KR102298650B1 - Service channel allocation method for transmitting WAVE service message - Google Patents

Abstract

The present invention relates to a method of allocating a service channel for transmission of a WAVE message in a vehicle communication network including a plurality of vehicle nodes, the method comprising: receiving a response message transmitted from a neighboring vehicle node in response to a status request message; constructing a channel state table based on the; If there is a vehicle node that wants to receive the service and there is no channel that is not currently being used, an expected PDR value for each channel and priority is calculated, and based on the calculated expected PDR value, the priority of transmission data and the channel to be transmitted judging; allocating a channel and a priority having the largest PDR value among expected PDR values when the service to be provided is an urgent service; and when the service to be provided is not an urgent service, allocating a priority having a highest PDR value among priorities of a channel having the largest overall PDR and a channel having the largest overall PDR.

Description

Service channel allocation method for transmitting WAVE service message}

The present invention relates to a service channel allocation method for efficiently transmitting a WAVE service message.

WAVE (Wireless Access in Vehicular Environments) is a technology that can transmit and receive packet messages up to 1km between vehicles or between vehicles or between vehicles and infrastructure in a radio environment in which vehicles move at high speed, and transmit and receive messages within a short time of 100 msec.

WAVE provides one control channel (CCH) and seven service channels (SCH), and provides a bandwidth of 10 MHz.

Because the vehicle to which WAVE technology is applied has dynamic and high mobility, a small delay time and fast processing are required to provide or receive a service. In particular, in the case of safety messages, a high data transfer success rate must be guaranteed.

In order to reliably and stably provide major services using WAVE technology, differentiated QoS for each service must be guaranteed.

WAVE is designed to support QoS by giving different channel access probabilities according to the priority of a transmission frame through an enhanced distributed channel access (EDCA) method.

In EDCA, there are four ACs (Access Category) with different priorities, and each AC has different AIFS and Contention Window values, so that a queue with a high priority has a high channel access probability.

However, EDCA also does not fully guarantee QoS in a VANET (Vehicular Ad hoc NETwork) environment.

In the current WAVE mechanism such as EDCA, depending on the density of vehicles and the priority of transmitted packets, packet collisions and many delays may occur. do.

In order to reduce packet collisions in an environment where many vehicles are densely populated, it is important to efficiently distribute and use the currently provided 6 service channels and 1 control channel.

Because of the rapidly changing topology, in order to provide effective QoS, vehicle movement information such as density, speed, and direction of the current location of the vehicle becomes an important factor.

In order to guarantee QoS based on such information, related parameters must be checked in all vehicles, but only some parameters can be checked through the WSA message provided in the WAVE standard.

Therefore, there is a need for a method for effectively using channels because alternative content is not stipulated in the standard for channel allocation.

Also, in the case of broadcast, WAVE does not receive a separate ack, so there is a problem in that it is not possible to know whether the transmitted packet has been successfully transmitted or whether a collision has occurred. A method for solving this problem is also required.

Accordingly, the present invention has been proposed to solve the problems of the prior art as described above, and an object of the present invention is to find a channel and a priority through which a service message can be delivered most efficiently among a plurality of service channels to provide a service message. It relates to a method of assigning and transmitting.

In a service channel assignment method for transmitting a WAVE service message according to an embodiment of the present invention for achieving the above object, a channel state table is generated based on a response message transmitted from a nearby vehicle node in response to a status request message. constructing; If there is a vehicle node that wants to receive the service and there is no channel that is not currently being used, the expected PDR value for each channel and priority is calculated, and based on the calculated expected PDR value, the priority of transmission data and the channel to be transmitted judging; allocating a channel and a priority having the largest PDR value among expected PDR values when the service to be provided is an urgent service; and when the service to be provided is not an urgent service, allocating a priority having a highest PDR value among priorities of a channel having the largest overall PDR and a channel having the largest overall PDR.

According to the present invention, the service message is allocated to the channel and the priority having the best expected packet transmission rate and transmitted.

Accordingly, it is possible to compensate for the disadvantage that the transmission probability decreases due to packet collisions in a situation in which many vehicles are simultaneously providing multiple services through a service channel, that is, when additional services are provided in a situation with high communication complexity.

Accordingly, the service message can be stably delivered through a channel that has low complexity and can be effectively delivered.

1 is a diagram illustrating an example of a vehicle communication network including a plurality of vehicle nodes according to a preferred embodiment of the present invention.
2 is a diagram illustrating an example of the configuration of a vehicle node according to a preferred embodiment of the present invention.
3 is a diagram for explaining a method for a vehicle node to transmit a status request message according to a preferred embodiment of the present invention.
4 is a diagram illustrating an example of a channel state table generated by a vehicle node according to a preferred embodiment of the present invention.
5 is a diagram for explaining a method of allocating a channel and priority for WSA message transmission according to a preferred embodiment of the present invention.
6 is a diagram illustrating an example of an expected PDR value table according to a preferred embodiment of the present invention.

