Duplicate message filtering system for industrial wireless networks

Abstract

This invention relates to the technical field of industrial wireless communication. Specifically, it provides a duplicate packet filtering system for industrial wireless networks. The system includes: a packet feature extraction module, a hash value calculation module, a dynamic filter module, and a filtering decision and execution module. The packet feature extraction module extracts features from the current wireless packet. The hash value calculation module calculates the corresponding hash value based on the source MAC address of a first terminal. The dynamic filter module queries the hash RAM table based on the hash value to obtain the SA RAM index. The dynamic filter module retrieves the current entry corresponding to the SA RAM based on the SA RAM index. The dynamic filter module determines whether the current wireless packet is a duplicate packet based on the current entry corresponding to the SA RAM. The filtering decision and execution module filters out the current wireless packet when it is a duplicate packet. This invention reduces network resource waste, significantly reduces terminal processing load, and ensures real-time and reliable communication.

Description

Technical Field

[0001] This invention relates to the technical field of industrial wireless communication, and more specifically, to a duplicate message filtering system for industrial wireless networks. Background Technology

[0002] In industrial wireless networks, hardware-level message retransmission is a common technique to ensure high reliability and real-time performance of communication. In unreliable wireless channels, transmitted messages may be lost. The sending device retransmits the same data message multiple times to improve the reliability of the network, but the receiver will receive multiple identical copies of the message.

[0003] Traditional industrial wireless networks' wireless-to-wired packet forwarding schemes do not identify duplicate packets at the hardware level. This causes duplicate packets to continue being passed up to the software protocol stack of terminal devices (such as PLCs and controllers). At the receiving end's protocol stack, higher layers (such as the transport or application layers) parse information such as sequence numbers in the packets to maintain the receiving status, thereby identifying and discarding duplicate packets. This requires the terminal's Central Processing Unit (CPU) to consume additional computing resources to identify and process these duplicate packets, leading to processing bottlenecks under high load, increased processing latency, impacting the execution of core control tasks, and reducing network throughput.

[0004] Therefore, we urgently need a method for efficient, low-overhead, and low-latency hardware-based duplicate packet filtering to improve network bandwidth utilization, save terminal equipment resources, and reduce system latency while maintaining high reliability. Summary of the Invention

[0005] The present invention aims to solve the prominent problems caused by the use of hardware retransmission mechanisms in the prior art, such as duplicate packets occupying network bandwidth, consuming terminal processing resources, and increasing system latency.

[0006] Therefore, in view of the shortcomings of the existing technology, the purpose of this invention is to provide a duplicate packet filtering system for industrial wireless networks.

[0007] To achieve the above objectives, the present invention provides a duplicate packet filtering system for industrial wireless networks. A first device and a second device in the industrial wireless network communicate via the wireless network. A first terminal in the industrial wireless network communicates with the first device via a wired connection, and a second terminal in the industrial wireless network communicates with the second device via a wired connection. The first device includes a first hardware forwarding module, a first wireless module, and a first radio frequency (RF) module. The second device includes a second hardware forwarding module, a second wireless module, and a second RF module. The first RF module is connected to a first antenna. The second RF module is connected to a second antenna. The current wireless packet sent by the first terminal sequentially passes through the first hardware forwarding module, the first wireless module, the first RF module, the first antenna, the second antenna, the second RF module, the second wireless module, and the second hardware forwarding module. A duplicate packet filtering module is integrated on the second hardware forwarding module. The duplicate packet filtering module includes: a packet feature extraction module, a hash value calculation module, a dynamic filtering module, and a filtering decision and execution module. The dynamic filtering module includes several sub-hash values. RAM; the packet feature extraction module is used to extract features from the current wireless packet sent by the first terminal when it arrives at the hardware forwarding channel of the second hardware forwarding module, so as to extract the source MAC address of the first terminal and the sequence number of the wireless data frame of the current wireless packet; the HASH value calculation module is used to calculate the corresponding hash value according to the source MAC address of the first terminal through the cyclic redundancy polynomial corresponding to the randomly selected sub-HASH RAM; the dynamic filtering module is used to query the HASH RAM table according to the corresponding hash value to obtain the index of SA RAM; the dynamic filtering module is also used to obtain the current table entry corresponding to SA RAM according to the index of SA RAM; wherein, the fields of the current table entry corresponding to SA RAM include valid, SA and Index; the dynamic filtering module is also used to determine whether the current wireless packet is a duplicate packet according to the valid, SA and Index; the filtering decision and execution module is used to filter out the current wireless packet when the current wireless packet is a duplicate packet.

