KR102446715B1 - A method and apparatus for distributed congestion control using local dynamic map - Google Patents

Abstract

The present invention relates to a method and apparatus for distributed congestion control using regional dynamic maps. Distributed congestion control method using a local dynamic map according to an embodiment of the present invention, (a) receiving at least one of probe vehicle data (PVD) and V2X communication information of a vehicle for a V2X service from an RSU step; (b) generating LDM (Local Dynamic Map) information including V2X communication channel congestion information based on at least one of the probe vehicle information and V2X communication information; and (c) transmitting the LDM information to the RSU, wherein the LDM information may be used to determine at least one of a transmission period and transmission power of a message transmitted by an OBU of the vehicle. .

Description

A method and apparatus for distributed congestion control using local dynamic map

The present invention relates to distributed congestion control, and more particularly, to a method and apparatus for distributed congestion control using a local dynamic map including V2X communication channel congestion information.

To support Collision Avoidance (CA) safety service or autonomous driving, each vehicle's V2X (Vehicular to Everything) communication terminal, OBU (On Board Unit), sends messages containing various information to multiple surrounding objects. It can be transmitted simultaneously to the users.

In order to transmit a message, each vehicle performs contention-based channel access. As the number of competing vehicles increases, the probability that different vehicles transmit a message at the same time increases, and as a result, different vehicles transmit the message. As messages collide, the probability of an error occurring increases, which increases the probability that the CA safety service or autonomous driving service will fail.

Therefore, when channel access contention intensifies as the number of vehicles increases, each vehicle reduces the total amount of messages generated per second by lowering the message transmit rate by itself to reduce the probability of collision between messages, or to receive a message by lowering the transmission power It uses techniques to reduce the number of competing vehicles by reducing the spatial extent of the vehicle.

This technology is called Distributed Congestion Control (DCC), and IEEE 802.11p/WAVE (Wireless Access Vehicular Environment) and 3GPP LTE C-V2X (C-V2X) and 5G NR (New Radio) C-V2X communication technologies are used. Technology is being developed for this purpose, but research on it is insufficient.

[Patent Document 1] Korean Patent No. 10-1119437

The present invention was created to solve the above problems, and an object of the present invention is to provide a method and apparatus for distributed congestion control using a local dynamic map.

In addition, an object of the present invention is to provide a method and apparatus for determining a transmission period and transmission power of a message using LDM information including V2X communication channel congestion information.

Objects of the present invention are not limited to the objects mentioned above, and other objects not mentioned will be clearly understood from the description below.

In order to achieve the above objects, a distributed congestion control method using a local dynamic map according to an embodiment of the present invention is, (a) probe vehicle data (PVD) and V2X communication information of a vehicle for V2X service receiving at least one of from the RSU; (b) generating LDM (Local Dynamic Map) information including V2X communication channel congestion information based on at least one of the probe vehicle information and V2X communication information; and (c) transmitting the LDM information to the RSU, wherein the LDM information may be used to determine at least one of a transmission period and transmission power of a message transmitted by an OBU of the vehicle. .

In an embodiment, the probe vehicle information may include at least one of location information, direction information, and speed information of the vehicle.

In an embodiment, the V2X communication information may include QoS (Quality of Service) information corresponding to the V2X communication service information of the vehicle and the V2X communication service information.

In an embodiment, the V2X communication channel congestion information may include the number of vehicles competing for each frequency channel for the V2X service, the V2X data rate and transmission power of the vehicle, and congestion level information for each channel.

In an embodiment, the LDM information may be updated according to a predetermined time cycle.

In an embodiment, the distributed congestion control apparatus using a local dynamic map includes: a communication unit for receiving at least one of probe vehicle data (PVD) and V2X communication information of a vehicle for a V2X service from the RSU; and a control unit generating LDM (Local Dynamic Map) information including V2X communication channel congestion information based on at least one of the probe vehicle information and V2X communication information, wherein the communication unit transmits the LDM information to the RSU and the LDM information may be used to determine at least one of a transmission period and transmission power of a message transmitted by the OBU of the vehicle.

