KR102438684B1 - Message processing method and device in drone communication - Google Patents

Abstract

According to an embodiment of the present invention, a message processing method performed by a receiving side during communication between an unmanned aerial vehicle (UAV) and ground control equipment includes the steps of: decrypting a received message at a data link layer; determining a distribution of preamble symbol energy of the received message in a physical layer, if an error occurs during the decrypting; transmitting a NACK message for the received message when a preset distribution characteristic is shown based on a result of grasping the distribution; and forwarding the received message to an upper layer, when an error does not occur during the decrypting. Therefore, even when an error occurs in the physical layer or the lower layer of an application layer, whether or not an ACK is required can be known.

Description

METHOD AND APPARATUS FOR PROCESSING MESSAGE IN UAV COMMUNICATIONS

The present invention relates to a method and apparatus for processing messages in an unmanned aerial vehicle communication.

Unlike manned aircraft, unmanned aerial vehicles are controlled by the operator's remote control through ground control equipment, rather than by the pilot on board the aircraft. The ground control equipment sends a control command to the UAV, and the UAV executes the control command and transmits mission data to the ground control device. Therefore, in the UAV system, communication between the ground control equipment and the UAV is important.

The ground control equipment and the unmanned aerial vehicle are connected wirelessly, and in the case of wireless communication, communication errors may occur depending on the surrounding environment and various situations. For example, a transmitted packet may not be accurately transmitted due to various geographical factors and/or environmental factors, such as when the line of sight between antennas is violated, when there is severe ambient interference, or when signal attenuation occurs because of a large distance. If important messages are not transmitted correctly, the performance of the UAV system will be reduced, and if the communication disruption is serious, it may be out of the control of the ground control equipment. Therefore, accurate transmission of specific control messages or status information is essential. If a specific message is not transmitted correctly, the transmitter may retransmit the message until the receiver correctly receives the message. However, since the transmitter cannot know whether the corresponding message has been transmitted correctly after transmitting the signal, it cannot determine whether retransmission is necessary or not.

In general commercial communication, there is an ACK (acknowledgement) message that transmits a message and returns whether or not the receiver has correctly received it. If the message is correctly received, an ACK message is sent, and if there is an error in the message, a NACK (negative ACK) message is sent.

However, STANAG-4586, a UAV communication protocol that is currently used worldwide, has a function to request ACK, but only errors in message format and structure can be detected in the application layer. In other words, if the transmitted signal is normally received, the transmitted bit is decoded as it is, and transmitted to the application layer, if the values and format of the corresponding bit do not deviate from the predefined protocol, it is read as normal. It is only possible to forward this to the transmitter.

Therefore, only normal/abnormal reception response to logical and message structural errors is possible, and if the bit itself is not properly decoded due to an error occurring before the application layer or an error in the physical and data link layers, ACK/NACK can be delivered to the transmitter. there is no way

Republic of Korea Patent Publication No. 10-1115520, registration date February 06, 2012.

According to one embodiment, by differentiating the modulation scheme for the preamble of the message according to whether the transmitter requires ACK during communication between the UAV and the ground control equipment, the receiver determines the distribution of the preamble symbol energy of the received message in the physical layer. A message processing method and apparatus for determining whether to process an ACK based on an identified result are provided.

The problems to be solved of the present invention are not limited to those mentioned above, and other problems to be solved that are not mentioned will be clearly understood by those of ordinary skill in the art to which the present invention belongs from the following description.

A message processing method performed by a receiving side during communication between an unmanned aerial vehicle and a ground control device according to a first aspect comprises the steps of: decrypting a received message in a data link layer; Recognizing a distribution of preamble symbol energy, and transmitting a NACK (Negative ACK) message to the received message when a preset distribution characteristic is shown based on a result of determining the distribution; and if no error occurs, forwarding the received message to an upper layer.

An apparatus for processing a received message during communication between an unmanned aerial vehicle and a ground control device according to a second aspect includes a communication unit for transmitting and receiving a message to and from a transmitting side, and a processor unit controlling the communication unit, wherein the processor unit includes: data through the communication unit The link layer decodes the received message, and when an error occurs during the decoding, the physical layer determines the distribution of the preamble symbol energy of the received message, and shows a preset distribution characteristic based on the result of understanding the distribution. In this case, the communication unit controls the communication unit to transmit a NACK message for the received message, and if an error does not occur during the decoding, the received message is transmitted to an upper layer.

