 180 cameras can be supported to transmit back uplink data. Therefore, the data transmission scheme can support more cameras to transmit uplink data back under the same bandwidth.

TABLE 2

Fig. 7B shows a system architecture for point-to-multipoint communication, comprising: the optical fiber distribution Frame (FDT) comprises a plurality of ONUs and a plurality of cameras (IPCs), wherein the components of the OLT and the ONUs comprise optical transceiving components. Under the system architecture shown in fig. 7B, it is assumed that the demand index at the time of data transmission is also shown in table 1.

Under the system architecture of fig. 7B, by using the data transmission method provided in the present application, both uplink and downlink use discontinuous data packets for data transmission, and the achievable effect is shown in table 3, where table 3 is only schematically described and is not particularly limited. Table 3 illustrates two different cases, where the time for uplink and downlink handover is 10uS and 50uS, respectively, and the time delay is 10mS. In the case of 10mS delay, uplink and downlink 20. The actual bandwidth needs to be multiplied by the FEC rate, that is, 0.87, when the transceiving switching time is 10uS, the actual working bandwidth is 0.12G bps, which can support 6 cameras to transmit back uplink data, and when the transceiving switching time is 50uS, the actual working bandwidth is 0.08G bps, which can support 4 cameras to transmit back uplink data.

TABLE 3

Fig. 8 shows the architecture of another communication system, including: a Broadband Remote Access Server (BRAS), an OLT, a gateway of an ONU, and a plurality of ONUs, where the gateway of an ONU may be a main gateway of a home network, different ONUs may be disposed in different rooms, and components of the OLT and the ONUs each include an optical transceiver component, and under the system architecture shown in fig. 8, it is assumed that a requirement index during data transmission is shown in table 4, that is, during data transmission, it is required to ensure that a main splitting ratio is less than 1. The maximum transmission distance, i.e. the distance between the OLT and the ONU, is less than 1km. The transmission delay needs to be less than 1mS, and since a user may upload more data or download more data when surfing the internet, the bandwidth is uncertain, and thus the bandwidth is indicated by TBD. The OLT can determine the uplink time window information and the downlink time window information according to the requirement index so as to meet the requirement of the requirement index as far as possible during data transmission.

TABLE 4

	Main stream split ratio	Maximum transmission distance	Time delay	Bandwidth of
					Index (I)	<1:8	<1km	<1mS	TBD

Under the system architecture of fig. 8, by using the data transmission method provided in the present application, both uplink and downlink use discontinuous data packets for data transmission, and the achievable effect is shown in table 5, where table 5 is only schematically described and is not particularly limited. Table 5 illustrates 5 different cases, where the time delay is 125uS when the uplink and downlink switching time is 1uS and 10uS, respectively; when the uplink and downlink switching time is 10uS, 50uS and 1uS respectively, the time delay is 1000uS. When the time delay is 125uS, and the uplink and downlink are 8; with a delay of 1000uS, uplink 8 and downlink 1, each slot may occupy 62.5uS. The FEC rate is needed to be multiplied when the actual bandwidth is calculated, namely 0.87, and when the receiving and transmitting switching time is 1uS and the time delay is 125uS, the actual working bandwidth is 0.47Gbps; when the receiving and transmitting switching time is 10uS and the time delay is 125uS, the actual working bandwidth is-1.5 Gbps; when the receiving and transmitting switching time is 10uS and the time delay is 1000uS, the actual working bandwidth is 0.46Gbps; when the receiving and transmitting switching time is 50uS and the time delay is 1000uS, the actual working bandwidth is 0.1Gbps; when the receiving and transmitting switching time is 1uS and the time delay is 1000uS, the actual working bandwidth is 0.53Gbps.

