System and method for controlling v2x communication

Abstract

The present invention discloses a V2X communication control system. More specifically, the present invention relates to a resource and power control system and method for a V2X sidelink using class-specific differential DCC and SCI extension. According to an embodiment of the present invention, the latency, PDR, and reach requirements of unicast and groupcast can be maintained by reducing global congestion of the sidelink channel through broadcast sacrifice, and class-specific resource separation is induced without protection or exclusion zones for class-specific resources. Accordingly, compared to batch DCC, there is an effect of improving the latency performance of unicast and groupcast and enhancing PDR.

Description

Technology Field

[0001] The present invention relates to a V2X communication control system, and more particularly to a resource and power control system and method for a V2X sidelink using class-specific differential DCC and SCI extension. Background Technology

[0002] The present invention relates to 3GPP-based V2X (Vehicle to Everything) sidelink communication, and to resource and power control technology that differentially applies Distributed Congestion Control (DCC) to each traffic class in an environment where various classes of traffic such as broadcast (BC), unicast (UC), and groupcast (GC) are mixed, and maintains service-specific QoS (latency, Packet Delivery Ratio (PDR), range, etc.) by utilizing the expansion of Sidelink Control Information (SCI).

[0003] In typical environments, sidelinks usually use sensing-based Semi-Persistent Scheduling (SPS) for periodic messages and Dynamic Scheduling (DS) for non-periodic messages. DCC reduces congestion by uniformly applying increased transmit cycles or decreased transmit power based on the Channel Busy Ratio (CBR); however, this can compromise the low latency, high PDR, and range requirements demanded by unicast and groupcast-based cooperative autonomous driving services (platooning, intersection coordination, etc.).

[0004] In particular, in real-world road environments where various services operate simultaneously, broadcast traffic significantly impacts overall congestion, whereas unicast and groupcast traffic require low latency and high reliability, necessitating the maintenance of transmission cycles and power.

[0005] As a prior art document regarding such a V2X communication control system, Registered Patent Publication No. 10-2219055 discloses a distributed congestion control method and apparatus using a vehicle operating state and V2X service QoS, comprising the steps of: determining a V2X service of a vehicle; determining a transmission period range and a transmission power range of a message for a V2X service based on a QoS (Quality of Service) value for the V2X service; determining a minimum transmission period within the transmission period range and determining a maximum transmission power within the transmission power range; and transmitting a message according to the determined minimum transmission period and maximum transmission power.

[0006] According to prior art literature, while it is possible to transmit a message at optimal transmission power by determining whether the message transmission period and transmission power are changeable, there are limitations in simultaneously satisfying class-specific delays, PDR, etc. Prior art literature

[0007] Registered Patent Publication No. 10-2219055 (Date of publication: Feb. 22, 2021) The problem to be solved

[0008] The present invention relates to a V2X communication control system, and specifically aims to implement a system that reduces global congestion by applying DCC intensively to broadcasts, prioritizes the preservation of service-specific QoS by not applying DCC or applying it minimally to unicasts and groupcasts, and simultaneously secures delay, PDR, and reach performance by class even under traffic where broadcasts, unicasts, and groupcasts are mixed by utilizing SCI extensions (class type, DCC application / non-application, adding required QoS to existing SCIs). means of solving the problem

[0009] To solve the aforementioned problem, a V2X communication control system according to an embodiment of the present invention is a V2X communication control system between a plurality of OBUs mounted in a vehicle and performing V2X communication, wherein the plurality of OBUs may include a receiver unit that demodulates and interprets a received signal and transmits it to a device in the vehicle and includes a CBR that estimates each channel occupancy rate, and a transmitter unit that modulates a signal including the state of the vehicle and transmits it externally through an antenna, while selectively determining a control policy for each message type according to traffic and transmitting it.

[0010] The above-mentioned transmitter may include a message generator that senses the channel usage status of a sidelink candidate resource of an OBU or RSU of another vehicle transmitting at least one of a broadcast, unicast, and groupcast message, and independently selects the resource.

