A reliable transmission method and system for large data packets of LPWAN Internet of Things

Abstract

The present invention discloses a reliable transmission method and system for large data packets of LPWAN Internet of Things, which are applied in the field of Internet of Things communication. The key points of the technical solution are: a terminal forwards a large data packet to a user server through a network server, and before transmitting the large data packet, it needs to slice it into multiple slice data packets of the same size and different tails, the terminal transmits the slice data packets to the user server through a dedicated channel of the network server, the user server writes a bitmap response according to the received slice data packets and replies to the terminal, the terminal determines whether there is a leakage according to the bitmap response, and if so, the missed slice data packets can be quickly and accurately returned; the technical effect is: the large data packet is cut into multiple slice data packets of equal size, so that the transmission of the large data packet can be completed by transmitting the slice data packets based on Internet of Things communication, and at the same time, the transmission distance is long, the transmission power consumption is low, and the application range is wider.

Description

Technical Field

[0001] The present invention relates to the field of Internet of Things communications, and in particular to a method and system for reliable transmission of large data packets of a LPWAN Internet of Things. Background Art

[0002] The data transmission of IoT has the characteristics of long distance, low power consumption and small capacity. The average data frame is about 120 bytes, and the maximum is about 240 bytes. In practical applications, many scenarios need to transmit larger data blocks, such as picture transmission scenarios. The low resolution of on-site photos can reach 20-30K, and the high resolution can reach 100-200K. At present, the IoT network cannot transmit these large data packets, let alone ensure the reliable transmission of these large data packets. Summary of the invention

[0003] The purpose of the present invention is to provide a method and system for reliable transmission of large data packets for LPWAN Internet of Things, which has the advantages of long transmission distance, low power consumption and large transmission capacity, while ensuring the integrity of the content of the large data packets.

[0004] The above technical objectives of the present invention are achieved through the following technical solutions:

[0005] A reliable transmission method for large data packets of LPWAN Internet of Things, wherein a terminal forwards a large data packet to a user server through a network server. Before transmitting the large data packet, it needs to be sliced ​​into multiple slice data packets. The transmission method comprises the following steps:

[0006] S1: The terminal calculates the large data packet to be transmitted according to the current spreading factor SF level, obtains the number of bytes transmitted by each slice data packet, and performs a slice operation on the large data packet;

[0007] S2: The terminal applies for a dedicated channel from the network server and sends a large data packet sending request message on the dedicated channel;

[0008] S3: The network server forwards the large data packet sending request message to the user server, and the user server replies with a response message to the network server, which is then forwarded to the terminal via the network server;

[0009] S4: The terminal starts to transmit the slice data packets one by one. After all the slice data packets are transmitted, the terminal sends a bitmap confirmation frame request to the user server;

[0010] S5: The user server replies a bitmap response to the terminal;

[0011] S6: The terminal analyzes the situation of receiving the fragmented data packet by the user server according to the received bitmap response. If the fragmented data packet is completely received, the terminal jumps to S8. If the fragmented data packet is not received, the terminal jumps to S7.

[0012] S7: retransmit the fragmented data packets that have not been received, and resend the bitmap confirmation frame request to the user server after the retransmission is completed;

[0013] S8: The terminal releases the channel resources and the transmission of the large data packet ends.

[0014] Through the above technical solution, the large data packet is divided into several smaller slice data packets through slicing operation, and the slice data packets can be forwarded to the user through the Internet of Things network server. The terminal divides the large data packet into the size most suitable for network server transmission according to the current SF and the size of the large data packet. During transmission, the dedicated channel can avoid interference, thereby ensuring that the slice data packets are not damaged. The bitmap response message sent to the terminal after all slice data packets are transmitted can prevent leakage. If leakage occurs, the missed slice data packet can be queried according to the bitmap response message, and the terminal will retransmit it.

[0015] The present invention is further configured as follows: the terminal records the total number of slice data packets after the slicing operation, and records the total number of slice data packets as FragNum, and allocates a slice number to each of the slice data packets, and records the slice number as PSeq.

[0016] Through the above technical solution, the slice number RSeq is a unique number for each slice data packet, and the information of the slice can be quickly found in the bitmap response message according to the slice number RSeq.

[0017] The present invention is further configured such that: the message structure of the bitmap response includes a MessageID field for identifying a slice data packet confirmation frame, a Bitmap field for indicating a receiving state of each slice data packet, and a BitmapLen field for indicating a Bitmap length.

[0018] Through the above technical solution, the fields MessageID, Bitmap and BitmapLen respectively record the information about the reception status of the current slice data packet.

