KR102208856B1 - Apparatus for controlling communication and method thereof - Google Patents

Abstract

The present invention relates to a communication control device and a communication control method. The communication control device includes: a communication unit which transmits data and receives a retransmission response signal depending on whether there is a transmission error in the transmitted data; and a processor which adjusts the size of a congestion window, wherein the size of the congestion window is reduced to a threshold value when the number of receptions of the retransmission response signal is greater than or equal to a predefined number. The minimum value of the threshold value may include n multiples of the maximum segment size (n is a natural number). The present invention can improve network security by adjusting a slow start threshold.

Description

Communication control device and communication control method {APPARATUS FOR CONTROLLING COMMUNICATION AND METHOD THEREOF}

The present invention relates to a communication control apparatus and method.

An electric vehicle refers to a vehicle that is driven by obtaining power required for rotation of a wheel by converting electrical energy obtained from external or self-generating into mechanical energy. Such an electric vehicle is, for example, a conventional electric vehicle (EV, Electric Vehicle), a hybrid electric vehicle (HEV, Hybrid Electric Vehicle), or a plug-in hybrid electric vehicle (PHEV, Plug-in Hybrid Electric Vehicle). ), etc.

With the spread of electric vehicles, electric vehicle chargers are also gradually spreading to supply electric power required for driving of electric vehicles. Recently, a technology for connecting an electric vehicle and a grid through an electric vehicle charger and transmitting and receiving mutual power and/or transmitting and receiving mutual data based on a network therebetween has been developed.

Even in the electrical connection between the electric vehicle and the grid, security issues are considered important. For example, in an electric vehicle-grid network (V2G network) environment, an electric vehicle is a predetermined protocol (e.g., Transmission Control Protocol (TCP) or User Datagram Protocol (UDP)) When communication is performed with the grid by using, communication between them may be interrupted by an attack using the security vulnerability of these protocols. This can lead to enormous economic losses. Specifically, for example, the electric vehicle may be designed to perform data communication while charging through a charging cable and to pay a charging fee. In this case, if a security problem occurs in the data communication process for fee processing, an error may occur in the payment process, which causes an economic loss. In addition, instability of communication due to a security vulnerability may not guarantee a desired level of throughput in communication between the electric vehicle and the grid.

Republic of Korea Patent Publication No. 2009-0003848 (published on January 12, 2009) Republic of Korea Patent Publication No. 2019-0096348 (published on August 19, 2019) Republic of Korea Patent Publication No. 2017-0076759 (published on July 4, 2017)

It is an object to be solved to provide a communication control apparatus and method capable of improving the security of a network by adjusting a slow start threshold (ssthresh).

Provides a communication control device and method that can effectively defend against attacks such as user datagram protocol flooding attack or TCP fairness attack under the network between vehicle and grid (V2G network). This is another task to be solved.

A communication control apparatus and method are provided to solve the above-described problems.

The communication control device transmits data and adjusts the size of the communication unit and the congestion window for receiving the retransmission response signal according to whether or not there is a transmission error of the transmitted data, but if the number of times of reception of the retransmission response signal is more than a predefined number, the A processor for reducing the size of the congestion window to a threshold value, wherein the minimum value of the threshold value may include n multiples of the maximum segment size (n is a natural number).

The communication control method includes transmitting data, receiving a retransmission response signal according to whether or not there is a transmission error in transmission data, and adjusting the size of a congestion window. And reducing the size of the congestion window to a threshold value, wherein the minimum value of the threshold value may include an n multiple of the maximum segment size (n is a natural number).

According to the above-described communication control apparatus and method, by appropriately adjusting and controlling the low-speed start threshold, it is possible to obtain an effect of improving the security of the network.

In addition, it is possible to effectively defend against a user datagram protocol flooding attack or a transmission control protocol fairness attack under a network environment between the vehicle and the grid, thereby improving the security of the network.

A detailed description of each drawing is provided in order to more fully understand the drawings cited in the detailed description of the present invention.
1 is a diagram showing an example of a system for charging an electric vehicle.
2 is a block diagram of an embodiment of a communication control device.
3 is a diagram illustrating an example of a temporal change of a congestion window according to an operation of a communication control device.
4 is a diagram showing an example of a code for explaining the operation of the communication control device.
5 is a diagram showing an example of a temporal change of a conventional congestion window.
6 is a graph for explaining the effect of a communication control device on a user datagram protocol flooding attack.
7 is a graph for explaining the effect of a communication control device on a transmission control protocol fairness attack.
8 is a flowchart of an embodiment of a communication control method.

