KR102269538B1 - Data transmitting and receiving performance test method for v2x module in network congestion - Google Patents

Abstract

The present invention relates to a method of testing data reception performance of a V2X module and, more specifically, to a method of testing data reception performance of a target test device receiving data based on wireless communication using V2X communication standards in case of network congestion. In accordance with the present invention, the method includes: a step wherein a test device including a V2X module causes congestion of a network by controlling the data transmission of the V2X module; a step wherein the test device transmits the data to a target test device including a V2X module; a step wherein the target test device re-transmits the received data to the test device; and a step wherein the test device compares the transmitted data to the re-transmitted data to test the data reception performance of the target test device.

Description

Method of testing data transmission/reception performance of V2X module during network congestion {DATA TRANSMITTING AND RECEIVING PERFORMANCE TEST METHOD FOR V2X MODULE IN NETWORK CONGESTION}

The present invention relates to a method for testing data reception performance of a V2X module, and more particularly, to a method for testing the reception performance of a device under test that receives data based on wireless communication using a V2X communication standard during network congestion.

As V2X communication, which refers to communication between vehicles and objects, became common, the V2X communication standard was established. For smooth V2X communication, a method conforming to the promised standard must be used, and verification of the V2X communication standard is required to confirm this. And for standard verification, it is necessary to test the V2X communication performance. The communication device for V2X communication includes a V2X module capable of transmitting and receiving data based on wireless communication using the V2X communication standard.

In general, in order to test the V2X communication performance, it is assumed that it has the status of another thing and it is assumed that it has the status of the test device that transmits data and the V2X vehicle terminal installed in the vehicle, and that the test device receives the data transmitted Prepare the device under test (DUT). The test device and the device under test each have a V2X module so that wireless communication using the V2X communication standard is possible. Under the conditions of the test, the test equipment and the equipment under test are connected wirelessly in the room, so that the data transmission/reception performance of the test equipment and the equipment under test can be tested.

On the other hand, the data transmission/reception performance of the device under test needs to reflect the on-site situation that will occur when it is mounted on a vehicle running on a real road. In detail, it is necessary to test the data reception performance of the device under test when a network congestion situation that may occur on an actual road occurs. Therefore, there is a need for a method for testing the data reception performance of the device under test that can cause network congestion for the data reception performance test of the device under network congestion.

Republic of Korea Patent Publication No. 10-2055364 (Notice on Dec. 13, 2019)

An object of the present invention for solving the above-described problems is to provide a method for verifying the V2X communication of the device under test when it is possible to generate a network congestion situation and when the network congestion occurs.

In order to achieve the above object, in the method for testing data transmission/reception performance of a V2X module during network congestion according to an embodiment of the present invention, a test device having a V2X module controls data transmission of the V2X module, thereby causing network congestion generating, by the test device transmitting the data to the device under test having a V2X module, retransmitting the data received by the device under test to the testing device, and the testing device transmitting the data and comparing one data with the retransmitted data to test data reception performance of the device under test.

The transmitting of the data to the device under test having the V2X module by the test device further includes controlling the strength of the data transmission output of the V2X module provided by the testing device.

After the step of controlling the strength of the data transmission output of the V2X module provided by the test apparatus, the method further includes controlling the period of the data transmission output of the V2X module provided by the test apparatus.

In the step of the test device transmitting the data to the device under test having a V2X module, the V2X module transmits a plurality of data each having a different unique ID, and a plurality of data with only a single V2X module Generates a virtual environment for transmitting the data from surrounding vehicles, and the test apparatus includes a plurality of V2X modules to control the data transmission output and period of each V2X module, thereby network congestion at a point separated by a virtual predetermined distance change the

The step of transmitting the data toward the device under test having the V2X module by the test device includes receiving a plurality of virtual location information from the GPS simulator and the data transmission output and period of the V2X module according to the location information It further comprises the step of controlling.

According to the method for testing the data transmission/reception performance of the V2X module during network congestion of the present invention, it is possible to transmit data to the device under test while maintaining excessive traffic of the network or channel, and it is possible to transmit data to the device under test in the state of excessive traffic of the network or channel. There is an effect that it is possible to test the data reception performance of the device.