[0019] The present invention is further configured as follows: the field MessageID is a confirmation frame identifying a slice data packet;

[0020] The Bitmap is an octet string, and each bit of the Bitmap represents whether the slice data packet corresponding to the slice number (PSeq) is received;

[0021] The BitmapLen is the byte length of the Bitmap.

[0022] Through the above technical solution, MessageID can identify the current identification slice data packet confirmation and determine which slice data packets failed to be transmitted by identifying the value of each bit in Bitmap.

[0023] The present invention is further configured as follows: the calculation formula of the slice number PSeq corresponding to the bit is: (PSeq mod8)+remainder-1 (wherein the initial value of remainder is 0).

[0024] Through the above technical solution, the terminal can calculate the corresponding bits in the corresponding Bitmap by the slice numbers in sequence, and then compare and search with the received bitmap, so as to identify which slice data packets failed to be transmitted.

[0025] The present invention is further configured as follows: the calculation formula of the byte length of the Bitmap is: BitmapLen=(FragNum mod 8)+1 (when not divisible).

[0026] Through the above technical solution, the number of slice data packets generated by each large data packet after the slicing operation is different, and the byte lengths of different Bitmaps can be calculated.

[0027] The present invention is further configured as follows: the large data packet sending request message includes a file name, a generation time, a total number of fragments and information about the length of each fragment.

[0028] Through the above technical solution, the dedicated channel can read the basic information of the large data packet into the network server by sending a request message through the large data packet, so as to generate a transmission record.

[0029] The present invention is further configured such that: the length of each of the slice data packets is the same, and the tail slices are different.

[0030] Through the above technical solution, the same length of the sliced ​​data packets can ensure the stability of the transmission process. At the same time, the different tail pieces make it easier for the receiving side to assemble the sliced ​​data packets, and the sending side can also better handle retransmission.

[0031] The present invention is further configured as follows: the spreading factor SF level is 5-12.

[0032] Through the above technical solution, by adjusting the level of the spreading factor SF, the range of the transmitted large data packet can be made 18k-450K.

[0033] The present invention is further configured as: a large data packet reliable transmission system for an LPWAN Internet of Things, comprising a terminal, a network server and a user server; the terminal is a sending side of the slice data packet and the bitmap confirmation frame, and is also a receiving side of the bitmap response; the user server is a receiving side of the slice data packet and the bitmap confirmation frame, and is also a sending side of the bitmap response; the network server is a transfer side of the slice data packet, the bitmap confirmation frame and the bitmap response, and the terminal, the network server and the user server are communicatively connected to implement a large data packet reliable transmission method for an LPWAN Internet of Things as described in claim 1.

[0034] In summary, the present invention has the following beneficial effects:

[0035] By dividing a large data packet into multiple slice data packets of equal size, the large data packet can be transmitted by transmitting the slice data packets based on the Internet of Things communication, while achieving long transmission distance and low transmission power consumption. The missed slice data packets can be accurately retransmitted according to the bitmap response to ensure the quality of large data packet transmission, so it has a wider range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of the terminal sending and receiving behavior of this embodiment;

[0037] Figure 2 This is a flow chart of sending a large data packet in this embodiment. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0039] Example:

[0040] refer to Figure 1 and Figure 2 , a reliable transmission method for large data packets of LPWAN Internet of Things. "LPWAN" is the full name of Low Power Wide Area Network. It is a widely used type of network technology in the field of Internet of Things, with the characteristics of long-distance transmission and low power consumption. The data transmitted by LPWAN network has the characteristics of long distance, low power consumption and small capacity. The average data frame is about 120 bytes, and the maximum is 240 bytes. The terminal needs to forward the large data packet to the user server through the network server. Before transmitting the large data packet, it needs to be sliced ​​into multiple slice data packets so that the slice data packets comply with the rules of LPWAN network transmission. Each slice data packet has the same length and different tail pieces, which is convenient for the receiving side to assemble the slice data packets and the sending side to better handle retransmission. The transmission method includes the following steps:

[0041] S1: The terminal calculates the large data packet to be transmitted according to the current spreading factor SF level. The terminal is the sending side at this time. The spreading factor SF level is determined by the terminal. The spreading factor SF level is 5-12. After calculation, the number of bytes transmitted by each slice data packet is obtained, and the large data packet is sliced ​​according to the number of bytes. After the slicing operation, the terminal records the total number of slice data packets and records it as FragNum, and assigns a fragment number to each slice data packet and records it as PSeq.

