KR101092235B1 - Apparatus and method for allocating radio resource - Google Patents

Abstract

The disclosed technology relates to a radio resource allocation apparatus and a radio resource allocation method. In one or more embodiments, a radio resource allocation apparatus for allocating radio resources for inter-vehicle communication may include: a progress direction classification module for mapping the vehicle to a first or second direction group by using the progress direction information of the vehicle; And if the vehicle is mapped to the first direction group, assigning a radio resource to the vehicle during the first time slot group, and if the vehicle is mapped to the second direction group, the vehicle to the second direction group. And a resource allocation module for first allocating the radio resource to the vehicle.

Description

Radio resource allocation device and radio resource allocation method {APPARATUS AND METHOD FOR ALLOCATING RADIO RESOURCE}

The disclosed technology relates to a radio resource allocation apparatus and a radio resource allocation method.

IEEE 802.11p is an international standard for intervehicle communication and vehicle-to-infrastructure communication. The IEEE 802.11p MAC protocol defines an existing WLAN-based carrier sense multiple access / collision avoidance (CSMA / CA) protocol. CSMA is a multiple access method that detects a carrier when sending a packet, determines whether a line is available, and initiates or waits for a connection. CSMA is a protocol that resolves a collision that occurs when multiple clients try to use a common communication line in a LAN. CSMA sends a packet immediately if no other carrier exists before sending the data packet. Wait as many times and try again. In wireless networks, collision detection is difficult, so CSMA / CA is used to avoid collisions.

1 is a view for explaining a radio channel access method according to the CSMA protocol. Referring to FIG. 1, a node having a packet to transmit waits for a DCF interframe space (DIFS) before transmitting data and checks whether a channel is idle. If the channel is in the BUSY state during DIFS, wait until the channel is idle and wait for another DIFS. When the node determines that the channel is idle during DIFS, the node waits for a random backoff and transmits a packet. At this time, the random backoff is randomly selected between 0 and a content window (CW). After each node detects a packet transmission during the backoff, it stops the backoff process and checks the channel status. If the channel becomes idle, it waits for DIFS and performs backoff for the remaining time.

Since the CSMA radio resource approach described above is a contention-based transmission method, when the number of nodes to transmit a packet increases, the probability of contention is increased and the retry is increased to increase communication efficiency. There is a drawback of sudden deterioration.

The technical problem to be achieved by the disclosed technology is to provide a radio resource allocation device and a radio resource allocation method.

A first aspect of the disclosed technology to achieve the above technical problem, in the apparatus for allocating radio resources of the inter-vehicle communication, mapping the vehicle to the first or second direction group using the direction information of the vehicle A progress direction classification module; And if the vehicle is mapped to the first direction group, the radio resource is first allocated to the vehicle during a first time slot group, and when the vehicle is mapped to the second direction group, the vehicle is mapped to the first direction group during the second time slot group. Provided is a radio resource allocation apparatus including a resource allocation module for first allocating the radio resources to a vehicle.

In order to achieve the above technical problem, a second aspect of the disclosed technology is a method of allocating radio resources for inter-vehicle communication according to a carrier sense multiple access / collision avoidance (CSMA / CA) based transmission scheme, wherein the direction of travel of the vehicle Mapping the vehicle to a first or second direction group using information; And if the vehicle is mapped to the first direction group, the radio resource is first allocated to the vehicle during a first time slot group, and when the vehicle is mapped to the second direction group, the vehicle is mapped to the first direction group during the second time slot group. Provided is a radio resource allocation method comprising allocating the radio resource to a vehicle first.

Embodiments of the disclosed technology can have the effect of including the following advantages. However, the embodiments of the disclosed technology are not meant to include all of them, and thus the scope of the disclosed technology should not be understood as being limited thereto.

According to one embodiment of the disclosed technology, the possibility of impulse due to competition for radio resource allocation is reduced. Therefore, the radio resource allocation is made efficiently, and the performance of the network is improved. According to the disclosed technology, the resource allocation priority is different for each group according to the driving direction of the vehicle, thereby reducing the number of devices competing in the competition period.

Further, according to one embodiment of the disclosed technology, it is possible to prevent the direction group of the vehicle from changing too frequently.

