Reliable transmission method and system for space-air-ground integrated network

Abstract

The invention provides a reliable transmission method and system for an air-space-ground integrated network. The method comprises the following steps that: an end A numbers each sent frame according to a frame serial number SN field; and the B end performs selective negative acknowledgement on each received frame according to the selective negative acknowledgement SNACK field. Through the design of the selective negative acknowledgement SNACK field, the technical bottlenecks of low efficiency, complexity and the like of reliable transmission of the air-space-ground integrated network can be solved, reliable transmission of the air-space-ground integrated network can be ensured efficiently and simply at low overhead, and the air-space-ground integrated network with high robustness and high bandwidth is constructed.

Description

Technical Field

[0001] The present invention belongs to the field of space-air-ground integrated networks, and particularly relates to reliable transmission at the link layer of satellite communication, space-based networks, and air-based networks. Specifically, it relates to a reliable transmission method and system for space-air-ground integrated networks. Background Art

[0002] The space-air-ground integrated network aims to achieve seamless coverage and efficient communication globally by integrating space-based networks (such as high, medium, and low earth orbit satellite networks), air-based networks (such as unmanned aerial vehicle networks, high-altitude aircraft networks, and aviation Internet), and ground-based networks (such as fiber optic networks and terrestrial mobile communication networks).

[0003] The Consultative Committee for Space Data Systems (CCSDS) in the space communication network protocol family defines four data link layer transmission protocols adapted to different scenarios: USLP (Unified Space Data Link Protocol) / AOS (Advanced Orbiting Systems) / TC (TeleCommand) / TM (TeleMetry) / Prox-1 (Proximity-1), which realizes efficient transmission and provides an infrastructure for building space-air-ground integrated networks.

[0004] Compared with the physical layer of the space-air-ground integrated network and the ground-based network, it has characteristics such as a high bit error rate (the bit error rate is as high as 10 -4 ), high latency (sub-microseconds), and high latency jitter (milliseconds). The requirement for reliable data transmission poses a huge challenge to the design of the data link layer. Although the CCSDS space communication network protocol family also defines process mechanisms such as COP-1 (Communication Operation Procedure-1)\COP-P (Communication Operation Procedure-Proximity) in the data link layer to improve the reliability of space transmission, there are defects such as a significant reduction in transmission efficiency, complex protocols, difficult implementation, and poor general compatibility. Summary of the Invention

[0005] The present invention aims to provide a reliable transmission method for space-air-ground integrated networks to solve the above problems.

[0006] In a first aspect, the present invention provides a reliable transmission method for space-air-ground integrated networks, including:

[0007] The A end numbers each frame to be sent according to the SN field of the frame sequence number;

[0008] The B-side performs selective negative acknowledgment on each received frame according to the selective negative acknowledgment SNACK field.

[0009] In some embodiments, the frame sequence number SN field indicates that each frame sent is incrementally numbered by natural number increment.

[0010] In some embodiments, the frame sequence number SN field indicates that the sequence number has a maximum value, and when the maximum value is exceeded, it starts incrementing and cycling from 0.

[0011] In some embodiments, the design principles of the selective negative acknowledgment SNACK field include:

[0012] The selective negative acknowledgment is carried in the data frame sent from the B-side to the A-side, and no additional acknowledgment frame is sent;

[0013] The B-side only acknowledges the sequence numbers of the frames that need to be retransmitted to the A-side;

[0014] It can cope with block continuous bit errors and occasional random bit errors in the physical layer channel.

