Passive optical network time sensitive service transmission method and system

Abstract

The invention provides a passive optical network time-sensitive service transmission method and system, and the method comprises the steps: distributing a logic link identifier to at least one optical network unit, receiving the number of bytes to be distributed in a buffer region of each optical network unit, and building a polling table record with communication round-trip time; sending authorization information to each optical network unit; according to the communication round-trip time, determining a sending sequence of data to be forwarded uploaded by the optical network unit to the queuing scheduling module in each forwarding period; receiving data packets which are forwarded by each optical network unit through a queuing scheduling module and are obtained by packaging data to be forwarded and control information, receiving a plurality of data packets forwarded by each optical network unit by the queuing scheduling module, and storing the data packets in a transmission queue of a corresponding ordinal number according to the delay time slot number of the data packets, forwarding to the optical terminal equipment one by one according to ordinal numbers in a forwarding period; and updating the polling table according to the remaining byte number of the buffer area of the corresponding optical network unit recorded in the control information and the actual communication round-trip time.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical communication technology, in particular to a passive optical network time-sensitive service transmission method and system. BACKGROUND

[0002] Industrial Internet is a communication link that builds full interconnection of people, machines and things in industrial environment. Its development provides a key path for digital transformation and network upgrade of industrial manufacturing, promotes deep integration of manufacturing and other industries, and promotes optimization and upgrading of industrial structure. According to the characteristics of business flow, the industrial Internet can be divided into isochronous flow, cyclic flow and burst flow. In order to ensure the continuous control of PLC on industrial equipment, the isochronous flow has very high requirements on end-to-end time delay jitter. In order to ensure the low time delay and jitter requirements of isochronous flow, strict time synchronization is required between industrial control system and transmission network. The cyclic flow is an asynchronous periodic flow. The industrial control system does not need to synchronize with the transmission network, but controls the sending of data packets through the local clock of the industrial equipment. It is a small bandwidth, low latency and high reliability industrial service. The data packet is periodically sent and the size is fixed. The burst flow is a burst form of data packet sent by industrial equipment. The size of the data packet is usually variable. This type of flow corresponds to a certain requirement for time delay in the application scenario. In the face of the three types of flow characteristics in the industrial Internet scene, how to effectively allocate bandwidth and schedule flow is the most important research.

[0003] In the prior art, the traditional bandwidth allocation scheme ensures the transmission performance of time-sensitive flow and the on-demand allocation of bandwidth resources in the industrial Internet scene, but ignores the specific position and adjacent relationship of the bandwidth allocation window. These traditional schemes are more suitable for traditional telecommunications services and cannot meet the data packet transmission requirements in the industrial Internet with low latency and jitter boundary. SUMMARY

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

[0005] One aspect of the present application provides a passive optical network time-sensitive service transmission method, which comprises the following steps:

[0006] allocating a logical link identifier for identifying the identity of the optical network unit to at least one optical network unit and recording the sending time, receiving the number of bytes waiting for allocation in the buffer of each optical network unit, and establishing a polling table record with the measured communication round trip time of each network unit and optical terminal device;

[0007] sending authorization information to the optical network units; the authorization information is used to mark the data to be forwarded of each optical network unit in each forwarding period;

[0008] determining, according to the communication round trip time in the polling table, a sending order of the data to be forwarded of each optical network unit uploaded to a queuing and scheduling module and broadcast to the optical network units in each forwarding period;

[0009] receiving the data packets forwarded by the optical network units via the queuing and scheduling module in each forwarding period, and recording the receiving time, the data packets being obtained by packaging the data to be forwarded and control information used to record the remaining byte number of the buffer of the corresponding optical network unit; wherein the queuing and scheduling module receives a plurality of the data packets forwarded by the optical network units according to the sending order, and stores the data packets in a transmission queue corresponding to the serial number according to the delay time slot number of the data packets, the delay time slot number of each data packet being obtained by taking the maximum allowed running delay modulo the number of the transmission queues and rounding up, and the data packets in each transmission queue being forwarded to the optical terminal device in sequence according to the serial number in one forwarding period;

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

[0011] In some embodiments, the data to be forwarded of each optical network unit in each forwarding period is determined by the transmission window size of each network unit, the transmission window size satisfying the following expression:

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

[0013] wherein Q i represents the number of bytes to be allocated in the buffer of the i th optical network unit, H ON represents the additional resource consumption in the passive optical network time-sensitive service transmission process, and W max represents the preset maximum transmission window.

[0014] In some embodiments, the delay time slot number of each data packet is obtained by taking the maximum allowed running delay modulo the number of the transmission queues and rounding up, the delay time slot number satisfying the following expression:

[0015]

[0016] wherein S represents the fiber length from the optical network unit to the optical terminal device, C wire represents the speed of light propagating in the fiber, T d represents the time slot in which the data packet is expected to be sent to the optical terminal device, T a represents the time slot in which the data packet is sent from the optical network unit, and n represents the number of the transmission queue.

