KR20160048020A - Method and Apparatus for Velocity based Self-Configuring Time Division Broadcasting Protocol for Periodic Messages in Vehicle-to-Vehicle Communication - Google Patents

Abstract

Disclosed are a method for active time division broadcasting of periodic messages for controlling congestion in vehicle-to-vehicle communications and a method and an apparatus for controlling a communication setting. The method for controlling a communication setting of periodic messages in vehicle-to-vehicle communications comprises the steps of: predicting a vehicle-to-vehicle density by using a minimum safety distance according to a vehicle speed and grasping a communication environment of the periodic messages in the vehicle-to-vehicle communications; and adjusting parameters of the communication environment including transmission power of the periodic messages, a transmission rate of the periodic messages, and a beacon generation period according to the vehicle-to-vehicle density and the communication environment of the periodic messages and dispersing transmission time points of the periodic messages.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active time-division broadcasting method and apparatus and a communication setting control method for periodic messages for controlling congestion in inter-

The present invention relates to an active time-division broadcasting method and an apparatus and method for communication setting control of periodic messages for controlling congestion in inter-vehicle communication.

In recent years, wireless communication technologies are rapidly evolving, and advanced wireless communications are creating new services and markets. In addition, new services have a great impact on our daily lives and industries. In the automobile industry, research and development are being conducted to provide new services for drivers and passengers using wireless communication. The IEEE 802.11p Working Group has established a wireless communication standard for vehicle environments that combines 802.11 and 1609 standards. This standard is called Wireless Access in Vehicular Environments (WAVE) and defines communication protocols for vehicles, vehicles, and road and vehicle sections. Recently, projects are being carried out to develop safety services using vehicle-to-vehicle communications centered on the United States and Europe. These projects performed and defined the service scenarios, communication requirements, message formats required for safety applications, and implementation and test verification based on them. A variety of services have been studied using this.

In order to provide safety service in inter-vehicle communication, periodic message distribution should be done. The periodic message includes vehicle status information (eg, speed, location, direction, etc.) and should be generated and sent in a short cycle in a typical traffic environment. In inter-vehicle communication, large network congestion and collisions can frequently occur due to the short interval of such periodic message broadcasting. These problems may reduce the message reception rate and may even result in messages not being received from nearby vehicles. This situation is called the broadcast storm problem. In particular, network congestion caused by periodic message exchange in a densely populated urban environment hinders delivery of urgent event occurrence messages. In this case, it may take more time than expected for all the surrounding vehicles to receive the urgent message in the emergency message propagation.

There are two approaches to solve the problem of periodic message broadcasting. One is competition-based and the other is a schedule-based method. Many studies have proposed competition-based algorithms to reduce collision and congestion of vehicle networks. Sepulcre et al. Proposed a method to reduce network load with application-based hybrid control policy. This method deals with the problem of periodic messages and controls the congestion through the transmission strength and packet generation period required by the application. This research designed and verified algorithms for lane change assistant applications. He et al. Proposed an adaptive congestion control algorithm that operates at the application layer. This algorithm is also a generation interval control method and it is characterized by detecting the direct / indirect collision event occurring in the MAC layer and operating it. The authors have studied both cyclic safety and event safety applications. Torrent-Moreno et al. Proposed a method to adjust the transmission strength to reduce the collision caused by the broadcasting of periodic messages in the vehicle network environment. This method is called Distributed Fair Power Adjustment for Vehicular Environments (D-FPAV). Each node collects status information of all nodes within the maximum receiving distance. Then, each node broadcasts the message by calculating the optimized transmission strength. Other studies have proposed methods using a schedule-based approach to reduce network load on vehicle networks. Yu et al. Proposed a Time Division Multiple Access (TDMA) MAC method for vehicle security services in the intervehicle communication environment. This method is designed to operate with knowledge of the position and movement of the vehicles. In a crowded driving situation of the vehicle, the MAC slots are allocated slots to be used depending on the relative positions of the vehicles. This method deals with the delivery of event occurrence messages through the Cooperative Collision Avoidance (CCA) application. Bai et al. Proposed a context - aware periodic message exchange scheduling scheme to reduce congestion on the vehicle network. This method is included in the time division based periodic message scheduling method. And we define Virtual Time Frame (VTF) which means periodic message generation interval. The vehicles are allocated time slots for periodic message exchange through the surrounding vehicle situation (location, speed, direction, etc.) and communication load information. This method also includes adjusting the VTF from 100ms to 500ms depending on the safety application. In addition, Bae, Jeong-Kyu et al. Proposed a congestion control method based on vehicle movement speed by combining time-offset values according to moving speed of each vehicle and random backoff time of unicast packet to collect the traffic information .