1 is a block diagram schematically showing the configuration of a system according to the present invention.
2 is a view showing a result of controlling the data transmission power of the V2X module by the controller according to the present invention.
3 is a view showing a result of controlling the data transmission period of the V2X module by the controller according to the present invention.
4 is a flowchart illustrating a method for testing data transmission/reception performance of a V2X module during network congestion according to the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to components in each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated in different drawings.

And in describing the embodiment of the present invention, if it is determined that a detailed description of a related known configuration or function interferes with the understanding of the embodiment of the present invention, the detailed description thereof will be omitted.

In addition, in describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the components from other components, and the essence, order, or order of the components are not limited by the terms.

As used herein, the singular also includes the plural, unless the phrase specifically states otherwise. As used herein, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other components in addition to the stated components.

The V2X module according to the present invention is capable of transmitting and receiving data based on wireless communication using the V2X communication standard, and may be a known one. The V2X communication standard described in this specification may be a well-known one, and in one embodiment, it may be a Wireless Access for Vehicular Environment (WAVE) consisting of IEEE 802.11p and IEEE 1609.x standards, but is not limited thereto.

V2X communication refers to communication between a vehicle and everything on the road, such as a vehicle and a vehicle (V2V), a vehicle and a pedestrian (V2P), and a vehicle and a traffic facility (V2I) such as a traffic light. Hereinafter, as an embodiment, when V2X communication is described, it is assumed that it is V2V communication.

As an embodiment of a service using V2X communication, a vehicle safety service may be provided. For vehicle safety services, one vehicle on the road periodically broadcasts a safety message (BSM) to another vehicle. The safety message may have basic information of the vehicle, such as the location, speed, and acceleration of the vehicle. However, due to the nature of the safety message being communicated in a broadcast manner, excessive traffic is generated in the network or communication channel in a vehicle-dense area, which sharply increases the safety message transmission failure probability and delay.

On the other hand, a V2X communication device having a V2X module or V2X module for V2X communication is installed in any vehicle and other vehicles described above. Assuming that a safety message is transmitted from one vehicle to another vehicle, the need for testing the reception performance of the V2X module for receiving the safety message has emerged when excessive traffic occurs in the network or channel for the same reason as described above, and the present invention is a test device for testing the reception performance of a V2X module that receives a safety message when excessive traffic occurs and a performance test system including the same.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a block diagram schematically showing the configuration of a system according to the present invention.

The data transmission/reception performance test system of the V2X module during network congestion according to the present invention includes a V2X (Vehicle to everything) module 101 to transmit data based on wireless communication using the V2X communication standard with reference to FIG. 1 . The test apparatus 100 and the V2X module 201 are provided to receive data from the test apparatus 100 based on wireless communication using the V2X communication standard, and transmit the received data to the test apparatus 100 through wired communication. and a device under test 200 that

The test apparatus 100 according to the present invention includes a V2X module 101, a control unit 110 for controlling the V2X module 101, and an analysis unit 120 for testing data transmission/reception performance of the device under test 200. include

The V2X module 101 provided in the test apparatus 100 is capable of wireless communication using the V2X communication standard. The V2X module 101 included in the test device 100 transmits data to the device under test 200 . The V2X module 101 provided in the testing device 100 may be a known V2X module 101, and a card directly inserted, coupled, or connected to the testing device 100 or the controller 110 of the testing device 100 may be in the form The V2X module 101 provided in the test apparatus 100 may be plural. The V2X module 101 provided in the test apparatus 100 may be assumed to be a V2X module 101 of any virtual vehicle (neighboring vehicle, Remote Vehicle, RV) that transmits data such as BSM on the road. The V2X module 101 provided in the test apparatus 100 can transmit a plurality of data having a plurality of unique IDs with only one V2X module 101 . Therefore, one V2X module 101 included in the test apparatus 100 may generate a situation in which a plurality of vehicles (RV) transmit data to other vehicles (own vehicle, Host Vehicle, HV). The test apparatus 100 may include a plurality of V2X modules 101 , and each V2X module 101 may generate and transmit a plurality of data having different unique IDs, respectively.