[0017] In some embodiments, the process of forwarding the data packets in each transmission queue to the optical terminal device in order of sequence within one forwarding cycle comprises:

[0018] setting the gate code of the first-sequence transmission queue to open and the gate codes of other transmission queues to close, and forwarding the data packets in the first-sequence transmission queue to the optical terminal device through a delay time slot;

[0019] changing the gate code of the first-sequence transmission queue to close and the gate code of the second-sequence transmission queue to open, and the gate codes of other transmission queues to close, and forwarding the data packets in the second-sequence transmission queue to the optical terminal device through a delay time slot; the gate codes of the transmission queues are changed every delay time slot until all data packets are sent to the optical terminal device to complete the data packet forwarding of the current forwarding cycle.

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

[0021] sending the ranging request information containing the logical link identifier to each optical network unit and recording the timestamp of sending the ranging request information, so that each network unit receives the ranging response information returned by the optical terminal device in response to the ranging request information;

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

[0023] calculating the communication round trip time of each network unit and the optical terminal device according to the timestamp of sending the ranging request information and the timestamp of receiving the ranging response information.

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

[0025] constructing the sending time, the receiving time, the size of the data packet, and the authorization information into a parameter array, performing parameter partitioning on the parameter array according to the time dimension, and sending and storing to the cloud platform using an encryption algorithm;

[0026] The sending time, the receiving time, the size of the data packet and the authorization information of the cloud platform are indexed by names, so that a user can query corresponding parameters in the cloud platform according to the name index.

[0027] In another aspect, the present application also provides a passive optical network time-sensitive service transmission system, which comprises:

[0028] An optical terminal device is configured to implement the passive optical network time-sensitive service transmission method according to any one of the above, assign a logical link identifier for identifying the identity of an optical network unit to at least one optical network unit and record a sending time, receive the number of bytes in the buffer of each optical network unit waiting for allocation, establish a polling table record with the measured communication round trip time of each network unit and the optical terminal device, send authorization information to each optical network unit, determine the sending order of the data to be forwarded by each optical network unit to the queuing scheduling module and broadcast to each optical network unit in each forwarding period according to the communication round trip time in the polling table, and receive the data packet forwarded by each optical network unit via the queuing scheduling module in each forwarding period.

[0029] An optical network unit is configured to receive the logical link identifier and send the number of bytes in the buffer of each optical network unit waiting for allocation to the optical terminal device, and forward a plurality of the data packets to the queuing scheduling module according to the sending order.

[0030] A queuing scheduling module is configured to receive a plurality of the data packets forwarded by each optical network unit according to the sending order, and store the data packets in a transmission queue corresponding to the ordinal number according to the number of delay time slots of the data packets, and sequentially forward the data packets in each transmission queue to the optical terminal device in one forwarding period.

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

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

[0033] In another aspect, the present application also provides a computer readable storage medium having a computer program / instruction stored thereon, which is executed by a processor to implement the steps of the method according to any one of the above.

[0034] In another aspect, the present application also provides a computer program product comprising a computer program / instruction, which is executed by a processor to implement the steps of the method according to any one of the above.

[0035] In the passive optical network time-sensitive service transmission method, each optical network unit transmits data packets in the current forwarding period through authorization information, and the data packets are temporarily stored through the queuing and scheduling module and forwarded to the optical terminal device in the predetermined time slot, effectively alleviating the problem of data packet competition for the same time slot of multiple optical network units, improving the orderliness and delay controllability of the transmission queue scheduling, and still maintaining an efficient and stable data packet transmission process in the case of a large number of industrial terminal devices.

[0036] Additional advantages, objects, and features of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the application. The objects and other advantages of the application can be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

[0037] It will be understood by those skilled in the art that the objects and advantages of the present application can be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0038] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0039] Figure 1 The flowchart of the passive optical network time-sensitive service transmission method according to an embodiment of the present application.

[0040] Figure 2 The structure diagram of the passive optical network time-sensitive service transmission system according to an embodiment of the present application.

[0041] Figure 3 The flowchart of the queuing and scheduling module according to an embodiment of the present application.

[0042] Figure 4 The flowchart of the passive optical network time-sensitive service transmission method with three optical network units according to an embodiment of the present application.

[0043] Figure 5 The effect comparison diagram of the different bandwidth allocation methods in the average data packet delay index of the optical network unit according to an embodiment of the present application.

[0044] Figure 6 The effect comparison diagram of the different bandwidth allocation methods in the polling frequency index according to an embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments and drawings. Here, the illustrative embodiments of the present application and their descriptions are used to explain the present application, but are not intended to limit the present application.

[0046] Here, it should also be noted that, in order to avoid the present application being obscured by unnecessary details, only the structures and / or processing steps closely related to the solutions according to the present application are shown in the drawings, and other details not closely related to the present application are omitted.

[0047] It should be emphasized that the terms "comprise / comprising" when used in this text, refer to the presence of stated features, elements, steps or components, but do not preclude the presence or addition of one or more other features, elements, steps or components.

[0048] Here, it should also be noted that, if not specifically stated, the term "connected" in this text can not only mean direct connection, but also indirect connection with an intermediate.