In an embodiment, the probe vehicle information may include at least one of location information, direction information, and speed information of the vehicle.

In an embodiment, the V2X communication information may include QoS (Quality of Service) information corresponding to the V2X communication service information of the vehicle and the V2X communication service information.

In an embodiment, the V2X communication channel congestion information may include the number of vehicles competing for each frequency channel for the V2X service, the V2X data rate and transmission power of the vehicle, and congestion level information for each channel.

In an embodiment, the LDM information may be updated according to a predetermined time cycle.

Specific details for achieving the above objects will become clear with reference to the embodiments to be described in detail below in conjunction with the accompanying drawings.

However, the present invention is not limited to the embodiments disclosed below, and may be configured in various different forms, and those of ordinary skill in the art to which the present invention pertains ( Hereinafter, "a person skilled in the art") is provided to fully inform the scope of the invention.

According to an embodiment of the present invention, the vehicle itself adaptively adjusts the transmission period and transmission power of a message according to the V2X communication channel congestion in a VANET (Vehicular Ad-hoc network) using LDM information including V2X communication channel congestion information. Distributed congestion control can be performed.

The effects of the present invention are not limited to the above-described effects, and potential effects expected by the technical features of the present invention will be clearly understood from the following description.

Figure 1a is a diagram illustrating a frequency-time channel structure for conventional V2X communication.
1B is a diagram illustrating a conventional CBR mapping table.
2 is a diagram illustrating a wireless communication system according to an embodiment of the present invention.
3 is a diagram illustrating LDM information according to an embodiment of the present invention.
4 is a diagram illustrating a signal flow for distributed congestion control using a regional dynamic map according to an embodiment of the present invention.
5 is a diagram illustrating an example of determining a transmission period according to an embodiment of the present invention.
6 is a diagram illustrating a method for distributed congestion control using a regional dynamic map according to an embodiment of the present invention.
7 is a diagram illustrating a functional configuration of an apparatus for distributed congestion control using a regional dynamic map according to an embodiment of the present invention.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail.

Various features of the invention disclosed in the claims may be better understood upon consideration of the drawings and detailed description. The apparatus, methods, preparations, and various embodiments disclosed herein are provided for purposes of illustration. The disclosed structural and functional features are intended to enable those skilled in the art to specifically practice the various embodiments, and are not intended to limit the scope of the invention. The terms and sentences disclosed are for the purpose of easy-to-understand descriptions of various features of the disclosed invention, and are not intended to limit the scope of the invention.

In describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

Hereinafter, a method and apparatus for distributed congestion control using a regional dynamic map according to an embodiment of the present invention will be described.

Figure 1a is a diagram illustrating a frequency-time channel structure for conventional V2X communication. 1B is a diagram illustrating a conventional CBR mapping table.

Referring to FIG. 1A , an example of a frequency-time channel structure of 3GPP LTE C-V2X that transmits a message in a 100 ms period can be confirmed. Assuming that 2 messages are transmitted through 2 resources (sub-channels) per 1 ms during a 100 ms transmission period, a maximum of 200 vehicles can transmit 200 messages.

In the conventional case, the average received signal strength (RSSI) for the past 1 second is measured for 200 resources R usable during the transmission period in each vehicle, and this value exceeds the predetermined threshold RSSI _th . In this case, it is determined as a resource being used by another competing vehicle.

In this case, Channel Busy Ratio (CBR) represents a ratio of resources determined to be used by other competing vehicles among all available resources (200 in the case of FIG. 1A ).

Referring to FIG. 1b , a method of mapping the maximum value (CR _limit ) of radio resources that can be used by each vehicle is used according to the section to which the CBR measured by each vehicle belongs, and each vehicle transmits a transmission period within the limit of the CR _limit . The message can be transmitted by determining each and the transmission power.

The mapping table of the CBR value of FIG. 1 and the corresponding CR _limit value may be derived by the following process.

Each vehicle measures the ratio of radio resources in which the average Received Signal Strength Indicator (RSSI) of available resources exceeds the set criteria as CBR, and the number of competing vehicles using the measured CBR value; N _sta can be estimated as in Equation 1 below.

