A protocol adaptation method for 5G network and EtherCAT network

Abstract

The present invention relates to a protocol adaptation method for a 5G network and an EtherCAT network, and belongs to the field of industrial network technology. The method allocates a dedicated 5G QoS flow to the EtherCAT service flow through a control plane unit; a protocol identification unit extracts the network segment address and subsequent message type of the EtherCAT data frame; a service flow / 5QI mapping unit matches the EtherCAT service flow with the 5G service quality flow and loads it into a priority queue; a protocol encapsulation unit encapsulates the mapped EtherCAT data into a 5G data message, or encapsulates the 5G data message carrying the EtherCAT service flow into an EtherCAT data frame; and a clock synchronization unit performs EtherCAT cross-domain clock error compensation based on the residence time. The present invention achieves efficient adaptation of the EtherCAT network and the 5G network, while ensuring the service quality of cross-network industrial data flows.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial networks and relates to a protocol adaptation method for a 5G network and an EtherCAT network. Background Art

[0002] Ethernet Control Automation Technology (EtherCAT) is the current mainstream full-duplex, real-time industrial Ethernet technology. It uses lumped data frames, where a single frame can contain multiple slave messages, offering high real-time performance and significantly improving bandwidth utilization. Furthermore, EtherCAT uses distributed clocks for clock synchronization, providing a highly accurate clock reference across the entire network, thereby controlling the synchronous execution of tasks across various devices. Due to its flexible topology and advantages such as high real-time performance, high synchronization, fast transmission speed, and high bandwidth utilization, EtherCAT has been widely used in industrial control fields such as robotics and CNC.

[0003] 5G wireless communication technology, with its high speed, low latency, and large connectivity, can meet the diverse communication requirements for latency, reliability, speed, and bandwidth for different types of services within the Industrial Internet, making it a highly efficient wireless solution for the future Industrial Internet. Therefore, adapting EtherCAT networks to 5G networks and enabling EtherCAT industrial devices to effectively connect to 5G networks has become a critical issue facing the development of the Industrial Internet. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a protocol adaptation method for 5G network and EtherCAT network, which converts EtherCAT data frames and 5G messages into each other through an adaptation system, ensures the service quality of cross-network industrial data flow, and realizes efficient adaptation of 5G network and EtherCAT network.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A protocol adaptation method for 5G networks and EtherCAT networks converts EtherCAT data frames and 5G messages into each other through a control plane unit, a protocol identification unit, a service flow / 5QI mapping unit, a protocol encapsulation unit, and a clock synchronization unit. The method specifically includes the following steps:

[0007] S1: Accesses the 5G network through the control plane unit and allocates EtherCAT-specific QoS flows;

[0008] S2: Extract the network segment address and subsequent message type of the EtherCAT data frame through the protocol identification unit;

[0009] S3: Use the service flow / 5QI mapping unit to match the EtherCAT service flow with the 5G service quality flow, map it to the 5QI (5G service quality identifier) ​​parameter set, and load it into the priority queue;

[0010] S4: The protocol encapsulation unit loads the EtherCAT data after business flow / 5QI mapping into the SDAP (5G service data application) layer, and then constructs 5G data packets layer by layer through the 5G protocol stack, or encapsulates the 5G data packets carrying the EtherCAT business flow into EtherCAT data frames;

[0011] S5: The clock synchronization unit records the ingress and egress delays of the EtherCAT time synchronization frame in the 5G system, and compensates for the EtherCAT reference clock error based on the residence time, thus achieving cross-network clock synchronization between the EtherCAT system and the 5G system.

[0012] Furthermore, in step S1, the control plane unit performs the following steps:

[0013] S101: Establish an NG interface connection between the gNB (5G base station) and the core network AMF (access management unit);

[0014] S102: The user accesses the core network after authentication, security check, and context establishment. The core network allocates a QoS flow for carrying EtherCAT data.

[0015] S103: Set the access flag to notify the protocol identification unit that data can be received and identified. At this point, user access and allocation of EtherCAT dedicated QoS flows are completed.