[0042] S2: The terminal applies for a dedicated channel from the network server. The network server determines whether there are idle channel resources based on the gateway to which the terminal is currently attached. If so, a confirmation response is returned to the terminal. At this time, the terminal sends a large data packet sending request message on the dedicated channel. The large data packet sending request message includes the file name, generation time, total number of fragments and length of each fragment. If there are no idle channel resources, the network server returns a prohibition sending response to the terminal and starts calculating the delay. Only after the delay ends can the application from the terminal continue to be accepted until the application for the dedicated channel is successful.

[0043] S3: After the dedicated channel application is successful, the network server forwards the large data packet sending request message to the user server and starts timing. If no response message is received from the user server within the timing time, the large data packet sending request message is resent until the user server replies with a response message to the network server and forwarded to the terminal via the network server.

[0044] S4: After receiving the response message of permission to send, the terminal starts to transmit the slice data packets one by one. After all the slice data packets are transmitted, the terminal sends a bitmap confirmation frame request to the user server and starts timing, while waiting for the user server to reply with a bitmap response. If no bitmap response is received from the user server within the timing time, the bitmap confirmation frame is resent;

[0045] When SF=5 / 6 / 7 / 8, the maximum size of a single slice data packet that can be transmitted is 238 Byte, and the bitmap confirmation frame can confirm a maximum of 1920 slice data packets, so the maximum size of a large data packet that can be transmitted is 456960 Byte. When SF=9, the maximum size of a single slice data packet that can be transmitted is 111 Byte, and the bitmap confirmation frame can confirm a maximum of 904 slice data packets, so the maximum size of a large data packet that can be transmitted is 100344 Byte. When SF=10 / 11 / 12, the maximum size of a single slice data packet that can be transmitted is 47 Byte, and the bitmap confirmation frame can confirm a maximum of 392 slice data packets, so the maximum size of a large data packet that can be transmitted is 18424 Byte.

[0046] "Bitmap" is a data structure used to represent the reception status of slice data packets. The user server uses the bitmap response to feedback to the terminal whether each slice data packet is received successfully. The terminal determines the retransmission requirement based on this. For example, "Bitmap is an octet string, and each bit represents whether the slice data packet corresponding to the slice number PSeq is received."

[0047] S5: The user server replies a bitmap response to the terminal according to the current received slice data packet situation. The message structure of the bitmap response includes a MessageID field for identifying the slice data packet confirmation frame, a Bitmap field for indicating the receiving status of each slice data packet, and a BitmapLen field for indicating the length of the Bitmap. The field MessageID is a confirmation frame for identifying the slice data packet. The Bitmap is an eight-bit byte string. Each bit of the Bitmap represents whether the slice data packet corresponding to the fragment number PSeq is received. The BitmapLen is the byte length of the Bitmap. The MessageID is used by the terminal to identify that the currently received is a slice data packet confirmation frame for the current large data packet transmission, so as to ensure the accuracy and relevance of the information interaction. As an eight-bit byte string, each bit of the Bitmap corresponds to the slice data packet fragment number PSeq according to a specific rule, which intuitively reflects whether each slice data packet is received or not. The BitmapLen is calculated based on the total number of slice data packets FragNum (such as BitmapLen = (FragNum mod 8) + 1 (when not divisible)), which is used for the terminal to accurately parse the bitmap data.

[0048] The calculation formula for the bit corresponding to the fragment number PSeq is: (PSeq mod 8) + remainder - 1 (where the initial value of remainder is 0);

[0049] The calculation formula of the byte length of Bitmap is: BitmapLen = (FragNum mod 8) + 1 (when not divisible), remainder is the parameter for calculating the offset, and its initial value is set to 0. When calculating the bit position corresponding to the fragment number PSeq, first take PSeq mod 8 to get the remainder of 0 - 7, add remainder and subtract 1 to determine the corresponding bit position of the fragment number in Bitmap, ensuring that the terminal can accurately judge the reception status of the slice data packet based on the bitmap response;

[0050] S6: The terminal analyzes the situation of receiving the fragmented data packets by the user server according to the received bitmap response. If all the fragmented data packets are received by the user server, the terminal jumps to S8. If there is a situation where the fragmented data packets are not received, the terminal jumps to S7.

[0051] S7: The terminal retransmits the fragmented data packets that have not been received, and resends the bitmap confirmation frame request to the user server after the retransmission is completed.

[0052] S6 and S7 can be repeated multiple times until the terminal analyzes the bitmap response and finds that all slice data packets have been sent.