In the following specification, the same reference numerals refer to the same elements unless otherwise specified. The term "unit" used below may be implemented in software or hardware, and according to an embodiment, one "unit" is implemented as one physical or logical part, or a plurality of "units" It may be implemented as a physical or logical part, or one'unit' may be implemented as a plurality of physical or logical parts.

When it is said that a part is'connected' to another part throughout the specification, it may mean physical connection or electrical connection depending on the part and other part. In addition, when a part is said to'include' another part, it does not exclude another part other than the other part unless specifically stated to the contrary, and may further include another part at the designer's choice. Means there is.

Terms such as'first' or'second' are used to distinguish one part from another, and unless otherwise specified, they do not mean sequential expressions. In addition, expressions in the singular may include plural expressions unless there is clearly an exception in the context.

Hereinafter, an embodiment of a communication control device will be described with reference to FIGS. 1 to 5.

1 is a diagram showing an example of a system for charging an electric vehicle.

As shown in FIG. 1, a system 1 for charging an electric vehicle may include one or more electric vehicles 10-1 to 10-5. The electric vehicles 10-1 to 10-5 may include a conventional electric vehicle (EV), a hybrid electric vehicle, a plug-in hybrid electric vehicle, and/or a fuel cell vehicle (FCEV), but are not limited thereto. Each of the electric vehicles 10-1 to 10-5 uses an electric vehicle communication controller (EVCC) to control communication with external devices, for example, supply device communication controllers 31 and 32. You may have it.

One or more electric vehicles 10-1 to 10-5 may be connected to one or more electric vehicle chargers 20-1 to 20-5, respectively. Each of the chargers 20-1 to 20-5 may be connected to at least one supply equipment communication controller 31, 32 (SECC: Supply Equipment Communication Controller). Between electric vehicles 10-1 to 10-5 and chargers 20-1 to 20-5 and/or between chargers 20-1 to 20-5 and supply device communication controllers 31 and 32, a power line It may be connected using communication (PLC: Power Line Connection). That is, at least one of the automobiles 10-1 to 10-5, the chargers 20-1 to 20-5, and the supply device communication controllers 31 and 32 enables transmission and reception of data as well as transmission of power. Can be.

The supply device communication controller (31, 32) is a device for controlling communication at a side providing a charging service, and at least one supply device communication controller (31, 32) includes one or a plurality of chargers (20-1 to 20). -5) can be connected. The supply device communication controllers 31 and 32 may be communicatively connected to the service providing device 40.

The service providing device 40 may include a computing device provided to provide various services such as payment, and may include, for example, a server device.

At least two of the above-described electric vehicles 10-1 to 10-5, chargers 20-1 to 20-5, supply device communication controllers 31 and 32, and service providing device 40, in one embodiment According to this, data can be transmitted/received using predetermined rules. For example, these devices 10-1 to 40 may perform communication using Internet Protocol Version 6 (IPv6), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), or the like. In addition, if necessary, these devices 10-1 to 40 may perform communication further using transport layer security (TLS) and/or extensible markup language (XML). It is possible.

2 is a block diagram of an embodiment of a communication control device.

The communication control device 100 shown in FIG. 2 is a device capable of controlling communication between the device 100 and the outside, for example, means a device capable of controlling communication based on the above-described transmission control protocol. do. The communication control device 100 is, for example, an electric vehicle 10-1 to 10-5 of FIG. 1, a charger 20-1 to 20-5, a supply device communication controller 31, 32, and a service provision It may include at least one of the devices 40, and/or may include an electronic device or module installed in at least one of the devices 10-1 to 40 and manufactured to perform communication. For example, the communication control device 100 may be separately mounted in the electric vehicles 10-1 to 10-5 and may include communication equipment physically separated from the electric vehicles 10-1 to 10-5, , More specifically, for example, it may include an electric vehicle communication controller.

Referring to FIG. 2, the communication control apparatus 100 may include a communication unit 110 and a processor 120, and may further include a storage unit 130 if necessary.

