A data transmission method, system and storage medium

Abstract

The present invention discloses a data transmission method, apparatus and storage medium. The method includes that the source end and the destination end perform TCP data transmission through a forwarding device, wherein the forwarding device is directly or indirectly connected to the destination end through an air interface; when the forwarding device detects that the packet forwarding through the air interface fails, it sends an ACK packet to the source end; the source end records the sequence number and length of the packet whose forwarding through the air interface fails, and associates them with the corresponding TCP data stream to form a list of data with failed forwarding through the air interface. By applying the method of the present invention, after packet loss occurs in the air interface, the forwarding device sends the sequence number and length of the lost packet to the source end, and the source end no longer processes according to packet loss when receiving duplicate acknowledgment numbers subsequently, and does not adjust the congestion window and the slow start threshold, so as not to reduce the performance of data transmission.

Description

Technical Field

[0001] The present invention relates to a data transmission method, system and storage medium, belonging to the technical field of data transmission, especially in the field of transmitting data using air interfaces such as 4G and 5G, such as air interface data transmission in the field of edge computing and data transmission of mobile broadband. Background Art

[0002] The 5G technology promotes the development of all walks of life in society, such as vehicle-to-everything (V2X) and intelligent mines, making the industry more intelligent and efficient. Many technologies are involved behind these transformations, such as AI model optimization and data transmission. In the field of mobile broadband, the download and live broadcast of high-definition videos also involve the transmission of data over the air interface.

[0003] There are two commonly used technologies in the transport layer for data transmission: one is the UDP (User Datagram Protocol), which provides a method for application programs to send encapsulated IP data packets without establishing a connection; the other is the TCP (Transmission Control Protocol), which is a connection-oriented, reliable, byte-stream-based transport layer communication protocol.

[0004] TCP transmission includes four parts: slow start, congestion avoidance, fast retransmission, and fast recovery.

[0005] (1) Slow Start

[0006] Whenever a TCP connection is established or a TCP connection times out and retransmits, the connection enters the slow start phase. After entering the slow start, the TCP entity initializes the size of the congestion window to one segment, that is: cwnd = 1 (congestion window). Thereafter, for each acknowledgment (ACK) of a segment received, the cwnd value is incremented by 1, that is, the congestion window increases exponentially. When the cwnd value exceeds the slow start threshold (ssthresh slow start thresh) or a segment is lost and retransmitted, the slow start phase ends. In the former case, it enters the congestion avoidance phase, and in the latter case, it re-enters the slow start phase.

[0007] (2) Congestion Avoidance

[0008] In the slow start phase, when the cwnd value exceeds the slow start threshold (ssthresh), the slow start process ends, and the TCP connection enters the congestion avoidance phase. In the congestion avoidance phase, after all the cwnd segments sent each time are fully acknowledged, the cwnd value is incremented by 1. In this phase, the cwnd value increases linearly.

[0009] (3) Fast Retransmission

[0010] Fast retransmission is an improvement over timeout retransmission. When the source end receives three duplicate acknowledgments for the same packet, it determines that a packet segment has been lost, so it immediately retransmits the lost packet segment without waiting for the retransmission timer (RTO, Retransmission Time Out, the RTO value is usually set large to avoid false retransmissions) to time out, reducing unnecessary waiting time.

[0011] (4) Fast recovery

[0012] Fast recovery is an improvement over the loss recovery mechanism. After fast retransmission, it directly enters the congestion avoidance phase without going through the slow start process. Whenever fast retransmission occurs, set ssthresh = cwnd / 2 and cwnd = ssthresh + 3.

[0013] After a network packet loss occurs in TCP, it will enter slow start or fast recovery. Detecting packet loss through the acknowledgment sequence number usually significantly reduces cwnd, thus reducing the data transmission efficiency. These algorithms adjust and control the slow start threshold (ssthresh) and the congestion window cwnd to control the data sending rate of TCP. When detecting the existence of packet loss, the congestion control algorithm logic of TCP will reduce the congestion window to avoid network congestion. When the congestion window decreases, the sending rate of TCP will decrease, thus reducing the data transmission efficiency.