Since most algorithms follow a competitive-based solution, the probability of collision between messages at high vehicle densities can be high. Various algorithms must collect information (vehicle status, network status, etc.) necessary to perform congestion control in real time. However, the steps for collecting the necessary information at a minimum were not separately described. Therefore, it is necessary to predict the vehicle density on the road from the speed of the vehicle and to control the network load caused by the cyclic message broadcasting, without including the initial information collection for the network load control by the schedule-based congestion control method .

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a vehicle safety service system and a method thereof, which can prevent a network overload (i.e., a broadcast storm) problem caused by a basic safety message (BSM or Beacon Message) And to provide a method and apparatus for solving the above problems. Therefore, we propose a speed based active time division broadcasting method and apparatus that efficiently distribute periodic message transmission time points of nearby vehicles according to the density of vehicles.

According to an aspect of the present invention, there is provided a method for adjusting periodic message communication settings for inter-vehicle communication, the method comprising: predicting inter-vehicle density using a minimum safety distance according to vehicle speed; Wherein the periodic message transmission rate is adjusted by adjusting parameters of the communication environment including a transmission power of the periodic message, a transmission rate of the periodic message, and a beacon period according to the inter-vehicle density and the communication environment of the periodic message, . ≪ / RTI >

The step of distributing the transmission time of the periodic message includes configuring Beacon Slot Time (hereinafter, referred to as BST), which is a time-divisional slot of a periodic message of inter-vehicle communication, and each vehicle randomly selecting its BST to transmit a periodic message .

The step of distributing the transmission time point of the periodic message may include a step of variably controlling transmission and reception ranges of the beacon according to the vehicle speed by adjusting transmission power of the periodic message.

The step of distributing the transmission time of the periodic message may include a step of increasing the transmission rate of the periodic message and a transmission time of the periodic message and increasing a beacon slot using the reduced BST.

The step of increasing the beacon slot may include calculating a density of an adjacent vehicle according to a current speed of the reference vehicle, calculating a BST of the periodic message, calculating a time division scheduling period of the reference vehicle using the BST, , Adjusting a transmission range of the periodic message when the calculated density of the neighboring vehicle is greater than the number of the time-divided BSTs, selecting a random slot among the time-divided BSTs, And transmitting the beacon when the beacon is reached.

The step of distributing the transmission time of the periodic message may include adjusting the interval of generation of the periodic message by increasing the period of the beacon period as the vehicle speed is slower.

According to another aspect of the present invention, there is provided an active time-division broadcasting method for inter-vehicle communication, the method including calculating a density of a nearby vehicle according to a current speed of a reference vehicle, calculating a BST of a periodic message of inter- Dividing the time division scheduling period of the reference vehicle into a predetermined number of BSTs using the BST, and adjusting the transmission range of the periodic message when the density of the neighboring vehicles is greater than the number of the time- , And each vehicle may select its BST to distribute the transmission time of the periodic message.

According to another aspect of the present invention, there is provided an apparatus for adjusting periodic message communication settings of inter-vehicle communication proposed in the present invention, which estimates the inter-vehicle density using the minimum safety distance according to the vehicle speed, Wherein the control unit controls parameters of the communication environment including a predictive unit for recognizing the periodic message, a transmission power of the periodic message according to the communication environment of the periodic message, a transmission rate of the periodic message, And a control unit for dispersing the viewpoints.

Wherein the control unit adjusts a transmission power of the periodic message to variably adjust a transmission and reception range of a beacon according to a vehicle speed, a transmission power control unit for increasing a transmission rate of the periodic message, A rate control unit for increasing the beacon slot using the shortened BST, and a message generator for adjusting the beacon generation period by adjusting the generation interval of the periodic message as the vehicle speed is slow.