The communication unit 110 is provided to transmit data to the outside and/or to receive data from the outside, for example, another external receiving device 190, for example, electric vehicle chargers 20-1 to 20- 5) may be provided to transmit a signal 90 (hereinafter, a transmission signal), and to receive a response signal 91 (ACK signal) corresponding to the transmission data 90 from the reception device 190. The communication unit 110 may perform communication through a wired network and/or a wireless network, and may perform communication using, for example, power line communication.

The processor 120 controls the communication unit 110 to transmit the transmission data 90, and/or congestion according to the response signal 91 received by the communication unit 110 in response to transmission of the transmission data 90 Congestion control can also be performed. According to an embodiment, the processor 120 may include a response check unit 121, a retransmission control unit 123, a threshold value setting unit 125, and a congestion window processing unit 127 for congestion control. These will be described later.

The processor 120 may drive an application stored in the storage unit 130 to perform a predefined operation, determination, processing, and/or control operation. Here, the application stored in the storage unit 130 may be directly created by a designer and stored in the storage unit 120, or may be obtained using a wired or wireless communication network. Depending on the embodiment, the processor 120 may be an electronic device specially designed for performing communication (for example, a specially designed modem chip, etc.), and/or may be a general electronic device capable of performing/processing calculation and control. have. In the latter case, the processor 120 is an application processor (AP), a central processing unit (CPU), an electronic control unit (ECU), a microcontroller unit (MCU). , A Micom (Micro Processor), a modem chip, and/or other electronic devices capable of processing various operations and generating a control signal may be included. These devices can be implemented using, for example, one or more semiconductor chips and related components.

The storage unit 130 may store at least one data necessary for the operation of the communication control device 100, for example, a low-speed start threshold or a congestion window set by the threshold value setting unit 125 It is possible to temporarily or non-temporarily store the size of. The storage unit 130 may include, for example, at least one of a main memory device and an auxiliary memory device, and these main memory devices or auxiliary memory devices may be implemented using a semiconductor chip or a magnetic disk.

Hereinafter, the operation of the processor 120 will be described in more detail.

3 is a diagram illustrating an example of a temporal change of a congestion window according to an operation of a communication control device.

A communication control device 100, for example a vehicle 10-1 to 10-5 or a supply device communication controller 31, 32, etc., is an external receiving device 190, for example a supply device communication controller 31, 32 B When communicating with the vehicle (10-1 to 10-5), the communication control device 100 transmits the transmission data 90 to the reception device 190, but transmits the transmission data 90 Can be transmitted in segments. For example, the transmission data 90 may be divided into a maximum segment size (MSS) and then sequentially or non-sequentially transmitted to the receiving device 190. The communication control device 100 transmits the transmission data 90 to the reception device 190 and then waits for a response signal 91 from the reception device 190. The reception device 190 receives the transmission data 90, specifically, each segment obtained by dividing the transmission data 90, and the transmission data 90, specifically, a response signal 91 corresponding to each segment. Can be created. The generated response signal 91 is transmitted to the communication control device 100.

Referring to FIG. 2, the response check unit 121 may check whether the response signal 91 is received from the receiving device 190 or count the number of times the response signal 91 is received in response to the transmitted segment. I can. The response signal 91 may include a signal transmitted from the reception device 190 to the communication control device 100 to confirm reception of the transmission data 91 or a segment divided therefrom. In addition, the response confirmation unit 121 may check whether the retransmission response signal 92 (Duplicate ACK) is received, or may count the number of times the retransmission response signal 92 is received. The retransmission response signal 92 is a signal related to a request for retransmission of a segment, and when the reception device 190 fails to receive some segments or the order of the segments is incorrect, the communication control device 100 ) Can be transmitted. That is, it means a signal transmitted to the communication control device 100 when an error occurs in transmission of transmission data. When it is determined that the retransmission response signals 92 of a predefined number (eg, three, etc.) have been received, the response confirmation unit 121 may transmit the determination result to the retransmission control unit 125. In this case, the retransmission control unit 125 may control the communication unit 110 to immediately retransmit the segment corresponding to the retransmission response signal 92 without any other determination (fast retransmission, Fast Retransmit). In addition, the response verification unit 121 may transmit a determination result according to reception of the retransmission response signal 92 to the congestion window processing unit 123. The congestion window processing unit 123 may adjust the size (cwnd) of the congestion window based on the retransmission response signal 92.

