A passive optical network time sensitive service transmission method and system

Abstract

The application provides a passive optical network time-sensitive service transmission method and system, which allocates a logical link identifier to at least one optical network unit, receives the number of bytes waiting for allocation in the buffer of each optical network unit, and establishes a polling table record with the communication round trip time; sends authorization information to each optical network unit; determines the sending order of the optical network unit to the queuing scheduling module for forwarding data in each forwarding cycle according to the communication round trip time; receives the data packet obtained by packing the data to be forwarded and control information forwarded by the queuing scheduling module of each optical network unit, the queuing scheduling module receives a plurality of data packets forwarded by each optical network unit, and stores the data packets in the transmission queue corresponding to the ordinal number according to the delay time slot number of the data packets, and forwards the data packets to the optical terminal device one by one according to the ordinal number in one forwarding cycle; and updates the polling table according to the remaining byte number of the buffer of the corresponding optical network unit recorded in the control information and the actual communication round trip time.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to a method and system for transmitting time-sensitive services in a passive optical network. Background Technology

[0002] The Industrial Internet (IIoT) serves as a communication link for the comprehensive interconnection of people, machines, and things in an industrial environment. Its development provides a crucial path for the digital transformation and network upgrade of industrial manufacturing, promoting the deep integration of manufacturing with other industries and facilitating the optimization and upgrading of the industrial structure. Based on business traffic characteristics, the IIoT can be categorized into isochronous flow, cyclical flow, and burst flow. To ensure continuous control of industrial equipment by the PLC, isochronous flow has extremely high requirements for end-to-end latency jitter. Strict time synchronization between the industrial control system and the transmission network is necessary to guarantee the low latency and jitter requirements of isochronous flow. Cyclic flow is an asynchronous periodic flow where the industrial control system does not need to synchronize with the transmission network. Instead, it uses the local clock of the industrial equipment to control the transmission of data packets. It is a low-bandwidth, low-latency, and high-reliability industrial service where data packets are sent periodically and are of fixed size. Burst flow involves industrial equipment sending data packets in bursts, with the packet size typically varying. This type of flow corresponds to a type of application scenario with certain latency requirements. Therefore, effectively allocating bandwidth and scheduling traffic for these three types of flow characteristics in the IIoT scenario is a crucial research focus.

[0003] In existing technologies, traditional bandwidth allocation schemes ensure the transmission performance of time-sensitive traffic and the on-demand allocation of bandwidth resources in scenarios such as industrial internet. However, they neglect the specific location and adjacency relationship of the bandwidth allocation window. These traditional schemes are more suitable for traditional telecommunications services and cannot meet the data packet transmission requirements of industrial internet with low latency and jitter boundaries. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a method and system for transmitting time-sensitive services in a passive optical network (PON) to eliminate or improve one or more defects in the prior art, and solve the problem that time-sensitive services for industrial Internet scenarios cannot be transmitted efficiently and stably in a PON.

[0005] One aspect of the present invention provides a method for transmitting time-sensitive services in a passive optical network, the method comprising the following steps:

[0006] Assign a logical link identifier to at least one optical network unit to identify the optical network unit and record the transmission time; receive the number of bytes waiting to be assigned in the buffer of each optical network unit and establish a polling table to record the communication round-trip time of each network unit and optical terminal equipment obtained by measurement.

[0007] Authorization information is sent to each optical network unit; the authorization information is used to mark the data to be forwarded by each optical network unit in each forwarding cycle;

[0008] Based on the communication round-trip time in the polling table, the optical network unit determines the transmission order of the data to be forwarded in each forwarding cycle and broadcasts it to each optical network unit.

[0009] The system receives data packets forwarded by each optical network unit via the queuing and scheduling module in each forwarding cycle and records the reception time. The data packets are obtained by packaging the data to be forwarded and control information. The control information is used to record the number of bytes remaining in the buffer of the corresponding optical network unit. The queuing and scheduling module receives multiple data packets forwarded by each optical network unit according to the sending order and stores them in the corresponding ordinal transmission queue according to the delay slot number of the data packets. The delay slot number of each data packet is obtained by taking the maximum allowable runtime delay modulo the number of transmission queues and rounding up. The data packets in each transmission queue are forwarded to the optical terminal device one by one in ordinal order within one forwarding cycle.

[0010] The number of bytes waiting to be allocated in the polling table is updated according to the number of remaining bytes in the corresponding optical network unit buffer recorded in the control information, and the communication round-trip time in the polling table is updated according to the actual communication round-trip time obtained from the sending time and the receiving time.

[0011] In some embodiments, the data to be forwarded by each optical network element in each forwarding cycle is determined by the transmission window size of each network element, and the transmission window size satisfies the following expression:

[0012] W i =min(Q) i +H ON W max );

[0013] Among them, Q i H represents the number of bytes waiting to be allocated in the buffer of the i-th optical network unit. ON W represents the additional resource consumption during time-sensitive service transmission in a passive optical network. max This indicates the preset maximum transmission window.

[0014] In some embodiments, the number of delay slots for each data packet is obtained by taking the maximum allowed runtime delay modulo the number of transmission queues and rounding up, and the number of delay slots satisfies the following expression:

[0015]

[0016] Where S represents the fiber length from the optical network unit to the optical terminal equipment, and C wire T represents the speed at which light travels in an optical fiber. d T represents the time slot in which the data packet is expected to be delivered to the optical terminal equipment. a The time slot represents the data packet sent from the optical network unit, and n represents the number of transmission queues.

[0017] In some embodiments, the process of forwarding the data packets in each transmission queue sequentially to the optical terminal device within a forwarding cycle includes:

[0018] The gating code of the first sequential transmission queue is set to open, and the gating code of the other transmission queues is set to close. The data packets in the first sequential transmission queue are forwarded to the optical terminal device through a delay time slot.