[0049] In the following, embodiments of the present application will be described 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 the prior art, the traditional bandwidth allocation scheme ensures the transmission performance of time-sensitive traffic and the on-demand allocation of bandwidth resources in such scenarios as industrial interconnection, but ignores the specific location and adjacent relationship of the bandwidth allocation window, and these traditional schemes are more suitable for traditional telecommunications services and cannot meet the data packet transmission requirements in the industrial Internet with low latency and jitter boundaries; the present application provides a passive optical network time-sensitive service transmission method and system, which allocates a logical link identifier for identifying the identity of at least one optical network unit and records the sending time, 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 for marking the data to be forwarded of each optical network unit in each forwarding period.

[0051] Figure 1 The flowchart of the passive optical network time-sensitive service transmission method according to an embodiment of the present application is shown. Specifically, one aspect of the present application provides a passive optical network time-sensitive service transmission method, which comprises the following steps S101-S105:

[0052] Step S101: allocate a logical link identifier for identifying the identity of at least one optical network unit and record the sending time, receive the number of bytes waiting for allocation in the buffer of each optical network unit, and establish a polling table record with the measured communication round trip time of each network unit and optical terminal device.

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

[0054] Step S103: According to the communication round trip time in the polling table, the optical network unit uploads the sending order of the data to be forwarded to the queuing and scheduling module in each forwarding period and broadcasts to each optical network unit.

[0055] Step S104: Receive the data packet forwarded by each optical network unit via the queuing and scheduling module in each forwarding period and record the receiving time, the data packet is obtained by packing the data to be forwarded and control information, and the control information is used to record the remaining byte number of the corresponding optical network unit buffer; wherein 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 transmission queue corresponding to the serial number according to the delay time slot number of the data packet, the delay time slot number of each data packet is obtained by taking the maximum allowed running delay modulo the number of transmission queues and rounding up, and the data packets in each transmission queue are forwarded to the optical terminal device one by one according to the serial number in one forwarding period.

[0056] Step S105: Update the number of bytes to be allocated in the polling table according to the remaining byte number of 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 the receiving time.

[0057] In step S101, in a passive optical network system, a single optical terminal device (OLT) is usually connected with multiple optical network units (ONU), and the optical terminal device allocates different logical link identifiers (LLIDs) to the multiple optical network units to mark each optical network unit; the number of bytes to be allocated in the buffer of each optical network unit can be obtained by self-reporting or polling, the process of self-reporting includes that the network unit monitors its own buffer state, and when the buffer data reaches a preset threshold or a specific event occurs, it actively sends the number of bytes to be allocated in the buffer to the optical terminal device, so as to ensure that the optical terminal device can timely grasp the data change and make reasonable bandwidth allocation decision; the process of polling includes that the optical terminal device sends a polling request to the optical network unit, and the optical network unit receives the polling request and returns the number of bytes to be allocated in the buffer. The optical terminal device constructs a polling table (Polling Table) that can be changed at any time.

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

[0059] Step S1011: Send the ranging request information containing the logical link identifier to each optical network unit, and record the timestamp of sending the ranging request information, so that the ranging response information returned by each network unit receiving the ranging request information reaches the optical terminal device.

[0060] Step S1012: receiving the ranging response information of each optical network unit and recording the time stamp of receiving the ranging response information.

[0061] Step S1013: calculating the communication round trip time of each network unit and optical terminal device according to the time stamp of sending the ranging request information and the time stamp 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 to obtain the corresponding data to be forwarded according to the logical link identifier, and the data to be forwarded is the authorized service data that can be transmitted by the optical terminal device; in the industrial internet scene, the service data is the data sent by each industrial device connected to each optical network unit; further, the authorization information contains not only the data to be forwarded for marking each optical network unit, but also the time slot expected to arrive at the optical terminal device after the data packet is sent from the optical network unit, and the time slot expected to arrive at the optical terminal device is obtained by calculating half of the communication round trip time and is used to calculate the number of delay time slots; the data to be forwarded is obtained according to the total number of bytes to be allocated in the polling table of each optical network unit, and the data to be forwarded is the data allowed to be forwarded by each optical network unit, in some embodiments, the data to be forwarded of each optical network unit in each forwarding period is determined by the transmission window size of each network unit, and the transmission window size satisfies the following expression:

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

[0064] Wherein, Q i represents the number of bytes waiting for allocation in the buffer of the i-th optical network unit, H ON represents the additional resource consumption in the process of passive optical network time sensitive service transmission, and W max represents the preset maximum transmission window.

[0065] Further, the communication round trip time (RTT) in the polling table is sorted in ascending order to obtain the sending order of the data to be forwarded, so as to determine the order of sending uplink data by each optical network unit, the data transmission from the optical terminal device to the optical network unit belongs to downlink transmission, the downlink transmission is carried out by the optical terminal in a broadcast manner, the data transmission from the optical network unit to the optical terminal device belongs to uplink transmission, and the passive optical network time sensitive service transmission method of the application acts on the uplink transmission process of the data packet sent from the optical network unit to the optical terminal device.