In this case, since CBR is proportional to the number of competing vehicles, N _sta can be expressed as an arbitrary function f() with CBR as an input value.

The maximum CR _limit of the channel capacity that can be used by each vehicle can be calculated as shown in Equation 2 below by dividing CR _{total_limit} , which is the maximum value of the total amount of radio resources, by N _sta .

In the conventional case, the most important process for determining accuracy is a process for determining N _sta from the measured CBR of <Equation 1>. However, due to the movement of the OBU of the transmitting end and the receiving end of the V2X, a small fading phenomenon occurs in which the received power is instantaneously changed, and thereby the RSSI of the received signal strength may be instantaneously changed up to 30 dB.

For this reason, if the distance between the transmitter and the receiver is long or in the case of a NLOS (Non Line-of-Sight) environment, a low received _{RSSI occurs} . An instantaneous rise or fall occurs.

Therefore, many errors occur in determining whether the radio resource R is in use, which may cause errors in CBR estimation. Therefore, it is impossible to determine the optimal CR _limit and the optimal message transmission period and transmission power of each vehicle.

2 is a diagram illustrating a wireless communication system 100 according to an embodiment of the present invention.

Referring to FIG. 2 , the wireless communication system 100 may include at least one vehicle On Board Unit (OBU) 110 , at least one Road Side Unit (RSU) 120 , and an edge node 130 . .

Probe Vehicle Data (PVD) and V2X communication of each vehicle from the On Board Unit (OBU) 110, which is a V2X communication device of each vehicle in which the RSU 120, which is an infrastructure communication device of V2X communication, operates in the service area information can be received.

In an embodiment, the probe vehicle information may include at least one of location information, direction information, and speed information of the vehicle OBU 110 .

In an embodiment, the V2X communication information may include V2X communication service to be operated by each vehicle OBU 110 and required QoS (eg, data transmission rate and transmission delay, etc.) information.

In addition, the edge node 130 connected to the RSU 120 receives the probe vehicle information and V2X communication information from the RSU 120, and uses the probe vehicle information and the V2X communication information to determine the number of vehicles competing to access each frequency channel. Its required data transfer rate can be estimated.

Here, each vehicle OBU 110 receives a corresponding service by accessing a frequency channel determined according to a service (eg, CA safety service, cooperative sensing, cooperative manuburing service, etc.).

In an embodiment, the RSU 120 may broadcast the number of competing vehicles for each frequency channel generated by the edge node 130 and their requested data transmission rate to each vehicle OBU 110 operating in a corresponding area.

In one embodiment, the RSU 120 uses various infrastructure sensors (not shown) to extract location information and movement direction information of the OBU 110 of each vehicle operating in the region, and the edge node 130 is each vehicle. It can be generated by adding congestion information for each frequency channel to LDM (Local Dynamic Map) information on which the location and dynamic trajectory of the OBU 110 are mapped.

The RSU 120 may broadcast the LDM information including the congestion level information for each frequency channel generated by the edge node 130 to each vehicle OBU 110 operating in the corresponding area (D).

Each vehicle 110 is Q-learning ( Based on Q-Learning) technology or DQN (Deep Q-network) technology based on reinforcement learning, distributed congestion control can be performed by adaptively controlling the message transmission period and transmission power according to the congestion level of the V2X communication channel.

In an embodiment, the congestion level information for each frequency channel and each frequency channel may include the number of competing vehicles and their requested data rate information.

In an embodiment, the RSU 120 may be referred to as a “roadside base station” or a term having an equivalent technical meaning.

The edge node 130 may be referred to as “Multi-Access Edge Computing (MEC)” or a term having an equivalent technical meaning. In one embodiment, the edge node 130 may be installed in the same place as the RSU 120 or may be installed in a separate place through a wired network.

That is, according to the present invention, the V2X communication channel in VANET (Vehicular Ad-hoc network) using vehicle operation information or Local Dynamic Map (LDM) collected in a limited area centered on the RSU 120 . Distributed congestion control in which the car 110 adaptively controls the message transmission period and transmission power by itself according to the degree of congestion may be performed.