[0019] The gating code of the first sequential transmission queue is changed to off, and the gating code of the second sequential transmission queue is changed to on, while the gating codes of the other transmission queues are off. The data packets in the second sequential transmission queue are forwarded to the optical terminal equipment through a delay time slot. The gating code in the transmission queue is changed once every time delay time slot until all data packets are sent to the optical terminal equipment to complete the data packet forwarding of the current forwarding cycle.

[0020] In some embodiments, the process of measuring the round-trip communication times of each network unit and optical terminal device includes:

[0021] The ranging request information containing the logical link identifier is sent to each optical network unit, and the timestamp of sending the ranging request information is recorded, so that each network unit receives the ranging request information and returns ranging response information to the optical terminal device.

[0022] Receive ranging response information from each optical network unit and record the timestamp of receiving the ranging response information;

[0023] The round-trip time between each network unit and the optical terminal device is calculated based on the timestamp of sending the ranging request information and the timestamp of receiving the ranging response information.

[0024] In some embodiments, the method further includes:

[0025] The sending time, the receiving time, the size of the data packet, and the authorization information are constructed into a parameter array. The parameter array is partitioned according to the time dimension, and an encryption algorithm is used to send and store it to the cloud platform.

[0026] A name index is established for the sending time, receiving time, data packet size, and authorization information of the cloud platform, so that users can query the corresponding parameters in the cloud platform according to the name index.

[0027] On the other hand, the present invention also provides a passive optical network time-sensitive service transmission system, the system comprising:

[0028] An optical terminal device is used to implement the passive optical network time-sensitive service transmission method described in any of the above claims. It assigns a logical link identifier to at least one optical network unit (ONU) to identify the ONU and records the transmission time. It receives the number of bytes waiting to be allocated in the buffer of each ONU and establishes a polling table with the measured round-trip time between each ONU and the optical terminal device. It sends authorization information to each ONU. Based on the round-trip time in the polling table, it determines the transmission order of the data to be forwarded in each forwarding cycle by having each ONU upload the order to the queuing and scheduling module and broadcast it to each ONU. It also receives data packets forwarded by each ONU via the queuing and scheduling module in each forwarding cycle.

[0029] An optical network unit is used to receive the logical link identifier and send the number of bytes waiting to be allocated in the buffer of each optical network unit to the optical terminal device, and forward multiple data packets to the queuing and scheduling module according to the sending order;

[0030] The queuing and scheduling module is used to receive multiple data packets forwarded by each optical network unit according to the sending order, and store them in the corresponding ordinal transmission queue according to the delay slot number of the data packets. The data packets in each transmission queue are forwarded to the optical terminal device one by one in ordinal number within one forwarding cycle.

[0031] In some embodiments, the queuing scheduling module further includes:

[0032] The fault queue switching module is used to monitor the transmission status of each transmission queue in real time, and to transfer the data packets to be forwarded in the faulty transmission queue to the normally operating transmission queue when a transmission queue fails.

[0033] On the other hand, the present invention also provides a computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implement the steps of any of the methods described above.

[0034] On the other hand, the present invention also provides a computer program product, including a computer program / instructions that, when executed by a processor, implement the steps of any of the methods described above.

[0035] In the passive optical network time-sensitive service transmission method of the present invention, each optical network unit transmits data packets for the current forwarding cycle through authorization information, and the data packets are temporarily stored by the queuing scheduling module and forwarded to the optical terminal equipment within a predetermined time slot. This effectively alleviates the problem of data packets from multiple optical network units competing for the same time slot, improves the orderliness of transmission queue scheduling and the controllability of latency, and can still maintain an efficient and stable data packet transmission process even when faced with a large number of industrial terminal equipment accesses.

[0036] Additional advantages, objects, and features of the invention will be set forth in part in the description which follows, and will also become apparent in part to those skilled in the art upon studying the description, or may be learned by practice of the invention. The objects and other advantages of the invention can be realized and obtained by means of the structures specifically pointed out in the description and drawings.

[0037] Those skilled in the art will understand that the objectives and advantages achievable with this invention are not limited to those specifically described above, and that the above and other objectives achievable with this invention will become clearer from the following detailed description. Attached Figure Description

[0038] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, are not intended to limit the scope of the invention. In the drawings:

[0039] Figure 1 This is a flowchart illustrating a passive optical network time-sensitive service transmission method according to an embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram of the structure of a passive optical network time-sensitive service transmission system according to an embodiment of the present invention.

[0041] Figure 3 This is a flowchart illustrating the queuing scheduling module according to an embodiment of the present invention.

[0042] Figure 4 This is a schematic diagram of a passive optical network time-sensitive service transmission process with three optical network units, according to an embodiment of the present invention.

[0043] Figure 5 This is a schematic diagram comparing the effects of different bandwidth allocation methods in terms of average data packet latency at an optical network unit according to an embodiment of the present invention.

[0044] Figure 6 This is a schematic diagram comparing the effects of different bandwidth allocation methods in terms of polling frequency in one embodiment of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. Here, the illustrative embodiments and descriptions of this invention are used to explain the invention, but are not intended to limit the invention.

[0046] It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only the structures and / or processing steps closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0047] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, element, step, or component, but does not exclude the presence or addition of one or more other features, elements, steps, or components.

[0048] It should also be noted that, unless otherwise specified, the term "connection" in this article can refer not only to a direct connection, but also to an indirect connection involving an intermediary.

[0049] In the following description, embodiments of the invention will be illustrated with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same or similar parts, or the same or similar steps.