The description of the disclosed technique is merely an example for structural or functional explanation and the scope of the disclosed technology should not be construed as being limited by the embodiments described in the text. That is, the embodiments may be variously modified and may have various forms, and thus, the scope of the disclosed technology should be understood to include equivalents capable of realizing technical mappings.

On the other hand, the meaning of the terms described in the present application should be understood as follows.

The terms " first ", " second ", and the like are used to distinguish one element from another and should not be limited by these terms. For example, the first component may be named a second component, and similarly, the second component may also be named a first component.

Each step may occur differently from the stated order unless the context clearly dictates the specific order. That is, each step may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. Terms defined in commonly used dictionaries should be interpreted to be consistent with meaning in the context of the relevant art and can not be construed as having ideal or overly formal meaning unless expressly defined in the present application.

2A is a diagram for describing a characteristic of a road on which inter-vehicle communication is performed. In general, as shown in FIG. 2A, a road is adjacent to a lane traveling in a forward direction and a lane traveling in a reverse direction. In other words, if the movement direction of node A that proceeds to the east is the forward direction, the movement direction of node B that proceeds to the west may be referred to as the reverse direction. Circle A represents the area of the signal that Node A transmits to communicate with other surrounding vehicles, and Circle B represents the area of the packet signal that Node B transmits. At this time, if each vehicle continues to move in its own direction, it can be seen that the areas of the signal overlap. That is, there is no problem even if Node A and Node B transmit data using the same radio resources at first, but when circle A and circle B overlap as the vehicle moves, collisions occur in the use of radio resources, which causes problems in signal transmission. Can occur.

2B is a diagram for explaining a radio resource allocation method according to one embodiment of the disclosed technology. According to the disclosed technique, in order to reduce the collision of radio resources that may occur when circle A and circle B overlap and to efficiently allocate radio resources, group 1, which is a group of vehicles traveling east, is given priority to time slot 1 Resource allocation is performed, and group 2, a group of vehicles moving to the west, is first allocated to time slot 2. For example, if nodes A, B, D, and E want to transmit packets, node A, B, or C preferentially transmits packets in time slot 1, and node D or E preferentially transmits packets in time slot 2. Done. If there is no packet that the vehicle in group 1 wants to transmit in time slot 1, the node in group 2 may transmit the packet. In this way, odd-numbered time slots such as slots 1, 3, and 5 are assigned to group 1 first, and even-numbered time slots such as slots 2, 4, and 6 are assigned to group 2 first.

3 is a diagram illustrating an apparatus for allocating a radio resource according to an embodiment of the disclosed technology. Referring to FIG. 3, the apparatus 300 for allocating radio resources includes a progress direction classification module 310 and a resource allocation module 320.

The radio resource assignment apparatus 300 is an apparatus for allocating radio resources used for communication to a terminal in a vehicle for inter-vehicle communication. The method of allocating a radio resource by the radio resource allocating apparatus 300 may be a random access method in which respective terminals occupy resources through competition. For example, CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) may be used.

The progress direction classification module 310 maps the vehicle to the first or second direction group using the direction information of the vehicle. For example, the first direction group may be a direction group moving eastward as in Group 1 of FIG. 2B, and the second direction group may be a direction group moving westward as in Group 2 of FIG. 2B. There are two types of lanes on a normal road, going in the forward or reverse direction, except at the intersection. Therefore, in the present embodiment, it is described that priority is given to resource allocation by dividing the direction group into two, but there may be two or more direction groups and time slot groups.

The progress direction classification module 310 according to an embodiment may include a direction angle calculator 312, a direction group initializer 314, and a direction group updater 316.

 The direction angle calculator 312 calculates a direction angle in which the vehicle moves using the direction information of the vehicle. The driving direction information of the vehicle may be obtained through a magnetic compass, a front wheel compass, or a GPS (Global Positioning System) receiving device. The direction angle calculator 312 may obtain a motion vector of the vehicle based on the obtained direction information and calculate a direction angle of the vehicle's motion vector with respect to the reference angle.