[0015] In some embodiments, the selective negative acknowledgment SNACK field includes:

[0016] Selective negative acknowledgment identifier SNACK FLAG, indicating the start bit of the selective negative acknowledgment SNACK field;

[0017] Selective negative acknowledgment identification number SNACK ID, indicating the frames of the A-side belonging to the same round of sequence numbers;

[0018] The first serial number of the first block of continuously unreceived frames NACK FSN, indicating the first serial number of the first block of frames with continuous serial numbers that need to be retransmitted;

[0019] The last serial number of the first block of continuously unreceived frames NACK LSN, indicating the last serial number of the first block of frames with continuous serial numbers that need to be retransmitted;

[0020] The tail of the first block of continuously unreceived frame area NACK FBM, indicating the identification by bit of the frame sequence numbers that have not been received starting from the second frame. Those that need to be retransmitted are set to "1", and those that do not need to be retransmitted are set to "0".

[0021] In a second aspect, the present invention provides a reliable transmission system for an integrated space-air-ground network, including:

[0022] An A-side, used to number each frame sent according to the frame sequence number SN field;

[0023] A B-side, used to perform selective negative acknowledgment on each received frame according to the selective negative acknowledgment SNACK field.

[0024] In some embodiments, the frame sequence number SN field indicates that each frame sent is incrementally numbered by a natural number.

[0025] In some embodiments, the frame sequence number SN field indicates that the sequence number has a maximum value, and after exceeding the maximum value, it starts incrementing and cycling from 0 again.

[0026] In some embodiments, the design principles of the selective negative acknowledgment SNACK field include:

[0027] The selective negative acknowledgment is carried in the data frame sent from end B to end A, and no additional acknowledgment frame is sent;

[0028] End B only acknowledges the sequence numbers of the frames that need to be retransmitted to end A;

[0029] It can handle block continuous errors and occasional accidental errors in the physical layer channel.

[0030] In some embodiments, the selective negative acknowledgment SNACK field includes:

[0031] The selective negative acknowledgment identifier SNACK FLAG, which indicates the start bit of the selective negative acknowledgment SNACK field;

[0032] The selective negative acknowledgment identification number SNACKID, which indicates the frames of the same round of sequence numbers at end A;

[0033] The first sequence number of the first block of continuously unreceived frames NACK FSN, which represents the first sequence number of the first block of frames with consecutive sequence numbers that need to be retransmitted;

[0034] The last sequence number of the first block of continuously unreceived frames NACK LSN, which represents the last sequence number of the first block of frames with consecutive sequence numbers that need to be retransmitted;

[0035] The tail of the first block of continuously unreceived frame area NACK FBM, which indicates that starting from the second frame, the identification of the unreceived frame sequence number by bit is set to "1" for frames that need to be retransmitted and "0" for frames that do not need to be retransmitted.

[0036] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are:

[0037] Through the design of the selective negative acknowledgment SNACK field, the present invention can solve the technical bottlenecks such as low efficiency and complexity in reliable transmission of the space-air-ground integrated network, and can ensure the reliable transmission of the space-air-ground integrated network with low overhead, high efficiency and simplicity, and build a highly robust and high-bandwidth space-air-ground integrated network. Brief Description of the Drawings

[0038] Figure 1Schematic diagram of the send - receive model for transmission in the embodiments of the present invention.

[0039] Figure 2 Schematic diagram of the design of the Selective Negative - ACKnowledgment (SNACK) field in the embodiments of the present invention.

[0040] Figure 3 Schematic diagram of an example of the sequence number of the received frame at end B in the embodiments of the present invention.

[0041] Figure 4 Schematic diagram of an example of the Selective Negative - ACKnowledgment (SNACK) field at end B in the embodiments of the present invention. Detailed implementation manners

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0043] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0044] Embodiment 1

[0045] As Figure 1 shown, the embodiments of the present invention propose a reliable transmission method for an air - space - ground integrated network, including:

[0046] According to the send - receive model for transmission, in the frame header transmitted at the network link layer, design a frame sequence number SN (Sequence Number) field and a Selective Negative - ACKnowledgment (SNACK) field;

[0047] End A numbers each frame transmitted according to the frame sequence number SN field;

[0048] End B makes selective negative acknowledgments for each received frame according to the Selective Negative - ACKnowledgment (SNACK) field, that is, end B acknowledges the sequence numbers of the frames that need to be re - transmitted.