[0011] The above-mentioned transmitter may include a class recognition engine that determines and tags whether a message belongs to one of broadcast, unicast, and group cast depending on the transmission type.

[0012] The above transmitter may include a DCC state machine / policy engine that receives class information and CBR estimates from the class recognition engine and CBR meter, respectively, and selects a control policy for each traffic type.

[0013] The above transmitter may include a resource selector that selects candidate resources through SB-SPS and DS, respectively, for periodic and non-periodic messages according to a selected control policy.

[0014] The above-mentioned transmitter may include a power controller that calculates and maintains transmission power within a class-specific upper limit based on target reception SNR and path loss estimation for unicast and groupcast according to a selected control policy.

[0015] The above-mentioned transmitter may include a retransmission controller that performs message retransmission of unicast and group cast, excluding broadcast, according to the above-mentioned control policy, and increases the number of message retransmissions.

[0016] The above-mentioned transmitter may include a message transmitter that causes the OBU of the target vehicle to receive a message according to a PSSCH or PSCC procedure.

[0017] In addition, the V2X communication control system of the present invention may further include one or more RSUs installed on a road and communicating with the plurality of OBUs.

[0018] In addition, a V2X communication control method according to another embodiment of the present invention for solving the aforementioned problem may include, in a method for controlling V2X communication between a plurality of in-vehicle OBUs or between said OBU and RSU, a step of generating a message to be transmitted, a step of tagging a class according to the message transmission type, a step of estimating CBR, a step of selecting a control policy according to traffic type, a step of increasing DCC strength or maintaining QoS according to the selected control policy, a step of selecting a candidate resource and determining transmission power, and a step of transmitting the generated message.

[0019] The step of generating the message to be transmitted above may include sensing the channel usage status of a sidelink candidate resource of an OBU or RSU of another vehicle transmitting at least one of a broadcast, unicast, and groupcast message, and independently selecting a resource.

[0020] The step of selecting candidate resources and determining transmission power may include, according to a selected control policy, selecting candidate resources through SB-SPS and DS for periodic and non-periodic messages, respectively, and calculating and maintaining transmission power within a class-specific upper limit based on target reception SNR and path loss estimation for unicast and group cast.

[0021] Between the step of selecting the candidate resources and determining the transmission power, and the step of transmitting the generated message, the method may further include the step of performing message retransmission of unicast and group cast, excluding broadcast, and increasing the number of message retransmissions according to the control policy. Effects of the invention

[0022] According to an embodiment of the present invention, the latency, PDR, and reach requirements of unicast and groupcast can be maintained by reducing global congestion of the sidelink channel through broadcast sacrifice, and class-specific resource separation is induced without protection or exclusion zones for class-specific resources. Accordingly, compared to batch DCC, there is an effect of improving the latency performance of unicast and groupcast and enhancing PDR. Brief explanation of the drawing

[0023] FIG. 1 is a diagram showing the structure of a V2X communication control system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating whether DCC is applied and the control policy for each message class of a V2X communication control system according to an embodiment of the present invention. Figures 3 and 4 are diagrams showing the comparison results of platooning speed tracking performance when DCC is applied uniformly and differently for each class, respectively. FIG. 5 is a diagram showing a V2X communication control method according to an embodiment of the present invention. Specific details for implementing the invention

[0024] The present invention as described above will be explained in detail through the attached drawings and embodiments.

[0025] It should be noted that the technical terms used in this invention are used merely to describe specific embodiments and are not intended to limit the invention. Furthermore, unless specifically defined otherwise in this invention, the technical terms used in this invention should be interpreted in the sense generally understood by those skilled in the art to which this invention pertains, and should not be interpreted in an overly broad or overly narrow sense. Additionally, if a technical term used in this invention is an incorrect technical term that fails to accurately express the concept of the invention, it should be replaced with a technical term that can be correctly understood by those skilled in the art. Moreover, general terms used in this invention should be interpreted according to their prior definitions or the context, and should not be interpreted in an overly narrow sense.