[0008] Preferably, the dynamic filtering module is specifically used to: determine whether the current entry corresponding to the original address RAM is valid based on the valid field of the current entry corresponding to the original address RAM; when valid equals 0, it indicates that the current entry corresponding to the SA RAM is invalid; and the filtering decision and execution module is further used to forward the current wireless packet to the second terminal.

[0009] Preferably, when valid equals 1, it indicates that the current entry corresponding to SA RAM is valid. The dynamic filtering module is further configured to: determine whether the SA field of the current entry corresponding to SA RAM is the same as the source MAC address of the first terminal; when the SA field is the same as the source MAC address of the first terminal, it indicates that there is no hash collision. The dynamic filtering module is further configured to: obtain the corresponding SEQ RAM entry based on the index field of the current entry corresponding to SA RAM, to obtain the sequence number obtained from the table lookup; the dynamic filtering module is further configured to: determine whether the SEQ RAM entry is valid; the dynamic filtering module is further configured to: when the SEQ RAM entry is valid... When a RAM entry is valid, the system determines whether the sequence number of the wireless data frame of the current wireless packet extracted by the packet feature extraction module is the same as the sequence number obtained by looking up the table. If the sequence number of the wireless data frame of the current wireless packet is the same as the sequence number obtained by looking up the table, it indicates that the current wireless packet is a duplicate packet. The dynamic filtering module is further configured to: send a request to filter the packet to the filtering decision and execution module. The filtering decision and execution module is further configured to: filter out the current wireless packet according to the received request to filter the packet.

[0010] Preferably, when the SA field is different from the source MAC address of the first terminal, it indicates that a hash collision exists. In this case, the HASH value calculation module is used to automatically calculate the corresponding hash value based on the source MAC address of the first terminal using the cyclic redundancy polynomial corresponding to the next randomly selected sub-HASHRAM.

[0011] Preferably, when the SEQ RAM entry is invalid, the dynamic filtering module is further configured to: automatically update the sequence number in the SEQ RAM entry; and the filtering decision and execution module is further configured to forward the current wireless packet to the second terminal.

[0012] Preferably, when the sequence number of the wireless data frame of the current wireless packet is different from the sequence number obtained by looking up the table, the dynamic filtering module is further configured to: automatically update the sequence number in the SEQ RAM table entry; and the filtering decision and execution module is further configured to forward the current wireless packet to the second terminal.

[0013] Preferably, the dynamic filtering module includes 10 sub-HASH RAMs; the 10 sub-HASH RAMs are: HASH RAM0, HASH RAM1, HASH RAM2, HASH RAM3, HASH RAM4, HASH RAM5, HASH RAM6, HASH RAM7, HASH RAM8 and HASH RAM9; the cyclic redundancy polynomial corresponding to each sub-HASH RAM supports the selection of 8 different cyclic redundancy polynomials.

[0014] Preferably, the cyclic redundancy polynomials corresponding to each sub-HASH RAM are the same or different.

[0015] Preferably, the duplicate message filtering module further includes: a filter maintenance module; the filter maintenance module is used to receive instructions to initialize the dynamic filtering module, so as to initialize each sub-HASH RAM and initialize SARAM; the filter maintenance module is also used to associate the MAC address of the first terminal, the valid value being true, and the index being indexed to SA RAM, and at the same time, the position of the corresponding entry in SA RAM is mapped to each sub-HASH RAM; the filter maintenance module is also used to select the cyclic redundancy polynomial corresponding to each sub-HASH RAM.

[0016] Preferably, the first terminal is a first desktop computer or a first PLC, the first device is a wireless station STA, the second device is a wireless access point AP, and the second terminal is a second desktop computer or a second PLC.

[0017] The duplicate packet filtering system for industrial wireless networks provided by this invention has the following beneficial technical effects:

[0018] (1) Reduce network resource waste: Due to the existence of the duplicate message filtering module, the hardware will not forward duplicate messages to the terminal when forwarding messages, which can effectively reduce the waste of network resources;

[0019] (2) Significantly reduce the processing load of terminal devices: Terminal devices do not need to consider retransmissions caused by instability in the wireless environment, or the processing of duplicate packet filtering, which can significantly reduce the processing load of terminal devices.