The computer readable recording medium storing the computer program according to the third aspect, when the computer program is executed by a processor, comprises the steps of: decrypting a received message in a data link layer; Recognizing a distribution of the preamble symbol energy of the received message in a layer, and transmitting a NACK message for the received message when a preset distribution characteristic is indicated based on a result of identifying the distribution; Including instructions for causing the processor to perform a message processing method performed by the receiving side during communication between the UAV and the ground control equipment, including transmitting the received message to an upper layer if no error occurs during decoding do.

The computer program stored in the computer-readable recording medium according to the fourth aspect, when the computer program is executed by a processor, comprises the steps of: decrypting a received message in a data link layer; Recognizing a distribution of the preamble symbol energy of the received message in a layer, and transmitting a NACK message for the received message when a preset distribution characteristic is indicated based on a result of identifying the distribution; Including instructions for causing the processor to perform a message processing method performed by the receiving side during communication between the UAV and the ground control equipment, including transmitting the received message to an upper layer if no error occurs during decoding do.

According to an embodiment of the present invention, by differentiating the modulation scheme for the preamble of the message according to whether the transmitter needs ACK during communication between the UAV and the ground control equipment, the receiver can adjust the preamble symbol energy of the received message in the physical layer. Whether to process ACK may be determined based on the result of determining the distribution of Therefore, even when an error occurs in the physical layer or the lower layer of the application layer, it is possible to know whether ACK is required or not, and there is an effect that a request for retransmission of a message can be performed.

1 is a block diagram of a message processing apparatus according to an embodiment of the present invention.
2 is a flowchart illustrating a message processing method performed by a message processing apparatus according to an embodiment of the present invention.
3 is a message structure diagram of STANAG-4586 protocol.
4 is a BPSK constellation diagram.
5 is a QBPSK constellation diagram.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention pertains It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

Terms used in this specification will be briefly described, and the present invention will be described in detail.

The terms used in the present invention have been selected as currently widely used general terms as possible while considering the functions in the present invention, but these may vary depending on the intention or precedent of a person skilled in the art, the emergence of new technology, and the like. In addition, in a specific case, there is a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, rather than the name of a simple term.

In the entire specification, when a part 'includes' a certain element, this means that other elements may be further included, rather than excluding other elements, unless otherwise stated.

In addition, the term 'unit' used in the specification means software or hardware components such as FPGA or ASIC, and 'unit' performs certain roles. However, “part” is not meant to be limited to software or hardware. The 'unit' may be configured to reside on an addressable storage medium or may be configured to refresh one or more processors. Thus, as an example, 'part' refers to components such as software components, object-oriented software components, class components and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays and variables. Functions provided within components and ‘parts’ may be combined into a smaller number of components and ‘parts’ or further divided into additional components and ‘parts’.

Hereinafter, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the embodiments of the present invention. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description will be omitted.

In communication between the UAV and the ground control equipment, the ground control equipment may be the transmitting side and the UAV may be the receiving side, and the UAV may be the transmitting side and the ground control equipment may be the receiving side. That is, the UAV and the ground control equipment each include at least one transmitter and at least one receiver. During communication between the UAV and the ground control equipment, if the transmitter does not carry out the control command that the message means for a certain period of time after sending the message, or if the receiver does not separately transmit the reception of the related status information, the receiver considers that it has not received the message re-send

In STANAG-4586, an unmanned aerial vehicle communication protocol, for the efficiency of message transmission and reception, the ACK is returned only when the message is received by the transmitter for which the ACK has been requested. The transmitter separately indicates whether ACK is required by using a specific bit in the message header, and the receiver checks this bit in the application layer and transmits the ACK message.

3 shows the message structure of the STANAG-4586 protocol. In the message structure of FIG. 3 , after the receiver receives the message and decodes the header correctly, it can know whether the ACK is received by looking at the value of the 15th bit in the “Message Properties” field. This is possible only when the message is correctly decrypted to the application layer, and if the header is not decoded correctly or an error in the lower layer of the application layer occurs, the corresponding packet can be restored by checking the value of the 15th bit in the “Message Properties” field. It is unknown whether an ACK was requested.