[0049] In an embodiment, the design of the frame sequence number SN field at end A is as follows: 1 byte (8 bits), ranging from 0 to 255, and each frame sent is incrementally numbered by natural numbers; when it exceeds the maximum value of 225, it starts incrementing and cycling from 0 again. Thus, each round of numbering can identify 255 transmission frames.

[0050] In an embodiment, the design of the selective negative acknowledgment SNACK field at end B has the following three design principles:

[0051] (1) Low link overhead. The selective negative acknowledgment is slightly carried in the data frame sent from end B to end A, without sending a separate acknowledgment frame.

[0052] (2) High transmission efficiency. End B only acknowledges the sequence numbers of the frames that need to be retransmitted to end A, avoiding duplicate frame transmission.

[0053] (3) Applicable to many scenarios. It can handle different scenarios such as block continuous bit errors and occasional accidental bit errors in the physical layer channel.

[0054] Based on the above design principles, as Figure 2 shown, the 4-byte (32-bit) selective negative acknowledgment SNACK field is designed as follows:

[0055] Selective negative acknowledgment identifier SNACK FLAG, 2 bits, indicating the start bit of the selective negative acknowledgment SNACK field. For example, 0b11 indicates that the 4-byte field starting from this bit is the selective negative acknowledgment field, and other values are reserved for future use.

[0056] Selective negative acknowledgment identification number SNACK ID, 2 bits, indicating the frames at end A with the same round of sequence numbers. That is, if the frames at end A with the same round of sequence numbers (the frame sequence numbers are counted from 0 to 255 without cyclic counting), the selective negative acknowledgment identification number SNACK ID is set to be the same. The selective negative acknowledgment identification number SNACK ID can be designed to cycle through values from 0 to 3.

[0057] The first sequence number of the first block of continuously unreceived frames NACK FSN (Negative-ACKnowledgment FirstSequence Number), 8 bits, representing the first sequence number of the first block of frames with consecutive sequence numbers that need to be retransmitted.

[0058] The last sequence number of the first block of continuously unreceived frames NACK LSN (Negative-ACKnowledgment LastSequence Number), 8 bits, representing the last sequence number of the first block of frames with consecutive sequence numbers that need to be retransmitted.

[0059] The tail NACK FBM (Negative-ACKnowledgment Following Bit Mapping) of the first consecutive unacknowledged frame region indicates, starting from the second frame, the identification of the unacknowledged frame sequence number by bit. For retransmission, it is set to "1", and for no retransmission, it is set to "0". It is 12 bits and can be used to acknowledge the subsequent 13 frames in a consecutive unacknowledged frame region. Since the first frame after the region of the first consecutive unacknowledged frames is definitely received correctly, there is no need for identification.

[0060] An example design of a selective negative acknowledgment SNACK field:

[0061] If Party A sends a series of transmission frames with the frame sequence number SN field starting from 0 after the transmission is enabled, due to blocky consecutive bit errors and occasional random bit errors caused by poor physical layer channel quality, arranging the received frame sequence numbers at Party B together, the intuitive representation is as Figure 3 shown. The dark colors represent the correctly received frame sequence numbers, and the light colors represent the incorrectly received frame sequence numbers. It can be seen that the sequence numbers of the first consecutive unacknowledged frames are from 22 to 25, and the frames with subsequent sequence numbers 27 and 28 are also not received.

[0062] As Figure 4 shown, the selective negative acknowledgment SNACK field filled by Party B is as follows.

[0063] SNACK FLAG: 0b11. A fixed identifier for the selective negative acknowledgment SNACK field.

[0064] SNACK ID: 0b00. The first round of loop after the transmission is enabled.

[0065] NACK FSN: 0b0001_0110. The first sequence number 22 of the first consecutive unacknowledged frames.