The control unit 110 controls the data transmission of the V2X module 101 provided in the test device 100 to change the congestion degree of the wireless communication network using the V2X communication standard to generate a network congestion situation. The control unit 110 may control the data transmission power, output, and/or period of the V2X module 101 provided in the test apparatus 100 . The controller 110 may control the congestion level of the network or channel by controlling the data transmission power, output, and/or period of the V2X module 101 provided in the test apparatus 100 . That is, the controller 110 may control the data transmission power, output, and/or period of the V2X module 101 to generate excessive traffic to the network or channel, and maintain the excessive traffic state to maintain the network congestion state. The control unit 110 can control data transmission of the V2X module 101 through CBR and an algorithm using the CBR to maintain a traffic state that is capable of data transmission in the network network when generating and maintaining an excessive traffic state, and the like, and the control unit (110) to control the V2X module 101 to generate and maintain excessive traffic to the network or channel, a description of the CBR and the algorithm using the same will be described later.

The device under test 200 may include a V2X module 201 like the testing device 100 . The V2X module 201 included in the device under test 200 may receive data transmitted from the test device 100 based on wireless communication using the V2X communication standard. The device under test 200 may be a V2X communication device or a V2X communication terminal having the V2X module 201 . It can be assumed that the device under test 200 is a V2X communication device or a V2X communication terminal provided by another virtual vehicle (HV). The test apparatus 100 transmits data to the apparatus under test 200 in an excessive traffic state. The device under test 200 receives data in an excessive traffic state. As for the device under test 200, any one of several known V2X modules 201 may be selected to test data reception performance in an excessive traffic state. That is, the V2X module 201 of the device under test 200 may be coupled to be replaceable. Alternatively, the device under test 200 itself may be replaced.

The device under test 200 retransmits the data received from the testing device 100 back to the testing device 100 . At this time, the device under test 200 may be connected to the testing device 100 through a wired communication network through Ethernet, etc., and when data received to the testing device 100 is transmitted again, it may be transmitted through a wired network in a stable network state. However, the present invention is not limited thereto, and even when retransmitting the received data, it may be transmitted through wireless communication through V2X communication. As the received data is retransmitted through wireless communication through V2X communication, it may be possible to test the transmission performance as well as the data reception performance of the device under test 200 . Meanwhile, a dotted arrow in FIG. 1 means a wireless communication network, and a solid arrow indicates a wired communication network.

The test apparatus 100 further includes an analysis unit 120 for testing the data reception performance of the apparatus under test 200 .

The analysis unit 120 tests the data reception performance of the device under test 200 in a network congestion situation. The analysis unit 120 compares the data transmitted by the test apparatus 100 with the data received by the apparatus under test 200 and transmitted back to the test apparatus 100, and in the case of network congestion, Data reception performance can be tested. According to another embodiment of the present invention, the data transmission/reception performance of the V2X module 201 is PER (Packet Error Rate) performance, latency performance, data throughput performance, maximum effective communication distance performance or RSSI ( Received Signal Strength Indicator) performance can be evaluated. For example, when the analysis unit 120 compares the data transmitted by the test device 100 to the device under test 200 with the data received from the device under test 200, using the PER as an index, the device under test ( 200) can test the data reception performance.

The test device 100 may further include a simulator for generating data to be transmitted to the device under test 200 , and the data generated by the simulator and data transmitted again after the device under test 200 is received are stored. It may further include a database unit 130 to be.

2 is a view showing a result of controlling the data transmission power of the V2X module 101 by the controller 110 according to the present invention.

As described above, the control unit 110 may control the V2X module 101 provided in the test apparatus 100 to generate a virtual environment for transmitting and receiving data on the road. The control unit 110 controls the strength of the data transmission power (or output) of the V2X module 101 provided in the test apparatus 100 .

The control unit 110 controls the data transmission power of the V2X module 101 to vary the received signal strength indication (RSSI) value of the data received by the device under test 200 or the V2X module 201. . As described above, the V2X module 201 provided by the device under test 200 may mean the own vehicle (V2X communication device, etc.), and the V2X module 101 provided by the test device 100 is It may mean a surrounding vehicle (such as a V2X communication device).

