KR101486464B1 - Method for processing data dissemination of cooperative road side units in ad-hoc based vehicular network - Google Patents

Abstract

The present invention relates to road side unit (RSU) cooperation system and method, for transmitting data in an ad-hoc-based vehicular network. In an RSU which includes: a request queue for receiving a request of a user and storing data to be transmitted; a scheduler for classifying the data to be transmitted to a vehicle according to a priority; and an item queue for storing the data to be transmitted through a ad-hoc-based vehicular network according to the priority, the method comprises: a step of registering vehicles present within a radius of RSU; a step of classifying the data to be transmitted to a vehicle into safe data and non-safe data; a step of scheduling the safe data with high priority; a step of selectively transmitting the safe data and non-safe data to the vehicle within the radius of RSU according to the scheduling; and a step of transmitting a request message to the next RSU if the current RSU cannot process the non-safe data. According to the present invention, the information can be transmitted to the maximum number of vehicles by making a balance between the RSUs, and efficiently transmitting the safe data and non-safe data which are serviced to the vehicles.

Description

TECHNICAL FIELD [0001] The present invention relates to an RSU collaborative system and method for data transmission in an ad hoc based vehicle network,

The present invention relates to an RSU collaborative strategy for efficiently distributing data based on V2I in a VANET environment, more specifically, connecting multiple RSUs through a backbone network and detecting the load status of RSUs to improve safety data and non- To an RSU collaboration system and method for data transmission in an ad hoc based vehicle network.

VANET (Vehicular Ad-hoc NETworks) establishes an ad hoc network between moving vehicles through wireless communication, and provides traffic information, file sharing, and location information. VANET can provide stability, economy, and convenience through communications between vehicles and communication between vehicle and infrastructure, and it can improve information service satisfaction on the move by providing information suitable for driver's needs. In addition, it is possible to reduce the cost of collision and traffic congestion, so that comfortable and safe operation can be performed. Since VANET provides services to vehicles moving faster than MANET (Mobile Ad-hoc NETworks), network topology changes drastically and it is difficult to directly use data transmission and routing techniques provided by MANET.

VANET communication methods are classified into V2I (Vehicle To Infrastructure) and V2V (Vehicle To Vehicle). The V2V-based communication system constructs an ad hoc network between vehicles and transmits data similar to the P2P method. Because of this, it takes a lot of communication costs to provide information required by a large number of drivers or to provide the same information to all drivers. In addition, due to rapid movement of the vehicle, stable information transmission can not be guaranteed. In recent years, communication methods using V2I have been proposed in order to efficiently provide necessary information to a large number of drivers. In V2I, RSU (Road Side Units) is used to transmit information requested by a plurality of drivers or specific information to a large number of users. The RSU is installed around the road, and serves as a base station for receiving the request of the vehicle or transmitting the necessary information to the vehicle. However, since the communication range of the RSU is limited, a transmission technique for distributing information to a plurality of vehicles is required.

Therefore, a single RSU scheduling scheme has been proposed as a data transmission scheduling scheme of an RSU. However, the single RSU scheduling scheme has a limitation in providing stable data to the vehicles because the communication radius of the RSU is small and the connection time between the RSU and the vehicle is short. To overcome these limitations, multiple RSU collaborative strategies have been proposed to connect multiple RSUs over the backbone network and communicate with each other between RSUs. Generally, in a multiple RSU environment, it grasps the load state of the RSU and transmits a request message to another RSU. In this paper, we propose RSU scheduling scheme for RSU. In this paper, we propose RSU scheduling scheme for RSU. do. Increasing the load on the RSU means that the deadline failure rate increases for multiple vehicle requests. Therefore, considering the location of the RSUs, a part of the request is transmitted to the RSU having the low load. Assuming that a load occurs in RSU1 and no load occurs in RSU2, the following three conditions must be satisfied in order to transmit a request received from RSU1 to RSU2. That is, if the three conditions are satisfied, the RSU2 sends a request to the RSU2 to provide the request of the vehicle from the RSU2.