[0026] Furthermore, singular expressions used in the present invention include plural expressions unless the context clearly indicates otherwise. In the present invention, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the invention, and should be interpreted as meaning that some of the components or steps may not be included, or that additional components or steps may be included.

[0027] Additionally, terms including ordinal numbers, such as first, second, etc., used in the present invention may be used to describe components, but the components should not be limited by these terms. The terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component.

[0028] Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. Identical or similar components are given the same reference number regardless of the drawing symbols, and redundant descriptions thereof will be omitted.

[0029] FIG. 1 is a diagram showing the structure of a V2X communication control system according to an embodiment of the present invention.

[0030] Referring to FIG. 1, a V2X communication control system according to an embodiment of the present invention is a V2X communication control system between a plurality of OBUs (110, 120) mounted in a vehicle and performing V2X communication, wherein the plurality of OBUs (100, 110) may include a receiver (120) that demodulates and interprets a received signal and transmits it to a device in the vehicle and estimates each channel occupancy rate, and a transmitter (130) that modulates a signal including the state of the vehicle and transmits it to the outside through an antenna, and selectively determines a control policy for each type of message according to traffic and transmits it.

[0031] The OBU (On-board unit; 110, 120) refers to a V2X communication means mounted inside a vehicle, which can directly handle communication between vehicles, between a vehicle and infrastructure, and between a vehicle and a network.

[0032] Messages transmitted from such OBU (110) can be classified into broadcast (BC), unicast (UC), and groupcast (GC) depending on the transmission method.

[0033] Broadcast (101) is a method of transmitting a message to all receivers surrounding itself, so that the transmitted message can be received by multiple surrounding OBUs, and can be used to transmit vehicle operation status information to surrounding vehicles, such as BSM (Basic safety message).

[0034] Unicast (102) transmits messages to only one specific target, and the transmitter and receiver communicate 1:1, and can be used in Maneuver Sharing and Coordination Service between vehicles.

[0035] Additionally, the group cast (103) performs 1:N (N is a natural number) communication between the transmitter and a designated group of receivers by transmitting messages only to selected targets. For example, it can be used to transmit speed and direction information of the lead vehicle in platooning to subsequent vehicles in the platooning.

[0036] In a V2X environment, as various classes (methods) are mixed, conventionally, Distributed Congestion Control (DCC) was applied to reduce congestion. However, this may cause delays in cooperative autonomous driving services based on unicast (102) and groupcast (103). Accordingly, the V2X communication control system according to an embodiment of the present invention is characterized by adaptively applying DCC.

[0037] To this end, the system may include functions for class awareness and signaling, class-specific DCC separation, and setting power and repetition policies. Class awareness and signaling capability is a function that assigns an SCI extension encoding the transport class, QoS grade (e.g., delay, PDR, distance), and DCCX (Distributed Congestion Control eXception) to each message, and allows the policy engine of the message receiver to interpret this. Here, 'DCCX' refers to a flag indicating whether the message is subject to DCC application or DCC non-application and mitigation.

[0038] In addition, the class-specific DCC separation function applies CBR-based DCC (at least one of increasing the transmit period or reducing power) to broadcasts, while not applying DCC or applying it minimally to unicasts and group casts to prioritize QoS preservation.

[0039] And, the function for setting power and repetition policies is the overall congestion CBR total The interval to which this belongs, for example, θ1 or less, greater than θ1 to θ2 or less, greater than θ2 to θ3 or less, greater than θ3 (where, θ n Based on a threshold value (where n is a natural number), the region is divided into uncongested, less congested, congested, and extremely congested segments. For unicast and groupcast, power settings based on the target received SNR (Signal to Noise Ratio) and path loss estimation are maintained in the uncongested, less congested, and congested segments, while a small upper cap (e.g., 1 dB or more) on the reduction of transmit power is allowed only in the extremely congested segment. If necessary, retransmission techniques are utilized to preserve the PDR.

[0040] To implement these functions, a V2X communication control system according to an embodiment of the present invention may include a receiver (120) and a transmitter (130) having a structure shown in one OBU (110).