[0020] (3) Ensure the real-time performance and reliability of communication: This invention aims to design a hardware filtering architecture with low resource consumption and high processing efficiency, which can meet the stringent real-time requirements in industrial automation scenarios and does not affect the high reliability of the original hardware retransmission mechanism.

[0021] Additional aspects and advantages of the invention will become apparent from the description which follows, or may be learned by practice of the invention. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 A schematic block diagram of a basic scenario for a traditional industrial wireless network system is shown.

[0024] Figure 2 A schematic block diagram of a duplicate message filtering module according to an embodiment of the present invention is shown.

[0025] Figure 3 A schematic diagram of the structure of a HASH RAM according to an embodiment of the present invention is shown;

[0026] Figure 4 This diagram illustrates the workflow of a hardware-based duplicate packet filtering system for industrial wireless networks according to an embodiment of the present invention. Detailed Implementation

[0027] To better understand the above-mentioned objects, features, and advantages of the present invention, such as Figures 1 to 4 As shown in the accompanying drawings and specific embodiments, the present invention will be further described in detail below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0029] This invention proposes a duplicate packet filtering system for industrial wireless networks. A first device and a second device in the industrial wireless network communicate via the wireless network. A first terminal in the industrial wireless network communicates with the first device via a wired connection, and a second terminal in the industrial wireless network communicates with the second device via a wired connection. The first device includes a first hardware forwarding module, a first wireless module, and a first radio frequency (RF) module. The second device includes a second hardware forwarding module, a second wireless module, and a second RF module. The first RF module is connected to a first antenna. The second RF module is connected to a second antenna. The current wireless packet sent by the first terminal sequentially passes through the first hardware forwarding module, the first wireless module, the first RF module, the first antenna, the second antenna, the second RF module, the second wireless module, and the second hardware forwarding module. A duplicate packet filtering module is integrated on the second hardware forwarding module. The duplicate packet filtering module includes: a packet feature extraction module, a hash value calculation module, a dynamic filtering module, and a filtering decision and execution module. The dynamic filtering module includes several sub-hash values. RAM; the packet feature extraction module is used to extract features from the current wireless packet sent by the first terminal when it arrives at the hardware forwarding channel of the second hardware forwarding module, so as to extract the source MAC address of the first terminal and the sequence number of the wireless data frame of the current wireless packet; the HASH value calculation module is used to calculate the corresponding hash value according to the source MAC address of the first terminal through the cyclic redundancy polynomial corresponding to the randomly selected sub-HASH RAM; the dynamic filtering module is used to query the HASH RAM table according to the corresponding hash value to obtain the index of SA RAM; the dynamic filtering module is also used to obtain the current table entry corresponding to SA RAM according to the index of SA RAM; wherein, the fields of the current table entry corresponding to SA RAM include valid, SA and Index; the dynamic filtering module is also used to determine whether the current wireless packet is a duplicate packet according to the valid, SA and Index; the filtering decision and execution module is used to filter out the current wireless packet when the current wireless packet is a duplicate packet.

[0030] In this embodiment, in an industrial wireless network employing a hardware packet retransmission mechanism, by integrating a lightweight, low-latency duplicate packet filtering module on the hardware forwarding channel, duplicate packets can be identified and discarded in real time before they are forwarded, greatly improving network efficiency.

[0031] In one embodiment of the present invention, the dynamic filtering module is specifically used to: determine whether the current table entry corresponding to the original address RAM is valid based on the valid field of the current table entry corresponding to the original address RAM; when valid equals 0, it indicates that the current table entry corresponding to the SA RAM is invalid; and the filtering decision and execution module is further used to forward the current wireless packet to the second terminal.