Condition 1: The vehicle must move from RSU1 to RSU2.

Condition 2: The allowable delay time for the request of the vehicle must be greater than the travel time of the vehicle and the time of receiving the data.

Condition 3: The RSU2 should not generate a load when transmitting a request from RSU1 to RSU2.

MPO, a multi-RSU collaboration strategy, predicts the movement of vehicles and adjusts the load balance between the RSUs and simultaneously provides a large amount of data to multiple vehicles. We use the mobility model of the Manhattan mobility model to predict vehicle movement. Predicts movement of vehicles, and transfers failed requests from one RSU to another RSU. The mobility model of the Manhattan mobility model basically uses the grid road topology, and the vehicle moves along the grid of the horizontal and vertical distances of the map. We use a probabilistic approach to the choice of node motion. Vehicle mobility has a probability of 0.5 in the same direction and 0.25 in the left or right. There are four scenarios where the RSU predicts the movement of the vehicle to the Manhattan mobility model if a request is made that can not be handled by the load. The RSU_available_time of the next RSU is estimated by predicting the travel path of the vehicle. At this time, the sum of RSU_available_time and duration must be larger than the deadline. The RSU_available_time is the time when the vehicle can receive data when it moves to the next RSU. duration is the time at which the vehicle downloads data.

The multiple RSU collaborative strategy technique can solve a problem of a single RSU model and process multiple requests. In addition, it is possible to effectively process a hot spot where a lot of requests are generated. However, the existing multi - RSU collaboration strategy does not classify safety data and non - safety data separately.

Korean Patent Publication No. 10-2011-0059091 (published on June 2, 2011)

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and it is an object of the present invention to provide a safety data management system In addition, the non-safety data is calculated by calculating the correct data reception time of the vehicle because the speed of the vehicle and the arrangement of the RSU are different according to the traffic situation. Thus, the ad hoc basis And to provide an RSU collaboration system and method for data transmission in a vehicle network.

According to an aspect of the present invention, there is provided an RSU collaborative system for data transmission in an ad hoc based vehicle network including an RSU (ROAD SIDE UNITS), the RSU comprising: A request queue for storing the request message; A scheduler for selecting data to be transmitted to the vehicle according to a priority order; And an item queue for storing data to be transmitted through the Ad-hoc based vehicle network according to the priority, wherein the scheduler, when the unsafe data can not be processed by the current RSU, And transmits a request message to the RSU.

Wherein the request queue includes two upload queues and one download queue, and the upload queue is a queue for storing data transmitted from the vehicle, the neighboring RSU, and the server, Safe data, and the download queue stores the request-based service as a queue that receives and stores the user's request. The safety data is preferentially stored in an item queue and transmitted to a vehicle. When there is a free space in the item queue, the safety data is selectively stored and transmitted. The scheduler prioritizes the information stored in the request queue, the item queue stores information according to the priority, and the data stored in the item queue is broadcast through wireless communication.

Meanwhile, an RSU collaboration method for data transmission in an ad hoc based vehicle network of the present invention includes the steps of: (a) registering a vehicle existing within a radius of a RSU (ROAD SIDE UNITS); (b) distinguishing safety data to be transmitted to the vehicle from non-safety data, and scheduling the safety data as a priority; And (c) selectively transmitting, in accordance with the scheduling, the safety data and the non-safety data within the radius of the RSU to the vehicle and, when the unsafe data can not be processed in the current RSU, And transmitting the message.

Preferably, the request message is transmitted to the next RSU and the delay count value of the request message is increased, and the delay count value is deleted from the set value or more.

The request message includes the speed and location of the vehicle and calculates the time to arrive at the next RSU through the speed and location of the vehicle.

The deadline of the safety data is defined as the time at which the vehicle reaches the position associated with the safety data, and the deadline of the unsafe data is defined as the time at which the vehicle leaves the communication radius of the RSU. Preferably, the safety data is scheduled in order of a deadline, a reception ratio, and a data size, and the non-safety data is scheduled in order of a deadline, a request number, and a data size.