[0050] In existing technologies, traditional bandwidth allocation schemes ensure the transmission performance of time-sensitive traffic and the on-demand allocation of bandwidth resources in scenarios such as industrial internet. However, they neglect the specific location and adjacency relationship of the bandwidth allocation window. These traditional schemes are more suitable for traditional telecommunications services and cannot meet the data packet transmission requirements of industrial internet with low latency and jitter boundaries. This invention proposes a method and system for transmitting time-sensitive services in passive optical networks. It allocates a logical link identifier to at least one optical network unit (ONU) to identify the ONU and records the transmission time. It receives the number of bytes waiting to be allocated in the buffer of each ONU and establishes a polling table with the round-trip time. It sends authorization information to each ONU to mark the data to be forwarded by each ONU in each forwarding cycle. Based on the round-trip time in the polling table, it determines that in each forwarding cycle, the ONU uploads the data to be forwarded to the queuing and scheduling module. The system sends data packets in sequence and broadcasts them to each optical network unit (ONU). It receives data packets forwarded by each ONU via the queuing and scheduling module during each forwarding cycle and records the reception time. Data packets are obtained by packaging forwarding data and control information. The control information records the remaining bytes in the buffer of the corresponding ONU. The queuing and scheduling module receives multiple data packets forwarded by each ONU according to the sending order and stores them in the corresponding ordinal transmission queue according to the delay slot number of each data packet. The delay slot number of each data packet is obtained by modulo the maximum allowable runtime delay with the number of transmission queues and rounding up. Data packets in each transmission queue are forwarded sequentially to the optical terminal equipment within one forwarding cycle. The number of bytes waiting to be allocated in the polling table is updated according to the remaining bytes in the buffer of the corresponding ONU recorded in the control information. The actual round-trip time obtained from the sending and receiving times is also updated in the polling table.

[0051] Figure 1 This is a flowchart illustrating a passive optical network (PON) time-sensitive service transmission method according to an embodiment of the present invention. Specifically, one aspect of the present invention provides a PON time-sensitive service transmission method, which includes the following steps S101 to S105:

[0052] Step S101: Assign a logical link identifier to at least one optical network unit to identify the optical network unit and record the transmission time; receive the number of bytes waiting to be allocated in the buffer of each optical network unit and establish a polling table record with the measured round-trip communication time of each network unit and optical terminal equipment.

[0053] Step S102: Send authorization information to each optical network unit; the authorization information is used to mark the data to be forwarded by each optical network unit in each forwarding cycle.

[0054] Step S103: Based on the round-trip time in the polling table, determine the transmission order of the data to be forwarded in each forwarding cycle by the optical network unit uploading it to the queuing and scheduling module and broadcasting it to each optical network unit.

[0055] Step S104: Receive the data packets forwarded by each optical network unit via the queuing and scheduling module in each forwarding cycle and record the reception time. The data packets are obtained by packaging the data to be forwarded and control information. The control information is used to record the number of bytes remaining in the buffer of the corresponding optical network unit. The queuing and scheduling module receives multiple data packets forwarded by each optical network unit according to the sending order and stores them in the corresponding ordinal transmission queue according to the delay slot number of the data packets. The delay slot number of each data packet is obtained by taking the modulo operation of the maximum allowable running delay on the number of transmission queues and rounding up. The data packets in each transmission queue are forwarded to the optical terminal equipment one by one in ordinal order within one forwarding cycle.

[0056] Step S105: Update the number of bytes waiting to be allocated in the polling table according to the number of remaining bytes in the corresponding optical network unit buffer recorded in the control information, and update the communication round-trip time in the polling table according to the actual communication round-trip time obtained from the sending time and receiving time.

[0057] In step S101, in a passive optical network system, a single optical terminal device (OLT) is typically connected to multiple optical network units (ONUs). The OLT assigns distinct Logical Link Identifiers (LLIDs) to each ONU to identify them. The number of bytes waiting to be allocated in the buffer of each ONU can be obtained through autonomous reporting or polling. Autonomous reporting involves the network unit monitoring its own buffer status and proactively sending the number of bytes waiting to be allocated in the buffer to the OLT when the buffer data volume reaches a preset threshold or a specific event occurs, ensuring that the OLT can promptly grasp data changes and make reasonable bandwidth allocation decisions. Polling involves the OLT sending a polling request to the ONU, which receives the request and returns the number of bytes waiting to be allocated in its buffer. The OLT constructs a polling table that can be changed at any time.

[0058] Furthermore, in some embodiments, the process of measuring the round-trip time of communication between each network unit and the optical terminal device includes steps S1011 to S1013:

[0059] Step S1011: Send ranging request information containing logical link identifiers to each optical network unit and record the timestamp of sending the ranging request information, so that each network unit receives the ranging request information and returns ranging response information to the optical terminal equipment.

[0060] Step S1012: Receive ranging response information from each optical network unit and record the timestamp of the received ranging response information.

[0061] Step S1013: Calculate the round-trip time of communication between each network unit and the optical terminal equipment based on the timestamp of sending the ranging request information and the timestamp of receiving the ranging response information.

[0062] In steps S102 and S103, after the optical terminal device broadcasts the authorization information, each optical network unit filters and obtains its corresponding forwardable data according to the logical link identifier. The forwardable data is the service data that the optical terminal device is authorized to transmit. In the industrial internet scenario, the service data is the data sent by each industrial device connected to each optical network unit. Furthermore, in addition to marking the forwardable data of each optical network unit, the authorization information also includes the time slot expected to arrive at the optical terminal device after the data packet is sent from the optical network unit. The expected arrival time slot is obtained by calculating half of the round-trip time and used to calculate the number of delay time slots. The forwardable data is obtained according to the total number of bytes to be allocated in each optical network unit in the polling table. The forwardable data is the data that each optical network unit is allowed to forward. In some embodiments, the forwardable data of each optical network unit in each forwarding cycle is determined by the transmission window size of each network unit. The transmission window size satisfies the following expression:

[0063] W i =min(Q) i +H ON W max );

[0064] Among them, Q i H represents the number of bytes waiting to be allocated in the buffer of the i-th optical network unit. ON W represents the additional resource consumption during time-sensitive service transmission in a passive optical network. max This indicates the preset maximum transmission window.