According to the embodiments of the present invention, the problem of network overload (i.e., broadcast storm) due to periodic messages (BSM) can be solved according to the density of surrounding vehicles when collecting information of nearby vehicles in a vehicle safety service. Therefore, it is possible to reduce the packet collision and increase the network efficiency due to the speed based active time division broadcasting which efficiently disperses the periodic message transmission time point of the surrounding vehicles according to the density of the vehicle.

1 is a flowchart for explaining a communication setting adjustment method for controlling congestion in inter-vehicle communication according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining an alternative channel approach of the WAVE standard according to an embodiment of the present invention. Referring to FIG.
3 is a diagram illustrating an example of an N-beacon slot according to an embodiment of the present invention.
4 is a diagram illustrating an example of the density of low speed and high speed vehicles according to an embodiment of the present invention.
5 is a flowchart illustrating an active time-division broadcasting method of a periodic message for controlling congestion in inter-vehicle communication according to an exemplary embodiment of the present invention.
6 is a diagram illustrating an example of a beacon transmission period for a time division scheduling period according to an embodiment of the present invention.
7 is a diagram for explaining a communication setting control device for controlling congestion in inter-vehicle communication according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart for explaining a communication setting adjustment method for controlling congestion in inter-vehicle communication according to an embodiment of the present invention.

A communication setting adjustment method for controlling congestion in inter-vehicle communication includes estimating inter-vehicle density using a minimum safety distance according to a vehicle speed, determining a communication environment of a periodic message of inter-vehicle communication (110) (120) by adjusting parameters of the communication environment including a transmission power of the periodic message, a transmission rate of the periodic message and a beacon period according to a communication environment of the periodic message ).

In step 110, the inter-vehicle density can be predicted using the minimum safety distance according to the vehicle speed, and the communication environment of the periodic message of inter-vehicle communication can be grasped. In other words, it is possible to predict the density of the vehicle by the speed using the minimum safety distance (MSD) according to the vehicle speed.

FIG. 2 is a diagram for explaining an alternative channel approach of the WAVE standard according to an embodiment of the present invention. Referring to FIG.

The proposed algorithm has the following advantages as an active time - sharing schedule method. It is convenient that there is no procedure for acquiring advance information (for example, position and speed information of the node) for applying the algorithm because it is based on the speed of the vehicle. Thereby restricting the propagation of beacon messages through different time slots at the same time. It also has the flexibility to set the appropriate communication environment to the speed varying vehicle.

The VSC-A project has developed vehicle-to-vehicle (V2V) safety services using communications and designed new communication-based safety applications. The VSC-A project recommends that safety applications in the intervehicular network should be preceded by an exchange of location information 10 times per second in order to provide the correct service. Therefore, each message should be generated and transmitted at intervals of 100 ms. This time interval is called the broadcast interval.

The proposed algorithm is to define the periodic message size and content based on the message proposed in the VSC-A project. For example, the proposed algorithm assumes that a wireless channel is accessed through a device using a single antenna, and a control channel (CCH) 210 and a service channel (SCH) 220) is used. WAVE / 1609.4 standard recommends that both control channels and service channels be accessible at alternate 100ms (230) intervals for alternate channel access.

In other words, as shown in FIG. 2, the channel usage time of 50 ms for the control channels 211 and 212 and 50 ms for the service channels 221 and 222 is guaranteed. However, when the channel is changed, when a control channel is changed to a service channel or a service channel is changed to a control channel, a guard interval 240 is provided for synchronization of the MAC layer. The corresponding time is 4ms, which guarantees the minimum time required for the channel change synchronization between the MAC layer and the service provider defined by WAVE. As a result, although there is a channel occupation time of 50 ms, except for the guard interval (240), the time available for the actual message exchange is 46 ms. Therefore, the proposed algorithm can design a time - divisional scheduling algorithm for periodic message transmission during each synchronized 46ms time of the radio channel.