[0032] In one embodiment of the present invention, when valid equals 1, it indicates that the current entry corresponding to SA RAM is valid. The dynamic filtering module is further configured to: determine whether the SA field of the current entry corresponding to SA RAM is the same as the source MAC address of the first terminal; when the SA field is the same as the source MAC address of the first terminal, it indicates that there is no hash collision. The dynamic filtering module is further configured to: obtain the corresponding SEQRAM entry based on the index field of the current entry corresponding to SA RAM, to obtain the sequence number obtained from the table lookup; the dynamic filtering module is further configured to: determine whether the SEQ RAM entry is valid; the dynamic filtering module is further configured to: when the SEQ RAM entry is valid... When a RAM entry is valid, the system determines whether the sequence number of the wireless data frame of the current wireless packet extracted by the packet feature extraction module is the same as the sequence number obtained by looking up the table. If the sequence number of the wireless data frame of the current wireless packet is the same as the sequence number obtained by looking up the table, it indicates that the current wireless packet is a duplicate packet. The dynamic filtering module is further configured to: send a request to filter the packet to the filtering decision and execution module. The filtering decision and execution module is further configured to: filter out the current wireless packet according to the received request to filter the packet.

[0033] In one embodiment of the present invention, when the SA field is different from the source MAC address of the first terminal, it indicates that a hash collision exists. Then, the HASH value calculation module is used to automatically calculate the corresponding hash value by using the cyclic redundancy polynomial corresponding to the next randomly selected sub-HASH RAM based on the source MAC address of the first terminal.

[0034] In one embodiment of the present invention, when the SEQ RAM entry is invalid, the dynamic filtering module is further configured to: automatically update the sequence number in the SEQ RAM entry; and the filtering decision and execution module is further configured to forward the current wireless packet to the second terminal.

[0035] In one embodiment of the present invention, when the sequence number of the wireless data frame of the current wireless packet is different from the sequence number obtained by looking up the table, the dynamic filtering module is further configured to: automatically update the sequence number in the SEQ RAM table entry; and the filtering decision and execution module is further configured to forward the current wireless packet to the second terminal.

[0036] In one embodiment of the present invention, the dynamic filtering module includes 10 sub-HASH RAMs; the 10 sub-HASH RAMs are: HASH RAM0, HASH RAM1, HASH RAM2, HASH RAM3, HASH RAM4, HASH RAM5, HASH RAM6, HASH RAM7, HASH RAM8 and HASH RAM9; the cyclic redundancy polynomial corresponding to each sub-HASH RAM supports the selection of 8 different cyclic redundancy polynomials.

[0037] In one embodiment of the present invention, the cyclic redundancy polynomials corresponding to each sub-HASH RAM may be the same or different.

[0038] In one embodiment of the present invention, the duplicate message filtering module further includes: a filter maintenance module; the filter maintenance module is configured to receive an instruction to initialize the dynamic filtering module, so as to initialize each sub-HASHRAM and initialize SA RAM; the filter maintenance module is also configured to associate the MAC address of the first terminal, the valid condition, and the index index to SA RAM, and at the same time, the position of the table entry corresponding to SA RAM is mapped to each sub-HASHRAM; the filter maintenance module is also configured to select the cyclic redundancy polynomial corresponding to each sub-HASHRAM.

[0039] In one embodiment of the present invention, the first terminal is a first desktop computer or a first PLC, the first device is a wireless station STA, the second device is a wireless access point AP, and the second terminal is a second desktop computer or a second PLC.

[0040] The following will illustrate the duplicate packet filtering system for industrial wireless networks according to a specific embodiment of the present invention. Figure 1As shown, in the industrial wireless network, device 1 and device 2 communicate via the wireless network, while terminal 1 and device 1 communicate via wired connection, and terminal 2 and device 2 communicate via wired connection. Device 1 includes a first hardware forwarding module (i.e., a first hardware forwarding channel), a first wireless module (i.e., a first wireless), and a first radio frequency module (i.e., a first RF). Device 2 includes a second hardware forwarding module (i.e., a second hardware forwarding channel), a second wireless module (i.e., a second wireless), and a second radio frequency module (i.e., a second RF). The first radio frequency module is connected to the first antenna; the second radio frequency module is connected to the second antenna. The current wireless message sent by terminal 1 passes sequentially through the first hardware forwarding module, the first wireless module, the first radio frequency module, the first antenna, the second antenna, the second radio frequency module, the second wireless module, and the second hardware forwarding module. If poor wireless channel quality or other uncontrollable factors cause ACK loss, resulting in data packet retransmission, the wireless terminal of device 2 will receive two duplicate messages and simultaneously hand them over to the second hardware forwarding module of device 2. The second hardware forwarding module of device 2 will forward the original message and the duplicate message together, ultimately resulting in the technical problem of uploading the message twice to terminal 2.