[0041] The receiver (120) can receive messages from the OBU (110) of another vehicle. Specifically, the receiver (120) can receive periodic or non-periodic messages in broadcast (101), unicast (102), and groupcast (103) according to the content and requirements of the message.

[0042] Additionally, the receiver (120) may include a CBR meter (121). This CBR meter (121) estimates the channel occupancy rate in the sensing window and calculates the total CBR (CBR total ) and broadcast-weighted CBR(CBR BC ) can be calculated in parallel.

[0043] Here, CBR total It represents the ratio of currently used resources to the total resources of the observation window, and is a measure of congestion that indicates how much the entire channel is being used, and CBR BC represents the ratio of resources currently used for broadcast transmission to the total resources of the watch window, and is defined as the amount of congestion caused by BC transmission. In this case, CBR BC By emphasizing the congestion contribution of broadcast traffic, it can be used as a criterion for adjusting the intensity of broadcast-only DCC.

[0044] The transmitter (130) can transmit a message to the target OBU (110) according to an adaptively controlled DCC that reflects the current traffic situation. To this end, the transmitter (130) may include an application layer message generator (131), a class recognition engine (132), a DCC state machine / policy engine (133), a resource selector (134), a power controller (135), a retransmission controller (136), and a message transmitter (137).

[0045] When the message generator (131) receives a trug from the application layer at the OBU (110) that intends to transmit a message, it can generate a periodic or non-periodic message belonging to one of the classes of broadcast (BC), unicast (UC), or group cast (GC) depending on the transmission type. The message period can be determined based on the content and requirements of the message.

[0046] Here, unlike broadcast messages for sharing status and context, unicast and groupcast messages transmit path and control information, so higher QoS, i.e., low-latency and high-reliability performance, is required for message transmission, and this can be reflected in the DCC and control policies described below.

[0047] The class recognition engine (132) can recognize the class of the message to be transmitted. Specifically, the class recognition engine (132) can identify and tag the input message as one of broadcast (BC), unicast (UC), and group cast (GC). This information is transmitted to subsequent modules (i.e., machine / policy engine, resource selector, power controller) and used as a criterion for determining control policies by traffic type.

[0048] The DCC state machine / policy engine (133) receives class information tagged in a message input from the class recognition engine (132), and receives a local CBR estimate (CBR) from the CBR meter (121). total , CB RBC You can select a control policy by traffic type by receiving ) as input.

[0049] In detail, the DCC state machine / policy engine (133) responds to the broadcast (BC) with respect to the CBR totalYou can determine the congestion level (e.g., 4-level congestion level based on thresholds θ1, θ2, θ3) using [this method] and select a policy to enhance DCC operations, such as increasing the transmission period of broadcast messages and reducing transmission power. Additionally, for unicast and group cast (UC, GC), you can select a policy to apply a QoS priority policy to maintain the transmission period and transmission power calculated based on the message transmission period and target received SNR by default.

[0050] However, extreme congestion (e.g., CBR) total For the θ3) interval, the DCC state machine / policy engine (133) can select a policy that maintains the transmission cycle but slightly reduces the transmission power and applies a retransmission technique to compensate for the reduction in transmission power.

[0051] The resource selector (134) performs a sensing-based Semi-Persistent Scheduling (SPS) and dynamic scheduling process for periodic messages and non-periodic messages, and the resource selector (134) can select candidate resources through Sensing-Based SPS (SB-SPS) and Dynamic Scheduling (DS), respectively, as in the past.

[0052] Here, SB-SPS is a distributed scheduling method in which the OBU (110) directly senses surrounding channels and selects a resource (SB) that appears to have fewer collisions, and then repeatedly uses that resource for a certain period (SPS). DS refers to a method in which the channel condition is checked for every transmission, and the best resource is selected for transmission.

[0053] Additionally, the resource selector (134) reflects the policy selected by the DCC state machine / policy engine (133) during the resource selection process through this scheduling. That is, the broadcast (BC) to which DCC is applied can increase the message transmission cycle according to congestion, whereas the unicast (UC) and groupcast (GC) to which DCC is not applied can maintain the cycle according to service requirements.