3 is a diagram illustrating LDM information 200 according to an embodiment of the present invention.

Referring to FIG. 3 , the new wireless communication network LDM information 200 includes the number of vehicles competing for each frequency channel for V2X service, V2X data rate and transmission power information of the vehicle OBU 110, and congestion level information for each channel. It may include the V2X communication information 220 .

In addition, each layer information (210, 212, 214, 216) of LDM is a concept defined in international standards (eg ISO 18750, ETSI 302 895), and information related to vehicles and conditions on the road is spatially located and valid period. It can be standardized and expressed.

Each layer information 210, 212, 214, 216 of the LDM is a static layer 210 that changes or updates on a monthly basis, a semi-static layer 212 that changes or updates on a time basis, and a quasi-dynamic layer that changes or updates every minute It may further include a layer 214 , and a dynamic layer 216 that changes and updates every second.

The dynamic layer 216 may include location and size of a fixed and moving object (eg, the vehicle 110 ) within the service area, and movement trajectory information such as movement direction, speed, and acceleration.

Therefore, for example, each layer information (210, 212, 214, 216) of the LDM is a three-dimensional digital high-precision information such as traffic lights, signs, curbs, road surface marks, various structures, as well as information such as building and road center lines and boundary lines. It may be displayed on a map, and may include information such as the current location of pedestrians and vehicles, and the direction and speed of movement.

In the present invention, in each layer information (210, 212, 214, 216) of LDM, the number of vehicles competing for each frequency channel for V2X service, V2X data rate and transmission power information of the vehicle OBU 110, and congestion information for each channel By adding the V2X communication information 220 including the, it is possible to configure the new wireless communication network LDM information (200).

In one embodiment, the V2X communication information 220 is for each channel of the 28 GHz frequency band to be used for 7 channels of the 5.9 GHz band to be used for IEEE802.11p / WAVE and 3GPP LTE C-V2X communication and 5G NR C-V2X in the future. , may include at least one of the number of vehicles competing for channel access, their required data rate, or congestion level information for each frequency channel.

4 is a diagram illustrating a signal flow for distributed congestion control using a regional dynamic map according to an embodiment of the present invention.

Referring to FIG. 4 , in step S401 , the vehicle OBU 110 may transmit at least one of probe vehicle information and V2X communication information of the vehicle 110 to the RSU 120 .

In step S402 , the RSU 120 may transmit at least one of the received probe vehicle information and the V2X communication information of the vehicle OBU 110 to the edge node 130 .

In step S403 , the edge node 130 may generate LDM information including V2X communication channel congestion information based on at least one of probe vehicle information and V2X communication information of the vehicle OBU 110 .

In step S404 , the edge node 130 may transmit LDM information to the RSU 120 .

In step S405 , the RSU 120 may transmit the received LDM information to the vehicle OBU 110 .

In step S406 , the vehicle OBU 110 may determine at least one of a transmission period and transmission power of a message by using the LDM information. In an embodiment, the vehicle OBU 110 may determine at least one of a transmission period and transmission power of a message by using the V2X communication information included in the LDM information.

In one embodiment, in determining the transmission period and transmission power of the message, the vehicle OBU 110 includes the transmission period and transmission power based on the location information, direction information, and speed information of the vehicle OBU 110 included in the LDM information. priority can be calculated.

Thereafter, the vehicle OBU 110 may transmit a message by determining one of a transmission period and transmission power according to the priority by using the V2X communication information included in the LDM information.

Then, the vehicle OBU 110 uses the V2X communication information included in the updated LDM information corresponding to the feedback information according to the channel state of the V2X communication, and determines the other one of the transmission period and the transmission power according to the priority of the message can be sent.

For example, the vehicle OBU 110 may prioritize the transmission cycle as the first priority and the transmission power as the second priority in terms of communication efficiency based on the location information, direction information, and speed information of the vehicle OBU 110 . .

The vehicle OBU 110 may determine a transmission period using the V2X communication information included in the LDM information according to the priority at the first time point, and transmit the message according to the determined transmission period.