As described above, according to the RSU collaborative system and method for data transmission in an ad hoc based vehicle network according to the present invention, the load balancing between the RSUs and the efficient transmission of the safety data and the non- It is possible to provide information to as many vehicles as possible.

In addition, according to the present invention, when transmitting safety data and unsecured data through multiple RSUs, factors are considered in scheduling according to each data characteristic, and dynamic scheduling techniques are used. Thereby enabling a more efficient data service.

Also, according to the present invention, the RSU can respond in real time, especially in a situation where there are a large number of vehicles, by receiving a request for a vehicle and providing a scheduling technique for data transmission according to priority in order to provide a service for a plurality of users .

According to the present invention, by applying the technique according to the data type for efficient transmission of the safety data and the non-safety data to be provided to the vehicle, consideration is given to the safety data in consideration of the reception ratio, Can receive services.

1 is a block diagram of an RSU collaboration system for data transmission in an ad hoc based vehicle network according to an embodiment of the present invention.
2 is a diagram illustrating the generation of safety data in multiple RSUs.
3 is a diagram illustrating unsecured data transmission in multiple RSUs according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating a security data scheduling scheme in a multiple RSU according to an exemplary embodiment of the present invention. Referring to FIG.
5 is a diagram illustrating unsecured data scheduling in multiple RSUs according to an embodiment of the present invention.

Hereinafter, an RSU collaboration system and method for data transmission in an ad hoc based vehicle network according to the present invention will be described in detail with reference to the accompanying drawings.

In the VANET environment, RSU scheduling is intended to provide information to a large number of vehicles for safety data and unsecured data, and to reduce the deadline failure rate. For this purpose, RSU scheduling generally considers the number of requests, data size, and deadline. The proposed scheme reduces deadline failures by eliminating unnecessary requests, reducing resource waste and improving the data rate of latest data and safety data.

1, the RSU includes a request queue 1 for storing data to be received and transmitted by a user, a scheduler 2 for selecting data to be transmitted to the vehicle, And an item queue 3 for storing data to be transmitted through the network.

The RSU shall store and manage the data around the location and the data to be provided to other users and collect requests for vehicles that are within the RSU radius. To this end, the request queue 1 is composed of two upload queues 11a and 11b and one download queue 12. The download queue 12 is used to provide a request-based service as a queue for receiving and storing a user's request. The upload queues 11a and 11b receive and store the safety data and the unsecured data, respectively, as queues for storing data transmitted from the vehicle, the neighboring RSU, servers, and the like. Since the safety data is directly related to life or safety, it should be stored in the RSU and transmitted to the vehicle prior to the unsafe data. On the other hand, since non-safety data has infotainment (information and entertainment) characteristics such as file sharing, location information, and so on, it should be provided so that deadline failures do not occur to the latest data as much as possible. Therefore, the proposed scheme consists of two input queues for separate storage and management of safety data and unsafe data. The information stored in the request queue 1 is prioritized by the scheduler 2 and placed in the item queue 3 according to the priority. The data stored in the item queue 3 is broadcast via wireless communication.

가 요청한 안전 데이터

에 대한 데드라인

은 (식 1)과 같다. 이때,

는

을 요청한 차량

의 현재 위치에서 RSU 통신 반경의 끝 위치까지의 거리,

는 차량의 속도를 나타낸다. 안전 데이터

에 대한 데드라인

는 (식 2)과 같다. 이때,

는 차량

가 안전 데이터와 관련된 위치까지의 거리,

의 차량의 속도를 나타낸다.
One of the most important factors in RSU scheduling is the deadline. The deadline of the safety data is defined as the time at which the vehicle reaches the position associated with the safety data, that is, the time before the accident or danger zone is reached, and the deadline of the unsafe data is the time at which the vehicle is outside the communication radius of the RSU define. vehicle

Safety data requested by

Deadline for

Is the same as (Equation 1). At this time,

The

The requested vehicle

The distance from the current position of the RSU communication radius to the end position of the RSU communication radius,

Represents the speed of the vehicle. Safety data

Deadline for

Is the same as (Equation 2). At this time,

The vehicle

The distance to the location associated with the safety data,

Of the vehicle.