[0065] Furthermore, based on the round-trip time (RTT) in the polling table, each optical network unit is sorted in ascending order to obtain the transmission order of the data to be forwarded, thereby determining the order in which each optical network unit sends uplink data. Data transmission from the optical terminal equipment to the optical network unit is downlink transmission, which is performed by the optical terminal through broadcast. Data transmission from the optical network unit to the optical terminal equipment is uplink transmission. The passive optical network time-sensitive service transmission method of the present invention applies to the uplink transmission process of data packets from the optical network unit to the optical terminal equipment.

[0066] In step S104, the queuing scheduling module is built based on Cyclic Specified Queuing and Forwarding (CSQF), a high-precision traffic scheduling technology for deterministic networks, which provides strict low-latency and low-jitter transmission guarantees for scenarios such as industrial control and vehicle communication; the queuing scheduling module is based on minimum scheduling time T. slot The forwarding cycle of multiple transmission queues is calculated based on the number of transmission queues, expressed as: T slot =nT slot In a scheduling time slot, one transmission queue has its gating code open and is capable of forwarding data packets to the optical terminal equipment; the queue with the gating code open is the transmission queue, and the remaining queues with the gating code closed are delay queues; data packets are sent to the transmission queue corresponding to the number of delay time slots. In some embodiments, the number of delay time slots for each data packet is obtained by taking the maximum allowed runtime delay modulo the number of transmission queues and rounding up. The number of delay time slots satisfies the following expression:

[0067]

[0068] Where S represents the fiber length from the optical network unit to the optical terminal equipment, and C wire T represents the speed at which light travels in an optical fiber. d T represents the time slot in which the data packet is expected to be delivered to the optical terminal equipment. a This represents the time slot from which data packets are sent from the optical network unit, and n represents the number of transmission queues.

[0069] Furthermore, after a data packet in a transmission queue is forwarded according to a scheduled time slot, the gating code of the next transmission queue will be changed to enable the transmission queue to perform a responsibility switch. The transmission queue delayed by Δ time slots will be transformed into a transmission queue in the Δth time slot. In some embodiments, the process of forwarding data packets in each transmission queue to the optical terminal equipment one by one in sequence within a forwarding cycle includes steps S1041 to S1042:

[0070] Step S1041: Set the gating code of the first sequence transmission queue to on and the gating code of the other transmission queues to off, and forward the data packets in the first sequence transmission queue to the optical terminal equipment through a delay time slot.

[0071] Step S1042: Change the gating code of the first sequence transmission queue to off, and change the gating code of the second sequence transmission queue to on, while keeping the gating codes of the other transmission queues off. Forward the data packets in the second sequence transmission queue to the optical terminal equipment through a delay time slot. The gating code in the transmission queue is changed once every time delay time slot until all data packets are sent to the optical terminal equipment to complete the data packet forwarding of the current forwarding cycle.

[0072] In some embodiments, the passive optical network time-sensitive service transmission method further includes steps S1 to S2:

[0073] Step S1: Construct a parameter array from the sending time, receiving time, data packet size, and authorization information. Partition the parameter array according to the time dimension, and send and store it to the cloud platform using an encryption algorithm.

[0074] Step S2: Create a name index for the sending time, receiving time, data packet size, and authorization information of the cloud platform, so that users can query the corresponding parameters in the cloud platform based on the name index.

[0075] Specifically, a standardized data structure with a unified format is obtained by constructing a parameter array, and the data is transmitted through the application development interface of the cloud platform to improve the efficiency of data interaction; after partitioning the parameters according to the time dimension, the data corresponding to the target content at a specific time can be quickly located by name index, and the efficiency of fault location can be improved when tracing fault events.

[0076] In step S105, after receiving the data packet, the optical terminal device obtains the number of remaining bytes in the buffer of the optical network unit according to the control information, updates the number of bytes waiting to be allocated in the polling table, updates the polling table according to the actual round-trip time, and sends the next round of authorization information and forwards a new round of data packets according to the polling table.

[0077] On the other hand, the present invention also provides a passive optical network time-sensitive service transmission system, the system comprising:

[0078] An optical terminal equipment is used to implement the above-mentioned passive optical network time-sensitive service transmission method. It assigns a logical link identifier to at least one optical network unit (ONU) to identify the ONU and records the transmission time. It receives the number of bytes waiting to be allocated in the buffer of each ONU and establishes a polling table with the measured round-trip time between each ONU and the optical terminal equipment. It sends authorization information to each ONU. Based on the round-trip time in the polling table, it determines the transmission order of the data to be forwarded in each forwarding cycle by uploading it to the queuing and scheduling module and broadcasting it to each ONU. It receives the data packets forwarded by each ONU through the queuing and scheduling module in each forwarding cycle.

[0079] The optical network unit is used to receive the logical link identifier and send the number of bytes waiting to be allocated in the buffer of each optical network unit to the optical terminal equipment, and forward multiple data packets to the queuing and scheduling module according to the sending order.

[0080] The queuing and scheduling module is used to receive multiple data packets forwarded by each optical network unit according to the sending order, and store them in the corresponding ordinal transmission queue according to the delay time slot number of the data packets. The data packets in each transmission queue are forwarded to the optical terminal equipment one by one in order within a forwarding cycle.

[0081] In some embodiments, the queuing scheduling module further includes:

[0082] The fault queue switching module monitors the transmission status of each transmission queue in real time and transfers data packets awaiting forwarding in the faulty transmission queue to the normally operating transmission queue when a transmission queue fails. Specifically, the store-and-forward mechanism of the queuing scheduling module enables the passive optical network time-sensitive service transmission system to have stronger fault tolerance. When a transmission queue fails, data packets can be transferred in a timely manner. Furthermore, when transmission fluctuates or experiences sudden traffic surges, data packets can be buffered in the queue to ensure uninterrupted and packet-free transmission.

[0083] On the other hand, the present invention also provides a computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implement the steps of the above-described method.