Thereafter, the vehicle OBU 110 determines the transmission power using the included V2X communication information, based on the updated LDM information corresponding to the feedback information according to the channel state of the V2X communication at the second time point, and to the determined transmission power. You can send messages accordingly.

In step S407 , the vehicle OBU 110 may transmit a message based on at least one of the determined transmission period and transmission power. In an embodiment, the vehicle OBU 110 may simultaneously transmit a message to a plurality of surrounding objects (eg, vehicle, user's terminal, RSU, etc.) based on at least one of the determined transmission period and transmission power.

In one embodiment, each step of FIG. 4 may be performed repeatedly until the V2X communication is terminated by proceeding with each transmission period.

5 is a diagram illustrating an example of determining a transmission period according to an embodiment of the present invention.

Referring to FIG. 5 , an example in which each vehicle OBU 110 adaptively determines a transmission period based on the Q-learning technique can be identified.

As shown in FIG. 5 , assuming that the maximum number of messages that can be transmitted per 100 ms is 200, when the number of competing vehicles exceeds 200, if the transmission period is maintained at 100 ms, one or more message collisions may occur.

Accordingly, when the number of competing vehicles exceeds 200 and is less than or equal to 400, the transmission period is increased to 200 ms, so that up to 400 vehicles can transmit at least one message without collision within the transmission period of 200 ms.

In addition, each vehicle 110 may adaptively determine a transmission period based on a deep Q-network (DQN) technology based on reinforcement learning. That is, in the present invention, when the RSU 120 and the edge node 130 estimate the number of vehicles competing for each communication channel or congestion level information for each channel and broadcast this to the vehicle OBU 110 , the vehicle OBU 110 communicates Using a reinforcement learning-based neural network that takes as input at least one of the number of competing vehicles for each channel and congestion information for each communication channel, the maximum CR_limit or transmission period and transmission power of the radio resource share that the vehicle OBU 110 can use can be decided

6 is a diagram illustrating a method for distributed congestion control using a regional dynamic map according to an embodiment of the present invention. In one embodiment, each step of FIG. 6 may be performed by the edge node 130 .

Referring to FIG. 6 , step S601 is a step of receiving at least one of probe vehicle information and V2X communication information of the OBU 110 of the vehicle for the V2X service from the RSU 120 .

In an embodiment, the probe vehicle information may include at least one of location information, direction information, and speed information of the vehicle 110 .

In an embodiment, the V2X communication information may include QoS (Quality of Service) information corresponding to the V2X communication service information and the V2X communication service information of the vehicle OBU 110 .

Step S603 is a step of generating LDM information including V2X communication channel congestion information based on at least one of probe vehicle information and V2X communication information.

In an embodiment, the V2X communication channel congestion information may include the number of vehicles competing for each frequency channel for the V2X service, V2X data rate and transmission power information of the vehicle, and congestion level information for each channel.

Step S605 is a step of transmitting LDM information to the RSU. In one embodiment, the LDM information may be used to determine at least one of a transmission period and transmission power of a message transmitted by the OBU 110 of the vehicle.

In an embodiment, the LDM information may be updated according to a predetermined time cycle.

7 is a diagram illustrating a functional configuration of an edge node 130 for distributed congestion control using a local dynamic map according to an embodiment of the present invention.

Referring to FIG. 7 , the edge node 130 may include a communication unit 710 , a control unit 720 , and a storage unit 730 .

The communication unit 710 may receive at least one of probe vehicle data (PVD) and V2X communication information of the vehicle OBU 110 for the V2X service from the RSU 120 .

In an embodiment, the communication unit 710 may include at least one of a wired communication module and a wireless communication module. All or part of the communication unit 710 may be referred to as a 'transmitter', 'receiver', or 'transceiver'.

The controller 720 may generate LDM (Local Dynamic Map) information including V2X communication channel congestion information based on at least one of probe vehicle information and V2X communication information.