--- (식 1)

--- (1)

--- (식 2)

--- (Equation 2)

에 대해서는 스케쥴링에서 제거하여 실제 데이터 수신이 가능한 요청만을 배포할 수 있도록 한다. (식 3)은 요청된 데이터를 스케쥴링에서 제거하기 위한 조건을 나타낸 것이다. 이때,

는 데이터

을 요청한 차량

의 데드라인이며

을 전송하는데 소요되는 시간을 나타낸다.
In the process of distributing a large number of requests to the vehicle, the RSU can not receive all of the requested data in the deadline. If the requested data is large, the RSU divides the data into a plurality of packets and transmits the data. Therefore, when the deadline is short, the RSU can not receive all the data of the RSU communication range. In the proposed scheme, a request that does not receive all requested data within the RSU radius

Is removed from the scheduling so that only requests that can receive actual data can be distributed. (Equation 3) represents a condition for removing the requested data from the scheduling. At this time,

Data

The requested vehicle

Deadline of

And the time required to transmit the data.

--- (식 3)

--- (Equation 3)

에 대한 요청 수,

,

을 사용한다. 이때,

는 비안전 데이터

에 대한 요청 수,

는 차량

에서

에 대한

,

는

에 대한

의 수를 나타낸다.
The existing schemes only considered the number of download requests from the vehicle to calculate the number of requests. However, in the proposed technique, to calculate the number of requests,

The number of requests for,

,

Lt; / RTI > At this time,

Non-safety data

The number of requests for,

The vehicle

in

For

,

The

For

.

--- (식 4)

--- (Equation 4)

이다.

는 현재 RSU에 있는 차량의 수이고

는 안전 데이터를 수신 받은 차량의 수를 나타낸다.In order to solve the limitation of single RSU scheduling, we propose a multiple RSU based collaborative scheduling scheme that connects multiple RSUs to a wired network and provides data to multiple vehicles. The factors considered in the safety data are the deadline, the data size, and the reception ratio. The deadline is the time at which the vehicle reaches the position associated with the safety data, such as the one used in single RSU scheduling, ie, before the accident or danger zone is reached. The smaller the data size is the size of the data size for the safety data, the more data can be serviced to the vehicle. The reception ratio is the number of vehicles that received data in one RSU. To provide safety data to more vehicles in the same RSU, the reception ratio is given by (5)

to be.

Is the number of vehicles currently in the RSU

Represents the number of vehicles that received the safety data.

--- (식 5)

--- (Equation 5)

Safety data is very important in the VANET environment, so safety data is provided to the vehicle in advance in all RSU regions when safety data is generated. For example, if safety data is generated in the RSU (D) as shown in FIG. 2, it is provided to the vehicles in the RSU (A) and RSU (B) regions in advance so that the driver can operate more safely and comfortably.

값을 증가 시켜준다. 그리고 RSU 간의 메시지 전송은 n번 까지만 허용하고 그 다음에는 요청 메시지를 삭제 한다. 즉, 도 3과 같이 RSU(A)에서 발생하여 처리 할 수 없게 된 다음 RSU인 RSU(B)로 비안전 데이터가 전송되고, RSU(B)에서 처리하지 못한 비안전 데이터가 RSU(C)로 또 전송되어진다. 마지막으로 메시지 전송은 2번 까지만 허용하기 때문에 RSU(C) 에서도 처리 되지 않으면 삭제된다. 비안전 데이터는 인포태인먼트적인 정보를 가지고 있다. 그렇기 때문에 비안전 데이터를 요청한 차량은 요청한 지점과 점점 멀어 지면 멀어 질수록 필요 없는 정보(지역 정보)가 될 확률이 높아지기 때문이다.Since unsecured data is request-based data that is processed at the request of the user, the deadline failure rate increases when the load occurs in the RSU. In the unsecured data, if a load occurs in the current RSU and the request message can not be processed, the request message is transmitted to the next RSU. And transmits the request message to the next RSU,