[0084] On the other hand, the present invention also provides a computer program product, including a computer program / instructions that, when executed by a processor, implement the steps of the above-described method.

[0085] The present application will now be described with reference to a specific embodiment:

[0086] Figure 2This is a schematic diagram of the structure of a passive optical network time-sensitive service transmission system according to an embodiment of the present invention. This application provides a method and system for transmitting time-sensitive services in a passive optical network (PON), which is a time-sensitive scheduling technology for PONs based on periodic specified queuing and forwarding and geared towards industrial internet scenarios, particularly suitable for industrial automation control scenarios with deterministic transmission requirements. It aims to solve the deterministic transmission challenges caused by existing bandwidth allocation schemes in industrial internet scenarios. This method employs an interleaved polling mechanism in the interaction between optical terminal equipment (OLT) and optical network units (ONU) in the passive optical network, using periodic polling to allocate bandwidth, while employing dynamic window allocation to reduce idle time slots, allocating bandwidth on demand, and improving bandwidth utilization. Specifically, this application uses Periodic Specified Queuing and Forwarding (CSQF) technology to optimize the polling mechanism and window allocation of the entire system. The polling mechanism introduces the concept of multiple queues, each carrying buffer information from different optical network units, effectively reducing the number of polls and latency of the entire system. Regarding window allocation, this application strictly allocates the transmission time window, reducing latency jitter through queuing scheduling, and ensuring deterministic transmission of the entire system. This method can reduce the end-to-end latency and optical network unit processing latency of the entire transmission system while ensuring deterministic transmission in passive optical networks (PONs), thereby improving system reliability and making it suitable for more complex industrial PON environments. This application achieves this through the following technical solution: proposing a polling scheduling method based on periodically specified queuing and forwarding; and introducing multi-queue loops to optimize the polling scheduling method of PONs.

[0087] 1. Based on the current network conditions, establish a polling table for the optical terminal equipment.

[0088] In a Passive Optical Network (PON) time-sensitive service transmission system, a single optical terminal device (OPD) typically connects to multiple optical network units (ONUs). In industrial PONs, the OPD assigns a unique Logical Link Identifier (LLID) to each ONU to identify it. To optimize bandwidth allocation and resource scheduling, before each new scheduling round begins, the OPD knows in advance the number of bytes (Q) waiting to be allocated in the buffer of each ONU, as well as the round-trip time (RTT) when these different ONUs communicate with the OPD. The OPD records this information and uses it to construct a constantly changing polling table to track the basic information of ONUs with different LLIDs under the scheduling algorithm.

[0089] 2. The optical terminal equipment sends downlink authorization information.

[0090] The optical terminal equipment begins sending authorization information to all optical network units according to the polling table. The authorization message includes the time slot Td in which the data of the corresponding optical network unit should be forwarded, and the allocated size of the data to be forwarded.

[0091] Based on the number of bytes Q waiting to be allocated in the buffer of each optical network unit (ONU) in the polling table, the size of the data that an ONU is allowed to forward is defined. This allowed data size is determined by the transmission window size W. i The expression is:

[0092] W i =min(Q) i +H ON W max );

[0093] Among them, Q i H represents the number of bytes waiting to be allocated in the buffer of the i-th optical network unit. ON It refers to the control overhead in the entire passive optical network time-sensitive service transmission system, that is, the additional resource consumption of the non-valid data portion; the authorization message of the optical terminal equipment includes information such as the authorized transmission window size. max The maximum transmission window set for a passive optical network time-sensitive service transmission system is also the maximum queue length in multi-queue polling.

[0094] The optical terminal equipment (OTE) sorts all optical network units (ONUs) according to their round-trip times (RTTs) in a polling table. This sorting determines the order in which the ONUs send uplink data, with ONUs having shorter RTTs being prioritized. After sorting the ONUs, each ONU is assigned a time slot T for the data packets it expects to transmit within the current polling period. d That is, in T d At this moment, the data packets of the corresponding optical network unit will be delivered to the optical terminal equipment.

[0095] 3. After receiving the authorization information, the optical network unit begins to send data packets to the optical terminal equipment.

[0096] The optical terminal equipment (OPE) broadcasts authorization information downlink, which is then split and sent to each optical network unit (ONU). All ONUs receive the same data. Each ONU filters out its own data by matching logical link identifiers and discards other data. After receiving the authorization information, the ONUs transmit buffered uplink data. The uplink data transmitted by the ONUs includes the service data authorized for transmission by the OCE. This service data is transmitted by industrial equipment connected to each ONU. The time slot T during the transmission of this uplink data is specified. aThe data packet also includes control information at the end, which contains the number of bytes remaining in the optical network unit's buffer after it has sent the current data.

[0097] 4. Once the data arrives at the scheduling model, it enters the transmission queue and waits to be sent.

[0098] Figure 3 This is a flowchart illustrating a queuing scheduling module according to an embodiment of the present invention. A queuing scheduling module based on periodically specified queuing and forwarding technology is established for forwarding uplink data in a passive optical network system. The core idea of ​​this queuing scheduling module is to ensure that the latency of a single transmission queue is within a determinable range based on store-and-forward, thereby ensuring controllable end-to-end latency of data packet transmission. Queue scheduling is based on the minimum scheduling slot of the entire system and can control multiple queues before the output port. The number of transmission queues in the queuing scheduling module is generally n, which is the number of optical network units. When the minimum scheduling slot of the network is T... slot The minimum scheduling time slot is calculated based on the average time it takes for data in the queue to be forwarded, and the cycle period T of the entire transmission queue state is used. switch for:

[0099] T switch =nT slot ;