[0016] Furthermore, in step S2, the protocol identification unit performs the following steps:

[0017] S201: Parse the received Ethernet message. If the destination MAC address is FF FF FF FF FF FF, the connection mode is direct connection mode; if the destination address is a network segment MAC address, it is open mode; if the Ethernet Type field is 0x88A4, it indicates that the subsequent message is an EtherCAT data frame;

[0018] S202: Obtain the EtherCAT data length according to the Length field in the EtherCAT data frame header; obtain the subsequent message type according to the Type field, where (0001) B Indicates DL (data link) PDU, (0100) B Indicates network variables, (0101) B Indicates mailbox data, other values ​​are reserved;

[0019] S203: Parse the CMD index field in the EtherCAT sub-message header to obtain the EtherCAT intra-segment addressing mode, including device addressing and logical addressing;

[0020] S204: The protocol identification is now completed.

[0021] Furthermore, in step S3, the execution steps of the service flow / 5QI mapping unit include:

[0022] S301: According to the Type field in the EtherCAT data frame header, if it is (0101) B , then execute step S306; if it is (0001) B , then execute step S302;

[0023] S302: If the service flow type is logical read LRD, logical write LWR, or logical read and write LRW, according to the CMD index field in the EtherCAT sub-message header, execute step S303; otherwise, execute step S304;

[0024] S303: This EtherCAT sub-message data is periodic process data. According to the industrial service flow mapping relationship, the 5QI value mapped to 5G is 85, and the corresponding QoS flow identifier is 1;

[0025] S304: Parse the lower 16 bits of the Address field in the EtherCAT sub-message header, i.e., the memory offset address. If the value is 0x0000 to 0x0FFF, execute step S305.

[0026] S305: This EtherCAT sub-message data is register data. According to the industrial service flow mapping relationship, the 5QI value mapped to 5G is 3, and the corresponding QoS flow identifier is 2;

[0027] S306: This EtherCAT sub-message data is mailbox data. According to the industrial service flow mapping relationship, the 5QI value mapped to 5G is 6, and the corresponding QoS flow identifier is 3;

[0028] S307: At this point, the business flow / 5QI mapping is completed.

[0029] Furthermore, in step S4, the protocol encapsulation unit performs the following steps:

[0030] S401: Load the mapped business flows of different priorities into different priority queues. By managing the priority queues, the SDAP layer is notified to send data. If the data is cyclic process data, step S402 is executed; if the data is register data, step S403 is executed; if the data is mailbox data, step S404 is executed.

[0031] S402: According to the mapping relationship between EtherCAT and 5G service flows, the QoS flow identifier of the periodic process data is set to 1, the QFI field of the SDAP header is filled with 1, the data radio bearer is mapped to DRB4, and the process data is loaded into the SDAP payload. Then, step S405 is executed.

[0032] S403: Set the QoS flow identifier of the register data to 2, fill the QFI field of the SDAP header with 2, map it to the data radio bearer DRB5, and load the register data into the SDAP payload, and execute step S405;

[0033] S404: Set the QoS flow identifier of the mailbox data to 3, fill the QFI field of the SDAP header with 3, map it to the data radio bearer DRB6, and load the mailbox data into the SDAP payload, and execute step S405;

[0034] S405: After the SDAP layer is processed, it is encapsulated into a 5G message through the PDCP (Packet Data Convergence Protocol) layer, RLC (Radio Link Control Layer Protocol) layer and MAC (Media Access Control) layer in sequence and sent. At this point, the protocol encapsulation is completed.

[0035] Furthermore, in step S5, the clock synchronization unit performs the following steps:

[0036] S501: During the initialization phase, after receiving the system time frame sent by the EtherCAT master to the reference clock slave, the E-NR (EtherCAT to 5G NR) adapter system records the 5G system clock T1 when the first bit of the preamble is received, appends the 5G system time information to the SDAP payload, and transmits the data frame to the 5G UE via the 5G system.