[0054] The power controller (135) can calculate the transmission power within the upper limit for each class based on the target received SNR and path loss estimation for unicast (UC) and groupcast (GC) according to the selected policy. At this time, the calculated transmission power is maintained even if the congestion is high.

[0055] The retransmission controller (136) applies retransmission according to the decision of the DCC state machine / policy engine (133) and can increase the number of retransmissions to increase reliability. On the other hand, in the broadcast (BC), transmission power can be reduced according to congestion and retransmission may not be applied.

[0056] The message transmitter (137) can transmit messages to the corresponding OBU (100) according to the procedure, including PSSCH (Physical Sidelink Control Channel) and PSCCH (Physical Sidelink Shared Channel), and if necessary, PSFCH (Physical Sidelink Feedback Channel). At this time, whether DCC is applied to each transmitted message can be added to the 1st-stage SCI transmitted from the PSCCH channel.

[0057] In the conventional case, an example of a specific field added to the 1st-stage SCI according to the standard is "CLASS(2 bits) | DCCX(1 bit)". Here, the "CLASS" field indicates the class type (broadcast, unicast, group cast), and "DCCX" indicates whether DCC is applied. Through this, neighboring terminals can determine the class type (broadcast, unicast, group cast) and whether DCC is applied to messages transmitted in the subchannels of a corresponding subframe simply by looking at the 1st-stage SCI transmitted in the PSCCH at the beginning of each subframe, and can use this information to avoid collisions with the messages transmitted by the neighboring terminal. This series of processes can be updated cyclically for every subframe.

[0058] According to the structure described above, the V2X communication control system according to an embodiment of the present invention recognizes and signals the class of a message, separates DCC by class, and determines power and repetition policies, thereby reducing global congestion of the sidelink channel by sacrificing the broadcast class through adaptive resource allocation, and can improve the latency performance of unicast and groupcast and enhance PDR.

[0059] Hereinafter, the control policy of a V2X communication control system according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0060] FIG. 2 is a diagram illustrating whether DCC is applied and the control policy for each message class of a V2X communication control system according to an embodiment of the present invention.

[0061] Referring to FIG. 2, as a control policy and whether to apply DCC for each class applied to the V2X communication control system of an embodiment of the present invention, the broadcast (BC) is a delay target (L MAX) can be determined as a relaxed type, the delay range of the relaxed type can be 50 ms to 100 ms, and DCCX can maintain a default value (DCCX=0). In addition, the PDR target can be 90%, and period and power control can be performed by increasing the message transmission period and decreasing the transmission power when congestion increases.

[0062] Additionally, for unicast (UC), the delay target can be determined more strictly than for broadcast and group cast, and the delay range can be equal to or less than within 20 ms to 30 ms, and DCCX is not applied or is relaxed (DCCX=1). Additionally, the PDR target can be equal to or greater than within the range of 97% to 99%, and cycle control maintains the service requirement cycle and allows only minimal changes in extreme cases.

[0063] In addition, power control is designed to meet the target SNR distance, but at extreme congestion, the transmission power is reduced within a small cap (less than 1 dB), and the retransmission (Rep) is increased to preserve PDR.

[0064] Additionally, for group cast (GC), the delay target can be determined more strictly than for broadcast and group cast, and the delay range can be equal to or less than within 30 ms to 40 ms, and DCCX is not applied or is relaxed (DCCX=1). Additionally, the PDR target can be equal to or greater than within the range of 97% to 99%, and the period, power, and retransmission control can be set the same as for unicast (UC).

[0065] Hereinafter, the technical concept of the present invention is explained in detail through the simulation results of a V2X communication control system according to an embodiment of the present invention.

[0066] Figures 3 and 4 are diagrams showing the comparison results of platooning speed tracking performance when DCC is applied uniformly and differently for each class, respectively.

[0067] Referring to FIGS. 3 and 4, the results of a comparative analysis of the performance of a V2X communication control system according to an embodiment of the present invention through simulation are shown. The simulation was performed under the assumption that six vehicles (Veh 1 to Veh 6) are driving in a platooning group in a straight highway environment and are transmitting a broadcast message in a situation where the density of surrounding vehicles is 500 vehicles / km.