For example, if the ground control equipment is the transmitting side and the UAV is the receiving side, if the corresponding packet is in error at the physical layer due to a poor wireless communication channel when the UAV receives a message, it is impossible to decode the bit of the basic message itself. Therefore, the UAV cannot convert the signal into a digital bit. In other words, the UAV cannot obtain any information including whether or not to request ACK from the corresponding signal. Therefore, the unmanned aerial vehicle cannot know whether the corresponding signal has requested an ACK or not, and cannot inform the ground control equipment whether or not it has been received. Therefore, the ground control equipment sends the corresponding message and waits for an ACK from the UAV. If the ACK does not come, the frequency change cannot be executed or the message is retransmitted after a specific time. In this case, an ACK method for notifying the transmitter of physical and data link layer errors is required because a large loss is concerned when an urgent change or a corresponding problem occurs in information transmission.

However, if retransmission is requested unconditionally when an error occurs in the physical and data link layers, this may cause a large load on the ground control equipment and the unmanned wireless communication link. can occur Therefore, it is efficient to classify whether or not ACK is required according to the importance of the message. However, when an error in the physical layer occurs, it is impossible to request an ACK in the form of a message based on the bit value because the exact bit value cannot be known.

In UAV communication, all messages have a preamble that performs frequency synchronization and time synchronization of signals. In general, since the preamble must be transmitted with high reliability, it is modulated using binary phase shift keying (BPSK). The modulation constellation of BPSK can be expressed as shown in FIG. 4 . Accordingly, the first symbols of the signal are modulated with BPSK and transmitted, and the receiver decodes them to synchronize the frequency and time, and decodes subsequent symbols in the physical layer.

In the embodiment of the present invention, in the modulation of the preamble during communication between the ground control equipment and the unmanned aerial vehicle, QBPSK (quadadrature BPSK) and BPSK having the same reliability and complexity as BPSK, but with the BPSK rotated by 90 degrees are selectively used. It determines whether ACK is required for a message including a preamble. The modulation constellation of QBPSK can be expressed as shown in FIG. 5 . BPSK is a modulation method that can contain 1 bit of information in one symbol by utilizing the in-phase dimension of the signal. On the other hand, QBPSK is a modulation method that contains 2 bits of information in one symbol by utilizing the quadrature-phase dimension of the signal. The two modulation schemes have the same distance between points in the constellation, but the dimension in which the energy of the symbol is distributed is different. In the case of BPSK, the energy of the symbol is distributed in the in-face dimension, and in the case of QBPSK, the energy of the symbol is distributed in the quadrature-face dimension. By utilizing this energy distribution difference, the presence or absence of an ACK request can be indicated. For example, when the preamble is modulated with BPSK, ACK for the corresponding message is required, and when the preamble is modulated with QBPSK, it can be defined in advance that ACK for the corresponding message is not required. In this case, the message receiving side checks whether the energy of the preamble symbol in the physical layer is distributed in the in-face dimension or not in the quadrature-face dimension, and whether the message requires ACK or not. You can tell if it's not

1 is a block diagram of a message processing device capable of configuring a receiving side when BPSK and QBPSK are selectively used for modulation of a preamble during communication between ground control equipment and an unmanned aerial vehicle according to an embodiment of the present invention.

Referring to FIG. 1 , the message processing apparatus 100 according to the embodiment includes a communication unit 110 and a processor unit 120 .

The communication unit 110 transmits and receives messages to and from the transmitting side under the control of the processor unit 120 .

The processor unit 120 controls the communication unit 110 . The processor unit 120 decodes the received message in the data link layer through the communication unit 110, and when an error occurs during decoding, the physical layer determines the distribution of the preamble symbol energy of the received message, and determines the distribution. Based on the result, when a preset distribution characteristic is indicated, the communication unit 110 is controlled to transmit a NACK message for the received message, and when an error does not occur during decoding, the received message is transferred to a higher layer. For example, the processor unit 120 may control the communication unit 110 to transmit the NACK message when the preamble symbol energy is distributed in the in-face dimension. In addition, the processor unit 120 may delete the received message without controlling the communication unit 110 to transmit the NACK message when the preamble symbol energy is distributed in the quadrature-phase dimension.