TABLE 5

In practical applications, the data transmission method of the present application is not limited to the communication architecture shown in fig. 7A and 7B or the communication architecture shown in fig. 8 for data transmission, and the communication system described above is applicable to the present application. The following describes the solution of the present application with reference to different situations of optical transceiver components in OLT and ONU, specifically as follows:

case 1: optical transceiver components of OLT and ONU are transceiver-integrated components

To illustrate the case 1 more clearly by using fig. 9, where the optical transceiver components at the OLT and the ONU are both optical transceiver components, fig. 9 is identified by a half transceiver half-duplex component, and if the downlink time windows calculated by the OLT according to the uplink and downlink bandwidth requirements and the ranging information are 2, 4, 6, 8, and 10, and the uplink time windows are 1, 3, 5, 7, and 9, the OLT may send downlink data in the

downlink time windows

2, 4, 6, 8, and 10. When the OLT sends downlink data, the working mode of the half-transceiving half-duplex component can be adjusted to be a transmitter, and an optical signal is sent to the ONU side at the wavelength of 1270nm, and the ONU can receive the optical signal in time windows of 2, 4, 6, 8 and 10 by taking the working mode of the half-transceiving half-duplex component as a receiver. Since there may be a time difference between the ONUs receiving the optical signal from the OLT, the clocks need to be synchronized. The same ONU may send upstream data to the OLT in

time windows

1, 3, 5, 7, 9. In actual operation, uplink data and downlink data can be carried in a superframe structure, and the OLT periodically sends a superframe header to the ONU, so that the ONU can know which specific time slot receives a downlink data packet and which specific time slot of the superframe structure sends an uplink data packet.

Case 2: the optical transceiver components of OLT and ONU only have one component integrating transceiving

To illustrate the case 2 more clearly by referring to fig. 10, where only the optical transceiver module at the ONU side is a transceiver module, if the downstream time windows calculated by the OLT according to the uplink and downlink bandwidth requirements and the ranging information are 2, 4, 6, 8, and 10, and the uplink time windows are 1, 3, 5, 7, and 9, the OLT may send downlink data in the

downstream time windows

2, 4, 6, 8, and 10. When the OLT sends downstream data, an optical signal is sent to the ONU side at the wavelength of 1270nm through the transmitter, and the ONU can receive the optical signal in time windows of 2, 4, 6, 8 and 10 by switching the working mode of the half-transceiving half-duplex component to the receiver. Since there may be a time difference between the ONUs receiving the optical signal from the OLT, the clocks need to be synchronized. The same ONU can send upstream data to the OLT in

time windows

In the present application, data transmission may be performed between the OLT and the ONUs in a point-to-point communication manner, or in a point-to-multipoint communication manner. And the OLT determines an uplink time window and a downlink time window according to the distance between the OLT and the ONU and the bandwidth condition required by uplink and downlink transmission data. And then the OLT informs the ONU of the information of the uplink time window and the information of the downlink time window through a superframe structure, sends a downlink data packet, namely a first data packet, in the downlink time window, and receives an uplink data packet, namely a second data packet, from the ONU in the uplink time window. The method can be suitable for the optical transceiving component with the separated transmitter and receiver, and can also be suitable for the optical device with the integrated transmitter and receiver.

In addition, it should be further noted that, because the downstream data packet sent by the OLT is a burst, when the ONU registers online with the OLT, the registration process may also be changed accordingly, and the registration process may be executed with reference to the process shown in fig. 11 when executing, which is specifically as follows:

step 1101: the OLT periodically broadcasts windowing information, namely the starting time and the length of an uplink window and a downlink window.

Step 1102: and the unregistered ONU receives the windowing information and sends an online registration request to the OLT.

Step 1103: the OLT and the ONU execute a ranging process and send a superframe structure according to a first period during the ranging; the ranging process also measures the distance information between the OLT and the ONU.

It should be noted that the superframe structure sent by the OLT during the ranging period does not carry downlink data, and the downlink data may be null.

Step 1104: and the OLT allocates bandwidth for the ONU according to the ranging information.