[0068] In particular, within a platooning group, the leader vehicle (Veh 6) transmits a leader status message containing the speed, acceleration, and direction information of the leader vehicle to the remaining 5 follower vehicles via a group cast method, and shows the results of a performance analysis of the subsequent vehicles rapidly decelerating by considering the time delay and message reception accuracy for the subsequent vehicles to receive the leader status message in a situation where the leader vehicle rapidly decelerates from 60 km / h to 20 km / h due to a sudden situation ahead.

[0069] Referring to FIG. 4, as a result of applying DCC to both the broadcast messages of surrounding vehicles and the group cast messages of the platooning group, it can be seen that when DCC is applied to the group cast messages, the transmission period of the leader status message increases at high congestion, and the follower vehicles (Veh 5, Veh 4, Veh 3) close to the leader vehicle (Veh 6) follow the speed change of the leader vehicle (Veh 6) relatively stably and decelerate, but the follower vehicles (Veh 2, Veh 1) far from the leader vehicle (Veh 6) experience a significant delay in receiving the leader status message, so they cannot immediately follow the deceleration of the leader vehicle and a collision may occur.

[0070] Referring to Fig. 5, DCC is applied to broadcast messages from surrounding vehicles to increase the transmission period according to congestion, and DCC is applied to group cast messages of the platooning group to reduce overall congestion despite high congestion environments, and DCC is not applied to group cast messages to satisfy the required transmission period, thereby confirming that all follower vehicles (Veh 1 to Veh 5) relatively stably follow the speed change of the leader vehicle (Veh 6) and decelerate their speeds.

[0071] Hereinafter, a communication control method using a V2X communication control system according to an embodiment of the present invention having the aforementioned structure will be described in detail with reference to the drawings. In the following description, the executing entity for each step shall be the V2X communication control system of the present invention and its control unit, unless otherwise specified.

[0072] FIG. 5 is a diagram showing a V2X communication control method according to an embodiment of the present invention.

[0073] Referring to FIG. 5, a V2X communication control method according to an embodiment of the present invention first performs message transmission between multiple OBUs in an environment where multiple vehicles are operating and performing V2X communication. First, a message generator of a transmitter mounted on an OBU generates messages according to a transmission type periodically or non-periodically (S200).

[0074] Next, the class recognition engine identifies the message to be transmitted and tags it as one of Broadcast (BC), Unicast (UC), or Group Cast (GC) depending on the class (S201). Subsequently, the DCCX and QoS grades can be determined based on these types.

[0075] Next, the CBR meter mounted on the OBU measures the total CBR according to channel occupancy. TOTAL and broadcast-weighted CBR BC It can be calculated in parallel (S202).

[0076] Next, the DCC state machine / policy engine selects a control policy for each traffic type using the class information generated in step S201 and the local CBR estimate calculated in step S202 (S203). Accordingly, the resource selector CBR TOTAL The congestion level is determined using [this method], and the DCC operation of broadcast messages is strengthened (S204), and for unicast and groupcast messages, a strengthening policy can be selected with QoS priority (S205).

[0077] Next, the power controller calculates the transmission power within the upper limit for each class based on the target reception SNR and path loss estimation (S206).

[0078] Then, the message transmitter controls V2X communication by transmitting a message according to the class-specific policy of the message to the corresponding OBU in accordance with the PSSCH and PSCCH procedures (S207).

[0079] Although many details are described in detail in the above description, this should be interpreted as an example of a preferred embodiment rather than as a limitation to the scope of the invention. Accordingly, the invention should not be determined by the described embodiment, but by the claims and equivalents thereof.