[0014] When using the air interface for data transmission, due to the rapid change of the channel or the existence of interference, some TCP data packets will experience transmission failures during the air interface transmission process, causing the congestion control algorithm to mistakenly think that network congestion has occurred, adjust the congestion window and the congestion control state, reduce the data transmission sending rate, and thus reduce the data transmission efficiency.

[0015] The TCP header contains an acknowledgment field for acknowledging the received packets. The source end can use this field to learn about the packets that the destination end has received.

[0016] Common TCP congestion control algorithms include Reno, NewReno, Westwood, Cubic, etc. The Reno algorithm can be referred to the description in 3.1. NewReno is an improved version based on Reno, mainly improving the fast recovery algorithm. The fast recovery algorithm proposed by Reno improves the throughput and robustness after packet loss, but its defect is that it only considers the case of losing only one packet. As long as one packet is lost, it is considered that a congestion has occurred. In the actual network, once congestion occurs, a large number of packets will be discarded. If the Reno algorithm is adopted, it will consider that multiple congestions have occurred in the network, and then it will halve cwnd and ssthresh multiple times, resulting in a significant decrease in throughput. When the sending window is less than 3, it will not be able to generate enough ACKs to trigger fast retransmission and lead to timeout retransmission. The impact of timeout retransmission is very large.

[0017] In the case of losing only one data packet, the processing methods of NewReno and Reno are the same. When multiple packets are lost in the same time period, NewReno has made improvements. In the Reno fast recovery algorithm, as long as the sender receives a new ACK, it will exit the fast recovery state and enter the congestion avoidance phase. In the NewReno algorithm, it will only exit after all the lost packets are retransmitted and acknowledged. This avoids the multiple rapid halvings of cwnd and ssthresh.

[0018] These algorithms handle the congestion window and the threshold of slow start based on packet loss events. There are two methods for judging packet loss events: one is retransmission timeout, and the other is receiving three duplicate acknowledgments continuously. The principle of timeout retransmission is that after sending a certain piece of data, a timer is started. If the ACK packet of the sent data packet is not received within a certain period of time, then the data is resent until the sending is successful. The destination end acknowledges the received TCP packets. When the same acknowledgment is received multiple times, the source end considers that the data packet starting from the acknowledgment sequence number is lost. In both of the above cases, the source end considers that a packet loss has occurred.

[0019] The current TCP algorithms (Reno, NewReno, Westwood, Cubic) will misinterpret the packet loss at the air interface as the packet loss caused by network congestion. The source end cannot distinguish between the packet loss caused by air interface reasons and the packet loss caused by network congestion. After the packet loss occurs due to air interface reasons, the congestion control logic adjusts the congestion control window and the slow start threshold, reducing the data packet sending rate, and thus reducing the data transmission efficiency. Summary of the Invention

[0020] To solve the above problems existing in the prior art, the present invention provides a data transmission method, system and storage medium, aiming to improve the TCP data transmission efficiency with an air interface transmission path, reduce or eliminate the decrease in TCP transmission efficiency caused by packet loss due to air interface reasons, and improve the TCP data transmission efficiency.

[0021] To achieve the above object, the first aspect of the present invention provides a data transmission method, including,

[0022] S1. The source end and the destination end perform TCP data transmission through a forwarding device, where the forwarding device is directly or indirectly connected to the destination end through the air interface;

[0023] S2. When the forwarding device detects that the air interface forwarding of a data packet fails, it sends an ACK data packet containing a TCP packet loss option to the source end;

[0024] S3. The source end parses the TCP packet loss option, records the sequence number and length of the data packet with failed air interface forwarding, and associates it with the corresponding TCP data stream to form a list of data packets with failed air interface forwarding.