Increase the value. The message transmission between the RSUs is allowed only n times, and then the request message is deleted. 3, unsecured data is transmitted to the RSU (B), which is the next RSU after the RSU (A) can not be processed, and the unsecured data not processed by the RSU (B) is transmitted to the RSU It is also transmitted. Finally, since the message transmission is permitted only up to 2 times, it is deleted if it is not processed by the RSU (C). Insecure data has infotainment information. This is because vehicles that request unsecured data are more likely to become unnecessary information (local information) as they move farther away from the requested point.

인 거리는 차량의 속도인

로 나눴을 때 나온 도착 시간에 맞춰 다음 RSU에서 스케쥴링을 처리한다.
In the existing multiple RSU scheme, if the request message is not provided to the vehicle but is passed to the next RSU, it is assumed that the vehicle can be received at the next RSU. However, the RSU must be provided by calculating the time it takes for the vehicle to enter the next RSU, depending on the situation where traffic is blocked due to various disposition and many vehicles. Therefore, in the proposed scheme, when the request message is transmitted to the next RSU, the speed and position of the vehicle are transmitted together with the request message sent to the next RSU so as to know when the vehicle arrives at the next RSU. The formula to calculate is (Equation 6).

The driving distance is the speed of the vehicle

The scheduling process is performed in the next RSU according to the arrival time when it is divided into < RTI ID = 0.0 >

--- (식 6)

--- (Equation 6)

In a multiple RSU collaborative strategy, safety data is the data that must be transmitted without deadline failures as much as possible. In addition, the safety data is provided to the vehicle in advance by the entire RSU, and it is transmitted in consideration of the deadline of the vehicle as well as the reception ratio. Figure 4 (a) is for safety data generation in multiple RSUs, and Figure 4 (b) is for scheduling safety data. Fig. 4 is an example in which safety data is provided to a vehicle in a multiple RSU collaborative strategy technique. Assume that the size of item_queue which is a queue for storing data to be transmitted is 50. The safety data generated in RSU (A) is {s2, s1, s3} and the safety data generated in RSU (D) is {s6, s9}. First, sorting is performed based on the deadline that minimizes the deadline failure, and sorting is performed based on the reception ratio and the data size of each data. {s6, s9} is added when there is free space in item_queue because reception ratio is smaller than {s2, s1, s3} but deadline is larger. Since the space {s2, s1, s3} generated in the RSU (A) remains in the item_queue, s6 generated by the RSU (D) is additionally stored in the item_queue and provided to the vehicle. Finally, the data to be transmitted is {s2, s1, s3, s6}, and data selected in the item_queue is stored and transmitted.

As with safety data, non-safety data can be handled by the next RSU by using multiple RSU collaboration strategy techniques to service as many vehicles as possible without deadline failures. In the multiple RSU collaborative strategy technique of safety data, the reception ratio is considered, but the unsafe data, that is, the message requested by the vehicle, becomes more and more meaningless as it gets further from the place. Therefore, in order to prevent the unsecured data from being received and to be continuously delayed in the unsecured data, a delay count value is added to the request message transmitted to the next RSU for scheduling.

If insecure data is generated within a particular RSU, and if the load does not provide unsafe data to the vehicle within the RSU, unsecured data can be sent to neighboring RSUs to receive unsecured data from other RSUs. For example, as shown in FIG. 3, when a vehicle requests unsecured data from the RSU (A), it transmits the unsafe data requested by the vehicle to the RSU (B) due to the load. If there is no load on the RSU (B), it distributes the unsecured data generated by the RSU (B) to the vehicles. If there is a load on the RSU (B), the next RSU, RSU (C) The non-safety data should be the deadline, number of requests and data size as the data requested by the vehicle. Especially, the delay count dc is additionally considered in the proposed technique.