Step 1105: and the ONU requests uplink and downlink bandwidth information from the OLT.

Step 1106: the OLT allocates the DBA and transmits the DBA to the ONU through a superframe structure.

Step 1107: and the ONU determines the uplink data transmission indication information and the downlink data transmission indication information in the DBA and transmits data according to the uplink data transmission indication information and the downlink data transmission indication information.

As shown in fig. 12, a communication apparatus provided by the present application includes a processing unit 1201 and a transceiving unit 1202. In practical applications, the communication device may be the above-mentioned optical line terminal or an optical network unit.

When the communication device is an optical line terminal, a processing unit 1201 is configured to determine a downlink time window and an uplink time window according to a data transmission bandwidth requirement and a distance between the optical line terminal OLT and an optical network unit ONU; a transceiver unit 1202, configured to send a superframe structure to the optical network unit; the superframe structure includes: information of the downlink time window and information of the uplink time window; and, in the downstream time window, sending a first data packet to the ONU; receiving a second data packet from the ONU in the upstream time window.

In the present application, data transmission may be performed between the OLT and the ONUs in a point-to-point communication manner, or in a point-to-multipoint communication manner. And the OLT determines an uplink time window and a downlink time window according to the distance between the OLT and the ONU and the bandwidth condition required by uplink and downlink transmission data. And then the OLT informs the ONU of the information of the uplink time window and the information of the downlink time window through a superframe structure, sends a downlink data packet, namely a first data packet, in the downlink time window, and receives an uplink data packet, namely a second data packet, from the ONU in the uplink time window. The method can be suitable for the optical transceiving components with the transmitter and the receiver separated, and can also be suitable for the optical device with the transmitter and the receiver integrated. In addition, the method can be applied to the scene that the transmission of the uplink and downlink data is not matched, such as the scene of video return (the scene of video return has a large amount of uplink data and a small amount of downlink data), the condition that the transmission resource is wasted due to continuous transmission of the downlink data is avoided, and in addition, the consumption of the electric quantity of equipment can be reduced under the condition that the downlink data is continuously transmitted. In the case where the power consumption of the device is small, the usage time that can be supported by the device is also increased appropriately.

It should be noted that the superframe structure may be transmitted according to a fixed period, for example, 125uS. The superframe structure is sent according to a fixed period, so that the superframe structure can be ensured to be timely notified to different ONUs, and the condition that the information of the OLT and the ONUs is not synchronous is avoided.

In an alternative mode, the super-frame header includes: frame number information, synchronization information and N DBAs of the superframe structure; said N is greater than or equal to 1; the DBA includes: identification information of one or more ONUs, uplink and downlink data transmission indication information and position information of data transmission.

It should be noted that the next N superframe structures can be understood as a certain superframe structure after the current superframe structure, for example, the current superframe structure is a 3 rd superframe structure, and assuming that N is 3, the superframe header can carry DBA of a 6 th (3 + 3) superframe structure. Wherein the DBA comprises: the identification information of one or more optical network units, the uplink and downlink data transmission indication information and the data transmission position information are used, so that the ONU can know which ONU needs to receive the downlink data packet or which ONU needs to send the uplink data according to the DBA. The frame number information in the superframe structure can record the several superframe structures sent by the olt, so that the ONU can better learn about the operations performed in different superframe structures. The synchronization information in the superframe structure may synchronize part of the information of the last superframe structure so that the ONU may know the timing relationship of the received superframe structure and other superframe structures.

When the communication device is an optical network unit, the transceiver unit 1202 is configured to receive a superframe structure from the optical line terminal OLT; the superframe structure includes: information of the downlink time window and information of the uplink time window; a processing unit 1201, configured to receive a first data packet from the OLT in the downlink time window; and sending a second data packet to the OLT in the uplink time window.