The congestion window processing unit 123 may adjust the size (cwnd) of the congestion window, as shown in FIG. 3. Specifically, for example, the congestion window processing unit 123 increases the size (cwnd) of the congestion window over time in the first period (p1, initial period), but the threshold value setting unit 127 from the initial value It can be increased up to the first low speed start threshold ssthresh1 set in advance (slow start, slow start). In this case, the size (cwnd) of the congestion window may increase rapidly, for example, may increase exponentially. If the size of the congestion window reaches the first slow start threshold, that is, the first slow start threshold ssthresh1, the congestion window processing unit 123 determines that congestion has occurred on the network, and the size of the congestion window ( cwnd) can be increased relatively gently to perform congestion avoidance (p2). For example, the congestion window processing unit 123 may linearly increase the size cwnd of the congestion window, and more specifically, for example, may increase the size cwnd of the congestion window by one. Here, the first slow start threshold value ssthresh1 may be set by the threshold value setting unit 127.

If the retransmission response signal 92 is received at a predetermined number of times (eg, 3 times) or more, the congestion window processing unit 123 sets the size of the congestion window (cwnd) to a second slow start threshold ( It can be reduced to a size corresponding to ssthresh2). In this case, the size (cwnd) of the congestion window may be the same as or different from the second slow start threshold value (ssthresh2). For example, the size cwnd of the congestion window may be set to a value obtained by adding 3 to the second slow start threshold value ssthresh2. The second slow start threshold value ssthresh2 may be set by the threshold value setting unit 127. In this case, the second slow start threshold value ssthresh2 may be defined as a value greater than a predefined value, where the predefined value may be, for example, a constant multiple of the maximum segment size. More specifically, for example, it may be defined as 10 times the maximum segment size.

After the size of the congestion window (cwnd) is reduced, the congestion window processing unit 123 determines the size of the congestion window (cwnd) for the third period (p3) in the same or similar method as in the second period (p2). It can be increased from the slow start threshold (ssthresh2). In this case, an increase in the size (cwnd) of the congestion window may be performed relatively gently. Specifically, for example, the size (cwnd) of the congestion window may be increased by one. Accordingly, the congestion window processing unit 123 does not perform the slow start performed in the first period p1 again, but only performs a congestion avoidance operation (fast recovery). When the retransmission response signal 92 is received again a predefined number of times (for example, three times) or more, the congestion window processing unit 123 uses the threshold value setting unit 127 as described above. After reducing the size of the congestion window cwnd up to the set third low speed start threshold value ssthresh3, the size of the congestion window cwnd may be increased relatively gently. Here, the third slow start threshold value ssthresh3 may be defined as, for example, a constant multiple of the maximum segment size, and more specifically, may be defined as 10 times the maximum segment size.

In addition, when the retransmission response signal 92 is re-received for a predetermined number of times (for example, 3 times) or a number exceeding this, the congestion window processing unit 123 determines the size of the congestion window up to the fourth slow start threshold value (ssthresh4). (cwnd) can be reduced. Here, the fourth slow start threshold value ssthresh4 may also be set by the threshold value setting unit 127. As in the case of the third period p3, the size cwnd of the congestion window may be relatively gradually increased in the fourth period p4 as well. According to an embodiment, the fourth slow start threshold value ssthresh4 may be defined as a constant multiple of the maximum segment size in the same manner as the third slow start threshold value ssthresh3, and specifically, for example, 10 times the maximum segment size. It can also be defined. If the third slow start threshold value ssthresh3 is defined as 10 times the maximum segment size, the fourth slow start threshold value ssthresh4 may be the same as or approximately approximate to the third slow start threshold value ssthresh3. Accordingly, as shown in FIG. 3, the size cwnd of the congestion window in the fourth period p4 is set to be substantially the same as the size cwnd of the congestion window in the third period p3. The slow start threshold (not shown) in other periods (p5, etc.) after the fourth period (p4) is also the same as the third slow start threshold (ssthresh3) and/or the fourth slow start threshold (ssthresh4) described above. Or it can be set to almost nicely. Accordingly, the size of the congestion window (cwnd) is almost not less than a constant value, for example, the third slow start threshold value ssthresh3 and/or the fourth slow start threshold value ssthresh4. In other words, a value equal to or close to the third slow start threshold value ssthresh3 and/or the fourth slow start threshold value ssthresh4 is set as the minimum value of the size of the congestion window cwnd. 3 illustrates an example in which the third slow start threshold value ssthresh3 and the fourth slow start threshold value ssthresh4 are the same or approximate, but the slow start threshold values ssthresh1 to ssthresh4 that are the same or approximate are not limited thereto. . For example, the i-th slow start threshold value (ssthresh_i) and the (i+1)th slow start threshold value (ssthresh_(i+1)) may be the same, where i may include a natural number greater than 1. I can. For example, according to an embodiment, the second slow start threshold value ssthresh2 and the third slow start threshold value ssthresh3 may be equal to or approximate to each other (i=2). According to another embodiment, it is also possible that the fourth slow start threshold value ssthresh4 and the fifth slow start threshold value ssthresh4 are the same (i=4). In this case, the third slow start threshold value ssthresh3 and the fourth slow start threshold value ssthresh4 may be different from each other.