4 is a diagram for describing a method of determining a direction group by a progress direction classification module. Referring to FIG. 4, the direction group initialization unit 314 initializes the direction group of the vehicle by comparing the direction angle calculated by the direction angle calculator 312 with the reference direction angle 420. The reference direction angle 420 may be predetermined by a device designer to a fixed value such as true north direction or true south direction as shown in FIG. 4, and the reference direction angle 420 may be dynamically adjusted by the radio resource allocation apparatus 300. You can decide. When the radio resource allocating apparatus 300 dynamically determines the reference direction angle 420, the reference direction angle 420 may be determined as a direction angle orthogonal to a direction in which the road proceeds with reference to GPS and map data. Can be. The direction group initializer 314 compares the reference direction angle 420 (eg, 180 degrees) with the calculated direction angle, and when the calculated direction angle is smaller than the reference direction angle 420, the vehicle as the first direction group. If greater than the reference direction angle 420, the vehicle is initialized to the second direction group.

The direction group updater 316 updates the direction group of the vehicle according to the change in the direction angle calculated by the direction angle calculator 312. For example, when the calculated direction angle is 140 degrees, the direction group initialization unit 314 initializes the vehicle to the first direction group, and when the calculated direction angle is changed to 200 degrees, the direction group updating unit 316 may change the vehicle. Update the direction group of to the second direction group.

The direction group updater 316 according to an exemplary embodiment gives a margin to the direction angle at which the direction group is changed to prevent the update of the direction group from occurring too frequently near the reference direction angle 420. Hysteresis can be imparted to directional group variations. For example, when the direction angle calculated by the direction angle calculator 312 is smaller than the first direction angle 430, the direction group of the vehicle is updated to the first direction group, and the calculated direction angle is the second direction angle ( If greater than 440, the direction group of the vehicle may be updated to the second direction group. In this case, when the calculated direction angle is greater than or equal to the first direction angle 430 and less than the second direction angle 440, the direction group of the vehicle is maintained. The first direction angle 430 may have a value smaller than the second direction angle 440 by a margin value. For example, the first direction angle 430 is an angle smaller by half of the margin value than the reference direction angle 420, and the second direction angle 440 is half the margin value than the reference direction angle 420. It can be set at a larger angle. The margin value may be set in advance by a communication system designer or the like.

The direction group updater 316 according to another exemplary embodiment of the present invention maintains a predetermined time when the calculated direction angle maintains a value smaller than the first direction angle 430 in order to impart greater hysteresis. The direction group of the vehicle may be updated to the second direction group when the direction group is updated to the first direction group and a time for which the calculated direction angle maintains a value greater than the second direction angle 440 is maintained for a predetermined time. .

The resource allocation module 320 first allocates a radio resource to the vehicle during a first time slot group when the vehicle is mapped to a first direction group, and when the vehicle is mapped to a second direction group, a second time. Radio resources are first assigned to the vehicle during the slot group.

This embodiment differs from the general TDMA scheme in that it assigns priority to resource allocation to a specific group of nodes, rather than unconditionally allocating a radio resource to a specific node during a specific time slot. The time slot has a preset length, and the radio resource allocating apparatus 300 may synchronize with another node using time information received by the GPS receiver in the vehicle. The time slot group is divided into time slots according to a predetermined criterion. For example, the first time slot group may be an odd-numbered time slot, and the second time slot group may be a group including even-numbered time slots.

The resource allocation module 320 according to an embodiment may adjust a content window (CW) in order to allocate radio resources first. That is, the resource allocation module 320 may set a short CW value to the vehicle in order to give priority to the competition by the CSMA method. For example, when the vehicle is mapped to the first direction group, the resource allocation module 320 sets the CW size to CW1 during the first time slot group and sets the CW size to CW2 during the second time slot group. Radio resources may be allocated to the vehicle first during one time slot group (CW1 <CW2). For example, CW2 may be set to the CW size used in the existing system, and CW1 may be set to the half value of CW2. Similarly, when the vehicle is mapped to the second direction group, the resource allocation module 320 sets the CW size to CW2 during the first time slot group and sets the CW size to CW1 during the second time slot group. Radio resources may be allocated to the vehicle first during two time slot groups.

5 is a flowchart illustrating a resource allocation method according to an embodiment of the disclosed technology. Referring to FIG. 3, a method of allocating a radio resource by the apparatus 300 for allocating a radio resource is as follows. In addition, since the time-series implementation of the radio resource allocation apparatus 300 of FIG. 3 also corresponds to the present embodiment, the portion described with respect to the radio resource allocation apparatus 300 is also applied to the present embodiment.