[0037] S502: After receiving the initialization system time frame, the NR-E (5G NR to EtherCAT) adapter system records the 5G system clock T2 at this time and extracts the time information T1 in the SDAP payload;

[0038] S503: Calculate the total residence time of the EtherCAT initialization system time frame in the 5G network, add the residence time to the EtherCAT initialization system time frame, and send it to the reference clock slave through the NR-E adaptation system. At this time, the time synchronization of the reference clock is completed;

[0039] S504: During the EtherCAT distributed clock synchronization phase, the EtherCAT master sends a broadcast read BRD command frame via the 5G system to obtain the local clock of each slave, calculate the offset time of each slave, and write the offset time into the system time offset register of each slave via the 5G system.

[0040] S505: The EtherCAT master calculates the delay time of each slave station based on the transmission delay of each slave station relative to the synchronized reference clock, and writes the delay time into the system time transmission delay register of each slave station via the 5G system;

[0041] S506: At this point, clock synchronization is completed.

[0042] The beneficial effects of the present invention are:

[0043] (1) The present invention can effectively achieve the adaptation of EtherCAT and 5G networks. By processing the time synchronization frame, cross-domain clock error compensation between EtherCAT and 5G is achieved; by converting the data frame, data interconnection and intercommunication between EtherCAT and 5G is achieved.

[0044] (2) While achieving EtherCAT and 5G network adaptation, the present invention can also effectively maintain the quality of service of cross-network industrial data flows. Through the protocol adaptation method of the present invention, the quality of service characteristics of different EtherCAT industrial service flows are utilized and mapped to different 5G QoS flows, thereby ensuring the cross-network quality of service of different types of data flows such as periodic process data, register data, and mailbox data.

[0045] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0047] Figure 1 This is the overall network framework diagram of the adaptation system of the present invention;

[0048] Figure 2 This is a diagram of the protocol adaptation system architecture of the present invention;

[0049] Figure 3 This is an overall flow chart of the protocol adaptation method of the present invention;

[0050] Figure 4 This is a clock synchronization flow chart of the protocol adaptation method of the present invention. DETAILED DESCRIPTION

[0051] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0052] See also Figures 1 to 4 , Figure 1 The figure shows the overall network architecture for 5G network and EtherCAT network protocol adaptation. It includes the EtherCAT system's EtherCAT master and multiple EtherCAT slaves; the 5G network core network UPF (User Plane Function) module, gNB module, and UE module; and the EtherCAT adaptation system, which includes the E-NR (EtherCAT to 5G NR) adaptation unit and the NR-E (5G NR to EtherCAT) adaptation unit, to achieve adaptation between the 5G system and the EtherCAT network. In the 5G network, the UE registers and connects to the core network through the gNB. EtherCAT QoS flows are allocated among the UE, gNB, and UPF based on defined mapping relationships. On the data plane, EtherCAT industrial service flows are transmitted to the 5G network through the EtherCAT adaptation system (E-NR adaptation unit / NR-E adaptation unit) and forwarded within the 5G system according to the configured 5QI.

[0053] Figure 2The diagram shows the protocol adaptation architecture for 5G networks and EtherCAT networks. The E-NR adapter unit in the 5G network and EtherCAT network protocol adaptation system converts EtherCAT data frames into 5G data message structures. This adaptation system includes a protocol identification unit, a service flow / 5QI mapping unit, a protocol encapsulation unit, and a clock synchronization unit. After processing by the E-NR adaptation system, the EtherCAT data frames are converted into 5G data messages, enabling user plane data adaptation between the EtherCAT and 5G networks. Similarly, the NR-E adapter unit converts 5G data messages into EtherCAT data frames through the protocol identification unit, service flow / 5QI mapping unit, and protocol encapsulation unit. The clock synchronization unit in the 5G network and EtherCAT network protocol adaptation system calculates the delay of the EtherCAT initial synchronization frame at the 5G ingress and egress, compensates for the error of the reference clock slave based on the dwell time, and finally transmits EtherCAT distributed clock synchronization messages between the EtherCAT master and slaves over the 5G network, achieving cross-domain clock synchronization between EtherCAT and 5G.