In the present application, data transmission may be performed between the OLT and the ONUs in a point-to-point communication manner, or in a point-to-multipoint communication manner. The OLT determines an uplink time window and a downlink time window according to the distance between the OLT and the ONU and the bandwidth condition required by uplink and downlink transmission data. And then the OLT informs the ONU of the information of the uplink time window and the information of the downlink time window through a superframe structure, sends a downlink data packet, namely a first data packet, in the downlink time window, and receives an uplink data packet, namely a second data packet, from the ONU in the uplink time window. The method can be suitable for the optical transceiving components with the transmitter and the receiver separated, and can also be suitable for the optical device with the transmitter and the receiver integrated. In addition, the method can be applied to scenes that the transmission of uplink and downlink data is not matched, such as a video return scene (a large amount of uplink data and a small amount of downlink data exist in the video return scene), the situation that the transmission resources are wasted due to continuous transmission of the downlink data is avoided, and in addition, the consumption of the electric quantity of equipment can be reduced under the situation that the downlink data is continuously transmitted. In the case of low power consumption of the device, the supportable use time of the device is also increased appropriately.

In an optional manner, the superframe structure further includes: a super-frame header; the superframe header is sent by broadcasting.

In the embodiment of the application, the superframe header can be sent to more ONUs by broadcasting, and a plurality of ONUs can receive the superframe header from the OLT.

In an optional manner, the super-frame end includes: synchronizing information, frame number information and next N DBAs of the superframe structure; the N is greater than or equal to 1; the DBA includes: identification of one or more ONU, uplink and downlink data transmission indication information and position information of data transmission.

It should be noted that the next N superframe structures can be understood as a certain superframe structure after the current superframe structure, for example, the current superframe structure is a 3 rd superframe structure, and assuming that N is 3, the superframe header can carry DBA of a 6 th (3 + 3) superframe structure. Wherein the DBA includes: the identification information of one or more optical network units, the uplink and downlink data transmission indication information and the data transmission position information are used, so that the ONU can know which ONU needs to receive the downlink data packet or which ONU needs to send the uplink data according to the DBA. The frame number information in the superframe structure can record the several superframe structures sent by the optical line terminal, so that the ONU can better learn the operations performed in different superframe structures. The synchronization information in the superframe structure may synchronize part of the information of the last superframe structure so that the ONU may know the timing relationship of the received superframe structure and other superframe structures.

In an optional manner, the uplink and downlink data transmission indication information is identified by a type value; if the type value is 1, one or more ONUs in the DBA perform uplink data transmission; and if the value of the type is 0, one or more ONUs in the DBA perform downlink data transmission.

In an optional manner, the processing unit 1202 is configured to: and determining that the identification of the ONU is the same as the identification of the ONU in the DBA, and receiving the first data packet according to the downlink data transmission indication information.

In the embodiment of the application, the ONU can determine whether data transmission is required according to the identification information of the ONU in the DBA, and the ONU can sequentially perform data transmission by this method.

Based on the same concept, the embodiment of the present application provides a communication apparatus 1300. Illustratively, the communication device 1300 may be a chip or a system of chips. Optionally, the chip system in the embodiment of the present application may be composed of a chip, and may also include a chip and other discrete devices.

The communications apparatus 1300 may include at least one processor 1310, and the communications apparatus 1300 may also include at least one memory 1320 for storing computer programs, program instructions, and/or data. A memory 1320 is coupled to the processor 1310. The coupling in the embodiments of the present application is an indirect coupling or a communication connection between devices, units or modules, and may be an electrical, mechanical or other form for information interaction between the devices, units or modules. The processor 1310 may operate in conjunction with the memory 1320. Processor 1310 may execute computer programs stored in memory 1320. Alternatively, the at least one memory 1320 may be integrated into the processor 1310.

The communications apparatus 1300 can also include a transceiver 1330, and the communications apparatus 1300 can exchange information with other devices through the transceiver 1330. The transceiver 1330 may be a circuit, a bus, a transceiver, or any other device that may be used to exchange information.