[0053] S8: The terminal releases the channel resources and the transmission of the large data packet ends.

[0054] refer to Figure 1 and Figure 2 A reliable transmission system for large data packets of an LPWAN Internet of Things includes a terminal, a network server and a user server; the terminal is a sending side of a slice data packet and a bitmap confirmation frame, and is also a receiving side of a bitmap response; the user server is a receiving side of a slice data packet and a bitmap confirmation frame, and is also a sending side of a bitmap response; the network server is a transfer side of slice data packets, bitmap confirmation frames and bitmap responses, and the terminal, the network server and the user server are communicatively connected to implement a reliable transmission method for large data packets of an LPWAN Internet of Things as claimed in claim 1.

[0055] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A reliable transmission method for large data packets of LPWAN Internet of Things, characterized in that: The terminal forwards the large data packet to the user server through the network server. Before transmitting the large data packet, it needs to be sliced ​​into multiple slice data packets. The transmission method includes the following steps: S1: The terminal calculates the large data packet to be transmitted according to the current spreading factor SF level, obtains the number of bytes transmitted by each slice data packet, and performs a slice operation on the large data packet; S2: The terminal applies for a dedicated channel from the network server and sends a large data packet sending request message on the dedicated channel; S3: The network server forwards the large data packet sending request message to the user server, and the user server replies with a response message to the network server, which is then forwarded to the terminal via the network server; S4: The terminal starts to transmit the slice data packets one by one. After all the slice data packets are transmitted, the terminal sends a bitmap confirmation frame request to the user server; S5: The user server replies a bitmap response to the terminal; S6: The terminal analyzes the situation of receiving the fragmented data packet by the user server according to the received bitmap response. If the fragmented data packet is completely received, the terminal jumps to S8. If the fragmented data packet is not received, the terminal jumps to S7. S7: retransmit the fragmented data packets that have not been received, and resend the bitmap confirmation frame request to the user server after the retransmission is completed; S8: The terminal releases the channel resources and the transmission of the large data packet ends.

2. According to claim 1, a reliable transmission method for large data packets of LPWAN Internet of Things is characterized in that: The terminal records the total number of sliced ​​data packets after the slicing operation, and records the total number of data packets as FragNum, and assigns a slice number to each of the sliced ​​data packets, and records the slice number as PSeq.

3. The reliable transmission method of large data packets of LPWAN Internet of Things according to claim 2 is characterized in that: The message structure of the bitmap response includes a MessageID field for identifying a slice data packet confirmation frame, a Bitmap field for indicating a receiving status of each slice data packet, and a BitmapLen field for indicating a length of the Bitmap.

4. The reliable transmission method of large data packets of LPWAN Internet of Things according to claim 3 is characterized in that: The field MessageID is a confirmation frame that identifies the slice data packet; The Bitmap is an octet string, and each bit of the Bitmap represents whether the slice data packet corresponding to the slice number PSeq is received; The BitmapLen is the byte length of the Bitmap.

5. The reliable transmission method of large data packets of LPWAN Internet of Things according to claim 4 is characterized in that: The calculation formula of the slice number PSeq corresponding to the bit is: (PSeq mod 8) + remainder - 1 (where the initial value of remainder is 0).

6. The reliable transmission method of large data packets of LPWAN Internet of Things according to claim 4 is characterized in that: The calculation formula of the byte length of the Bitmap is: BitmapLen = (FragNum mod 8) + 1 (when not divisible).

7. The reliable transmission method of large data packets of LPWAN Internet of Things according to claim 1 is characterized in that: The large data packet sending request message includes file name, generation time, total number of fragments and length information of each fragment.

8. The reliable transmission method of large data packets of LPWAN Internet of Things according to claim 1 is characterized in that: The length of each slice data packet is the same, but the tail slice is different.

9. The reliable transmission method of large data packets of LPWAN Internet of Things according to claim 1 is characterized in that: The spreading factor SF level is 5-12.

10. A reliable transmission system for large data packets of LPWAN Internet of Things, characterized in that: It includes a terminal, a network server and a user server; the terminal is the sending side of the slice data packet and the bitmap confirmation frame, and is also the receiving side of the bitmap response; the user server is the receiving side of the slice data packet and the bitmap confirmation frame, and is also the sending side of the bitmap response; the network server is the transfer side of the slice data packet, the bitmap confirmation frame and the bitmap response, and the terminal, the network server and the user server are communicatively connected to implement a large data packet reliable transmission method of a LPWAN Internet of Things as described in claim 1.

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