[0100] Within the same scheduling time slot, there is one and only one sending queue (SQ) with its gated encoding set to open, capable of transmitting data packets to the optical terminal equipment. This sending queue is called the transmission queue. The remaining transmission queues are delay queues (DQ) with their gated encoding set to closed. Transmission queues are further categorized based on the delay time slot, such as delay queues with a one-slot delay, delay queues with a two-slot delay, and so on. After the uplink data sent by the optical network unit arrives at the queuing and scheduling module, the time slot Δ that should be delayed in the model is calculated, expressed as:

[0101]

[0102] Where S is the length of the optical fiber between the optical network unit and the optical terminal equipment, and C wire The speed of light propagation in the optical fiber is the speed of light. Dividing the two gives the transmission delay of the data packet in a passive optical network time-sensitive service transmission system. The estimated time slot T for uplink data to arrive at the optical terminal equipment is then used. d Subtract the time slot T when the uplink data is first sent a Subtracting the interference of transmission delay, we obtain the number of time slots that the data packet should be delayed in the model. To prevent overflow, we take the remainder of the number of transmission queues and round up to ensure that the result is an integer. The obtained Δ is the transmission queue to which the data packet should be sent. The data packet waits to be rotated in the transmission queue.

[0103] 5. Multiple queues perform responsibility switching, forwarding data packets in the transmission queue according to the specified time slots. After each time slot T... slot The responsibilities of each transmission queue will then change. A queue delayed by one time slot will become a transmission queue and perform the transmission function, and the remaining queues will change in turn. A queue delayed by Δ time slots will become a transmission queue in the Δth time slot, forwarding the data packets in the queue to the optical terminal equipment.

[0104] 6. After receiving the information, the optical terminal equipment updates the polling table and prepares to send the next round of authorization information.

[0105] After receiving the data packet sent by the optical network unit, the optical terminal device updates the number of remaining bytes in the buffer of the current optical network unit according to the control information in the data packet, and updates the round-trip time between the current optical network unit device and the optical terminal device according to the actual transmission situation, so as to prepare for the next round of authorization information transmission.

[0106] 7. Next, we will simulate the transmission process of time-sensitive services in a passive optical network.

[0107] 1) Modeling of a passive optical network time-sensitive service transmission system.

[0108] First, a passive optical network (PON) time-sensitive service transmission system is modeled, and basic simulation parameters are set. The PON time-sensitive service transmission system comprises 16 optical network units (ONUs). The propagation speed of the optical signal in the optical fiber is set to 204218 km / s. Each ONU has a 10 kilobyte buffer. The size of both authorization and request messages is set to 64 bytes. The physical distance between each ONU and the optical terminal equipment is set to a range of 10 to 20 kilometers. The maximum single authorization data size for each ONU is set to 11000 bytes, which is the amount of data to be forwarded in a single forwarding cycle, avoiding excessive uplink bandwidth consumption by individual ONUs. The total uplink rate of the PON time-sensitive service transmission system is set to 24880 Mbps, and the maximum uplink rate for each ONU is set to 12440 Mbps. All rates are expressed in bits per second (bps) and further converted to bytes per second (Bps) for simulation use.

[0109] For data traffic modeling, the minimum length of Ethernet packets is defined as 640 bytes, the maximum length as 45420 bytes, and the average length as the arithmetic mean of the two. Furthermore, each optical network unit (ONU) buffers a maximum of 1000 packets to ensure data traffic stability during simulation. No guard time is introduced during uplink transmission by each ONU, eliminating the need to prevent signal collisions between uplink transmissions. During simulation, the network load (Lambda) is set from 0.1 to 1.0 in steps of 0.1, and independent simulations are performed for each of the aforementioned load conditions.

[0110] To support simulation operation, the following data structures are initialized for each optical network unit (ONU): packet arrival time array, packet size array, packet transmission time array, packet reception time array at the optical terminal equipment (OTE), packet loss counter array, time record array of the OTE sending authorization to the ONU, and time record array of the ONU receiving authorization. These data structures are used to record the time points and data volumes of various events, supporting subsequent uplink bandwidth allocation scheduling and performance metric statistics.

[0111] A 16x4 polling table is established to store the polling scheduling information for each optical network unit (ONU). The number of rows corresponds to the number of ONUs, and the number of columns corresponds to various parameters. The first column records the ONU index number, which is a unique identifier for the ONU. The second column records the propagation delay between each ONU and the optical terminal equipment. The third column records the transmission time of the authorized data requested by each ONU in the current bandwidth allocation cycle. The fourth column calculates the end-to-end delay, which is the sum of the delays in the second and third columns.

[0112] 2) Establishment of queuing scheduling module and queuing strategy based on CSQF.

[0113] Define a time slot T for one rotation of a queue. slot The value is 0.125 milliseconds. There are a total of 16 optical network units (ONUs). The number of transmission queues is the same as the number of ONUs. According to T... switch =nT slot The cycle period T of the entire queue state is obtained. switch It takes 2 milliseconds.

[0114] For each data packet to be scheduled, the following processing is performed: First, based on the optical network unit to which the current data packet belongs, the arrival time slot T of the current data packet is initialized. b The expression is:

[0115]

[0116] Among them, T a S1 represents the time slot for data packet transmission, C represents the distance between the optical network unit and the queuing and scheduling module, and S2 represents the distance between the optical network unit and the queuing and scheduling module.wire The speed of light in an optical fiber.

[0117] Then the data packet leaves the queuing and scheduling module in time slot T. c Define:

[0118]

[0119] Among them, T d The estimated time slot for the uplink data to reach the optical terminal equipment can be obtained from the polling table. S2 is the distance between the queuing module and the optical terminal equipment. Adding S1 and S2 gives the distance S between the optical network unit and the optical terminal equipment.

[0120] T b and T c The number of time slots Δ in which the data packet is delayed in the permutation and scheduling model:

[0121]

[0122] Δ represents the number of delay queues in which the data packet is located, and the data packet then waits for Δ T times. slot Afterwards, it leaves the model and is forwarded to the optical terminal equipment.