In a possible embodiment, the communication apparatus 1300 may be applied to the OLT or the ONU. The memory 1320 holds the necessary computer programs, program instructions and/or data to implement the functionality of the network device in any of the embodiments described above. The processor 1310 can execute the computer program stored in the memory 1320 to perform the method of any of the above embodiments.

The specific connection medium among the transceiver 1330, the processor 1310 and the memory 1320 is not limited in the embodiments of the present invention. In the embodiment of the present application, the memory 1320, the processor 1310, and the transceiver 1330 are connected through a bus in fig. 13, the bus is represented by a thick line in fig. 13, and the connection manner between other components is only for illustrative purposes and is not limited thereto. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 13, but that does not indicate only one bus or one type of bus.

In the embodiments of the present application, the processor may be a general processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, and may implement or execute the methods, steps, and logic blocks disclosed in the embodiments of the present application. A general purpose processor may be a microprocessor or any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present application may be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules in a processor.

In the embodiment of the present application, the memory may be a nonvolatile memory, such as a Hard Disk Drive (HDD) or a solid-state drive (SSD), and may also be a volatile memory (RAM), for example. The memory can also be any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer, but is not limited to such. The memory in the embodiments of the present application may also be circuitry or any other device capable of performing a storage function for storing computer programs, program instructions, and/or data.

Based on the foregoing embodiments, the present application further provides a readable storage medium, which stores instructions that, when executed, cause the method performed by the security detection apparatus in any of the foregoing embodiments to be implemented. The readable storage medium may include: u disk, removable hard disk, read only memory, random access memory, magnetic or optical disk, etc. for storing program codes.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims

1. A data transmission method is applied to an Optical Line Terminal (OLT), and is characterized by comprising the following steps:

determining a downlink time window and an uplink time window according to the data transmission bandwidth requirement and the distance between the OLT and an optical network unit ONU;

sending a superframe structure to the ONU; the superframe structure includes: information of the downlink time window and information of the uplink time window;

sending a first data packet to the ONU in the downstream time window;

receiving a second data packet from the ONU in the upstream time window.

2. The method of claim 1, wherein the superframe structure comprises a plurality; the plurality of superframe structures are transmitted at a first periodicity.

3. The method of claim 1 or 2, wherein the superframe structure further comprises: super frame head; the superframe header is sent by broadcasting.

4. The method of claim 3, wherein the superframe header comprises: synchronizing information, frame number information and dynamic bandwidth allocation DBAs of next N superframe structures; said N is greater than or equal to 1;

the DBA includes: identification information of one or more ONUs, uplink and downlink data transmission indication information and position information of data transmission.

5. The method according to claim 4, wherein the uplink and downlink data transmission indication information is identified by a type value; if the value of the type is 1, one or more ONUs in the DBA perform uplink data transmission; and if the value of the type is 0, one or more ONUs in the DBA perform downlink data transmission.

6. The method of any of claims 1-5, wherein the first packet is separated from the second packet by a time interval; the time interval is greater than the uplink and downlink data transmission switching time.

7. A data transmission method is applied to an Optical Network Unit (ONU), and is characterized by comprising the following steps:

receiving a superframe structure from an Optical Line Terminal (OLT); the superframe structure includes: information of the downlink time window and information of the uplink time window;

receiving a first data packet from the OLT in the downlink time window;

and sending a second data packet to the OLT in the uplink time window.

8. The method of claim 7, wherein the superframe structure comprises a plurality; the plurality of superframe structures are transmitted at a first cycle; receiving a superframe structure from an optical line terminal, comprising:

and the ONU receives the superframe structure according to the first period.

9. The method of claim 7 or 8, wherein the superframe structure further comprises: super frame head; the superframe header is sent by broadcasting.

10. The method of claim 9, wherein the superframe header comprises: synchronizing information, frame number information and dynamic bandwidth allocation DBAs of next N superframe structures; said N is greater than or equal to 1;

the DBA includes: identification of one or more ONU, uplink and downlink data transmission indication information and position information of data transmission.