The apparatus 300 for allocating radio resources allocates radio resources for inter-vehicle communication according to a carrier sense multiple access / collision avoidance (CSMA / CA) scheme. The radio resource allocating apparatus 300 maps the vehicle to the first or second direction group by using the heading information of the vehicle. If it is mapped to one direction group, the radio resource is assigned to the vehicle during the first time slot group first, and if the vehicle is mapped to the second direction group, the radio resource is allocated to the vehicle during the second time slot group. First assigning (S520). According to an embodiment, when the vehicle is mapped to the first direction group, the radio resource allocating apparatus 300 sets a content window (CW) size to CW1 during the first time slot group, and the second time slot. During the group, the CW size may be set to CW2 to first allocate radio resources to the vehicle during the first time slot group. Similarly, when the vehicle is mapped to the second direction group, the radio resource allocator 300 sets the CW (Contention Window) size to CW2 during the first time slot group, and sets the CW size to CW1 during the second time slot group. In this case, radio resources may be allocated to the vehicle first during the second time slot group. The apparatus 300 for allocating radio resources updates a time slot group for allocating the radio resources first as the traveling direction of the vehicle changes (S530).

6 is a flow chart for explaining in detail the step S510 in accordance with an embodiment of the disclosed technology. In order to determine the direction group of the vehicle, the radio resource allocating apparatus 300 calculates a direction angle in which the vehicle moves using the direction information of the vehicle (S610). The apparatus 300 for allocating radio resources compares the calculated direction angle with the reference direction angle 420 and maps the vehicle to the first or second direction group (S620).

7 is a flowchart for describing operation S530 in detail according to an embodiment of the disclosed technology. In order to update the time slot group as the traveling direction of the vehicle changes, the radio resource allocating apparatus 300 calculates a direction angle in which the vehicle moves using the traveling direction information of the vehicle (S710). The radio resource allocating apparatus 300 according to an embodiment may give hysteresis to the direction group change by giving a margin to the direction angle at which the direction group is changed to prevent the direction group from being changed frequently near the reference direction angle 420. Can be. That is, when the direction angle calculated in step S710 is smaller than the first direction angle 430, the radio resource allocating apparatus 300 updates the time slots allocated to the vehicle to the first time slot group and calculates the direction. If the angle is larger than the second direction angle 440, the time slot allocated to the vehicle first may be updated to the second time slot group (S720). In this case, the first direction angle 430 is set to a value smaller than the second direction angle 440 by a margin value, and a direction group between the first direction angle 430 and the second direction angle 440 corresponding to the margin. It maintains its previous state. For example, the first direction angle 430 is an angle smaller by half of the margin value than the reference direction angle 420, and the second direction angle 440 is half the margin value than the reference direction angle 420. Can be set at a larger angle.

The radio resource allocating apparatus 300 according to another embodiment may provide wireless hysteresis if the time at which the direction angle calculated in operation S710 maintains a value smaller than the first direction angle 430 is maintained for a predetermined time. A time slot to which a resource is allocated first is updated to a first time slot group, and when a time for which the calculated direction angle maintains a value larger than the second direction angle 440 is maintained for a predetermined time, a time for which a radio resource is assigned first The slot is updated to the second time slot group (S720).

The disclosed method and apparatus have been described with reference to the embodiments illustrated in the drawings for ease of understanding, but these are merely exemplary, and various modifications and equivalent other embodiments are possible to those skilled in the art. Will understand. Therefore, the true technical protection scope of the disclosed technology should be defined by the appended claims.

1 is a view for explaining a radio channel access method according to the CSMA protocol.

2A is a diagram for describing a characteristic of a road on which inter-vehicle communication is performed.

2B is a diagram for explaining a radio resource allocation method according to one embodiment of the disclosed technology.

3 is a diagram illustrating an apparatus for allocating a radio resource according to an embodiment of the disclosed technology.

4 is a diagram for describing a method of determining a direction group by a progress direction classification module.

5 is a flowchart illustrating a resource allocation method according to an embodiment of the disclosed technology.

6 is a flow chart for explaining in detail the step S510 in accordance with an embodiment of the disclosed technology.

7 is a flowchart for describing operation S530 in detail according to an embodiment of the disclosed technology.