The control unit 110 is provided in the test apparatus 100 so that the received signal strength value of the data received by the V2X module 101 of the device under test 200 that receives the data maintains the previously measured received signal strength value. Controls the data transmission power of the V2X module 101 . The control unit 110, for example, after providing the transmitting-side V2X module 101 and the receiving-side V2X module 201 separated by 50 m, 100 m, 200 m, 300 m, 400 m, and 500 m respectively on the actual road, when transmitting and receiving data The received signal strength of the receiving-side V2X module 201 is measured. When the measured received signal strength is, for example, 50m, RSSI may be −50dbm, at 100m, RSSI may be −60dbm, and if 200m, RSSI may be measured as −70dbm. As described above, the control unit 110 controls the data transmission power of the V2X module 101 provided in the test apparatus 100 so that the V2X module 201 provided in the apparatus under test 200 maintains the previously measured received signal strength. to control By the V2X module 101 provided in the test apparatus 100 in which the data transmission power is controlled by the control unit 110 , it is possible to generate a situation in which the surrounding vehicles are separated by a predetermined distance. Accordingly, the controller 110 controls the data transmission power (output) of the V2X module 101 to generate a virtual situation in which the V2X modules 101 and 201 that transmit and receive data are separated from each other by a predetermined distance.

3 is a view showing a result of controlling the data transmission period of the V2X module 101 by the controller 110 according to the present invention.

The control unit 110 may control the data transmission period of the V2X module 101 to increase the congestion level of the network or channel to generate excessive traffic.

The control unit 110 may control the period of data transmission power (or output) of the V2X module 101 provided in the test device 100 to change the network congestion level at a point where the V2X module 101 is a predetermined distance away. . The controller 110 may generate a virtual state in which vehicles at a specific location are concentrated by controlling the period to be short or long while the amplitude of the data transmission power of the V2X module 101 is maintained.

3 , the controller 110 may control the data transmission power and cycle of the V2X module 101 to generate a state in which the vehicles in which the V2X module 101 is installed are concentrated at a location 100 m away. As a result of changing only the period while maintaining the size of the data transmission power of the V2X module 101, the control unit 110 may generate a state in which surrounding vehicles located 100 m away from the own vehicle are concentrated as shown in FIG. 3 . have. When surrounding vehicles are densely located at a distance of 100m, it can be assumed that the network congestion in the corresponding area is increased.

As described above, the V2X module 101 included in the test device 100 can transmit a plurality of data having a unique ID (ID) with only one V2X module 101 . The V2X module 101 provided in the test apparatus 100 transmits a plurality of data each having a different unique ID, and transmits data from a plurality of surrounding vehicles only with a single V2X module 101. create environment.

On the other hand, the test apparatus 100 may include a plurality of V2X modules 101, and as described above, by controlling the size and period of data transmission power of each V2X module 101, a virtual point separated by a predetermined distance can change the degree of network congestion of

The test apparatus 100 according to the present invention further includes a GPS (or GNSS) simulator 150 . The GPS simulator 150 models the location of the vehicle so that basic information of the vehicle, such as the virtual vehicle location, speed, and acceleration, is included in the data transmitted and received by the V2X modules 101 and 201 . The virtual vehicle location may have any latitude, longitude and altitude values.

In the GPS simulator 150 , driving scenarios of surrounding vehicles and own vehicles may be built-in. The GPS simulator 150 may generate location information of each vehicle so that the distance between the surrounding vehicle and the own vehicle is maintained within 500 m when generating the location of the surrounding vehicle and the own vehicle. For vehicle safety services, a safety message (BSM) transmission period of 100 ms and a transmission distance of 200 m to 400 m are generally recommended. This is because, if the transmission delay becomes longer, problems such as receiving incorrect information after the validity period of the vehicle may occur.

The controller 110 receives a plurality of virtual location information from the GPS simulator 150 . The control unit 110 may control the data transmission power (output) and period of the V2X module 101 according to the received location information. The controller 110 may change the transmission power and period of a plurality of data transmitted by the V2X module 101 according to a plurality of location information received from the GPS simulator 150 . That is, the controller 110 may control the intensity and period of data transmission during data transmission of the V2X module 101 to match the distance between the V2X modules 101 and 201 according to the received location information.

Therefore, the location information or speed information of the data transmitted by the V2X module 101 may be a value that changes with time rather than a fixed value, so that the device under test 200 receives data while actually driving on the road. environment can be created.

On the other hand, the test apparatus 100 according to the present invention transmits data to the apparatus under test 200 in order to test the data reception performance of the apparatus under test 200 in a situation such as a dense vehicle network or channel. generate excessive traffic. In order to generate and maintain such an excessive traffic situation, it is necessary to measure the congestion level of a network or channel.