[0041] To address the technical problem of uploading the message twice to terminal 2, the core design of this invention requires integrating a duplicate message filtering module into the second hardware forwarding module of device 2; for example... Figure 2 As shown, the duplicate message filtering module includes: a message feature extraction module, a hash value calculation module, a dynamic filtering module, a filtering decision and execution module, and a filter maintenance module; as shown... Figure 3 As shown, the dynamic filter module includes 10 sub-HASH RAMs; the 10 sub-HASH RAMs are: HASHRAM0, HASH RAM1, HASH RAM2, HASH RAM3, HASH RAM4, HASH RAM5, HASH RAM6, HASH RAM7, HASH RAM8 and HASH RAM9;

[0042] The functions of each of the above modules are as follows:

[0043] (1) Message feature extraction module: used to extract information such as the source MAC address (Media Access Control Address) of the transmitter and the sequence number of the current frame from the wireless data frame;

[0044] (2) HASH value calculation module: Calculates the index of HASH RAM based on the polynomial;

[0045] (3) Dynamic filtering module: This filter has three RAMs with different functions, which are used for fast matching and to determine whether the current data packet is a duplicate message. It has the characteristics of fast query speed and high security.

[0046] (4) Filtering Decision and Execution Module: Makes and executes decisions based on the results of the previous level's judgment;

[0047] (5) Filter maintenance module: hardware maintains RAM, while providing a software interface for RAM operation, making it more flexible.

[0048] Specifically, the technical solutions for each sub-module are as follows:

[0049] 1. When the second wireless module of device 2 receives the wireless frame and sends it to the second hardware forwarding module, it will first perform message feature extraction, parse the frame content of the wireless data frame, and extract the source MAC address and sequence number of the sending end (i.e. terminal 1) required by the subsequent modules.

[0050] 2. Based on the source MAC address, calculate a hash value using a Cyclic Redundancy Check (CRC) polynomial. This scheme supports a total of 8 different CRC polynomials and can handle 7 hash collisions. For example, one of the polynomials is:

[0051] (1)

[0052] In equation (1), here x It's just a marker, it doesn't have any concrete meaning. x The various indices are used to mark the position of a particular number in the binary data string.

[0053] 3. Locate the corresponding entry in the HASH RAM based on the HASH value. The structure of the HASH RAM (i.e., the dynamic filter module) is as follows: Figure 3 As shown, the present invention designs the HASH RAM to be divided into 10 sub-RAMs (0-9) for handling hash collisions.

[0054] The HASH RAM table returns the index of SA RAM. The corresponding table entry for SA RAM is retrieved based on this index. The table entry structure is shown in Table 1.

[0055] Table 1. Item Structure Corresponding to SA RAM

[0056] ,

[0057] The `valid` field is used to determine the validity of the current table entry. If `valid=0`, the current table entry is invalid, and the search result is returned. If the current table entry is valid, the value of `SA` (Source Address) is compared with the source MAC address in the parsed message to determine if the MAC addresses match. If the match fails, it indicates a hash collision, and the search continues in the next block of HASH RAM to find the corresponding index of `SA` RAM. If the match is successful, the `index` field in `SA` RAM is used to search `SEQ` RAM to obtain the sequence number (`SEQ`). The sequence number in the parsed message is compared with the sequence number obtained from the table lookup. If they match, a filtering request is initiated.

[0058] 4. Based on the return value of the dynamic filter module, if a request to filter packets is initiated, the decision is to filter the current packet and not forward it to terminal 2; otherwise, the packet is forwarded to terminal 2.

[0059] like Figure 4 As shown, the hardware filtering process for duplicate packets in this industrial wireless network duplicate packet filtering system is as follows:

[0060] Step 1: Initialize the duplicate message filtering module in software, i.e., initialize the HASH RAM and SA RAM. Through the filter maintenance module interface, add the MAC address of the associated device, the "valid" value, and the index to the SA RAM, while simultaneously mapping the position of the entries to the HASH RAM. Through the filter maintenance module interface, select the HASH polynomials corresponding to RAM0-9 in the HASH RAM;

[0061] Step 2, wireless packet reception, that is, the wireless reception of messages arrives at the second hardware forwarding module (i.e., enters the hardware forwarding channel of device 2). First, the message features are extracted to extract the corresponding source MAC and serial number.