With respect to the embodiments of the present invention disclosed in the text, specific structural or functional descriptions are only exemplified for the purpose of describing the embodiments of the present invention, the embodiments of the present invention may be implemented in various forms and It should not be construed as being limited to the described embodiments.

Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

When a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but it is understood that other components may exist in between. it should be On the other hand, when it is mentioned that a certain element is "directly connected" or "directly connected" to another element, it should be understood that there is no other element in the middle. Other expressions describing the relationship between components, such as “between” and “immediately between” or “neighboring” and “directly adjacent to”, should be interpreted similarly.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a disclosed feature, number, step, action, component, part, or combination thereof exists, but includes one or more other features or numbers, It should be understood that the possibility of the presence or addition of steps, operations, components, parts or combinations thereof is not precluded in advance.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

On the other hand, when an embodiment can be implemented differently, functions or operations specified in a specific block may occur differently from the order specified in the flowchart. For example, two consecutive blocks may be performed substantially simultaneously, or the blocks may be performed in reverse according to a related function or operation.

The present invention is to compensate for the disadvantage that the transmission probability decreases due to packet collisions in a situation where many vehicles are simultaneously providing multiple services through a service channel, that is, when additional services are provided in a situation with high communication complexity. suggest a way

At this time, the method proposed in the present invention determines whether the service is provided by determining the number of vehicles that want to use the service before transmitting the WAVE service message, and when providing the service, the number of currently unused channels or nodes on each channel, the data size , it is characterized in that a service message is allocated and transmitted by finding a channel and a priority having the best expected packet transmission rate based on the data priority.

According to this method, the service message can be stably delivered through a channel that has low complexity and can be effectively delivered.

Hereinafter, a method for allocating a service channel for transmitting a WAVE service message proposed by the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating an example of a vehicle communication network including a plurality of vehicle nodes according to a preferred embodiment of the present invention.

Referring to FIG. 1 , a plurality of vehicle nodes 11 , 12 , 13 , and 14 may exist in a vehicle communication network, and each vehicle node may transmit/receive a WSA message according to a method described below.

However, in FIG. 1 , four vehicle nodes 11 , 12 , 13 , and 14 exist in the vehicle communication network, but the number of vehicle nodes in the vehicle communication network is not limited thereto.

In addition, each of the vehicle nodes 11 , 12 , 13 , and 14 may be a service providing node or a service receiving node in some cases.

2 is a diagram illustrating an example of the configuration of a vehicle node according to a preferred embodiment of the present invention.

At this time, each vehicle node 11 , 12 , 13 , and 14 may be composed of a message processing unit 21 , a transceiver 22 , and a storage unit 23 as shown in FIG. 2 , but The configuration is not limited thereto.

For explanation, it is assumed that the first vehicle node 11 is a service providing node and the second to fourth vehicle nodes 12, 13, and 14 are service receiving nodes.

And, hereinafter, it is assumed that the first vehicle node 11 is configured as shown in FIG. 2 .

Before transmitting the WSA message, the message processing unit 21 transmits the second to fourth status request (WSA_p) messages to determine whether the second to fourth vehicle nodes 12 to 14 have received the service and the channel use status. It is transmitted to the vehicle nodes 12 to 14.

A WAVE Service Advertisement (WSA) message is a message that a service providing node periodically delivers to all nearby vehicle nodes through a control channel section, and the WSA message includes service information, priority, channel information, and the like.

In addition, the message processing unit 21 receives a response message transmitted from the second to fourth vehicle nodes 12 to 14 in response to the status request (WSA_p) message, and according to the received response message, the second to second to fourth vehicle nodes 12 to 14 are received. The WSA message is transmitted to the fourth vehicle nodes 12 to 14 .

The message processing unit 21 may transmit a status request (WSA_p) message and a WSA message through the transceiver 22 through the transceiver 22 or receive a response message.

At this time, as shown in FIG. 3 , the message processing unit 21 transmits a WSA message and a status request (WSA_p) message in a control channel (CCH) section, and alternately transmits a WSA message and a status request (WSA_p) message. do.

3 is a diagram for explaining a method for a vehicle node to transmit a status request message according to a preferred embodiment of the present invention.