V2X communication, as described above, generally uses WAVE technology. WAVE technology is a short-distance wireless communication standard technology that supports a communication distance of 1km and supports a communication speed of at least 1Mbps to a maximum of 54Mbps. WAVE technology is a technology for communication between vehicles moving at high speed and requires transmission of individual broadcast messages in a very short wireless connection time. In addition, it supports multiple channels (7 channels) and variable transmission power, and direct vehicle-to-vehicle communication is possible through multiple overlaps in the communication area and fast initialization.

The test apparatus 100 according to the present invention measures the congestion level by observing the channel load in order to measure the congestion level of the network or channel. In the present invention, the concept of Channel Busy Ratio (CBR) is introduced to observe the channel load. The channel load tends to increase as there are more nodes that communicate in a short distance, ie, surrounding vehicles.

In the present invention, the relationship between CBR and the number of surrounding vehicles is approximated mathematically, and the total network congestion is estimated using this. In the present invention, since problems such as the Hidden Node Problem and the Exposed Node Problem occur between nodes within a two-hop distance in a wireless ad-hoc communication environment, the overall network congestion is defined as a two-hop network congestion.

CBR represents the percentage of channel utilization within the safety message transmission period. As shown in Equation 1, CBR can be defined as a value obtained by dividing packet transmission/reception times (tT, tR) by the safety message transmission period (T). In the present invention, CBR is used as an indicator indicating how congested the channel is.

(수식 1)

(Formula 1)

The number of remote vehicles (RVs) is the number of vehicles within a one-hop communication distance of the host vehicle (HV) and means the number of vehicles within a distance that can communicate with the HV. In the present invention, in order to organize the relationship between CBR and the number of surrounding vehicles, a virtual time slot is introduced by applying the virtual time frame (VTF) concept of the S. Bai thesis. The size of the virtual time slot (Ss) is the time it takes to transmit or receive one safety message, and the number of virtual time slots (Sn) is the maximum number of times that a safety message can be transmitted/received during the safety message transmission period (T). . Therefore, the size of the virtual time slot is the size of the safety message (M) divided by the communication speed (C), and the number of virtual time slots is the safety message transmission period divided by the size of the virtual time slot. If this is expressed as a formula, it is as (Equations 2, 3).

(수식 2)

(Equation 2)

(수식 3)

(Equation 3)

For example, if the size of the safety message is assumed to be 400 bytes and the safety message broadcast period is fixed to 100 ms, the size of one virtual time slot is about 1.08 ms based on the 3Mbps communication speed and the number of virtual time slots is about 93.

Since CBR is the ratio of channel utilization within the safety message transmission period, it is obtained by dividing the product of the virtual time slot size, the number of virtual time slots, and the probability (p) of using one virtual time slot by the safety message transmission period (T) (Equation 4) can be expressed as

(수식 4)

(Equation 4)

Here, the probability that one virtual time slot is not used is expressed as (Equation 5) if the number of RVs within a one-hop distance is N. Therefore, CBR can be approximated by (Equation 6).

(수식 5)

(Equation 5)

(수식 6)

(Equation 6)

Reference Figure 1 is a table showing the communication distance per data transmission power of the V2X module 101 according to the present invention, Reference Figure 2 is a pseudo code of the data transmission power control algorithm of the V2X module 101 according to the present invention.

(참고도 1)

(Reference 1)

(참고도 2)

(Reference Figure 2)

The present invention proposes an algorithm for adjusting the data transmission power of the V2X module 101 provided in the test device 100 based on the congestion level. The test device 100 calculates the congestion level (CBR2hop) of the network or channel, increases or decreases the transmission power (TX Power) based on this, applies excessive traffic to the network or channel, and maintains the channel load of the excessive traffic state constant It further includes a congestion maintenance unit 140 that does. Also, it is assumed that the communication distance per transmission power is known as shown in FIG. 1 . Reference Figure 2 is a pseudo code of the proposed algorithm.