[0062] The output of step 3 and step 2 flows to the hash calculation module, which uses the corresponding HASH polynomial to calculate the hash value of the MAC address of the message source.

[0063] Step 4: The output of Step 3 flows to the dynamic filtering module. Based on the hash value, the table entry of HASH RAM is obtained. The table lookup return value is used to obtain the index of SA RAM. Then, based on the index of SA RAM, the SA RAM table entry is obtained. It is determined whether the validity is true. If it is not true, the table lookup ends and proceeds to Step 9; if it is true, proceeds to Step 5.

[0064] Step 5: Check if the SA address in the SA RAM entry is the same as the source MAC address of the packet. If they are different, it means there is a HASH collision. The output of Step 2 will automatically flow to the next HASH RAM and return to Step 3 to continue execution. If they are the same, proceed to Step 6.

[0065] Step 6: Based on the index in the SA RAM entry, obtain the corresponding SEQ RAM entry to get the sequence number. First, determine if the entry is valid; if valid, proceed to step 7; otherwise, proceed to step 8.

[0066] Step 7: Determine if the message sequence number is the same as the sequence number obtained from the table lookup; if the message sequence number is the same as the sequence number obtained from the table lookup, filter the message; otherwise, proceed to step 8.

[0067] Step 8: Update the serial number in the SEQ RAM table entry;

[0068] Step 9: Hardware forwards the message to terminal 2.

[0069] In this specific embodiment, the existing technical solution directly sends duplicate packets to terminal 2 for deduplication by the terminal 2's software protocol stack. This reduces network bandwidth utilization and increases processing latency. The core idea of ​​this specific embodiment is to integrate a lightweight, low-latency duplicate packet filtering module into the hardware forwarding channel of device 2. This duplicate packet filtering module can identify and discard duplicate packets in real time before they are forwarded.

[0070] In this specific embodiment, terminal 1 is a first desktop computer or a first PLC, device 1 is a wireless station STA, device 2 is a wireless access point AP, and terminal 2 is a second desktop computer or a second PLC. Terminal 1 sends wired messages to device 1, device 1 converts the wired messages into industrial wireless messages and sends them to device 2, and device 2 sends non-repeating wired messages to terminal 2. This reduces network resource waste, significantly reduces the processing load of terminal 2, ensures the real-time performance and reliability of communication, and provides an efficient and low-cost hardware implementation solution.

[0071] In summary, the duplicate packet filtering system for industrial wireless networks provided by this invention has unparalleled technical advantages.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A repeated message filtering system for an industrial wireless network, a first device and a second device in the industrial wireless network communicate through a wireless network, a first terminal in the industrial wireless network communicates with the first device through a wire, and a second terminal in the industrial wireless network communicates with the second device through a wire; the first device comprises a first hardware forwarding module, a first wireless module and a first radio frequency module; the second device comprises a second hardware forwarding module, a second wireless module and a second radio frequency module; the first radio frequency module is connected to a first antenna; the second radio frequency module is connected to a second antenna; a current wireless message sent by the first terminal passes through the first hardware forwarding module, the first wireless module, the first radio frequency module, the first antenna, the second antenna, the second radio frequency module, the second wireless module and the second hardware forwarding module in sequence; characterized in that, The second hardware forwarding module is integrated with a repeated message filtering module; the repeated message filtering module comprises a message feature extraction module, a HASH value calculation module, a dynamic filtering module and a filtering decision and execution module; the dynamic filtering module comprises a plurality of sub-HASH RAMs; The message feature extraction module is configured to, when a current wireless message sent by the first terminal arrives at a hardware forwarding channel of the second hardware forwarding module, extract features of the current wireless message to extract a source MAC address of the first terminal in a wireless data frame of the current wireless message and a sequence number of the wireless data frame of the current wireless message; The HASH value calculation module is configured to calculate a corresponding HASH value through a cyclic redundancy polynomial corresponding to a randomly selected sub-HASH RAM according to the source MAC address of the first terminal; The dynamic filtering module is configured to query a HASH RAM table according to the corresponding HASH value to obtain an index of a SA RAM; The dynamic filtering module is further configured to obtain a current table item corresponding to the SA RAM according to the index of the source address SA RAM; wherein fields of the current table item corresponding to the SA RAM include valid, SA and Index; The dynamic filtering module is further configured to determine whether the current wireless message is a repeated message according to the valid, SA and Index; The filtering decision and execution module is configured to filter out the current wireless message when the current wireless message is a repeated message; The dynamic filtering module is specifically configured to determine whether the current table item corresponding to the source address SA RAM is valid according to a valid field of the current table item corresponding to the source address SA RAM; when the valid is equal to 0, it indicates that the current table item corresponding to the SA RAM is invalid; and The filtering decision and execution module is further configured to forward the current wireless message to the second terminal; When the valid is equal to 1, it indicates that the current table item corresponding to the SA RAM is valid, and the dynamic filtering module is further specifically configured to determine whether an SA field of the current table item corresponding to the SA RAM is the same as the source MAC address of the first terminal; When the SA field is the same as the source MAC address of the first terminal, it indicates that there is no hash conflict, and the dynamic filtering module is further specifically configured to obtain a sequence number SEQ RAM table item at a corresponding position according to an index field of the current table item corresponding to the SA RAM to obtain a sequence number obtained by table lookup; The dynamic filtering module is further specifically configured to determine whether the SEQ RAM table item is valid; The dynamic filtering module is further specifically configured to determine whether the sequence number of the wireless data frame of the current wireless message extracted by the message feature extraction module is the same as the sequence number obtained by table lookup when the SEQ RAM table item is valid; When the sequence number of the wireless data frame of the current wireless message is the same as the sequence number obtained by table lookup, it indicates that the current wireless message is a repeated message, and the dynamic filtering module is further specifically configured to send a request for filtering a message to the filtering decision and execution module; The filtering decision and execution module is further configured to filter out the current wireless packet according to the received request of filtering the packet.