Generally, if a periodic message is broadcast at intervals of 100 ms in order to provide security services in an area where many vehicles exist, such as an urban area, a large number of messages will be difficult to receive due to a collision. This problem is called a broadcast storm problem. Safety applications rarely receive information about nearby vehicles. In this case, communication-based safety applications are difficult to operate normally. In other words, the reception rate of the periodic message can be lowered in a place where the vehicle density is high.

The proposed algorithm belongs to Time Division Multiple Access (TDMA) and schedule based methods. The proposed algorithm can solve the periodic message problem by defining the beaconslot. The maximum time required when one periodic message is sent is called a beacon slot time (BST), and is composed of a transmission time and a maximum random back off time domain. The transmission time is determined by the transmission rate and the size of the periodic message. For example, the size of the periodic message is defined as 378 Bytes and the transmission rate is defined as 6 Mbps. The size and the transmission rate of these messages refer to the VSC-A communication requirements. The maximum random backoff time setting is based on the following criteria. Since the WAVE communication standard is a communication protocol based on 802.11, a random backoff approach is used to access wireless channels. In particular, WAVE uses 802.11e EDCA (Enhanced Distributed Channel Access) wireless media access method that provides priority based QoS (Quality of Service) and AC (Access Category) As shown in FIG.

<Table 1>

In the proposed method, periodic messages follow the AIFN (Arbitration Inter-Frame Space Number) and CWmin values of AC1 (AC_BK). Therefore, the beacon slot time (BST) defines the maximum random backoff time as the slot time of CWMin and AIFSN1, and when the size (S) of the periodic message is changed in bit units and divided by the transmission rate (R) Time is called transmission time. This content can be summarized by the following equation (1).

수학식(1)

Equation (1)

To determine the transmission time that constitutes the beacon slot time, we refer to the service requirement of VSC-A for the data rate and message size. The WAVE / 802.11p standard is used for the EDCA parameter values and slot time to compute the maximum random backoff, which is another component.

3 is a diagram illustrating an example of an N-beacon slot according to an embodiment of the present invention.

For example, when the length of the beacon is 378 bytes, the transmission time 313 is calculated to be 504 mu s, and the maximum random backoff 312 time becomes 312 mu s by substituting the respective values into the above-described equation (1). Eventually, it takes 816 μs of time to broadcast one periodic message. However, in the case of the random backoff 312, since the value may be smaller than the maximum value, the message transmission may be terminated within 816s. Thus, the beaconslot thus created can create a total of 56 time-division slots 314 during a 46 ms time period except for a guard interval 311 for 50 ms of the control channel or service channel 310, As shown in Fig.

In step 120, parameters of the communication environment including the transmission power of the periodic message, the transmission rate of the periodic message and the beacon generation period according to the inter-vehicle density and the communication environment of the periodic message are adjusted to transmit the periodic message The viewpoint can be dispersed. The step of distributing the transmission time point of the periodic message may include configuring a time slot of the periodic message of the intervehicular communication, and each vehicle may randomly select its BST to transmit the periodic message.

The step of distributing the transmission time of the periodic message by adjusting the parameters of the communication environment includes the step 121 of variably adjusting transmission and reception ranges of the beacon according to the vehicle speed by adjusting transmission power of the periodic message, (Step 122) of increasing the transmission rate of the periodic message by increasing the transmission rate of the periodic message and increasing the beacon slot by using the reduced BST, And adjusting the period (step 123).

The proposed algorithm is designed so that all vehicles allocate beacon slots themselves to broadcast periodic messages. In other words, determining which slot to occupy the channel and broadcast is determined by random variables in the vehicle. It is expected that entry and exit frequently occurs in the network of the vehicle because the change of the movement of the vehicle is large. In addition, the slot allocation scheme can be a temporary allocation scheme. The temporary allocation scheme means that the slot is continuously changed during the simulation time. In this environment, congestion is controlled by allocating slots. However, in the actual environment, more than 56 of the initially proposed slots described above are in operation on the road. Therefore, the efficiency of the proposed algorithm increases as the number of vehicles is lower than the number of slots. If the number of vehicles is more than 56, the radio channel becomes saturated and the problem of network load increase due to periodic messages occurs. Therefore, in order to predict the problem, we try to adjust the communication setting parameters according to density. It is also assumed that the vehicle speed reflects the current traffic situation in order to calculate the vehicle density required for problem prediction. In other words, if the vehicle speed is slow, the closer the distance between the vehicles is, and the faster the speed, the farther the distance between the vehicles becomes.