[0025] Further, it further includes S4. When the source end receives a duplicate ACK packet, it searches in the list of data packets with failed air interface forwarding according to the acknowledgment number and flow identifier to check if there is a corresponding entry. If there is a sequence number that matches the acknowledgment number, the congestion window and slow start threshold are not changed; otherwise, the congestion window and slow start threshold are adjusted. If the acknowledgment number is greater than the sequence number in the entry, the corresponding entry is deleted.

[0026] Further, after S3 or S4, it further includes SS. The source end retransmits the lost packet.

[0027] Further, the ACK packet containing the TCP packet loss option is constructed by the forwarding device as a TCP ACK packet corresponding to the destination end, and then the TCP packet loss option is inserted, or the TCP packet loss option is inserted into the ACK packet of the destination end.

[0028] Further, the forwarding device is a base station, CPE or baseband processing unit. When the forwarding device is a baseband processing unit, the source end and the baseband processing unit are located inside the same device with mobile communication functions.

[0029] Furthermore, the device with mobile communication functions is a smart phone, vehicle-mounted terminal, edge computing device, camera or radar.

[0030] Further, the TCP packet option of the ACK data packet includes the sequence number and length of the data packet with failed air interface forwarding.

[0031] Furthermore, the TCP packet option of the ACK packet further includes available bandwidth for the source end to adjust relevant parameters of the flow, such as congestion window, slow start threshold, etc.

[0032] In a second aspect of the present invention, a data transmission system is provided, including a source end, a forwarding device, and a destination end, where

[0033] The source end is used to send data to the destination end and receive ACK packets from the forwarding device and the destination end. When a packet forwarding fails over the air interface, it is used to parse the TCP packet loss option, record the sequence number and length of the packet that fails to be forwarded over the air interface, and associate it with the corresponding TCP data flow to form a list of data that fails to be forwarded over the air interface;

[0034] The forwarding device is communicatively connected to the source end and the destination end on both sides, and is directly or indirectly connected to the destination end through the air interface; when detecting that a packet forwarding fails over the air interface, it is used to send an ACK packet containing the TCP packet loss option to the source end;

[0035] The destination end is used to receive data from the source end and send ACK packets to the source end.

[0036] In a third aspect of the present invention, a storage medium is provided, in which a computer program is stored, and the computer program is configured to execute any one of the above data transmission methods when running.

[0037] The present invention has the following beneficial effects: after a packet loss occurs over the air interface, the forwarding device sends the sequence number and length of the lost packet to the source end. When the source end receives duplicate acknowledgment numbers subsequently, it no longer processes according to packet loss and does not adjust (reduce) the congestion window and slow start threshold, thus not reducing the data transmission efficiency. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0039] Figure 1 It is a flowchart of the data transmission method according to the embodiment of the present invention;

[0040] Figure 2 It is a schematic diagram of the TCP packet header structure in the embodiment of the present invention;

[0041] Figure 3 It is a flowchart of the processing after the source end receives a duplicate ACK packet in the embodiment of the present invention;

[0042] Figure 4 It is a flowchart of the data transmission method in a specific example of the embodiment of the present invention;

[0043] Figure 5 It is a flowchart of another specific example. Detailed implementation manners

[0044] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0045] It should be noted that the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those clearly listed steps or units, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or devices.

[0046] In this embodiment, the source end refers to a device, program (process, thread, function) that sends data using the TCP protocol, and the destination end is a device, program that receives data using the TCP protocol. At least one of the source end and the destination end communicates directly or indirectly through a forwarding device via the air interface. Direct means that the source end (destination end) directly connects to the forwarding device via the air interface, and indirect means that the source end (destination end) connects to a wired device (such as a switch or CPE) and then connects to the forwarding device via the air interface.

[0047] This embodiment provides a data transmission method, and the process is as Figure 1 shown, including the following steps:

[0048] S1. The source end and the destination end perform TCP data transmission through a forwarding device, where the forwarding device is directly or indirectly connected to the destination end via the air interface.