[0066] In step S104, the queuing and scheduling module is based on the periodic specified queuing and forwarding (CSQF, Cyclic Specified Queuing and Forwarding) construction, which is a high-precision traffic scheduling technology for deterministic networks, and provides strict low-latency and low-jitter transmission guarantee for industrial control and vehicle communication scenarios; the queuing and scheduling module is based on the minimum scheduling time sequence T slot and the number of transmission queues to calculate the forwarding period of multiple transmission queues, expressed as: T slot = nT slot In one scheduling time slot, there is one transmission queue whose gate code is open and can forward data packets to the optical terminal device; the queue whose gate code is open is the sending queue, and the remaining queues whose gate code is off are delay queues; the data packets are sent to the transmission queue corresponding to the number of delay time slots, and in some embodiments, the number of delay time slots of each data packet is obtained by taking the maximum allowed running delay modulo the number of transmission queues and rounding up, and the number of delay time slots satisfies the following expression:

[0067]

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

[0069] Further, when the data packets in one transmission queue are forwarded according to one scheduling time slot, the gate code of the next transmission queue will be changed to make the transmission queue perform duty conversion, and the transmission queue with a delay of Δ time slots will be converted into a sending queue at the Δth time slot. In some embodiments, the process of forwarding the data packets in each transmission queue to the optical terminal device one by one according to the ordinal number within one forwarding period includes steps S1041-S1042:

[0070] Step S1041: Set the gate code of the first ordinal number transmission queue to open, and the gate codes of the other transmission queues to off, and forward the data packets in the first ordinal number transmission queue to the optical terminal device through a delay time slot.

[0071] Step S1042: change the gating code of the first ordinal transmission queue to off and the gating code of the second ordinal transmission queue to on, the gating codes of other transmission queues are off, and the data packets in the second ordinal transmission queue are forwarded to the optical terminal device through a delay time slot; the gating code of the transmission queue is changed once every delay time slot until all the data packets are sent to the optical terminal device to complete the data packet forwarding in the current forwarding period.

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

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

[0074] Step S2: establish 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 according to the name index.

[0075] Specifically, by constructing a parameter array to obtain a standardized data structure in a unified format, the data interaction efficiency is improved by using the application program development interface of the cloud platform; after parameter partitioning according to the time dimension, the data corresponding to the specific time target content is quickly located through the name index, and the fault locating efficiency is improved when tracing fault events.

[0076] In step S105, after the optical terminal device receives the data packets, the remaining number of bytes in the buffer area of the optical network unit is obtained according to the control information, and the number of bytes waiting for allocation in the polling table is updated, and the polling table is updated according to the actual communication round trip time; the next round of authorization information is sent according to the polling table, and a new round of data packet forwarding is performed.

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

[0078] The optical terminal device is used to implement the above-mentioned passive optical network time-sensitive service transmission method, allocates a logical link identifier for identifying the identity of the optical network unit to at least one optical network unit and records the sending time, receives the number of bytes waiting for allocation in the buffer area of each optical network unit, and establishes a polling table record with the measured communication round trip time of each network unit and the optical terminal device, sends authorization information to each optical network unit, determines the sending order of the data to be forwarded by the optical network unit to the queuing and scheduling module in each forwarding period according to the communication round trip time in the polling table and broadcasts to each optical network unit, and receives the data packets forwarded by each optical network unit through the queuing and scheduling module in each forwarding period.

[0079] The optical network unit is configured to receive the logical link identifier and send the number of bytes waiting for allocation in the buffer of each optical network unit to the optical terminal device, and forward the plurality of data packets to the queuing and scheduling module according to the sending order.

[0080] The queuing and scheduling module is configured to receive the plurality of data packets forwarded by each optical network unit according to the sending order, and store the data packets in the transmission queue corresponding to the ordinal number according to the number of delay time slots of the data packets, and forward the data packets in each transmission queue to the optical terminal device one by one according to the ordinal number within one forwarding period.

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

[0082] The fault queue switching module is configured to monitor the transmission state of each transmission queue in real time, and transfer the data packets to be forwarded in the fault transmission queue to the normally operating transmission queue when the transmission queue fails. Specifically, the storage and forwarding mechanism of the queuing and scheduling module enables the passive optical network time-sensitive service transmission system to have stronger fault tolerance, and the data packets can be transferred in time when the transmission queue fails, and further, the data packets can be buffered and waited in the queue when the transmission fluctuates or bursts, so as to ensure that the transmission process is not interrupted and no packets are lost.

[0083] In another aspect, the present application also provides a computer readable storage medium having a computer program / instruction stored thereon, and the program / instruction is executed by a processor to implement the steps of the above method.

[0084] In another aspect, the present application also provides a computer program product comprising a computer program / instruction, and the computer program / instruction is executed by a processor to implement the steps of the above method.

[0085] The present application will be described below in conjunction with a specific embodiment:

[0086] Figure 2The structure diagram of the passive optical network time sensitive service transmission system is described in an embodiment of the present application. The present application provides a passive optical network time sensitive service transmission method and system, which is a passive optical network (PON) time sensitive scheduling technology based on periodic designated queuing and forwarding and oriented to an industrial internet scene, and is especially suitable for an industrial automation control scene with deterministic transmission requirements. The present application aims to solve the deterministic transmission challenge caused by the existing bandwidth allocation scheme in the industrial internet scene. In the interaction between the optical terminal equipment (OLT) and the optical network unit (ONU) in the passive optical network, the present application adopts an interleaved polling mechanism, adopts a periodic polling mode to allocate bandwidth, and adopts a dynamic window allocation to reduce idle time slots, allocate on demand, and improve bandwidth utilization. The periodic designated queuing and forwarding technology (CSQF) is adopted to optimize the polling mechanism and the window allocation of the entire system. The concept of multiple queues is introduced on the polling mechanism, and the queues respectively bear the buffer information of different optical network units, effectively reducing the polling times and the time delay of the entire system. In terms of window allocation, the present application strictly allocates the time window for sending, reduces the delay jitter through the queuing scheduling mode, and ensures the deterministic transmission of the entire system. Through the method, the end-to-end delay and the optical network unit processing delay of the entire transmission system can be reduced under the premise of ensuring the deterministic transmission of the passive optical network, the reliability of the system can be improved, and the method is suitable for the industrial passive optical network environment with more complex environment. The present application is implemented through the following technical solutions: a polling scheduling method based on periodic designated queuing and forwarding is proposed; and a multiple queue cycle is introduced to optimize the polling scheduling mode of the passive optical network.

[0087] 1. A polling table is established at the optical terminal equipment according to the current network status.

[0088] In the entire passive optical network (PON) time sensitive service transmission system, a single optical terminal equipment is usually connected with multiple optical network units. In the industrial passive optical network, the optical terminal equipment allocates different logical link identifiers (LLIDs) to each optical network unit, which are used to mark each optical network unit. In order to better allocate bandwidth and schedule resources, the optical terminal equipment knows the number of bytes Q waiting for allocation in the buffer of each optical network unit in the network and the communication round trip time (RTT) of the optical network unit and the optical terminal equipment before a new round of scheduling starts. The optical terminal equipment records these information, and uses the information to form a polling table that can be changed at any time, which is used to track the basic information of the optical network unit with different logical link identifiers in the scheduling algorithm.

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

[0090] The optical terminal device starts to send 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 that is allowed to be transmitted.

[0091] According to the number of bytes Q waiting for allocation in the buffer of each optical network unit in the polling table, the size of the data to be forwarded that is allowed to be allocated is defined, which is determined by the transmission window size W i The expression is:

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

[0093] Wherein, Q i is the number of bytes waiting to be allocated in the buffer of the i-th optical network unit, H ON is the control overhead in the entire passive optical network time-sensitive service transmission system, i.e. the additional resource consumption of the non-effective data part; the authorized transmission window size and other information are included in the authorization message of the optical terminal device. W max is the maximum transmission window set for the passive optical network time-sensitive service transmission system, which is also the maximum length of the queue in the multi-queue polling.

[0094] The optical terminal device sorts all optical network units according to the communication round trip time in the polling table, so as to determine the order of the optical network units to send uplink data. The optical network unit with smaller communication round trip time will be placed in the front row. After the optical network units are sorted, each optical network unit is allocated a time slot T d in which the optical terminal device expects the data packets transmitted by the optical network unit in the polling period to be delivered to the optical terminal device, i.e. at the moment T d , the data packets of the corresponding optical network unit will be delivered to the optical terminal device.

[0095] 3. The optical network unit receives the authorization information and starts to send data packets to the optical terminal device.

[0096] The optical terminal device broadcasts the authorization information downstream and sends it to each optical network unit through the splitter. All optical network units receive the same data, and each optical network unit filters out the data belonging to itself by matching the logical link identifier and discards other data. After receiving the authorization information, the optical network unit will send the uplink data in the buffer and transmit the data packets. The uplink data sent by the optical network unit includes the service data authorized by the optical terminal device to be transmitted, which is sent by the industrial equipment connected to the optical network unit. The time slot T aand attach control information at the end of the data packet, including the number of bytes remaining in the buffer of the optical network unit after it has finished transmitting the current data.

[0097] 4. The data arrives at the scheduling model, into the transmission queue waiting to be sent.

[0098] Figure 3 The flowchart of the queuing scheduling module is described for an embodiment of the present application. A queuing scheduling module based on periodic queuing and forwarding technology is established for forwarding uplink data in a passive optical network system. The core idea inside the queuing scheduling module is to guarantee the delay of a single transmission queue within a determinable range based on store-and-forward, so as to guarantee the controllable end-to-end delay of data packet transmission. The queue scheduling is based on the minimum scheduling time slot of the entire system and can control multiple queues in front of the output port. The number of transmission queues in the queuing scheduling module is generally n, i.e. the number of optical network units, and the minimum scheduling time slot T slot is the average time for data to be transmitted out of the queue. The cycle period T switch of the entire transmission queue state is:

[0099] T switch = nT slot ;

[0100] In the same scheduling time slot, there is only one transmission queue with the sending queue (SQ) gate code turned on, which can transmit data packets to the optical terminal device. This transmission queue is called the sending queue, and the remaining transmission queues are delay queues (DQ) with the gate code turned off. The transmission queues are divided into delay queues with one time slot delay, delay queues with two time slot delays, and so on according to the different time slots of the delay. After the uplink data sent by the optical network unit arrives at the queuing scheduling module, the time slot Δ that the information should be delayed in the model is calculated, and the expression is:

[0101]

[0102] where S is the length of the optical fiber between the optical network unit and the optical terminal device, C wire is the speed of light propagation in the optical fiber, and the transmission delay of the data packet in the passive optical network time-sensitive service transmission system is obtained by dividing the two, T d is the time slot when the uplink data is expected to arrive at the optical terminal device, T a is the time slot when the uplink data is just sent, and the interference of the transmission delay is subtracted to obtain the number of time slots that the data packet should be delayed in the model. To prevent overflow, the number of transmission queues is taken modulo and rounded up to ensure that the result is an integer. The obtained Δ is the transmission queue to which the data packet should be sent, and the data packet waits to be rotated at the transmission queue.