Referring to FIG. 3, a service channel (SCH) section and a control channel (CCH) section alternately exist under the WAVE communication network, and the message processing unit 21 sends a status request (WSA_p) message in the first CCH section (CCH1). and transmits a WSA message in the second CCH period (CCH), and transmits a status request (WSA_p) message in the third CHH period (CCH3).

Meanwhile, the second to fourth vehicle nodes 12 to 14 that have received the status request (WSA_p) message transmit a response message to the first vehicle node 11 .

Here, the response message includes service reception status information, data size information (used service data size information) for the service currently being used (including the service currently provided and the service provided), service priority information, and channel information. .

Then, the message processing unit 21 receives response messages from the second to fourth vehicle nodes 12 to 14, and configures a channel state table related to neighboring vehicle nodes based on information in the received response message, or update

At this time, the message processing unit 21 stores the channel state table in the storage unit 23 .

4 is a diagram illustrating an example of a channel state table generated by a vehicle node according to a preferred embodiment of the present invention.

As shown in FIG. 4 , the channel state table may be configured based on used service data size information, service priority information, and channel information.

At this time, in constructing the channel state table, the message processing unit 21 is provided by bundling the used service data size information and the used service data size by similar size based on the service channel and priority provided under the WAVE communication network. Record the number of nodes.

In addition, each vehicle node has a transmission queue that is four ACs having different transmission priorities, and data to be transmitted is contained in the AC according to each priority and transmitted.

Meanwhile, since the status request (WSA_p) message and the response message are periodically transmitted, the message processing unit 21 updates the channel status table whenever there is new content until the service is provided.

In addition, since the status request (WSA_p) message and response message contain the required amount of information, the network load does not increase much when the status request (WSA_p) message and response message are added.

5 is a diagram for explaining a method of allocating a channel and priority for WSA message transmission according to a preferred embodiment of the present invention.

The sequence shown in FIG. 5 may be performed by a message processing unit of a vehicle node, and the message processing unit 21 transmits a status request (WSA_p) message to a neighboring vehicle node, and a response message received in response thereto A channel state table is constructed based on the data (S500).

Here, configuring the channel state table includes generating the channel state table for the first time and updating the generated channel state table.

After configuring the channel state table according to the step S500, the message processing unit 21 determines whether a vehicle node to receive a service ('service reception desired vehicle node') exists by referring to the channel state table (S501).

In step S501 , if there is a vehicle to receive the service, the message processing unit 21 may determine the number of service reception desired vehicle nodes.

As a result of the determination in step S501, if it is determined that the service reception desired vehicle node does not exist (S501 - No), the message processing unit 21 does not transmit the WSA message (S502).

Meanwhile, the message processing unit 21 may not receive a response message after transmitting the status request (WSA_p) message (eg, when there is no nearby vehicle node, etc.). Even in this case, the WSA don't send messages

As a result of the determination in step S501, if it is determined that the service reception desired vehicle node exists (S501 - Yes), the message processing unit 21 refers to the channel state table and determines whether an unused channel exists (S503) .

As a result of the determination in step S503, if it is determined that there is no unused channel (S503-No), the message processing unit 21 checks the size and priority of service data to be provided (S504).

Then, the message processing unit 21 confirms the urgency of the service to be provided according to the type of service or the user's request (S505).

The PDR (Packet Delivery Ratio) indicates a rate at which data is transmitted, and refers to a ratio of the number of data actually transmitted to the total number of data that should be transmitted to other vehicle nodes.

At this time, the message processing unit 21 calculates an expected PDR value based on the number of channel nodes within the service radius, the data size of the nodes, and the priority of the data.

When calculating the expected PDR value, the message processing unit 21 may also calculate the total PDR value for each channel, and store the calculated PDR value in the form of a table.

Alternatively, the message processing unit 21 may use a table of predicted PDR values calculated and stored in advance according to the data size, the number of channel nodes, and the priority ratio.

6 is a diagram illustrating an example of an expected PDR value table according to a preferred embodiment of the present invention.

According to the expected PDR value table as shown in FIG. 6, when service data is transmitted with a priority of being transmitted from AC0 to the channel of SCH1, it is expected to be transmitted with a PDR of 30%.

Then, the message processing unit 21 determines whether the service to be provided is an urgent service based on the check result in step S505 (S506).

As a result of the determination in step S506, if it is determined that the service to be provided is not an urgent service (S506-No), the message processing unit 21 determines the channel having the largest overall PDR value, and the highest among the priorities of the determined channels. A priority having a PDR value is determined (S507), and the determined channel and priority are allocated as a channel and priority for a service to be provided (S508).

According to the expected PDR value table as shown in FIG. 6 , the message processing unit 21 allocates SCH6, which is a channel having the largest overall PDR value, as a service providing channel, and as a service provision priority, SCH6 to AC0 having the largest PDR value. Assign the appropriate priority.