If all the response signals 91 corresponding to the transmitted transmission data 90 are received during the above-described process, the congestion window processing unit 123 determines the size of the congestion window cwnd at the time when the response signals 91 are all received. Is set to the low-speed start threshold values (ssthresh1 to ssthresh4) and ends the above-described high-speed restoration operation. If necessary, the congestion window processing unit 123 may further sequentially perform slow start and congestion avoidance operations.

According to an embodiment, when the retransmission response signal 92 is received for a predefined number of times (for example, 3 times), the retransmission control unit 125 determines that loss has occurred in the transmission process, and the communication unit ( By controlling 110), the transmission data 90 may be transmitted back to the receiving device 190. In this case, the retransmission control unit 125 may cause the segment corresponding to the retransmission response signal 92 to be retransmitted to the receiving device 190 (high-speed retransmission). When retransmission is initiated, the retransmission control unit 125 may transmit information on the retransmission start to the threshold value processing unit 127, and the threshold value processing unit 127 may define a low speed start threshold (ssthresh1 to ssthresh4) in response thereto. have.

The threshold value processor 127 may determine the low speed start threshold values ssthresh1 to ssthresh4. According to an embodiment, the threshold value processor 127 may determine the threshold value equal to or greater than a predefined value. That is, the threshold value processing unit 127 may determine the threshold value such that the minimum value of the threshold value is equal to a predefined value. Specifically, for example, the threshold value processing unit 127 may define a larger value among half the flight size (flightsize/2) and n multiples of the maximum segment size as the threshold value. Here, n is an integer greater than 1, and may include, for example, 10. In addition, the size of the flight may mean the size of the transmission data 91 transmitted to the receiving device 190 but not receiving a corresponding response signal or a segment included therein. As the threshold value processing unit 127 determines the low speed start threshold values ssthresh1 to ssthresh4 as described above, the low speed start threshold values ssthresh1 to ssthresh4 are not defined as a value smaller than n times the maximum segment size. . That is, the minimum value of the slow start threshold values ssthresh1 to ssthresh4 is given by n*maximum segment size. The low-speed start threshold values ssthresh1 to ssthresh4 determined by the threshold value processing unit 127 are transmitted to the congested window processing unit 123 according to the operation of the congested window processing unit 123, and the congested window processing unit 123 is The size of the congestion window (cwnd) may be adjusted based on the start threshold values (ssthresh1 to ssthresh4).

FIG. 4 is a diagram showing an example of a code for explaining the operation of the communication control device, in which the operation of the communication control device 100 shown in FIG. 3 is displayed in the form of a program code.

As shown in FIG. 4, when the retransmission response signal 92 is first received a predetermined number of times or more and high-speed retransmission is started (first line), the low-speed start threshold ssthresh is the flight size. ) Is set to the largest value (flightsize/2) and n times (10 times in FIG. 4) of the maximum segment size (second line). According to this setting, as shown in the fourth period p4 and the fifth period p5 of FIG. 3, the size of the congestion window cwnd is not set to be less than a certain value (ssthresh3 or ssthresh4).