In an embodiment, the controller 720 may include at least one processor or microprocessor, or may be a part of the processor. Also, the controller 720 may be referred to as a communication processor (CP). The controller 720 may control the operation of the edge node 130 according to various embodiments of the present disclosure.

In an embodiment, the communication unit 710 may transmit LDM information to the RSU 120 .

The storage unit 730 may store probe vehicle information and V2X communication information of the vehicle OBU 110 . In an embodiment, the storage 730 may store LDM information including V2X channel congestion information.

In an embodiment, the storage unit 730 may be configured as a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. In addition, the storage unit 730 may provide stored data according to the request of the control unit 720 .

Referring to FIG. 7 , the edge node 130 may include a communication unit 710 , a control unit 720 , and a storage unit 730 . In various embodiments of the present invention, the edge node 130 is not essential to the configurations described in FIG. 7 , so it may be implemented to have more configurations than those described in FIG. 7 , or to have fewer configurations. .

The above description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention.

The various embodiments disclosed herein may be performed out of order, and may be performed simultaneously or separately.

In an embodiment, at least one step may be omitted or added in each figure described herein, may be performed in the reverse order, or may be performed simultaneously.

The embodiments disclosed in the present specification are not intended to limit the technical spirit of the present invention, but to illustrate, and the scope of the present invention is not limited by these embodiments.

The protection scope of the present invention should be construed by the claims, and all technical ideas within the scope equivalent thereto should be understood to be included in the scope of the present invention.

100: wireless communication system
110: OBU
120: RSU
130: edge node
200: LDM information
210: static layer
212: quasi-static layer
214: quasi-dynamic layer
216: dynamic layer
220: V2X communication information
710: communication unit
720: control unit
730: storage

Claims (10)

(a) receiving at least one of probe vehicle data (PVD) and V2X communication information of the vehicle for the V2X service from the RSU;
(b) the number of vehicles competing for each frequency channel for the V2X service based on at least one of the probe vehicle information and the V2X communication information, the V2X data transmission rate and transmission power of the vehicle, and LDM including congestion level information for each channel ( Local Dynamic Map) generating information; and
(c) transmitting the LDM information to the RSU;
including,
LDM information including the number of vehicles competing for each frequency channel for the V2X service, the V2X data transmission rate and transmission power of the vehicle, and congestion level information for each channel, the transmission period and transmission power of a message transmitted by the OBU of the vehicle used to determine at least one of
Distributed congestion control method using local dynamic map.
According to claim 1,
The probe vehicle information includes at least one of location information, direction information, and speed information of the vehicle.
Distributed congestion control method using local dynamic map.
According to claim 1,
The V2X communication information includes QoS (Quality of Service) information corresponding to the V2X communication service information of the vehicle and the V2X communication service information,
Distributed congestion control method using local dynamic map.
delete According to claim 1,
The LDM information is updated according to a predetermined time cycle (time cycle),
Distributed congestion control method using local dynamic map.
a communication unit for receiving at least one of probe vehicle data (PVD) and V2X communication information of a vehicle for V2X service from the RSU; and
Based on at least one of the probe vehicle information and V2X communication information, the number of vehicles competing for each frequency channel for the V2X service, the V2X data transmission rate and transmission power of the vehicle, and LDM (Local Dynamic Map) including congestion level information for each channel ) a control unit for generating information;
including,
The communication unit transmits the LDM information to the RSU,
LDM information including the number of vehicles competing for each frequency channel for the V2X service, the V2X data rate and transmission power of the vehicle, and the congestion level information for each channel, the transmission period and transmission power of a message transmitted by the OBU of the vehicle used to determine at least one of
Distributed congestion control device using local dynamic map.
7. The method of claim 6,
The probe vehicle information includes at least one of location information, direction information, and speed information of the vehicle.
Distributed congestion control device using local dynamic map.
7. The method of claim 6,
The V2X communication information includes QoS (Quality of Service) information corresponding to the V2X communication service information of the vehicle and the V2X communication service information,
Distributed congestion control device using local dynamic map.
delete 7. The method of claim 6,
The LDM information is updated according to a predetermined time cycle (time cycle),
Distributed congestion control device using local dynamic map.

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