11. The method of claim 10, wherein the uplink and downlink data transmission indication information is identified by a value of a type; if the type value is 1, one or more ONUs in the DBA perform uplink data transmission; and if the type value is 0, one or more ONUs in the DBA perform downlink data transmission.

12. The method of claim 10, wherein receiving a first packet from the OLT in the downstream time window comprises:

13. The method of any of claims 7-12, wherein the first packet is separated from the second packet by a time interval; the time interval is greater than the uplink and downlink data transmission switching time.

14. An optical line terminal, comprising:

the processing unit is used for determining a downlink time window and an uplink time window according to the data transmission bandwidth requirement and the distance between the optical line terminal OLT and the optical network unit ONU;

a transceiving unit for transmitting a superframe structure to the ONU; the superframe structure includes: information of the downlink time window and information of the uplink time window; and, in the downstream time window, sending a first data packet to the ONU; receiving a second data packet from the ONU in the upstream time window.

15. The olt of claim 14, wherein the superframe structure comprises a plurality; the plurality of superframe structures are transmitted at a first periodicity.

16. The olt of claim 14 or 15, wherein the superframe structure further comprises: super frame head; the superframe header is sent by broadcasting.

17. The olt of claim 16, wherein the superframe header comprises: synchronizing information, frame number information and dynamic bandwidth allocation DBA of next N superframe structures; said N is greater than or equal to 1;

18. The olt of claim 17, wherein the uplink and downlink data transmission indicator identifies via a type value; if the type value is 1, one or more ONUs in the DBA perform uplink data transmission; and if the value of the type is 0, one or more ONUs in the DBA perform downlink data transmission.

19. The olt of any of claims 14-18, wherein the first packet is separated from the second packet by a time interval; the time interval is greater than the uplink and downlink data transmission switching time.

20. An optical network unit, comprising:

a receiving and sending unit, which is used for receiving the superframe structure from the optical line terminal OLT; the superframe structure includes: information of the downlink time window and information of the uplink time window;

a processing unit, configured to receive a first data packet from the OLT in the downlink time window; and sending a second data packet to the OLT in the uplink time window.

21. The onu of claim 20, wherein the superframe structure comprises a plurality; the plurality of superframe structures are transmitted at a first cycle; the transceiver unit is configured to receive the superframe structure according to the first period.

22. The onu of claim 20 or 21, wherein the superframe structure further comprises: super frame head; the superframe header is sent by broadcasting.

23. The onu of claim 22, wherein the superframe header comprises: synchronizing information, frame number information and dynamic bandwidth allocation DBA of next N superframe structures; said N is greater than or equal to 1;

24. The onu of claim 23, wherein the uplink and downlink data transmission indication information is identified by a value of a type; if the type value is 1, one or more ONUs in the DBA perform uplink data transmission; and if the type value is 0, one or more ONUs in the DBA perform downlink data transmission.

25. The onu of claim 23, wherein the processing unit is configured to:

26. The onu of any one of claims 20-25, wherein the first packet is separated from the second packet by a time interval; the time interval is greater than the uplink and downlink data transmission switching time.

27. An optical line terminal, comprising: a processor and a memory;

the memory for storing a computer program;

the processor configured to execute the computer program stored in the memory to cause the optical line terminal to perform the method according to any one of claims 1 to 6.

28. An optical network unit, comprising: a processor and a memory;

the memory for storing a computer program;

the processor configured to execute the computer program stored in the memory to cause the optical network unit to perform the method according to any of claims 7-13.

29. A communication system comprising an optical line terminal according to any of claims 14 to 19 and an optical network unit according to any of claims 20 to 26.

30. A computer-readable storage medium having stored thereon instructions that, when executed, cause a computer to perform the method of any one of claims 1-6 or 7-13.