[0123] Figure 4 This is a schematic diagram of the time-sensitive service transmission process in a passive optical network (PON) with three optical network units (ONUs) according to an embodiment of the present invention. In time slot T0, the optical terminal equipment (ONE) broadcasts authorization information downwards. In time slot T1, after receiving the authorization message, ONUs 1, 2, and 3 begin sending data upwards. In time slot T2, the data packets arrive at the queuing-based scheduling module, and each data packet is assigned to a different delay queue for queuing according to the scheduling algorithm. Specifically, the data packets of ONU 1 are forwarded in the transmission queue (SQ), while the data packets of ONUs 2 and 3 are stored in delay queue 1 (DQ1) and delay queue 2 (DQ2), respectively, awaiting transmission. In time slot T3, the data packets of ONU 1 arrive at the OONE, and the transmission queue responsibilities in the model change; the transmission queue of ONU 2's data packets becomes the transmission queue, performing forwarding functions. This continues until time slot T5, when all data packets from the optical network units have arrived at the OONE, completing one cycle of data scheduling.

[0124] 3) Polling data packets to collect data metrics.

[0125] During the continuous polling of data packets, the parameters of each data packet are recorded using an array created during the modeling of the passive optical network time-sensitive service transmission system. These parameters are used to collect data metrics for each round of data packet transmission and calculate performance parameters for subsequent comparison.

[0126] 8. Experimental process and effect comparison.

[0127] 1) Experimental conditions: Under the environment of Intel(R)Core(TM) i7-8750H CPU@2.20GHz, the passive optical network time-sensitive service transmission system was simulated using Matlab R2019a simulation tool.

[0128] 2) Experimental results: Two traditional dynamic bandwidth allocation algorithms were designed and compared, including the Interleaved Polling with Adaptive Cycle Time (IPACT) algorithm and the Limited Service bandwidth allocation algorithm.

[0129] Figure 5 This diagram illustrates a comparison of average packet latency at optical network units (ONUs) using different bandwidth allocation methods according to an embodiment of the present invention. As the effective network load increases, the latency of this application is significantly lower than other algorithms. This improvement is primarily due to a queue-based store-and-forward mechanism, which enables each ONU to transmit data within a predetermined time slot. Compared to the traditional polling scheme, which introduces additional waiting time due to repeated request-authorization interactions, the periodically specified queuing and forwarding mechanism eliminates this round-trip signaling process within a single cycle. Therefore, the ONU can begin transmission immediately upon receiving a single authorization, effectively reducing queuing time.

[0130] Figure 6 This diagram illustrates a comparison of the performance of different bandwidth allocation methods in terms of polling frequency in one embodiment of the present invention. The queuing scheduling algorithm based on CSQF exhibits significantly lower latency than other schemes. In traditional schemes, optical terminal equipment needs to poll each optical network unit sequentially using either polling or priority-based methods, requiring multiple control interactions within each scheduling cycle. In contrast, the CSQF framework embeds queue control into the model and utilizes a pre-calculated scheduling strategy, enabling the optical terminal equipment to send only one authorization message at the beginning of the scheduling cycle. This structural simplification not only reduces control overhead but also significantly improves system scalability.

[0131] As the load increases, the end-to-end latency of this application is significantly lower than that of other algorithms. This effect is attributed to the reduction of queuing delay on the optical network unit side and the deterministic transmission scheduling within the queuing scheduling module. The delay queue is accurately calculated and allocated according to the expected arrival time of the data packets, which effectively avoids time slot conflicts and transmission uncertainties. This deterministic transmission behavior not only improves link utilization but also reduces transmission jitter, thereby significantly improving the overall latency performance.

[0132] In summary, this invention provides a method and system for transmitting time-sensitive services in a passive optical network (PON). The method involves: assigning a logical link identifier to at least one optical network unit (ONU) to identify the ONU and recording the transmission time; receiving the number of bytes waiting to be allocated in the buffers of each ONU and establishing a polling table with the round-trip time (RTT); sending authorization information to each ONU to mark the data to be forwarded by each ONU in each forwarding cycle; determining the transmission order of the data to be forwarded by each ONU in each forwarding cycle based on the RTT in the polling table and broadcasting it to each ONU; and receiving data packets forwarded by each ONU via the queuing module in each forwarding cycle and recording the reception time. The packet is obtained by packaging the data to be forwarded and the control information used to record the number of remaining bytes in the buffer of the corresponding optical network unit. The queuing and scheduling module receives multiple data packets forwarded by each optical network unit according to the sending order, and stores them in the corresponding ordinal transmission queue according to the delay slot number of the data packets. The delay slot number of each data packet is obtained by taking the maximum allowable runtime delay modulo the number of transmission queues and rounding up. The data packets in each transmission queue are forwarded to the optical terminal equipment one by one in order within a forwarding cycle. The number of bytes waiting to be allocated in the polling table is updated according to the number of remaining bytes in the buffer of the corresponding optical network unit recorded in the control information, and the communication round-trip time in the polling table is updated according to the actual communication round-trip time obtained from the sending time and receiving time.

[0133] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the aforementioned edge computing server deployment method. The computer-readable storage medium can be a tangible storage medium, such as random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, floppy disks, hard disks, removable storage disks, CD-ROMs, or any other form of storage medium known in the art.

[0134] Those skilled in the art will understand that the exemplary components, systems, and methods described in conjunction with the embodiments disclosed herein can be implemented in hardware, software, or a combination of both. Whether implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention. When implemented in hardware, it can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this invention are programs or code segments used to perform the desired tasks. The programs or code segments can be stored in a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried in a carrier wave.

[0135] It should be clarified that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of the present invention.

[0136] In this invention, features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or in place of features of other embodiments.