2 is a flowchart illustrating a message processing method performed by the message processing apparatus 100 according to an embodiment of the present invention.

Hereinafter, a message processing method performed by the message processing apparatus 100 according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, the communication unit 110 of the message processing apparatus 100 may receive a message, and provide the received message to the processor unit 120 of the message processing apparatus 100 (S210).

Then, the processor unit 120 decodes the received message in the data link layer (S220), and determines whether an error occurs during decoding of the received message (S230).

If it is determined in step S230 that an error has occurred during decoding of the received message, the processor 120 determines the distribution of preamble symbol energy of the received message in the physical layer. For example, the processor unit 120 determines whether the preamble symbol energy of the received message is distributed in the in-face dimension or a characteristic in which the preamble symbol energy of the received message is distributed in the quadrature-face dimension. It is determined whether it represents (S240).

If it is determined in step S240 that the preamble symbol energy of the received message represents a characteristic that is distributed in the in-face dimension, the processor 120 may infer that the transmitting side has determined that ACK is necessary for the corresponding message. . For example, if the sending side's ground control equipment requests a communication frequency change from the receiving side's unmanned aerial vehicle, it must change the communication frequency after confirming that the request is correctly accepted. In this case, the processor unit 120 controls the communication unit 110 to transmit a NACK message because a reception error has occurred ( S250 ).

However, in step S240, if it is determined that the preamble symbol energy of the received message indicates a characteristic distributed in the quadrature-phase dimension, the processor 120 determines that the transmitting side does not need ACK for the message. It can be inferred, and the received message can be deleted along with not controlling the communication unit 110 to transmit the NACK message (S260).

If an error does not occur during decoding of the received message in step S230, the received message is transferred to a higher layer according to a general processing procedure (S270).

After step S270, the processor unit 120 checks the value of the 15th bit in the “Message Properties” field after correctly deciphering the header of the received message and checks whether ACK is required (S281). If the value of the 15th bit of the corresponding field is “1”, the processor unit 120 controls the communication unit 110 to transmit the ACK message (S282), and if the value of the 15th bit of the corresponding field is “0”, the processor unit 120 ) prevents the ACK message from being transmitted by not controlling the communication unit 110 to transmit the ACK message (S283).

As described so far, according to an embodiment of the present invention, the receiver differentiates the modulation method for the preamble of the message according to whether the transmitter needs ACK during communication between the UAV and the ground control equipment, so that the receiver can control the received message in the physical layer. Whether to process the ACK may be determined based on the result of determining the distribution of the preamble symbol energy. According to the embodiment of the present invention, since the most basic physical layer distinguishes whether or not ACK is required based only on the energy distribution, even if an error occurs in decoding a signal of a symbol, it is possible to know whether an ACK is requested or not, so if a packet is not correctly received, a NACK message can be sent to the transmitter to request retransmission within a short time. In addition, since BPSK and QBPSK are the same except for the energy distribution dimension, the corresponding function can be applied without any other performance degradation or major changes in terms of protocols and equipment.

Combinations of each step in each flowchart attached to the present invention may be performed by computer program instructions. These computer program instructions may be embodied in a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, such that the instructions performed by the processor of the computer or other programmable data processing equipment provide the functions described in each step of the flowchart. It creates a means to do these things. These computer program instructions may also be stored in a computer-usable or computer-readable medium that may direct a computer or other programmable data processing equipment to implement a function in a particular manner, and thus the computer-usable or computer-readable medium. The instructions stored in the recording medium are also capable of producing an article of manufacture including instruction means for performing the functions described in each step of the flowchart. The computer program instructions may also be mounted on a computer or other programmable data processing equipment, such that a series of operational steps are performed on the computer or other programmable data processing equipment to create a computer-executed process to create a computer or other programmable data processing equipment. It is also possible that instructions for performing the processing equipment provide steps for performing the functions described in each step of the flowchart.