[0049] In this embodiment, the connection between the source end and the forwarding device is usually a wired connection, such as through devices such as Ethernet, router, switch, etc., and the forwarding device and the destination end perform data transmission through mobile communication methods such as 4G and 5G.

[0050] S2. When the forwarding device detects that the packet forwarding through the air interface fails, it sends an ACK packet containing the TCP packet loss option to the source end.

[0051] To Figure 1The following describes the situation. For example, if a data packet with a sequence number of 1000 and a length of 100 fails during the air interface forwarding process, the forwarding device constructs an ACK data packet and uses the TCP option to record that the data packet with a sequence number of 1000 and a length of 100 fails during the air interface forwarding.

[0052] The above ACK data packet can be constructed based on the ACK packet at the destination end, and an option field is inserted into it. The sequence number and length of the data packet that fails in the air interface forwarding are recorded in the option field, or only the sequence number can be recorded; the forwarding device can also directly construct a brand-new ACK data packet, where the acknowledgment number can be the acknowledgment number of the previous ACK packet sent by the destination end, and an option field is added to the TCP header to record the sequence number and length of the data packet that fails in the air interface forwarding. The TCP header structure is as Figure 2 shown.

[0053] S3. The source end parses the TCP packet loss option, records the sequence number and length of the data packet that fails in the air interface forwarding, and associates it with the corresponding TCP data stream to form a list of data packets that fail in the air interface forwarding.

[0054] A table is established to store the data information of the data packets that fail in the air interface forwarding, which can include parameters such as flow identifier, sequence number, and length, as shown in Table 1. After the source end receives the ACK data packet sent by the forwarding device, according to the sequence number, length, and other information of the data packet that fails in the air interface forwarding carried in the ACK data packet, a record is inserted into Table 1 and associated with the TCP data stream that fails in forwarding.

[0055] Table 1

[0056]

[0057] In some specific embodiments, it further includes,

[0058] S4. When the source end receives a duplicate ACK packet, it searches in the list of data packets that fail in the air interface forwarding for whether there is a corresponding table entry according to the acknowledgment number and flow identifier. If there is a sequence number that matches the acknowledgment number, the congestion window and slow start threshold are not changed, otherwise the congestion window and slow start threshold are adjusted; if the acknowledgment number is greater than the sequence number in the table entry, the corresponding table entry is deleted. The above processing steps are as Figure 3 shown.

[0059] After S3 or S4, it further includes SS. The source end retransmits the lost packet.

[0060] The forwarding device can be a base station, a CPE (Customer Premise Equipment), or a baseband processing unit. When the forwarding device is a baseband processing unit, the source end and the baseband processing unit are located inside the same device with mobile communication functions.

[0061] It should be noted that the device with mobile communication function can be a smart phone, in-vehicle terminal, edge computing device, camera or radar.

[0062] In some specific embodiments, in the TCP message option of the ACK data packet, in addition to the sequence number and length of the packet that fails to be forwarded over the air interface, the available bandwidth is also included, which is used for the source end to adjust the relevant parameters of the stream, such as the congestion window, slow start threshold, etc.

[0063] Similarly, in the TCP message option of the first duplicate ACK packet sent by the forwarding device to the source end, the sequence number and length of the packet that fails to be forwarded over the air interface are also included.

[0064] The following further illustrates the process of the data transmission method of this embodiment through two examples.

[0065] Example 1

[0066] The method described in this embodiment is used in the process of data transmission between the base station and the mobile phone. Assume that the mobile phone downloads a file through the FTP protocol or the edge computing device downloads and updates the firmware through the air interface. At this time, the mobile phone or the edge computing device is the destination end of the data transmission, and the firmware server and the FTP server are the source ends. The source end and the destination end have established a TCP connection through a three-way handshake. Source IP address: 172.171.6.10, destination IP address: 9.171.6.11, source port 4500, destination port: 20100.