In the proposed algorithm, the density of the vehicle on the road is predicted by using the minimum safety distance (MSD) formula according to the speed. The minimum safety distance formula consists of vehicle speed (u _i ), driver response time (t _PRT ), road-tire friction coefficient (f), road gradient (G), and gravity deceleration (g) Equation (2) is obtained.

수학식(2)

Equation (2)

The proposed algorithm calculates the inter-vehicle distance according to the speed through equation (2) and predicts the density of the vehicle per km through the calculated distance. Each vehicle adjusts the communication settings according to the calculated density using the speed of the vehicle. Table 2 summarizes the vehicle densities according to speed.

<Table 2>

For example, the value of the minimum safety distance variable is set as follows. The driver's reaction time (t _PRT ): 2 seconds, the road-tire friction coefficient (f): 0.4, and the road gradient (G): 0. As shown in Table 2, the predicted density may be effective in an ideal environment, but there may be a difference from the actual vehicle density depending on the driving environment and the driving habits of the driver. However, it is also possible to predict the density of neighboring vehicles even if they are not able to receive beacons from neighboring vehicles due to network congestion, Future research should be added to the algorithms that can correct the velocity - based density prediction based on the vehicle network conditions.

4 is a diagram illustrating an example of the density of low speed and high speed vehicles according to an embodiment of the present invention.

For example, when vehicles are moving at low speeds as in FIG. 4A, there may be many vehicles while maintaining a narrow headway spacing (i.e., high density) 410. On the other hand, when the vehicles move at high speed as shown in FIG. 4B, there may be a large number of vehicles while maintaining a wide wheelbase (that is, low density) 420. Accordingly, in step 121, the transmit power of the periodic message may be adjusted to variably adjust the transmit and receive ranges of the beacon according to the vehicle speed.

Reliable reception of information of nearby vehicles is required in providing safety services. In other words, the information of a vehicle located at a distance is relatively unnecessary, and it needs information of a nearby vehicle. In addition, congestion may be expected at a peripheral vehicle density exceeding the maximum number of time-divided BSTs. In this case, the transmission power can be adjusted to vary the transmission and reception range of the beacon according to the speed, thereby increasing the communication success rate.

The step 122 of increasing the transmission rate of the periodic message to reduce the transmission time of the periodic message and increasing the beacon slot using the reduced BST may include calculating the density of the surrounding vehicle according to the current speed of the reference vehicle, Dividing the time-division scheduling period of the reference vehicle into a predetermined number of BSTs using the BST, and calculating the BST of the periodic message when the density of the neighboring vehicles is greater than the number of the time- And adjusting the transmission range of the periodic message. This will be described in more detail with reference to FIG.

5 is a flowchart illustrating an active time-division broadcasting method of a periodic message for controlling congestion in inter-vehicle communication according to an exemplary embodiment of the present invention.

Most safety services aim to determine potential risk factors in real-time and inform the driver of them. Blind Spot Warning (BSW), Lane Change Warning (LCW), and Forward Collision Warning (FCW) are typical examples. These services place more importance on the location information of the near vehicles in order to judge the potential risk to the driver. In other words, the location information of the surrounding vehicles is more important than the location information of the remote vehicles in order to provide the safety service. Therefore, when the vehicles run at low speed, it is necessary to adjust the transmission strength to reduce the message reach and concentrate on the information collection of the surrounding vehicles. Since the proposed algorithm is a congestion control algorithm based on the inter-vehicle distance according to the speed, it is necessary to control the number of vehicles in 1-hop by controlling the transmission strength when the speed is slow. In addition, the number of beaconslots is increased by increasing the transmission rate and applying the time division interval to the flow. Finally, since the change of movement is small when the moving speed of the vehicle is slow, it is desired to prevent the network congestion by adjusting the generation interval of the periodical message.

An active time-division broadcasting method of periodic messages for controlling congestion in inter-vehicle communication is shown in Fig.