[0080] This project (result) is the outcome of the Regional Innovation-Centered University Support System (RISE), carried out with funding from the Ministry of Education and Chungcheongbuk-do and supported by the Chungbuk RISE Center in 2025. (2025-RISE-11-004-03) Explanation of the symbols

[0081] 100, 110 : OBU 101 : Broadcast(BC) 102 : Unicast (UC) 103 : Groupcast (GC) 120 : Receiver 121 : CBR meter 130 : Transmitter 131 : Message generator 132: Class Recognition Engine 133: DCC State Machine / Policy Engine 134: Resource Selector 135: Power Controller 136 : Retransmission controller 137 : Message transmitter

Claims

Claim 1 A V2X communication control system between a plurality of OBUs mounted in a vehicle and performing V2X communication, wherein the plurality of OBUs include: a receiver unit that demodulates and interprets a received signal and transmits it to a device within the vehicle and estimates each channel occupancy rate, and a transmitter unit that modulates a signal including the state of the vehicle and transmits it externally through an antenna, and selectively determines a control policy for each message type according to traffic and transmits it, wherein the transmitter unit includes: a class recognition engine that determines whether a message belongs to one of broadcast, unicast, and group cast according to the transmission type and tags it; and a DCC state machine / policy engine that receives class information and CBR estimates from the class recognition engine and a CBR meter, respectively, and selects a control policy for each traffic type, wherein the control policy strengthens the DCC operation of increasing the transmission period of the message and decreasing the transmission power for broadcasts according to a determined congestion stage. Claim 2 A V2X communication control system according to claim 1, wherein the transmitting unit includes a message generator that senses the channel usage status of a sidelink candidate resource of an OBU or RSU of another vehicle transmitting at least one of a broadcast, unicast, and groupcast message, and independently selects the resource. Claim 3 delete Claim 4 delete Claim 5 A V2X communication control system according to claim 1, wherein the transmitting unit includes a resource selector that selects candidate resources through SB-SPS and DS, respectively, for periodic and non-periodic messages according to a selected control policy. Claim 6 A V2X communication control system according to claim 1, wherein the transmitter comprises a power controller that calculates and maintains transmission power within a class-specific upper limit based on target reception SNR and path loss estimation for unicast and groupcast according to the control policy. Claim 7 A V2X communication control system according to claim 1, wherein the transmitting unit performs message retransmission of unicast and group cast excluding broadcast according to the control policy, and includes a retransmission controller that increases the number of message retransmissions. Claim 8 In claim 1, the transmitting unit is a V2X communication control system comprising a message transmitter that causes the OBU of a target vehicle to receive a message according to a PSSCH or PSCC procedure. Claim 9 In claim 1, the V2X communication control system further comprises one or more RSUs installed on a road and communicating with the plurality of OBUs. Claim 10 A method for controlling V2X communication between multiple in-vehicle OBUs, or between said OBUs and RSUs, comprising: a step of generating a message to be transmitted; a step of determining and tagging whether said message belongs to one of broadcast, unicast, and group cast according to the transmission type; a step of estimating CBR; a step of receiving class information and an estimated CBR value and selecting a control policy for each traffic type; a step of increasing DCC strength or maintaining QoS according to the selected control policy; a step of selecting candidate resources and determining transmission power; and a step of transmitting the generated message, wherein the control policy strengthens the DCC operation of increasing the transmission period of the message and decreasing the transmission power for broadcast according to the determined congestion level. Claim 11 A V2X communication control method according to claim 10, wherein the step of generating the message to be transmitted comprises: sensing the channel usage status of a sidelink candidate resource of an OBU or RSU of another vehicle transmitting at least one of a broadcast, unicast, and groupcast message; and independently selecting a resource. Claim 12 A V2X communication control method according to claim 10, wherein the step of selecting candidate resources and determining transmission power comprises: a step of selecting candidate resources through SB-SPS and DS for periodic and non-periodic messages, respectively, according to the control policy; and a step of calculating and maintaining transmission power within a class-specific upper limit based on target reception SNR and path loss estimation for unicast and groupcast. Claim 13 A V2X communication control method according to claim 10, further comprising, between the step of selecting the candidate resource and determining the transmission power and the step of transmitting the generated message, the step of performing message retransmission of unicast and group cast excluding broadcast and increasing the number of message retransmissions according to the control policy.

Images