[0054] Table 1 shows the 5G and EtherCAT service quality of service mapping table. Based on the service's latency requirements, packet size, and criticality, EtherCAT service flows are mapped to the 5QI in the 5G network. EtherCAT service flows can be divided into periodic process data and aperiodic register data and mailbox data. EtherCAT process data has high real-time requirements, requiring microsecond-level latency and a typical cycle time of 1 to 10 milliseconds. Therefore, EtherCAT process data is mapped to the Delay Critical - GBR (Delay Critical Guaranteed Bit Rate) type in the 5G network. EtherCAT register service flows, with their larger data size and millisecond-level latency requirements, are aperiodic. Therefore, this type of service flow is mapped to the GBR (Guaranteed Bit Rate) and Guaranteed PDU Session Bandwidth type in the 5G network. EtherCAT mailbox data, with its low criticality and less bandwidth requirements, is mapped to the Non-GBR (Non-Guaranteed Bit Rate) type in the 5G network.

[0055] Table 1 5G and EtherCAT service flow quality of service mapping table

[0056]

[0057] Figure 3 The figure shows the overall flow chart of the 5G network and EtherCAT network protocol adaptation method, which specifically includes the following steps:

[0058] S1: When the EtherCAT / 5G adapter system receives an EtherCAT data frame, it parses the EtherCAT data frame header to determine whether it is an initialization clock synchronization frame. If so, it executes step S2; if not, it executes step S3;

[0059] S2: Processing flow of initializing clock synchronization process;

[0060] S3: parse the EtherCAT sub-message headers respectively and determine the data message type. If it is process data, execute step S4; if it is register data, execute step S5; if it is mailbox data, execute step S6;

[0061] S4: Set the process data flag and fill the real-time, periodic, and priority information of the message into the communication type field according to the mapping relationship between the process data message and the 5G service characteristics;

[0062] S5: Set the register data flag and fill the real-time, periodic, and priority information of the register data message into the communication type field according to the mapping relationship between the register data message and the 5G service characteristics;

[0063] S6: Set the mailbox data flag and fill the real-time, periodic, and priority information of the message into the communication type field according to the mapping relationship between the mailbox data message and the 5G service characteristics;

[0064] S7: Fill the data message processed in the above steps into the 5G application layer structure, map different types of messages to different QoS flows, and form 5G application data messages;

[0065] S8: Through the SDAP layer, process data fills the QFI field of the SDAP header with 1 and is mapped to the data radio bearer as DRB4; register data fills the QFI field of the SDAP header with 2 and is mapped to the data radio bearer as DRB5; mailbox data fills the QFI field of the SDAP header with 3 and is mapped to the data radio bearer as DRB6;

[0066] S9: Through the encryption and integrity protection operations of the 5G protocol stack, the EtherCAT data frame is converted into a 5G data message for transmission. At this point, E-NR adaptation is completed;

[0067] S10: Similarly, after receiving the 5G wireless frame, NR-E adaptation is completed through the protocol identification unit, service flow / 5QI mapping unit, and protocol encapsulation unit.

[0068] Figure 4The figure shows the clock synchronization flow chart of the 5G network and EtherCAT network protocol adaptation method. Based on the transparent clock method, the adapter / UPF and UE / adapter record the 5G entry and exit delays, and the reference clock error is compensated according to the residence time. Then, using the EtherCAT distributed clock mechanism, the EtherCAT master sends a broadcast read BRD command frame through the 5G system to obtain the local clock of each slave station, calculate the offset time of each slave station, and write the offset time into the system time offset register of each slave station through the 5G system, thereby realizing cross-domain clock synchronization between EtherCAT and 5G.

[0069] As shown in Table 2, the EtherCAT clock synchronization related register description table, the EtherCAT distributed clock function is implemented by reading and writing distributed clock related registers.