The congestion maintenance unit 140 uses the TX power information received from the CBR (CBR1hop) of one hop distance and all the surrounding RVs to estimate the overall network congestion level (CBR2hop). If this is written as a formula, it is as (Equation 7). Here, CBR1hop is a value actually measured by the device under test 200 and Rd is the network density around the V2X module 101 provided in the test device 100 calculated using TX power information received from the surrounding RVs. OA is the area in which the communication radius of the test apparatus 100 and the apparatus under test 200 overlaps.

(수식 7)

(Equation 7)

(수식 8)

(Equation 8)

(수식 9)

(Equation 9)

Rd is the network density around the V2X module 101 equipped with the test device 100 divided by the number of data transmitted by the V2X module 101 by the two-hop communication range (TX_Area2hop), where the V2X module 101 transmits The number of data can be calculated through (Equation 9), which is the inverse function of (Equation 6). This is possible by assuming that it is always maintained at 0.5 by the algorithm proposed by CBR2hop. When calculating Rd around the V2X module 101 provided by all the test devices 100 in the device under test 200 as shown in Equation 7, communication overlapping between the V2X modules 101 provided by the testing device 100 Considering the range, the complexity of the algorithm for calculating CBR2hop becomes O(2n). Therefore, in the present invention, CBR2hop was estimated by sampling the eight RVs furthest from the east, west, south, north, northeast, northwest, southeast, and southwest of HV.

Reference Figure 3 is a table showing a simulation environment for verifying the algorithm proposed in the present invention.

(참고도 3)

(Reference 3)

A simulation for verifying the algorithm proposed in the present invention was performed for 30 seconds in a two-lane 3km highway environment as shown in FIG. 3 . Nodes were performed in a static environment where they do not move. In addition, the simulation was divided into a case in which the data transmission power control algorithm according to the present invention is not applied (TPC Off) and a case in which it is applied (TPC On). In a scenario where the transmit power control algorithm is not applied, the vehicle transmit power is maintained as it is 15.0 dBm, and when the algorithm is applied, the initial transmit power is 15.0 dBm.

In order to evaluate the performance of the proposed two-hop congestion estimation-based safety message transmission power control algorithm, two evaluations are made. It is whether the congestion level of two hops has been correctly estimated and whether the congestion has been alleviated in the transmission of safety messages by adjusting the transmission power. For this, the performance indicators of Ideal CBR2hop, Estimated CBR2hop, CBR1hop and PER are used.

Ideal CBR2hop is a calculation of 2-hop CBR by directly sharing CBR measured in simulation by all nodes, Estimated CBR2hop is a calculation of 2-hop CBR using shared TX power through the algorithm proposed in the present invention, and CBR1hop is a unit The higher the channel is used during the time, the higher the channel utilization rate is, and the PER is the ratio of the packets with errors among the packets received during the unit time, and the lower it is, the higher the communication reliability is.

Reference Fig. 4 is a table showing parameter values for performance evaluation of the data transmission power control algorithm according to the present invention, Reference Fig. 5 is a graph comparing values calculated by averaging all the vehicles in the simulation, and Reference Fig. 6 is a time table This is a graph comparing Ideal CBR2hop and Estimated CBR2hop in the Free scenario.

(참고도 4)

(Reference 4)

(참고도 5)

(Reference 5)

(참고도 6)

(Reference Figure 6)

In the present invention, the performance of the proposed context-aware-based transmit power control algorithm is verified through simulation. The simulation was performed using Qualnet, a network simulator, and the parameter values are as shown in reference FIG. 4 .

Ideal CBR2hop and Estimated CBR2hop were compared to verify whether the overall network congestion estimation was correct. Reference Figure 5 is a comparison by averaging the values calculated by all vehicles in the simulation, and it can be seen that in the Medium or Free scenario except for the Heavy scenario, it is estimated similarly. The reason why similar estimates are not made in the Heavy scenario is that the proposed algorithm assumes that CBR2hop is maintained at 0.5 distributedly in each vehicle. However, in the heavy scenario, this assumption cannot be satisfied, so the Estimated CBR2hop also has a lot of errors. Reference Figure 6 shows that the Ideal CBR2hop and Estimated CBR2hop are compared in the free scenario over time, and it can be seen that it is estimated almost perfectly.

Reference Figure 7 is a graph comparing Packet Error Rate (PER) when the algorithm according to the present invention is applied and not applied, and Reference Figure 8 is one-hop when the algorithm according to the present invention is applied and not applied. Channel Busy Ratio (CBR1hop) It is a graph comparing according to the density in which the V2X modules 101 are distributed.