If the channel and priority to be allocated are already allocated, the message processing unit 21 changes to the channel and priority for the current service.

Then, the message processing unit 21 transmits the WSA message and service data to the desired receiving vehicle node based on the channel and priority assigned in step S508 (S509).

In this case, the message processing unit 21 transmits the WSA message to the neighboring vehicle node to which the desired reception vehicle node belongs, informs the service information, and then transmits the service data.

As a result of the determination in step S506, if it is determined that the service to be provided is an urgent service (S506-Yes), the message processing unit 21 provides the channel and priority with the highest expected PDR value among the expected PDR values, the service to be provided Channel and priority are allocated for (S510).

According to the expected PDR value table as shown in FIG. 6, when the service channel is SCH2 and the priority is AC3, the expected PDR value is 70%, which is the highest in the expected PDR value table.

Accordingly, when transmitting a message using the expected PDR value table as shown in FIG. 6 , the message processing unit 21 allocates an SCH2 channel and an AC3 priority for message transmission.

If the channel and priority to be allocated are already allocated, the message processing unit 21 changes to the channel and priority for the current service.

Then, according to step S509, the message processing unit 21 transmits the WSA message and service data to the desired receiving vehicle node based on the channel and priority assigned in step S510.

As a result of the determination in step S503, if it is determined that an unused channel exists (S503-Yes), the message processing unit 21 allocates the unused channel as a service providing channel (S511).

Then, according to step S509, the message processing unit 21 transmits the WSA message and service data to the desired receiving vehicle node based on the channel allocated in step S511 (S509).

Even though all the components constituting the embodiment of the present invention described above are described as being combined or operated in combination, the present invention is not necessarily limited to this embodiment. That is, within the scope of the object of the present invention, all the components may operate by selectively combining one or more. In addition, although all the components may be implemented as one independent hardware, some or all of the components are selectively combined to perform some or all functions combined in one or a plurality of hardware program modules It may be implemented as a computer program having In addition, such a computer program is stored in a computer readable media such as a USB memory, a CD disk, a flash memory, etc., read and executed by a computer, thereby implementing the embodiment of the present invention. The computer program recording medium may include a magnetic recording medium, an optical recording medium, a carrier wave medium, and the like.

As described above, the method for allocating a service channel for transmitting a WAVE service message according to the present invention has been described according to an embodiment, but the scope of the present invention is not limited to a specific embodiment, and common knowledge in relation to the present invention has been described. Various alternatives, modifications, and changes can be implemented within the range that is obvious to those who have it.

Accordingly, the embodiments and the accompanying drawings described in the present invention are for explanation rather than limiting the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments and the accompanying drawings. . The protection scope of the present invention should be construed by the claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

11, 12, 13, 14: Nodes
21: message processing unit
22: transceiver
23: storage

Claims (10)

In the vehicle node for WAVE service,
transceiver; and
A message processing unit, the message processing unit comprising:
Transmitting a status request message through the transceiver and receiving a response message from a neighboring vehicle node in response to the status request message,
Construct a channel state table based on the response message,
Checking whether a vehicle node to receive a service exists among the neighboring vehicle nodes based on the channel state table,
If the identified vehicle node exists and there are no unused channels in all channels for the service, check an expected packet delivery ratio (PDR) and priority of channels in use among all channels,
Allocating a channel and a priority to the identified vehicle node based on at least one of the expected packet rate and the priority,
The message processing unit,
calculating the expected packet rate based on the number of nodes per channel within the service radius, the data size of nodes, and the priority of data based on the channel state table,
Confirm the urgency of the service based on the service type or user request,
If it is determined that the service is not urgent, the total packet rate of the channels in use is calculated based on the expected packet rate, the first channel having the largest total channel rate is allocated to the identified vehicle node, and the first Among the priorities of channels, the priority with the highest packet transmission rate is determined.
and when it is determined that the service is urgent, assigning a second channel and a priority having the highest expected packet rate among the channels in use to the identified vehicle node. The method according to claim 1, The message processing unit,
and configuring the channel state table indicating the number of vehicle nodes that want to receive the service based on the total channels and the priorities of all channels. The method according to claim 1, The message processing unit,
and if there is an unused channel among all the channels, allocating the unused channel to the identified vehicle node. delete The method according to claim 1, The message processing unit,
and assigning a channel having a relatively high priority among the expected packet rate and the priority among the channels in use according to the urgency of the service. delete delete delete delete The method according to claim 1, The message processing unit,
and transmitting a message including the service information, the allocated channel information, and the allocated priority information to the identified vehicle node.

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