[0103] 5. Multi-queue duty cycle conversion, the data packets in the transmission queue are sent out according to the specified time slot, and every time a time slot T slot , the duty cycle of each transmission queue will be converted once, and the queue with a delay of one time slot will be converted into a sending queue to perform the sending function, and the remaining queues will be alternately changed in turn. The queue with a delay of Δ time slots will be converted into a sending queue at the Δth time slot, and the data packets in the queue will be forwarded to the optical terminal device.

[0104] 6. After the optical terminal device receives the information, it updates the polling table and prepares for the next round of authorized information transmission.

[0105] After the optical terminal device receives the transmitted data packets from the optical network unit, it updates the remaining byte size of the buffer in 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 during communication according to the actual transmission situation, and prepares for the next round of authorized information transmission.

[0106] 7. Next, the passive optical network time-sensitive service transmission process is simulated.

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

[0108] First, the passive optical network time-sensitive service transmission system is modeled and the basic simulation parameters of the passive optical network are set. The passive optical network time-sensitive service transmission system includes 16 optical network units. The propagation speed of optical signals in the optical fiber is set to 204218 km / s. Each optical network unit is provided with a buffer with a size of 10 kilobytes. The size of the authorization message and the request message is set to 64 bytes. The physical distance between each optical network unit and the optical terminal device is set to be in the range of 10 to 20 kilometers. The maximum single authorization data amount of the optical network unit is set to 11000 bytes, and the single authorization data amount is the amount of data to be forwarded in a single forwarding period, to avoid excessive occupation of uplink bandwidth resources by individual optical network units. The total uplink rate of the passive optical network time-sensitive service transmission system is set to 24880 Mbps, and the maximum uplink rate of each optical network unit is set to 12440 Mbps. The above rates are expressed in bits per second (bps) and are further converted to bytes per second (Bps) for simulation.

[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 is the speed of light in the fiber.

[0117] T is the time slot when the data packet leaves the queuing and scheduling module c is defined as:

[0118]

[0119] wherein T d is the time slot when the uplink data is expected to arrive at the optical terminal device, which can be obtained from the polling table. S2 is the distance between the queuing and scheduling module and the optical terminal device. The sum of S1 and S2 is the distance S between the optical network unit and the optical terminal device.

[0120] T b and T c are brought into the number of time slots Δ during which the data packet is delayed in the queuing and scheduling module:

[0121]

[0122] Δ is the number of delay queues in which the data packet is located, and then the data packet waits for Δ T slot after which it leaves the module and is forwarded to the optical terminal device.

[0123] Figure 4 is a schematic diagram of the transmission process of the passive optical network time-sensitive service with three optical network units according to an embodiment of the present application. At T0 time slot, the optical terminal device broadcasts authorization information downward. At T1 time slot, after receiving the authorization message, optical network unit 1, optical network unit 2 and optical network unit 3 start to send data upward; at T2 time slot, the data packets arrive at the queuing and scheduling module, and each data packet is allocated to a different delay queue for queuing according to the scheduling algorithm; wherein the data packets of optical network unit 1 are forwarded in the sending queue (SQ), while the data packets of optical network unit 2 and optical network unit 3 are respectively stored in delay queue 1 (DQ1) and delay queue 2 (DQ2) for waiting to be sent; at T3 time slot, the data packets of optical network unit 1 arrive at the optical terminal device, and at the same time, the transmission queue duty in the module is rotated, and the transmission queue in which the data packets of optical network unit 2 are located becomes the sending queue to perform the forwarding function. Until T5 time slot, all the data packets of the optical network units arrive at the optical terminal device, and thus the data scheduling of one cycle is completed.

[0124] 3) Polling data packet data index collection.

[0125] In the process of continuously polling the data packets, the parameters of each data packet are recorded by using the array created when the passive optical network time-sensitive service transmission system is modeled, and the collection of the data indexes during each round of data packet transmission is completed by using these parameters, and the performance parameters are calculated for subsequent comparison.

[0126] 8. Experimental process and effect comparison.

[0127] 1) Experimental conditions: In the environment of CPU model Inter(R) Core(TM) i7-8750H CPU@2.20GHz, Matlab R2019a simulation tool is used to simulate the passive optical network time sensitive service transmission system.

[0128] 2) Experimental results: Two traditional dynamic bandwidth allocation algorithms are designed and compared, including interleaved polling with adaptive cycle time (IPACT) and limited service bandwidth allocation algorithm.