[0066] NACK LSN: 0b0001_1001. The last sequence number 25 of the first consecutive unacknowledged frames.

[0067] NACK FBM: 0b1100_0000_0000. Starting from the second frame after the region of the first consecutive unacknowledged frames, that is, starting from sequence number 27, each bit represents whether the frame needs to be retransmitted in order. The frames with sequence numbers 27 and 28 need to be retransmitted, so fill in "11", and the frames with sequence numbers 29 to 38 do not need to be retransmitted, so fill in "0" for all bits.

[0068] The SNACK fields after sequence number 39 are filled in according to the above design method and are included in the next frame sent from Party B to Party A.

[0069] Embodiment 2

[0070] Based on the same technical concept, asFigure 1 As shown in the figure, an embodiment of the present invention provides a reliable transmission system for an integrated space-air-ground network, including:

[0071] An A end, which is used to number each frame sent according to the frame sequence number SN field;

[0072] A B end, which is used to selectively negatively acknowledge each received frame according to the selective negative acknowledgment SNACK field.

[0073] In the embodiment, the design of the frame sequence number SN field in the A end is: 1 byte (8 bit), 0 to 255, and each frame sent is incrementally numbered by natural number increment; when exceeding the maximum value 225, it starts incrementing and cycling from 0 again. Thus, each round of numbering can identify 255 transmission frames.

[0074] In the embodiment, the design of the selective negative acknowledgment SNACK field in the B end has the following three design principles:

[0075] (1) Low link overhead, and the selective negative acknowledgment is slightly carried in the data frame sent from the B end to the A end without sending an additional acknowledgment frame.

[0076] (2) High transmission efficiency, and the B end only acknowledges the sequence numbers of the frames that need to be retransmitted to the A end to avoid duplicate frame transmission.

[0077] (3) Suitable for multiple scenarios, and can cope with different scenarios such as block continuous bit errors and occasional bit errors in the physical layer channel.

[0078] Based on the above design principles, as Figure 2 shown, the design of the 4-byte (32-bit) selective negative acknowledgment SNACK field is as follows:

[0079] Selective negative acknowledgment identifier SNACK FLAG, 2 bits, indicating the start bit of the selective negative acknowledgment SNACK field. For example, 0b11 indicates that the 4-byte field starting from this bit is the selective negative acknowledgment field, and other values are reserved for future use.

[0080] Selective negative acknowledgment identification number SNACK ID, 2 bits, indicating the frames of the same round of sequence numbers at the A end. That is, if the frames of the same round of sequence numbers at the A end (the frame sequence numbers are counted from 0 to 255 without cyclic counting), the selective negative acknowledgment identification number SNACK ID is set to be the same. The selective negative acknowledgment identification number SNACK ID can be designed to cycle through 0 to 3.

[0081] The first sequence number of the first block of continuously unreceived frames, NACK FSN (Negative-ACKnowledgment FirstSequence Number), 8 bits, represents the first sequence number of the frames with consecutive sequence numbers that need to be retransmitted.

[0082] The last sequence number of the first block of continuously unreceived frames, NACK LSN (Negative-ACKnowledgment LastSequence Number), 8 bits, represents the last sequence number of the frames with consecutive sequence numbers that need to be retransmitted.

[0083] The tail of the first block of continuously unreceived frame area, NACK FBM (Negative-ACKnowledgment FollowingBit Mapping), indicates the identification of the unreceived frame sequence numbers in bit form starting from the second frame. Those that need to be retransmitted are set to "1", and those that do not need to be retransmitted are set to "0", 12 bits, and can be used to respond to the subsequent 13 frames in a block of continuously unreceived frame area. Since the first frame after the area of the first block of continuously unreceived frames must be correctly received, there is no need to identify it.

[0084] For the design examples of the frame sequence number SN (Sequence Number) field and the selective negative acknowledgment SNACK (Select Negative-ACKnowledgment) field in the above A end and B end, reference can be made to the description in the method of the foregoing embodiment, and details are not described herein again.