[0067] As Figure 4 shown, the source end sends a data packet with a sequence number of 1000 and a length of 100 to the destination end.

[0068] After the data packet arrives at the base station, the base station forwards it to the destination end. Due to reasons such as sudden changes in the channel, the bit error rate increases, resulting in incorrect decoding at the destination end and ultimately a forwarding failure.

[0069] After the base station obtains the message information (sequence number 1000, length 100, source and destination IP addresses and port numbers), it constructs a message loss option and inserts this option into the TCP header of the ACK message at the destination end, or a newly constructed TCP ACK message by the base station. TCP option is as follows: option type value 32, option length is 6, length is 100, sequence number is 1000. This function can be implemented by the RIC (Radio Intelligent Controller) in the base station.

[0070] This embodiment also provides a data transmission system, including a source end, a forwarding device and a destination end, where,

[0071] A source end, which is used to send data to a destination end and receive ACK data packets from a forwarding device and the destination end. When a packet forwarding fails over the air interface, it is used to parse the TCP packet loss option, record the sequence number and length of the packet that fails to be forwarded over the air interface, and associate them with the corresponding TCP data stream to form a list of data that fails to be forwarded over the air interface.

[0072] A forwarding device, which is communicatively connected to the source end and the destination end on both sides, and is directly or indirectly connected to the destination end through the air interface; when detecting that a packet forwarding fails over the air interface, it is used to send an ACK data packet containing the TCP packet loss option to the source end.

[0073] A destination end, which is used to receive data from the source end and send ACK data packets to the source end.

[0074] This embodiment also provides a storage medium, in which a computer program is stored. Wherein, the computer program is configured to execute any one of the above data transmission methods when running.

[0075] When the source end receives the above TCP ACK packet containing the packet loss option, it inserts a packet loss record into the list of data that fails to be forwarded over the air interface, as shown in Table 2.

[0076] Table 2

[0077]

[0078] The source end determines by whether the TCP header option of the received ACK data packet carries the sequence number and length. If the sequence number is the same as the previous acknowledgment number, no duplicate ACK processing is performed.

[0079] The source end learns that the packet segment has been lost and re-sends the packet segment, where the packet sequence number is 1000 and the length is 100.

[0080] When the source end receives a duplicate ACK data packet (acknowledgment number 1000), according to Figure 3 If a matching entry can be found in the list of data that fails to be forwarded over the air interface according to the process, the congestion window and slow start threshold are not adjusted. Send the packet corresponding to the sequence number of the duplicate acknowledgment number and delete the entry.

[0081] When there is no matching entry for the acknowledgment number of the received duplicate ACK data packet, it is processed according to the existing process, including adjusting the congestion window size and the slow start threshold.

[0082] Example 2

[0083] The method described in this embodiment is used inside a mobile device. For example, cameras and radars send the detected image and video data and radar data to an edge computing device through a mobile module.

[0084] As shown Figure 5 in the figure, the source end sends a data segment with a sequence number of 1000 and a length of 100 to the base station.

[0085] The data packet is forwarded by the baseband processing unit to the base station, but the forwarding fails. After obtaining the message information (sequence number 1000, length 100, source and destination IP addresses and port numbers), the baseband processing unit constructs a message loss option and inserts this option into the TCP header of the destination ACK message or a new TCP ACK message constructed by the baseband processing unit.

[0086] The TCP option is as follows: option type value 32, option length 6, length 100, sequence number 1000. This function can be implemented by the RIC (Radio Intelligent Controller) in the base station.

[0087] The source end receives the above TCP ACK message containing the message loss option and inserts a message loss record into the air interface forwarding failure data list, as shown in Table 3.

[0088] Table 3

[0089]

[0090] It is judged by whether the TCP header option of the ACK data packet received by the source end carries the sequence number and length. If the sequence number is the same as the previous acknowledgment number, no duplicate ACK processing is performed.