(참고도 7)

(Reference Figure 7)

(참고도 8)

(Reference figure 8)

In order to evaluate the performance of the proposed algorithm, the cases in which the algorithm is applied and the cases in which the algorithm is not applied are simulated and compared according to the distribution density of Packet Error Rate (PER) and 1-Hop Channel Busy Ratio (CBR1hop) vehicles. Reference Figure 7 and Reference Figure 8 are the results. According to Figure 7, when the proposed algorithm is applied (TPC ON), the Packet Error Rate shows an error rate of 0.1 or less in all scenarios, and when the proposed algorithm is not applied (TPC OFF), the Packet Error Rate is 0.1 in the Heavy scenario. shows that it exceeds This shows that the proposed algorithm effectively reduces the Packet Error Rate and improves the reliability of V2V communication in a congestion situation.

Referring to FIG. 8 , it can be seen that when the algorithm proposed in the Heavy and Medium scenarios is applied, the CBR1hop is lower than in the case where it is not, and is higher in the Free scenario. Through this, the proposed algorithm reduces channel utilization by reducing transmit power in scenarios with high congestion (Heavy, Medium), but increases communication reliability by reducing PER and increases transmission power in scenarios with low congestion (Free). It shows that communication efficiency is increased by increasing channel utilization.

In conclusion, in the present invention, it is possible to estimate the total network congestion by using CBR (Channel Busy Ratio), and based on this, a transmission power control algorithm for controlling transmission power is proposed. In addition, through this, the test apparatus 100 according to the present invention can generate and maintain an excessive traffic situation of a network or channel. Accordingly, it is possible to test the data reception performance of the device under test 200 in a network or channel excessive traffic situation generated by the testing device 100 .

4 is a flowchart illustrating a method for testing data transmission/reception performance of a V2X module during network congestion according to the present invention.

In the method for testing data transmission/reception performance of the V2X module during network congestion according to the present invention, referring to FIG. 4 , the test device 100 having the V2X module 101 controls the data transmission of the V2X module 101 to control the data transmission of the network. The step of generating a congestion situation (S101), the test device 100 transmitting data toward the device under test 200 having the V2X module 101 (S103), the device under test 200 receiving Retransmitting the data to the test apparatus 100 (S108) and comparing the data transmitted by the test apparatus 100 with the retransmitted data to test the data reception performance of the apparatus under test 200 (S109) do. Hereinafter, the same description as described above in each step will be omitted.

Step S101 is a step in which the test device 100 generates excessive traffic to a wireless network or channel using the V2X communication standard. The test apparatus 100 controls the data transmission/reception of the V2X module 101 through the control unit 110 to change the degree of congestion of the network to generate a congestion situation of the network. The control unit 110, as described above, may control the data transmission power, output, and/or period of the V2X module 101 provided in the test apparatus 100 . In step S101, as described above, the total network congestion is estimated using CBR, and transmission power is controlled based on this to generate and maintain network congestion.

Step S103 is a step in which the test device 100 transmits data toward the device under test 200 in an excessive traffic state of the wireless network using the V2X communication standard.

Step S103 is a step of controlling the intensity of the data transmission output of the V2X module 101 provided by the test apparatus 100 (S104), the period of the data transmission output of the V2X module 101 provided by the test apparatus 100 Controlling (S105), receiving a plurality of virtual location information from the GPS simulator 150 (S106), and data transmission output and period of the V2X module 101 according to the location information received from the GPS simulator 150 It may further include a step (S107) of controlling the.

However, step S103 does not always include all steps S104 to S107, and any one of steps S104 to S107 may be selected and performed.

The test apparatus 100 according to the present invention may further include a user interface unit 160 . The user interface unit 160 may receive an input from the user whether to test the device under test 200 including any of steps S104 to S107. The user interface unit 160 may include a predetermined application. Information received by the user interface unit 160 may be stored in the database unit 130 .

In step S103, the V2X module 101 provided by the test device 100 is capable of transmitting a plurality of data each having a different unique ID. Therefore, it is possible to generate a virtual environment that transmits data from a plurality of surrounding vehicles only with a single V2X module 101 .