[0129] Figure 5 The comparison diagram of different bandwidth allocation methods described in an embodiment of the application in terms of average packet delay index at the optical network unit. As the effective network load increases, the delay of the present application is significantly lower than that of other algorithms, and this improvement is mainly due to the queue-based store-and-forward mechanism, which enables each optical network unit to transmit data within a predetermined time slot; compared with the traditional polling scheme, the traditional scheme introduces additional waiting time due to repeated request-grant interactions, while the cycle-specific queuing and forwarding mechanism eliminates this back-and-forth signaling process within a cycle; therefore, the optical network unit can start transmitting immediately after receiving a single grant, effectively reducing the queuing waiting time.

[0130] Figure 6 The comparison diagram of different bandwidth allocation methods described in an embodiment of the application in terms of polling times index. The delay of the CSQF-based queuing scheduling algorithm is significantly lower than that of other schemes. In the traditional scheme, the optical terminal device needs to poll each optical network unit in turn in a polling or priority-based manner, and multiple control interactions are required within each scheduling cycle. In contrast, the CSQF framework embeds queue control inside the model and uses pre-computed scheduling strategies, so that the optical terminal device only needs to send one grant message at the beginning of the scheduling cycle. This structural simplification not only reduces the control overhead, but also significantly improves the scalability of the system.

[0131] As the load increases, the end-to-end latency of the present application is significantly lower than that of other algorithms, and this effect is due to the reduction of queuing delay at the optical network unit side and the deterministic transmission scheduling inside the queuing scheduling module, which accurately calculates and allocates the delay queue according to the expected arrival time of the data packet, effectively avoiding time slot conflicts and transmission uncertainty. This deterministic transmission behavior not only improves the link utilization, but also reduces the transmission jitter, thereby significantly improving the overall latency performance.

[0132] In summary, the present application provides a passive optical network time-sensitive service transmission method and system, which allocates a logical link identifier for identifying the identity of an optical network unit to at least one optical network unit and records the sending time, 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 for marking the data to be forwarded of each optical network unit in each forwarding period to each optical network unit; determines the sending order of the data to be forwarded by the optical network unit to the queuing and scheduling module in each forwarding period according to the communication round trip time in the polling table and broadcasts to each optical network unit; receives the data packet forwarded by each optical network unit via the queuing and scheduling module in each forwarding period and records the receiving time, the data packet is obtained by packaging the data to be forwarded and control information for recording the remaining number of bytes of the buffer of the corresponding optical network unit, the queuing and scheduling module receives a plurality of data packets forwarded by each optical network unit according to the sending order, and stores the data packets in the transmission queue corresponding to the ordinal number according to the number of delay time slots of the data packets, the number of delay time slots of each data packet is obtained by taking the maximum allowed running delay modulo the number of transmission queues and rounding up, and the data packets in each transmission queue are forwarded to the optical terminal device one by one according to the ordinal number in a forwarding period; update the number of bytes waiting for allocation in the polling table according to the remaining number of bytes of the buffer of the corresponding optical network unit 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 the receiving time.

[0133] The embodiment of the present application also provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the foregoing edge computing server deployment method. The computer readable storage medium can be a tangible storage medium, such as a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a floppy disk, a hard disk, a removable storage disk, a CD-ROM, or any other form of storage medium known in the technical field.

[0134] Those of ordinary skill in the art will appreciate that the various illustrative components, systems and methods described in connection with the embodiments disclosed herein can be implemented as hardware, software, or both. The particular implementation is dependent on the specific application and design constraints imposed on the overall system. Skilled persons can implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application. When implemented in hardware, for example, the hardware can comprise an electronic circuit, an Application Specific Integrated Circuit (ASIC), a suitable firmware, a plug-in, a functional card, etc. When implemented in software, the elements of the application are the program or code segments to perform a specific task. The program or code segments can be stored in a machine-readable medium, or transmitted by a carrier wave as data signals over a transmission medium or communication link.

[0135] It is to be understood that the application is not limited to the particular configurations and processes described herein and shown in the drawings. For simplicity, detailed descriptions of known methods and apparatuses are omitted so as not to obscure the disclosure. In the above-described embodiments, several specific steps are described and illustrated as examples. However, the method processes are not limited to the specific steps described and illustrated, and the order of the steps can be changed, or other steps can be added, or replaced, or eliminated, depending on the application.

[0136] In the present application, features described and / or illustrated in connection with one embodiment can be used in the same or a similar way or in conjunction with or in place of features of another embodiment.

[0137] The above description is only preferred embodiments of the present application, and is not intended to limit the present application. The embodiments of the present application can be variously changed and modified by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the present application.

Claims

1. A method for transmission of time sensitive traffic in a passive optical network, characterized in that, The method comprises the following steps: allocating a logical link identifier for identifying the identity of the optical network unit to at least one optical network unit and recording the sending time, receiving the number of bytes waiting for allocation in the buffer of each optical network unit, and establishing a polling table record with the measured communication round trip time of each network unit and optical terminal device; sending authorization information to each optical network unit; the authorization information is used to mark the data to be forwarded of each optical network unit in each forwarding period; determining the sending order of the data to be forwarded uploaded by the optical network unit to the queuing scheduling module in each forwarding period according to the communication round trip time in the polling table and broadcasting to each optical network unit; receiving the data packet forwarded by each optical network unit via the queuing scheduling module in each forwarding period and recording the receiving time, the data packet being obtained by packaging the data to be forwarded and control information, the control information being used to record the remaining number of bytes of the buffer of the corresponding optical network unit; wherein the queuing scheduling module receives a plurality of data packets forwarded by each optical network unit according to the sending order, and stores them in a transmission queue corresponding to the serial number according to the delay time slot number of the data packet, the delay time slot number of each data packet being obtained by taking the modulus of the maximum allowed running delay on the number of transmission queues and rounding up, and the data packets in each transmission queue being forwarded to the optical terminal device one by one according to the serial number in one forwarding period; updating the number of bytes waiting for allocation in the polling table according to the remaining number of bytes of the buffer of the corresponding optical network unit recorded in the control information, and updating the communication round trip time in the polling table according to the actual communication round trip time obtained from the sending time and the receiving time.