[0070] Table 2 EtherCAT clock synchronization related register description table

[0071]

[0072]

[0073] Clock synchronization specifically includes the following steps:

[0074] S1: The EtherCAT master sends the master system clock to the reference clock slave;

[0075] S2: The UPF adapter records the 5G ingress time T1 and appends T1 to the system clock frame payload.

[0076] S3: The UPF adapter forwards the EtherCAT time information to the UE adapter via the 5G network;

[0077] S4: The UE-side adapter calculates the difference between the 5G egress time T2 and the 5G ingress time T1 to obtain the residence time of the system time frame in the 5G network, thereby performing EtherCAT clock error compensation.

[0078] S5: The UE-side adapter sends the compensated system time frame to the EtherCAT reference clock slave;

[0079] S6: The EtherCAT reference clock slave sends a reference clock configuration completion response;

[0080] S7: The EtherCAT master obtains the local_time, receive_time_port0, and receive_time_port1 of each slave;

[0081] S8: The EtherCAT master calculates the deviation time and transmission delay of each slave;

[0082] S9: The EtherCAT master sends the deviation time and transmission delay time of each slave via the 5G network;

[0083] S10: Each slave station writes the deviation time into the time deviation register and the transmission delay into the transmission delay register;

[0084] S11: The EtherCAT master periodically sends RMW data packets and drift compensation packets via the 5G network.

[0085] S12: Each EtherCAT slave calculates the drift time and compensates the local time local_time for a drift time of 9ns, 10ns, or 11ns based on the positive or negative value of the drift time.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A protocol adaptation method for a 5G network and an EtherCAT network, characterized in that: The method converts EtherCAT data frames into 5G messages through a control plane unit, a protocol identification unit, a service flow / 5QI mapping unit, a protocol encapsulation unit, and a clock synchronization unit. Specifically, the method includes the following steps: S1: Accesses the 5G network through the control plane unit and allocates EtherCAT-specific QoS flows; S2: Extract the network segment address and subsequent message type of the EtherCAT data frame through the protocol identification unit; S3: Use the service flow / 5QI mapping unit to match the EtherCAT service flow with the 5G service quality flow, map it to the 5QI parameter set, and load it into the priority queue. 5QI represents the 5G service quality identifier. The execution steps of the service flow / 5QI mapping unit include: S301: According to the Type field in the EtherCAT data frame header, if it is 0101 B , then execute step S306; if it is 0001 B , then execute step S302; S302: If the service flow type is logical read LRD, logical write LWR, or logical read and write LRW, according to the CMD index field in the EtherCAT sub-message header, execute step S303; otherwise, execute step S304; S303: This EtherCAT sub-message data is periodic process data. According to the industrial service flow mapping relationship, the 5QI value mapped to 5G is 85, and the corresponding QoS flow identifier is 1; S304: Parse the lower 16 bits of the Address field in the EtherCAT sub-message header, i.e., the memory offset address. If the value is between 0x0000 and 0x0FFF, execute step S305. S305: This EtherCAT sub-message data is register data. According to the industrial service flow mapping relationship, the 5QI value mapped to 5G is 3, and the corresponding QoS flow identifier is 2; S306: This EtherCAT sub-message data is mailbox data. According to the industrial service flow mapping relationship, the 5QI value mapped to 5G is 6, and the corresponding QoS flow identifier is 3; S307: At this point, the business flow / 5QI mapping is completed; S4: The protocol encapsulation unit loads the EtherCAT data after the service flow / 5QI mapping into the SDAP layer, and then constructs 5G data packets layer by layer through the 5G protocol stack, or encapsulates the 5G data packets carrying the EtherCAT service flow into EtherCAT data frames. The SDAP layer represents the 5G service data application layer. The protocol encapsulation unit performs the following steps: S401: Load the mapped business flows of different priorities into different priority queues. By managing the priority queues, the SDAP layer is notified to send data. If the data is cyclic process data, step S402 is executed; if the data is register data, step S403 is executed; if the data is mailbox data, step S404 is executed. S402: According to the mapping relationship between EtherCAT and 5G service flows, the QoS flow identifier of the periodic process data is set to 1, the QFI field of the SDAP header is filled with 1, the data radio bearer is mapped to DRB4, and the process data is loaded into the SDAP payload. Then, step S405 is executed. S403: Set the QoS flow identifier of the register data to 2, fill the QFI field of the SDAP header with 2, map it to the data radio bearer DRB5, and load the register data into the SDAP payload, and execute step S405; S404: Set the QoS flow identifier of the mailbox data to 3, fill the QFI field of the SDAP header with 3, map it to the data radio bearer DRB6, and load the mailbox data into the SDAP payload, and execute step S405; S405: After the SDAP layer completes processing, it is encapsulated into a 5G message through the PDCP layer, RLC layer, and MAC layer in sequence and sent. At this point, the protocol encapsulation is completed; the PDCP layer represents the Packet Data Convergence Protocol layer, the RLC layer represents the Radio Link Control layer protocol, and the MAC layer represents the Medium Access Control layer. S5: The clock synchronization unit records the ingress and egress delays of EtherCAT time synchronization frames in the 5G system, and compensates for EtherCAT reference clock errors based on the dwell time, achieving cross-network clock synchronization between the EtherCAT system and the 5G system. The execution steps of the clock synchronization unit include: S501: During the initialization phase, after receiving the system time frame sent by the EtherCAT master to the reference clock slave, the E-NR adapter records the 5G system clock T1 when the first bit of the preamble is received, appends the 5G system time information to the SDAP payload, and transmits the data frame to the 5G UE via the 5G system. E-NR indicates that the EtherCAT network is converted to a 5G network. S502: After receiving the initialization system time frame, the NR-E adapter unit records the 5G system clock T2 at this time and extracts the time information T1 in the SDAP payload. NR-E indicates that the 5G network is converted to an EtherCAT network. S503: Calculate the total residence time of the EtherCAT initialization system time frame in the 5G network, add the residence time to the EtherCAT initialization system time frame, and send it to the reference clock slave through the NR-E adapter unit. At this time, the time synchronization of the reference clock is completed; S504: During the EtherCAT distributed clock synchronization phase, the EtherCAT master sends a broadcast read BRD command frame via the 5G system to obtain the local clock of each slave, calculate the offset time of each slave, and write the offset time into the system time offset register of each slave via the 5G system. S505: The EtherCAT master calculates the delay time of each slave station based on the transmission delay of each slave station relative to the synchronized reference clock, and writes the delay time into the system time transmission delay register of each slave station via the 5G system; S506: At this point, clock synchronization is completed.