2. The duplicate packet filtering system for an industrial wireless network of claim 1, wherein, When the SA field is different from the source MAC address of the first terminal, it indicates that there is a hash conflict, and the HASH value calculation module is configured to automatically calculate a corresponding hash value through a cyclic redundancy polynomial corresponding to a next sub-HASH RAM selected at random according to the source MAC address of the first terminal.

3. The duplicate packet filtering system for an industrial wireless network of claim 2, wherein, When the SEQ RAM table item is invalid, the dynamic filtering module is further configured to automatically update a sequence number in the SEQ RAM table item, and The filtering decision and execution module is further configured to forward the current wireless packet to the second terminal.

4. The duplicate message filtering system for an industrial wireless network of claim 3, wherein, When the sequence number of the wireless data frame of the current wireless packet is different from the sequence number obtained by the table lookup, the dynamic filtering module is further configured to automatically update a sequence number in the SEQ RAM table item, and The filtering decision and execution module is further configured to forward the current wireless packet to the second terminal.

5. The duplicate message filtering system for industrial wireless networks of claim 1, wherein, The dynamic filtering module includes 10 sub-HASH RAMs, which are HASH RAM0, HASH RAM1, HASH RAM2, HASH RAM3, HASH RAM4, HASH RAM5, HASH RAM6, HASH RAM7, HASH RAM8, and HASH RAM9. Each sub-HASH RAM corresponds to a cyclic redundancy polynomial supporting selection of 8 different cyclic redundancy polynomials.

6. The duplicate message filtering system for an industrial wireless network of claim 5, wherein, Each sub-HASH RAM corresponds to a cyclic redundancy polynomial that is the same or different.

7. The duplicate message filtering system for an industrial wireless network of claim 5, wherein, The repeated packet filtering module further includes a filter maintenance module. The filter maintenance module is configured to receive an instruction for initializing the dynamic filtering module to initialize each sub-HASH RAM and initialize the SA RAM. The filter maintenance module is further configured to associate the MAC address of the first terminal, the true valid, and the index to the SA RAM, and map the position of the table item corresponding to the SA RAM to each sub-HASH RAM. The filter maintenance module is further configured to select the cyclic redundancy polynomial corresponding to each sub-HASH RAM.

8. The duplicate packet filtering system for an industrial wireless network of any one of claims 1 to 7, wherein, The first terminal is a first desktop computer or a first PLC, the first device is a wireless station STA, the second device is a wireless access point AP, and the second terminal is a second desktop computer or a second PLC.

Images