The size of the congestion window (cwnd) is sequentially set according to the set slow start threshold value (ssthresh) (third line). For example, the congestion window size cwnd may be set to a value obtained by adding 3 to the slow start threshold value ssthresh. Sequentially, the congestion window size cwnd may be increased, for example, may be increased by 1 (the fourth line). The set value and increase width of the congestion window size cwnd of the third line and the fourth line are exemplary, and the congestion window size cwnd may be set or increased in various ways.

If the response signal 91, ACK is partially received (line 5), high-speed restoration can be continuously performed (line 6), and the transmitted data 90, which are lost sequentially or in random order It may be transmitted in the form of. It may also include a segment) may be retransmitted to the receiving device 190 (seventh line). Conversely, if all response signals 91, ACK are received (line 8), the size of the congestion window (cwnd) can be set to a slow start threshold value (ssthresh) (line 9), and fast recovery ends. Can be. Sequentially, the slow start and avoid operation may be performed again (the tenth and eleventh lines).

The above-described program code may be temporarily or non-temporarily stored in the storage unit 130 and may be driven according to a call from the processor 120. In addition, the above-described program code may be stored in an external storage medium (eg, a compact disk, an external hard disk, or an external memory device) mountable to the communication control device 100, and the communication control device 100 and It may be connected and stored in a separate hardware device (eg, a network access server (NAS) or a desktop computer).

Hereinafter, with reference to FIGS. 5 to 7, the communication control apparatus 100 according to FIGS. 1 to 4 and the conventional apparatus are compared with each other.

5 is a diagram showing an example of a temporal change of a conventional congestion window.

Conventionally, as shown in FIG. 5, the low-speed start thresholds ssthresh11 to ssthresh14 continue to decrease every time three retransmission response signals 92 are received. In other words, the size of the 14th slow start threshold value ssthresh14 was set to be smaller than the 13th slow start threshold value ssthresh13 (for example, about half the size), and the 15th slow start threshold value ( Not shown) is also set smaller than the 14th slow start threshold (ssthresh14). Accordingly, the size of the congestion window (cwnd) is continuously decreased even in the periods after the 11th to 13th periods (p11 to p13), that is, the 14th period (p14) and the 15th period (p15). Such a continuous decrease in the size of the congestion window (cwnd) inevitably poses a vulnerability to attacks such as user datagram protocol flooding attacks and transmission control protocol fairness attacks.

6 is a graph for explaining the effect of a communication control device on a user datagram protocol flooding attack. In FIG. 6, the x-axis is the data rate (Mbps) of the user datagram protocol, and the y-axis is the throughput (Mbps). Red is a result value in the case of using the prior art (NewReno), and blue is a result value in the case of using the communication control device 100 described above. 6, 20 electric vehicles per charging station (for example, 10-1 to 10-5 in FIG. 1) are connected to chargers (20-1 to 20-5, etc.), respectively, and a maximum bandwidth of about 10 Mbps. Electric vehicles (10-1 to 10-5, etc.) and chargers (20-1 to 20-5, etc.) communicate with a bandwidth of 10 Mbps and 0.9 ms using a power line communication link, and the service providing device 40 ) And supply device communication controllers (31, 32) are set to perform communication with a large bandwidth of 500 Mbps and 10 ms, 19 of 20 electric vehicles perform communication using the user datagram protocol. And, the remaining one electric vehicle shows a result obtained by performing communication with each of the transmission control protocol based on the conventional technology and the transmission control protocol based on the communication control device 100 described above.

Specifically, referring to FIG. 6, regardless of an increase in the data rate of the user datagram protocol, the throughput in the case of using the above-described communication control device 100 is always much higher than that in the case of using the prior art. Can be seen. Specifically, when the data rate of the user datagram protocol is 2.5 Mbps, the above-described communication control device 100 exhibited an excellent throughput performance of about 2.5 times that of the prior art. In addition, in an environment where the average packet loss rate is 5%, when the data rate of the user datagram protocol is the highest, that is, when the data rate of the user datagram protocol is 12.5 Mbps, the above-described communication control device 100 is It showed excellent throughput performance of about 3.2 to 4 times.