2. The method of claim 1, wherein, The data to be forwarded of each optical network unit in each forwarding period is determined by the transmission window size of each network unit, and the transmission window size satisfies the following expression: W i = min(Q i + H ON , W max ); wherein Q i represents the number of bytes waiting for allocation in the buffer of the ith optical network unit, H ON represents the additional resource consumption in the process of the transmission of the time-sensitive service of the passive optical network, W max represents the preset maximum transmission window. 3.The PON TSN transmission method of claim 1, wherein, The delay time slot number of each data packet is obtained by taking the modulus of the maximum allowed running delay on the number of transmission queues and rounding up, and the delay time slot number satisfies the following expression: where S represents the fiber length from the optical network unit to the optical terminal device, C wire represents the speed of light propagating in the fiber, T d represents the time slot in which the data packet is expected to be sent to the optical terminal device, T a represents the time slot in which the data packet is sent from the optical network unit, and n represents the number of transmission queues. 4.The PON TSN transmission method of claim 1, wherein, The process of forwarding the data packets in each transmission queue to the optical terminal device one by one according to the serial number in one forwarding period comprises: setting the gate code of the transmission queue of the first serial number to on and the gate codes of the other transmission queues to off, and forwarding the data packets in the transmission queue of the first serial number to the optical terminal device through one delay time slot; changing the gate code of the transmission queue of the first serial number to off and the gate code of the transmission queue of the second serial number to on, and the gate codes of the other transmission queues to off, and forwarding the data packets in the transmission queue of the second serial number to the optical terminal device through one delay time slot; the gate code in the transmission queue changes once every delay time slot until all data packets are sent to the optical terminal device to complete the data packet forwarding of the current forwarding period.

5. The method of claim 1, wherein, The process of measuring the communication round trip time of each network unit and optical terminal device comprises: sending a ranging request information containing the logical link identifier to each optical network unit and recording a timestamp of sending the ranging request information, so that each network unit receives the ranging request information and returns a ranging response information to the optical terminal device; receiving the ranging response information of each optical network unit and recording a timestamp of receiving the ranging response information; calculating a communication round trip time of each network unit and the optical terminal device according to the timestamp of sending the ranging request information and the timestamp of receiving the ranging response information. 6.The PON TSN transmission method of claim 1, wherein, The method further comprises: constructing the sending time, the receiving time, the size of the data packet and the authorization information into a parameter array, parameter partitioning the parameter array according to time dimension, sending and storing to the cloud platform using an encryption algorithm; establishing a name index for the sending time, the receiving time, the size of the data packet and the authorization information of the cloud platform, so that the user can query the corresponding parameters in the cloud platform according to the name index.

7. A passive optical network time sensitive traffic transmission system, characterized by, The system comprises: an optical terminal device for implementing the passive optical network time-sensitive service transmission method of any one of claims 1 to 6, assigning a logical link identifier for identifying the identity of an optical network unit to at least one optical network unit and recording the sending time, receiving the number of bytes waiting for allocation in the buffer of each optical network unit, and establishing a polling table record with the communication round trip time of each network unit and the optical terminal device obtained by measurement, sending authorization information to each optical network unit, determining the sending order of the data to be forwarded by the optical network unit to the queuing and scheduling module in each forwarding period according to the communication round trip time in the polling table and broadcasting to each optical network unit, and receiving the data packet forwarded by each optical network unit via the queuing and scheduling module in each forwarding period; an optical network unit for receiving the logical link identifier and sending the number of bytes waiting for allocation in the buffer of each optical network unit to the optical terminal device, forwarding a plurality of the data packets to the queuing and scheduling module according to the sending order; a queuing and scheduling module for receiving a plurality of the data packets forwarded by each optical network unit according to the sending order and storing in a transmission queue corresponding to the serial number according to the number of delay time slots of the data packet, and forwarding the data packets in each transmission queue to the optical terminal device one by one according to the serial number in one forwarding period.

8. The PON TSN transmission system of claim 1, wherein, The queuing and scheduling module further comprises: a fault queue switching module for monitoring the transmission state of each transmission queue in real time and transferring the data packets to be forwarded in the fault transmission queue to the transmission queue in normal operation when the transmission queue fails.

9. A computer readable storage medium having stored thereon computer programs / instructions, characterized in that, The computer program / instruction is executed by the processor to realize the steps of the method of any one of claims 1 to 6.

10. A computer program product comprising computer programs / instructions, characterized in that, The computer program / instruction is executed by the processor to realize the steps of the method of any one of claims 1 to 6.

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