Claims (14)

An apparatus for allocating radio resources for inter-vehicle communication, A progress direction classification module for mapping the vehicle to a first or second direction group by using the direction information of the vehicle; And When the vehicle is mapped to the first direction group, radio resources are first assigned to the vehicle during a first time slot group, and when the vehicle is mapped to the second direction group, the vehicle during a second time slot group And a resource allocation module for allocating the radio resources first. The method of claim 1, The radio resource allocating method is a CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) method. The method of claim 1, wherein the resource allocation module, If the vehicle is mapped to the first direction group, the CW size is set to CW1 during the first time slot group, and the CW size is set to CW2 during the second time slot group to set the first. First assigning a radio resource to the vehicle during a time slot group, When the vehicle is mapped to the second direction group, a CW (Contention Window) size is set to CW2 during the first time slot group, and the CW size is set to CW1 during the second time slot group and a second First assigning a radio resource to the vehicle during a time slot group, And the CW1 is a value smaller than the CW2. The method of claim 1, wherein the progress direction classification module, A direction angle calculator configured to calculate a direction angle in which the vehicle moves using the direction information of the vehicle; A direction group initialization unit for initializing the direction group of the vehicle by comparing the calculated direction angle with a reference direction angle; And And a direction group updater for updating the direction group of the vehicle according to the calculated change in the direction angle. The method of claim 4, wherein the direction group update unit, When the calculated direction angle is smaller than the first direction angle, the direction group of the vehicle is updated to the first direction group, and when the calculated direction angle is larger than the second direction angle, the direction group of the vehicle is determined by the first direction angle. Update to two direction groups, and maintain the direction group of the vehicle when the calculated direction angle is greater than or equal to the first direction angle and less than the second direction angle; And the first direction angle is smaller than the second direction angle by a margin value. The method of claim 5, The first direction angle is an angle smaller by half of the margin value than the reference direction angle, And the second direction angle is an angle larger than half of the margin value than the reference direction angle. The method of claim 5, wherein the direction group update unit, If the time for which the calculated direction angle is smaller than the first direction angle is maintained for a predetermined time, the direction group of the vehicle is updated to the first direction group, And updating the direction group of the vehicle to the second direction group when a time for which the calculated direction angle maintains a value greater than the second direction angle is maintained for a predetermined time. In a method for allocating radio resources for inter-vehicle communication according to a carrier sense multiple access / collision avoidance (CSMA / CA) scheme, Mapping the vehicle to a first or second direction group using the direction information of the vehicle; And When the vehicle is mapped to the first direction group, radio resources are first allocated to the vehicle during a first time slot group, and when the vehicle is mapped to the second direction group, the vehicle is mapped to the second direction group during the second time slot group. And allocating the radio resource to a vehicle first. The method of claim 8, wherein the first allocating of the radio resource comprises: If the vehicle is mapped to the first direction group, the CW size is set to CW1 during the first time slot group, and the CW size is set to CW2 during the second time slot group to set the first. First assigning a radio resource to the vehicle during a time slot group, When the vehicle is mapped to the second direction group, the CW size is set to CW2 during the first time slot group, and the CW size is set to CW1 during the second time slot group to set the second. Prioritizing radio resources to the vehicle during a time slot group; The CW1 is a value less than the CW2 radio resource allocation method. The method of claim 8, wherein the mapping comprises: Calculating a direction angle in which the vehicle moves using the direction information of the vehicle; And And comparing the calculated direction angle with a reference direction angle and mapping the vehicle to the first or second direction group. The method of claim 8, And updating a time slot group for first allocating the radio resources according to a change in the traveling direction of the vehicle. The method of claim 11, wherein updating the time slot group comprises: Calculating a direction angle in which the vehicle moves using the direction information of the vehicle; And When the calculated direction angle is smaller than the first direction angle, the time slot to which the radio resource is first allocated to the vehicle is updated with a first time slot group, and when the calculated direction angle is larger than the second direction angle, the Updating a time slot to which the radio resource is first assigned to a vehicle to a second time slot group, And the first direction angle is a value smaller than the second direction angle. The method of claim 12, And the first direction angle is an angle smaller by half of a margin value than the reference direction angle, and the second direction angle is an angle that is half as large as the margin value than the reference direction angle. The method of claim 12, wherein updating the time slot group comprises: A time for which the calculated direction angle maintains a value smaller than the first direction angle is updated for the predetermined time slot group, and a time for which the calculated direction angle maintains a value greater than the second direction angle And updating the second time slot group if the predetermined time period is maintained.

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