7 is a graph for explaining the effect of a communication control device on a transmission control protocol fairness attack. In FIG. 7, the x-axis is the average packet loss rate (%), and the y-axis is the throughput (Mbps). Red is a result value in the case of using the prior art (NewReno), and blue is a result value in the case of using the communication control device 100 described above. 7 shows that 19 of the 20 electric vehicles perform communication through a transmission control protocol using a congestion control algorithm based on any one of the conventional technologies (Illinois algorithm) under the same situation as in FIG. 6, and the remaining one The electric vehicle shows the results obtained by performing communication through each of a transmission control protocol using a congestion control algorithm based on another conventional technology (NewReno) and a transmission control protocol based on the above-described communication control device 100. will be.

Referring to FIG. 7, it can be seen that the packet loss rate shows better throughput performance in all intervals of 0.25 to 5% based on the communication control apparatus 100 described above. In particular, it can be seen that as the packet loss rate increases, the throughput is relatively improved. Specifically, when the packet loss rate is 5%, throughput is improved by about 2.3 times when based on the communication control apparatus 100 described above than when based on another conventional technology (NewReno).

As described above, the communication control device 100 exhibits high throughput performance even when a problem such as a user datagram protocol flooding attack or a transmission control protocol fairness attack occurs compared to other conventional technologies. Accordingly, the above-described attack, etc. It will be possible to solve the security problem that follows.

Hereinafter, an embodiment of a communication control method will be described with reference to FIG. 8.

8 is a flowchart of an embodiment of a communication control method.

As shown in FIG. 8, first, transmission data may be transmitted to a receiving device (300). Transmission of the transmission data may be performed by the communication control device, wherein at least one of the communication control device and the receiving device is, for example, an electric vehicle, a charger to which an electric vehicle can be connected, a supply device communication controller, and a service providing device. It may include at least one. Each of the communication control device and the receiving device can be implemented based on at least one of a wired communication network and a wireless communication network, and communication between them is performed using a predetermined communication protocol, for example, a transmission control protocol or a user datagram protocol. Can be.

The communication control apparatus adjusts the size of the congestion window after transmission of the transmission data, but may increase the size of the congestion window through slow start (302). At a low speed start, the size of the congestion window can be rapidly increased, for example, can be increased exponentially.

It may be determined whether the size of the congestion window reaches a preset low-speed start threshold (for example, a first low-speed start threshold) (304). Here, the low-speed start threshold may be set to a larger value among half the flight size and a multiple of the maximum segment size (eg, 10 times the maximum segment size). If the size of the congestion window does not reach the low-speed start threshold (No of 304, that is, if the size of the congestion window is less than the low-speed start threshold), the low-speed start operation may be continuously performed (302). . Conversely, if the size of the congestion window is equal to or exceeds the low-speed start threshold value and thus reaches the low-speed start threshold value (example of 304), the congestion avoidance operation may be performed (306).

In the congestion avoidance operation, the size of the congestion window may increase relatively gently. For example, the size of the congestion window may increase by 1.

Meanwhile, after data transmission, the receiving device may transmit a response signal or a retransmission response signal to the communication control device in response to reception of transmission data, for example, a packet or segment. The response signal is a signal transmitted to the communication control device when the reception device properly receives the transmission data, and the retransmission response signal is a signal transmitted when the reception device does not properly receive the transmission data. The communication device counts the reception coefficient of the retransmission response signal (308), and if the number of reception of the retransmission response signal is equal to or exceeds a predefined number (eg, 3 times) (example of 308), congestion The size of the window can be adjusted (310). For example, the communication control apparatus may adjust the size of the congestion window according to another low speed start threshold value (eg, a second low speed start threshold value to a fourth low speed start threshold value depending on the number of repetitions). In this case, the size of the congestion window may be determined as a value obtained by adding a predetermined number (eg, 3) to another slow start threshold. Conversely, if the number of times the retransmission response signal is received is less than the predefined number (No in 308), the above-described congestion avoidance operation may be continuously performed.

The congestion avoidance operation or the process of adjusting the size of the congestion window (306 to 310) can be repeated (312). In the iterative process (306 to 312), the minimum size of the congestion window decreases to a certain level and is maintained thereafter. That is, the minimum size of the congestion window is set larger than the low speed start threshold (eg, the above-described third low speed start threshold or the fourth low speed start threshold), and, for example, half of the flight size and the maximum segment It is not smaller than the larger of the n multiples of size (eg, 10 times).