[0137] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations of the embodiments of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for transmitting time-sensitive services in a passive optical network, characterized in that, The method includes the following steps: Assign a logical link identifier to at least one optical network unit to identify the optical network unit and record the transmission time; receive the number of bytes waiting to be assigned in the buffer of each optical network unit and establish a polling table to record the communication round-trip time of each network unit and optical terminal equipment obtained by measurement. Authorization information is sent to each optical network unit; the authorization information is used to mark the data to be forwarded by each optical network unit in each forwarding cycle; Based on the communication round-trip time in the polling table, the optical network unit determines the transmission order of the data to be forwarded in each forwarding cycle and broadcasts it to each optical network unit. The system receives data packets forwarded by each optical network unit via the queuing and scheduling module in each forwarding cycle and records the reception time. The data packets are obtained by packaging the data to be forwarded and control information. The control information is used to record the number of bytes remaining in the buffer of the corresponding optical network unit. The queuing and scheduling module receives multiple data packets forwarded by each optical network unit according to the sending order and stores them in the corresponding ordinal transmission queue according to the delay slot number of the data packets. The delay slot number of each data packet is obtained by taking the maximum allowable runtime delay modulo the number of transmission queues and rounding up. The data packets in each transmission queue are forwarded to the optical terminal device one by one in ordinal order within one forwarding cycle. The number of bytes waiting to be allocated in the polling table is updated according to the number of remaining bytes in the corresponding optical network unit buffer recorded in the control information, and the communication round-trip time in the polling table is updated according to the actual communication round-trip time obtained from the sending time and the receiving time.

2. The passive optical network time-sensitive service transmission method according to claim 1, characterized in that, The data to be forwarded by each optical network unit in each forwarding cycle is determined by the transmission window size of each network unit, and the transmission window size satisfies the following expression: ； in, This represents the number of bytes waiting to be allocated in the buffer of the i-th optical network unit. This indicates the additional resource consumption during the transmission of time-sensitive services in a passive optical network. This indicates the preset maximum transmission window.

3. The method for transmitting time-sensitive services in a passive optical network according to claim 1, characterized in that, The number of delay slots for each data packet is obtained by taking the maximum allowed runtime delay modulo the number of transmission queues and rounding up. The number of delay slots satisfies the following expression: ； in, S This indicates the fiber optic length from the optical network unit to the optical terminal equipment. This indicates the speed at which light travels in an optical fiber. This indicates the time slot in which the data packet is expected to be delivered to the optical terminal equipment. This indicates the time slot from which the data packet is sent from the optical network unit. This indicates the number of transmission queues.

4. The method for transmitting time-sensitive services in a passive optical network according to claim 1, characterized in that, The process of forwarding the data packets in each transmission queue to the optical terminal equipment one by one in sequence within one forwarding cycle includes: The gating code of the first sequential transmission queue is set to open, and the gating code of the other transmission queues is set to close. The data packets in the first sequential transmission queue are forwarded to the optical terminal device through a delay time slot. The gating code of the first sequential transmission queue is changed to off, and the gating code of the second sequential transmission queue is changed to on, while the gating codes of the other transmission queues are off. The data packets in the second sequential transmission queue are forwarded to the optical terminal equipment through a delay time slot. The gating code in the transmission queue is changed once every time delay time slot until all data packets are sent to the optical terminal equipment to complete the data packet forwarding of the current forwarding cycle.

5. The method for transmitting time-sensitive services in a passive optical network according to claim 1, characterized in that, The process of measuring the round-trip time of communication for each network unit and optical terminal device includes: The ranging request information containing the logical link identifier is sent to each optical network unit, and the timestamp of sending the ranging request information is recorded, so that each network unit receives the ranging request information and returns ranging response information to the optical terminal device. Receive ranging response information from each optical network unit and record the timestamp of receiving the ranging response information; The round-trip time between each network unit and the optical terminal device is calculated based on the timestamp of sending the ranging request information and the timestamp of receiving the ranging response information.

6. The method for transmitting time-sensitive services in a passive optical network according to claim 1, characterized in that, The method further includes: The sending time, the receiving time, the size of the data packet, and the authorization information are constructed into a parameter array. The parameter array is partitioned according to the time dimension, and an encryption algorithm is used to send and store it to the cloud platform. A name index is established for the sending time, receiving time, data packet size, and authorization information of the cloud platform, so that users can query the corresponding parameters in the cloud platform according to the name index.

7. A passive optical network time-sensitive service transmission system, characterized in that, The system includes: An optical terminal device is used to implement the passive optical network time-sensitive service transmission method according to any one of claims 1 to 6, which assigns a logical link identifier to at least one optical network unit to identify the identity of the optical network unit and records the transmission time, receives the number of bytes waiting to be allocated in the buffer of each optical network unit, establishes a polling table record with the measured round-trip time of communication between each network unit and the optical terminal device, sends authorization information to each optical network unit, determines the transmission order of the data to be forwarded in each forwarding cycle according to the round-trip time of communication in the polling table, and broadcasts it to each optical network unit, and receives data packets forwarded by each optical network unit through the queuing and scheduling module in each forwarding cycle; An optical network unit is used to receive the logical link identifier and send the number of bytes waiting to be allocated in the buffer of each optical network unit to the optical terminal device, and forward multiple data packets to the queuing and scheduling module according to the sending order; The queuing and scheduling module is used to receive multiple data packets forwarded by each optical network unit according to the sending order, and store them in the corresponding ordinal transmission queue according to the delay slot number of the data packets. The data packets in each transmission queue are forwarded to the optical terminal device one by one in ordinal number within one forwarding cycle.

8. The passive optical network time-sensitive service transmission system according to claim 7, characterized in that, The queuing scheduling module also includes: The fault queue switching module is used to monitor the transmission status of each transmission queue in real time, and to transfer the data packets to be forwarded in the faulty transmission queue to the normally operating transmission queue when a transmission queue fails.

9. A computer-readable storage medium having a computer program / instructions stored thereon, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method as described in any one of claims 1 to 6.

10. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method described in any one of claims 1 to 6.

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