Further, each step may represent a module, segment, or portion of code comprising one or more executable instructions for executing the specified logical function(s). It should also be noted that in some alternative embodiments it is also possible for the functions recited in the steps to occur out of order. For example, it is possible that two steps shown one after another may in fact be performed substantially simultaneously, or that the steps may sometimes be performed in the reverse order depending on the function in question.

The above description is merely illustrative of the technical idea of the present invention, and various modifications and variations will be possible without departing from the essential quality of the present invention by those skilled in the art to which the present invention pertains. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

100: message processing unit
110: communication department
120: processor unit

Claims (8)

A message processing method performed by the receiving side among the transmitting side and the receiving side by communication between the unmanned aerial vehicle and the ground control equipment,
decrypting the received message at the data link layer;
when an error occurs during the decoding, determining a distribution of preamble symbol energy of the received message in a physical layer;
Inferring whether the sender requires message ACK based on the result of determining the distribution, and inferring that the transmitter requires message ACK when the determined result shows a preset distribution characteristic;
When it is inferred that the sender needs a message ACK, transmitting a NACK (Negative ACK) message for the received message, but not transmitting the NACK message when it is inferred that the sender does not require a message ACK; ,
If an error does not occur during the decryption, comprising the step of forwarding the received message to an upper layer
How to process the message. The method of claim 1,
Transmitting the NACK message when the preamble symbol energy is distributed in an in-phase dimension as a result of the determination
How to process the message. 3. The method of claim 2,
Deleting the received message when the preamble symbol energy is distributed in a quadrature-phase dimension as a result of the determination
How to process the message. A device that processes received messages during communication between an unmanned aerial vehicle and ground control equipment,
a communication unit for transmitting and receiving messages to and from the transmitting side;
It includes a processor unit for controlling the communication unit,
The processor unit,
The data link layer decodes the message received through the communication unit, and when an error occurs during the decoding, the physical layer determines the distribution of the preamble symbol energy of the received message, and the transmission is performed based on the result of determining the distribution. It is inferred as to whether the side requires message ACK, but when the determined result shows a preset distribution characteristic, it is inferred that the transmitting side needs message ACK, and inferred that the transmitting side requires message ACK control the communication unit to transmit a NACK (Negative ACK) message to the received message, but if it is inferred that the sender does not require a message ACK, the NACK message is not transmitted, and no error occurs during decoding In case of forwarding the received message to the upper layer
message processing unit. 5. The method of claim 4,
The processor unit,
Controlling the communication unit to transmit the NACK message when the preamble symbol energy is distributed in the in-face dimension
message processing unit. 6. The method of claim 5,
The processor unit,
Deleting the received message when the preamble symbol energy indicates a characteristic distributed in the quadrature-phase dimension
message processing unit. As a computer-readable recording medium storing a computer program,
The computer program, when executed by a processor,
Deciphering a received message in a data link layer, and when an error occurs during the decoding, determining a distribution of preamble symbol energy of the received message in a physical layer, and transmitting based on a result of identifying the distribution Inferring whether the side requires message ACK, and inferring that the transmitting side requires message ACK when the determined result shows a preset distribution characteristic; transmitting a NACK (Negative ACK) message for the received message, but not transmitting the NACK message if it is inferred that the sender does not require a message ACK; , A computer-readable recording medium comprising instructions for causing the processor to perform a message processing method performed by a receiving side during communication between an unmanned aerial vehicle and a ground control equipment, which includes transmitting the received message to an upper layer. As a computer program stored in a computer-readable recording medium,
The computer program, when executed by a processor,
Deciphering a received message in a data link layer, and when an error occurs during the decoding, determining a distribution of preamble symbol energy of the received message in a physical layer, and a transmitting side based on a result of determining the distribution Inferring whether this message ACK is required, and inferring that the sender needs message ACK when the identified result shows a preset distribution characteristic; When inferred, transmitting a NACK (Negative ACK) message for the received message, but not transmitting the NACK message when it is inferred that the sender does not require a message ACK; A computer program comprising instructions for causing the processor to perform a message processing method performed by a receiving side during communication between an unmanned aerial vehicle and a ground control equipment, which includes transmitting the received message to an upper layer.

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