In addition, the test apparatus 100 may include a plurality of V2X modules 101 . The test apparatus 100, in detail, the control unit 110 controls the data transmission output and period of each V2X module 101 according to steps S104 to S107 to change the degree of network congestion at a point separated by a virtual predetermined distance it is possible

Step S108 is a step of retransmitting the data received by the device under test 200 to the testing device 100 . In step S108 , when the device under test 200 retransmits the received data to the test device 100 , unlike when data is received, it may be retransmitted through a wired network such as Ethernet having a stable network. As data received through a stable network is retransmitted, only the reception performance of the device under test 200 can be tested. However, the present invention is not limited thereto, and data may be retransmitted through a wireless network conforming to the same V2X communication standard as when receiving data. In this case, the transmission/reception performance of the device under test 200 can be tested together.

Step S109 is a step of testing the data reception performance of the apparatus under test 200 by comparing data transmitted by the apparatus 100 and data retransmitted by the apparatus under test 200 . As described above, the data reception performance of the device under test 200 may be analyzed by the analysis unit 120 , and the data transmission/reception performance of the device under test 200 is determined by the PER (Packet Error Rate) performance, the delay time ( Latency) performance, data throughput performance, maximum effective communication distance performance, or Received Signal Strength Indicator (RSSI) performance may be evaluated.

In this specification, the control unit 110 , the analysis unit 120 , the database unit 130 , the congestion maintenance unit 140 , and the user interface unit 160 may be processors that execute consecutive execution processes stored in a memory. Alternatively, it may operate as software modules driven and controlled by a processor. Furthermore, the processor may be a hardware device.

For reference, the data transmission/reception performance test method of the V2X module during network congestion according to an embodiment of the present invention may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the art of computer software. Examples of computer readable media include hard disks, magnetic media such as floppy disks and magnetic tapes, optical recording media such as CD-ROMs and DVDs, magneto-optical media such as floppy disks, and ROM, RAM, A hardware device specifically configured to store and execute program instructions, such as flash memory, may be included. Examples of program instructions include not only machine code such as generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

In this specification, a "part" includes a unit realized by hardware, a unit realized by software, and a unit realized using both. In addition, one unit may be implemented using two or more hardware, and two or more units may be implemented by one hardware.

The protection scope of the present invention is not limited to the description and expression of the embodiments explicitly described above. In addition, it is added once again that the protection scope of the present invention cannot be limited due to obvious changes or substitutions in the technical field to which the present invention pertains.

100: test device
101: V2X module
110: control unit
120: analysis unit
130: database unit
140: congestion maintenance unit
150 : GPS Simulator
160: user interface unit
200: device under test
201 : V2X module

Claims (5)

A test apparatus having a V2X module controlling data transmission of the V2X module to generate a network congestion situation;
transmitting, by the test device, the data toward the device under test having a V2X module;
retransmitting the data received by the device under test to the testing device; and
testing data reception performance of the device under test by comparing the transmitted data with the retransmitted data by the testing device;
including,
In the step of the test device transmitting the data toward the device under test having a V2X module,
The V2X module provided by the test device transmits a plurality of data each having a different unique ID, generating a virtual environment in which a plurality of surrounding vehicles transmit the data with only a single V2X module,
The test apparatus is provided with a plurality of V2X modules, and controls the data transmission output and period of each V2X module to change the network congestion degree at a point separated by a virtual predetermined distance, data of the V2X module during network congestion How to test transmit/receive performance. The method according to claim 1,
The step of the test device transmitting the data to the device under test having a V2X module,
controlling the strength of the data transmission output of the V2X module provided by the test device;
Data transmission/reception performance test method of the V2X module during network congestion, characterized in that it further comprises. 3. The method according to claim 2,
After the step of controlling the strength of the data transmission output of the V2X module provided by the test device,
controlling the period of data transmission output of the V2X module provided by the test device;
Data transmission/reception performance test method of the V2X module during network congestion, characterized in that it further comprises. delete 4. The method according to claim 3,
The step of the test device transmitting the data to the device under test having a V2X module,
Receiving a plurality of virtual location information from the GPS simulator; and
controlling the data transmission output and period of the V2X module provided by the test device according to the location information;
Data transmission/reception performance test method of the V2X module during network congestion, characterized in that it further comprises.

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