Algorithm performs time-division scheduling in units of BST set as shown in Equation (1) for every synchronized time-sharing scheduling interval (SI), and each vehicle is configured to transmit a beacon message in a random random slot among the divided BSTs have. In this paper, as shown in FIG. 2, the time division scheduling period is set to 50 ms by alternately accessing the channels in 50 ms units, and BST division is performed for 46 ms except for 4 ms of the guard interval.

Each vehicle performs time division scheduling if there is a beacon message to be transmitted 510 and the previous time division scheduling period SIt-1 has been completed 520. First, the density (dent) of the surrounding vehicle according to the current speed of the reference vehicle can be calculated using Equation (2) and Table 2 (530). The BST of the periodic message can then be calculated 510 according to Equation (1). The time division scheduling period of the reference vehicle may be time-divided into a predetermined number of BSTs using the BST (550). In other words, the current time division scheduling period (SIt) can be time-divided into N BSTs.

Next, if the calculated density of the neighboring vehicle is greater than the number of time-division-based BSTs, the transmission range of the periodic message may be adjusted (560). If the density of the calculated vehicle is compared with the number of BST N (561), the transmission range of the periodic message can be adjusted (562) if the calculated density of the vehicle is greater than or equal to the number of BSTs N. In other words, when the density of the calculated vehicle is equal to or greater than the number of BST N, network congestion is expected, so congestion can be prevented in advance by reducing the transmission range. The transmission range shall be set to a range exceeding the vehicle safe distance (dveh) in Table 2 since beacon transmission of 1-hop or more is required.

Each vehicle may then select its BST to distribute the transmission time of the periodic message. In other words, each vehicle can allocate any random slot of the time-divided BST (570). When the random slot time is reached (580), the beacon can be transmitted (590).

6 is a diagram illustrating an example of a beacon transmission period for a time division scheduling period according to an embodiment of the present invention.

The channel usage time of the control channel 610 of 50 ms and the service channel 620 of 50 ms is guaranteed as described above. And, when the channel is changed, when the control channel is changed to the service channel or the service channel is changed to the control channel, a guard interval 630 for synchronization of the MAC layer is set. The active time-division broadcasting method of periodic messages for controlling congestion in the proposed inter-vehicle communication consequently transmits a beacon within a time division schedule period of 50 ms as shown in FIG. Therefore, it is possible to transmit a periodic beacon message satisfying the period 660 of maximum 100 ms between the random slot 640 in the previous time-division scheduling period and the random slot 650 in the current time-division scheduling period while reducing the congestion of the inter-vehicle network. Respectively.

7 is a diagram for explaining a communication setting control device for controlling congestion in inter-vehicle communication according to an embodiment of the present invention.

The communication setting controller 700 for controlling congestion in inter-vehicle communication may include a predictor 710 and a controller 720.

The predicting unit 710 predicts the inter-vehicle density using the minimum safety distance according to the vehicle speed, and can grasp the communication environment of the periodic message of the inter-vehicle communication.

The control unit 720 adjusts the parameters of the communication environment including the transmission power of the periodic message, the transmission rate of the periodic message, and the beacon generation period according to the inter-vehicle density and the communication environment of the periodic message, Can be dispersed.

The control unit 720 includes a transmission power control unit 721 that adjusts the transmit power of the periodic message and variably adjusts transmission and reception ranges of the beacon according to the vehicle speed, A transmission rate control unit 722 for shortening the transmission time and increasing the beacon slot using the shortened BST, a message generation unit 722 for adjusting the beacon generation period by adjusting the generation interval of the periodic message as the vehicle speed is slow, (723).

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment 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, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as 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 embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI &gt; or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (1)

A method for adjusting periodic message communication settings of inter-vehicle communication,
Predicting the inter-vehicle density using the minimum safety distance according to the vehicle speed, and determining the communication environment of the inter-vehicle periodic message; And
Distributing the transmission time point of the periodic message by adjusting parameters of the communication environment including the transmission power of the periodic message, the transmission rate of the periodic message, and the beacon generation period according to the inter-vehicle density and the communication environment of the periodic message;
To-vehicle communication.

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