As with safety data, unsafe data also stores data to be sent to the RSU in one item_queue. 5 illustrates a scheduling process for distributing safety data through multiple RSU collaborations. Assume that the size of item_queue is 100 and let the RSU (B) call the unsafe data requested by the vehicles {c, x, a, b, g, t, w}. The deadline for the unsecured data {t, w} remains and the additional value added in the request count is the dc value added. In the unsecured data t, the dc value of 2 is because the vehicle requesting t was requested twice but not received, and likewise the dc value of 1 was requested 1 time, but was not provided and came to the next RSU. Multiple RSU collaborative schemes for unsecured data select data that does not have deadline failures. If the size of data to be transmitted in item_queue exceeds the size of item_queue, the data to be transmitted is re-determined considering the number of requests and data size. First, sorting is performed based on the deadline that minimizes the deadline failure. Next, when the number of requests is rearranged, unsafe data is sorted as shown in FIG. 5, and {a, x, g, c, b} is stored in the item_queue according to the scheduling. However, since the data size of the item_queue is 100, the remaining free space further fills the data to be transmitted in the next cycle. Therefore, the non-safety data t is additionally stored in the item_queue because the deadline, the number of requests, and the data size of t and w are the same, but the dc value is larger. The final data to be transmitted is {a, x, g, c, b, t}.

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, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

1: Request queue
11a, 11b: upload queue
12: Download Queue
2: Scheduler
3: item queue

Claims (10)

1. An RSU collaborative system for data transmission in an ad hoc based vehicle network comprising an RSU (ROAD SIDE UNITS)
The RSU includes:
A request queue for receiving user requests and storing data to be transmitted;
A scheduler for selecting data to be transmitted to the vehicle according to a priority order; And
And an item queue for storing data to be transmitted through the ad hoc based vehicle network according to the priority,
The deadline of the safety data is defined as the time at which the vehicle reaches the position associated with the safety data and the deadline of the unsafe data is defined as the time at which the vehicle leaves the communication radius of the RSU,
The scheduler transmits a request message to the next RSU when the unsafe data can not be processed in the current RSU, increases the delay count value of the request message while transmitting the request message to the next RSU, Wherein the request message is deleted at a value greater than or equal to a predetermined value.
The method according to claim 1,
The request queue includes:
It includes two upload queues and one download queue,
The upload queue is a queue for storing data transmitted from a vehicle, a neighboring RSU, and a server, and receives and stores the safety data and the unsafe data, respectively,
Wherein the download queue stores a request-based service as a queue upon receiving and storing a request from a user.
3. The method of claim 2,
The safety data is preferentially stored in the item queue and transmitted to the vehicle,
And if the free space exists in the item queue, the unsafe data is selectively stored and transmitted.
The method according to claim 1,
Wherein the scheduler prioritizes information stored in the request queue,
The item queue stores information according to a priority,
Wherein the data stored in the item queue is broadcast via wireless communication.
(a) registering a vehicle existing within a radius of a road unit (RSU);
(b) distinguishing safety data to be transmitted to the vehicle from non-safety data, and scheduling the safety data as a priority; And
(c) selectively transmitting the safety data and non-safety data within the radius of the RSU to the vehicle according to the scheduling, and when the unsafe data can not be processed in the current RSU, The method comprising:
The deadline of the safety data is defined as the time at which the vehicle reaches the position associated with the safety data, and the deadline of the unsafe data is defined as the time at which the vehicle is out of the communication radius of the RSU,
Wherein the delay count value of the request message is transmitted while the request message is transmitted to the next RSU, and the delay count value is deleted from the set value above the request message.
delete 6. The method of claim 5,
Wherein the request message includes the speed and location of the vehicle and calculates a time to arrive at the next RSU through the speed and location of the vehicle.
delete 6. The method of claim 5,
Wherein the safety data is scheduled in order of deadline, reception ratio, and data size.
6. The method of claim 5,
Wherein the unsecured data is scheduled in order of deadline, number of requests, and data size.

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