[0085] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A reliable transmission method for an integrated space-air-ground network, characterized in that Including: The A end numbers each frame to be sent according to the frame sequence number SN field. The B end makes selective negative acknowledgments for each received frame according to the selective negative acknowledgment SNACK field.

2. The reliable transmission method for the space-air-ground integrated network according to claim 1, wherein The frame sequence number SN field indicates that each frame to be sent is incrementally numbered by natural number increment.

3. The reliable transmission method for the space-air-ground integrated network according to claim 2, wherein The frame sequence number SN field indicates that the sequence number has a maximum value, and after exceeding the maximum value, it starts incrementing cyclically from 0.

4. The reliable transmission method for the space-air-ground integrated network according to claim 1, characterized in that The design principles of the selective negative acknowledgment SNACK field include: The selective negative acknowledgment is piggybacked in the data frame sent from the B end to the A end, and no additional acknowledgment frame is sent. The B end only acknowledges the sequence numbers of the frames that need to be retransmitted to the A end. It can cope with block continuous errors and occasional random errors in the physical layer channel.

5. The reliable transmission method for the space-air-ground integrated network according to claim 4, wherein The selective negative acknowledgment SNACK field includes: The selective negative acknowledgment identifier SNACK FLAG, indicating the start bit of the selective negative acknowledgment SNACK field. The selective negative acknowledgment identification number SNACK ID, indicating the frames of the A end belonging to the same round of sequence numbers. The first serial number NACK FSN of the first block of continuously unreceived frames, representing the first serial number of the frames with continuous serial numbers that need to be retransmitted. The last serial number NACK LSN of the first block of continuously unreceived frames, representing the last serial number of the frames with continuous serial numbers that need to be retransmitted. The tail NACK FBM of the first block of continuously unreceived frame area, indicating that starting from the second frame, the identification of the unreceived frame sequence number by bit is set to "1" for retransmission and "0" for no retransmission.

6. A reliable transmission system for an integrated space-air-ground network, characterized in that, Including: The A end is used to number each frame to be sent according to the frame sequence number SN field. The B end is used to make selective negative acknowledgments for each received frame according to the selective negative acknowledgment SNACK field.

7. The reliable transmission system for the integrated space-air-ground network according to claim 6, wherein, The frame sequence number SN field indicates that each frame to be sent is incrementally numbered by natural number increment.

8. The reliable transmission system for the integrated space-air-ground network according to claim 7, characterized in that, The frame sequence number SN field indicates that the sequence number has a maximum value, and after exceeding the maximum value, it starts incrementing cyclically from 0.

9. The reliable transmission system for the space-air-ground integrated network according to claim 1, wherein The design principles of the selective negative acknowledgment SNACK field include: The selective negative acknowledgment is piggybacked in the data frame sent from the B end to the A end, and no additional acknowledgment frame is sent. The B end only acknowledges the sequence numbers of the frames that need to be retransmitted to the A end. It can cope with block continuous errors and occasional random errors in the physical layer channel.

10. The reliable transmission system for the space-air-ground integrated network according to claim 9, wherein, The selective negative acknowledgment SNACK field includes: The selective negative acknowledgment identifier SNACK FLAG, indicating the start bit of the selective negative acknowledgment SNACK field. The selective negative acknowledgment identification number SNACK ID, indicating the frames of the A end belonging to the same round of sequence numbers. The first serial number NACK FSN of the first block of continuously unreceived frames, representing the first serial number of the frames with continuous serial numbers that need to be retransmitted. The last serial number NACK LSN of the first block of continuously unreceived frames, representing the last serial number of the frames with continuous serial numbers that need to be retransmitted. The tail NACK FBM of the first block of continuously unreceived frame area, indicating that starting from the second frame, the identification of the unreceived frame sequence number by bit is set to "1" for retransmission and "0" for no retransmission.

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