[0091] The source end learns that the message segment has been lost and re - sends the segment message, where the message sequence number is 1000 and the length is 100.

[0092] When the source end receives a duplicate ACK data packet (acknowledgment number 1000), according to Figure 3 the process, if a matching entry can be found in the air interface forwarding failure data list, no adjustment is made to the congestion window and slow start threshold. Send the message corresponding to the sequence number of the duplicate acknowledgment number and delete the entry.

[0093] When there is no matching entry for the acknowledgment number of the received duplicate ACK data packet, it is processed according to the existing process, including adjusting the congestion window size and the slow start threshold.

[0094] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A data transmission method, characterized in that, including, S1. The source end and the destination end perform TCP data transmission through a forwarding device, where the forwarding device is directly or indirectly connected to the destination end through an air interface; S2. When the forwarding device detects that the air interface forwarding of a data packet fails, it sends an ACK data packet containing a TCP packet loss option to the source end; S3. The source end parses the TCP packet loss option, records the sequence number and length of the data packet whose air interface forwarding fails, and associates them with the corresponding TCP data stream to form a list of data packets with failed air interface forwarding; It also includes S4. When the source end receives a duplicate ACK packet, it checks whether there is a corresponding entry in the list of data packets with failed air interface forwarding according to the acknowledgement number and flow identifier. If there is a sequence number that matches the acknowledgement number, the congestion window and slow start threshold are not changed; otherwise, the congestion window and slow start threshold are adjusted. If the acknowledgement number is greater than the sequence number in the entry, the corresponding entry is deleted.

2. The data transmission method according to claim 1, wherein After S3 or S4, it further includes SS. The source end re - sends the lost packets.

3. According to the data transmission method described in claim 1, the ACK packet containing the TCP packet loss option is constructed by the forwarding device as a TCP ACK packet corresponding to the destination end, and then the TCP packet loss option is inserted, or the TCP packet loss option is inserted into the ACK packet of the destination end.

4. The data transmission method according to claim 1, wherein The forwarding device is a base station, a CPE or a baseband processing unit. When the forwarding device is a baseband processing unit, the source end and the baseband processing unit are inside the same device with mobile communication functions.

5. The data transmission method according to claim 4, characterized in that The device with mobile communication functions is a smart phone, a vehicle terminal, an edge computing device, a camera or a radar.

6. The data transmission method according to claim 1, characterized in that, The TCP packet option of the ACK data packet includes the sequence number and length of the data packet with failed air interface forwarding.

7. The data transmission method according to claim 6, wherein The TCP packet option of the ACK data packet also includes the available bandwidth.

8. A data transmission system, characterized in that, It includes a source end, a forwarding device and a destination end, where The source end is used to send data to the destination end and receive ACK data packets from the forwarding device and the destination end. When the air interface forwarding of a data packet fails, it is used to parse the TCP packet loss option, record the sequence number and length of the data packet with failed air interface forwarding, and associate them with the corresponding TCP data stream to form a list of data packets with failed air interface forwarding; The forwarding device is communicatively connected to the source end and the destination end on both sides, where it is directly or indirectly connected to the destination end through an air interface; when it detects that the air interface forwarding of a data packet fails, it is used to send an ACK data packet containing a TCP packet loss option; The destination end is used to receive data from the source end and send ACK data packets to the source end; When the source end receives a duplicate ACK packet, it checks whether there is a corresponding entry in the list of data packets with failed air interface forwarding according to the acknowledgement number and flow identifier. If there is a sequence number that matches the acknowledgement number, the congestion window and slow start threshold are not changed; otherwise, the congestion window and slow start threshold are adjusted. If the acknowledgement number is greater than the sequence number in the entry, the corresponding entry is deleted.

9. A computer-readable storage medium, characterized in that, A computer program is stored in the computer-readable storage medium, wherein the computer program is configured to execute the method described in any one of claims 1 to 7 when running.

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