On the other hand, if all response signals are received during the congestion avoidance operation 306, the size of the congestion window is defined as a low-speed start threshold value, and the low-speed start operation 302 may be performed again according to an embodiment.

In addition, according to an embodiment, after transmission of the transmission data, when receiving a retransmission response signal, the communication control device may all or part of the transmission data (for example, depending on whether the retransmission response signal is received or the number of , Transmission failed segment, etc.) may be retransmitted. For example, upon receiving three identical or different retransmission response signals, the communication control device may transmit all or part of the transmitted data back to the receiving device.

The communication control method according to the above-described embodiment may be implemented in the form of a program that can be driven by a computer device. Here, the program may include a program command, a data file, a data structure, or the like alone or in combination. The program may be designed and produced using machine code or high-level language code. The program may be specially designed to implement the above-described communication control method, or may be implemented using various functions or definitions that are known and available to those skilled in the computer software field. Here, the computer device may be implemented by including a processor or a memory that enables the function of a program to be realized, and may further include a communication device if necessary.

The program for implementing the above-described communication control method can be recorded in a computer-readable recording medium. The computer-readable recording medium includes, for example, a magnetic disk storage medium such as a hard disk or a floppy disk, a magnetic tape, an optical recording medium such as a compact disk or a DVD, a magnetic-optical recording medium such as a floppy disk, and a ROM. , A semiconductor storage device such as RAM or flash memory, etc., may include various types of hardware devices capable of storing a specific program executed according to a call from a computer.

Although various embodiments of the communication control apparatus and method have been described above, the communication control apparatus and method are not limited to the above-described embodiments. Various devices or methods that can be implemented by modifying and modifying based on the above-described embodiment by a person of ordinary skill in the art may also be an example of the above-described communication control device and method. For example, the described techniques are performed in an order different from the described method, and/or components such as systems, structures, devices, circuits, etc. described are combined or combined in a form different from the described method, or other components or Even if it is replaced or substituted by an equivalent, it may be an embodiment of the above-described communication control apparatus and method.

100: communication control device 110: communication unit
120: processor 121: response confirmation unit
123: congestion window processing unit 125: retransmission control unit
127: threshold value setting unit 130: storage unit

Claims (14)

A communication unit that transmits data and receives a retransmission response signal according to whether or not there is a transmission error of the transmission data; And
Including; a processor for adjusting the size of the congestion window, but reducing the size of the congestion window to a threshold value when the number of times of receiving the retransmission response signal is more than a predefined number,
The minimum value of the threshold value includes n times the maximum segment size (n is a natural number),
The processor linearly increases the size of the congestion window when the size of the congestion window is an i-th low speed start threshold value, and the congestion window linearly increases when the number of times of receiving the retransmission response signal is 3 or more Reduce the magnitude of (i+1) to the slow start threshold,
The i-th slow start threshold and the (i+1)th slow start threshold are the same as each other,
Communication control device.
The method of claim 1,
The communication control device, wherein the n multiple is a multiple of 10.
The method of claim 1,
The threshold value is determined to be a larger value of half of the flight size and n multiples of the maximum segment size.
delete delete delete The method of claim 1,
The processor exponentially increases the size of the congestion window until the size of the congestion window reaches a first low speed start threshold.
Transmitting data;
Receiving a retransmission response signal according to whether or not there is a transmission error of transmission data; And
Adjusting the size of the congestion window, but if the number of times of receiving the retransmission response signal is equal to or greater than a predefined number, reducing the size of the congestion window to a threshold value; Including,
The minimum value of the threshold value includes n times the maximum segment size (n is a natural number),
Adjusting the size of the congestion window,
If the size of the congestion window is an i-th slow start threshold, linearly increasing the size of the congestion window; And
If the number of times of reception of the retransmission response signal is 3 or more, reducing the size of the congestion window which has been linearly increased to a (i+1)th slow start threshold value,
The i-th slow start threshold and the (i+1)th slow start threshold are the same as each other,
Communication control method.
The method of claim 8,
The communication control method including the n multiples 10.
The method of claim 8,
Determining the threshold value as a larger value of half of the flight size and n multiples of the maximum segment size.
delete delete delete The method of claim 8,
Adjusting the size of the congestion window,
And exponentially increasing the size of the congestion window until the size of the congestion window reaches a first low speed start threshold.

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