2. The protocol adaptation method for a 5G network and an EtherCAT network according to claim 1, wherein: In step S1, the control plane unit performs the following steps: S101: Establish an NG interface connection between the gNB and the core network AMF; S102: The user accesses the core network after authentication, security check, and context establishment. The core network allocates a QoS flow for carrying EtherCAT data. S103: Set the access flag to notify the protocol identification unit to receive and identify data. At this point, the user access and the allocation of the EtherCAT dedicated QoS flow are completed.

3. The protocol adaptation method for a 5G network and an EtherCAT network according to claim 1, wherein: In step S2, the protocol identification unit performs the following steps: S201: Parse the received Ethernet message. If the destination MAC address is FF FF FF FF FF FF, the connection mode is direct connection mode; if the destination address is a network segment MAC address, the connection mode is open mode; if the Ethernet Type field is 0x88A4, it indicates that the subsequent message is an EtherCAT data frame; S202: Obtain the EtherCAT data length according to the Length field in the EtherCAT data frame header; The Type field obtains the subsequent message type, where 0001 B Indicates DL PDU, 0100 B Indicates network variables, 0101 B Indicates mailbox data, other values ​​are reserved; DL PDU indicates data link PDU; S203: Parse the CMD index field in the EtherCAT sub-message header to obtain the EtherCAT intra-segment addressing mode, including device addressing and logical addressing; S204: The protocol identification is now completed.

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