KR100785268B1 - Method and device for providing distributed activation of dsrc and computer-readable medium having thereon a program performing function embodying the same - Google Patents

Abstract

The present invention provides a distributed activation method for dedicated short range communication (DSRC), the method comprising: acquiring an activation slot (ACTS) slot number using unique data; and activating each ACTS slot using the obtained ACTS slot number. And a method of modifying the probability and attempting communication using the modified activation probability.

According to the present invention, it is possible to improve the inefficiency of ACTS allocation that occurs when attempting activation using an activation probability in the conventional DSRC standard used in an intelligent transportation system, and activate using unique data such as LID. Through this, multiple OBEs can reduce the occurrence of collision when sending a request message to a limited ACTS slot and efficiently distribute the use of the ACTS slot.

ITS, DSRC, MAC, OBE, RSE, ACTS, Enabled, AP, LID, FCMS

Description

TECHNICAL AND DEVICE FOR PROVIDING DISTRIBUTED ACTIVATION OF DSRC AND COMPUTER-READABLE MEDIUM HAVING THEREON A PROGRAM PERFORMING FUNCTION EMBODYING THE SAME }

1 is a view showing the structure of a DSRC slot in the DSRC scheme according to the prior art.

2 is a flow chart of a distributed activation method for DSRC in accordance with the present invention.

3 is a view comparing a distributed activation method for a DSRC according to the present invention with a conventional DSRC activation method.

4 is a block diagram of a distributed activation device for DSRC according to the present invention;

5 shows an example of a hashing function used in a distributed activation device for DSRC in accordance with the present invention.

<Description of the symbols for the main parts of the drawings>

110: FCMS receiver 120: unique data extraction unit

130: ACTS slot number acquisition unit 140: activation probability correction

150: association

The present invention relates to a computer-readable recording medium recording a program for realizing a distributed activation method and apparatus for short-range dedicated communication (DSRC) and a function for implementing the same, and more particularly, to the DSRC standard used in an intelligent transportation system. Improving the inefficiency of ACTS allocation that occurs when attempting activation using the activation probability in the system, and causing a collision when multiple OBEs send request messages to limited ACTS slots through activation using unique data such as LID The present invention relates to a distributed activation method and apparatus for a DSRC, which reduces the cost and efficiently distributes the use of an ACTS slot, and a computer readable recording medium having recorded thereon a program for realizing a function for implementing the same.

ITS (Intelligent Transport System) refers to a traffic management system that combines the existing traffic information system with advanced communication technology to reduce traffic congestion, safe driving and air pollution. Unlike the existing public wireless communication network, these ITS services are installed on a roadside relatively simple base station (RSE, Road Side Equipment, or RSU, Road Side Unit) for vehicles running on the road. A low cost communication terminal called a communication device (OBE, On Board Equipment or OBU, On Board Unit) is mounted to perform wireless packet communication at high speed.

Since the wireless communication device usually has a wireless link within 100m as a communication range, a new concept of communication method called dedicated short range communication (DSRC) has been established.

DSRC is a ITS-only short-range communication method that provides short-range wireless high-speed packet communication function between a roadside communication device (RSE) installed on a roadside and a vehicle communication device (OBE) installed in a vehicle. Through this, various ITS services such as automatic toll collection service, roadside search, traffic information collection and provision, and traffic signal transmission are possible. DSRC is evaluated as an optimal technology for ITS construction, and as the field of application is expanded with the development of ITS-provided services, developed countries are putting a lot of effort into standardization research and related product development.

The DSRC is composed of a physical layer, a media access control (MAC) layer, a logical link control (LLC) layer, and an application layer. The standardization of the DSRC standard was conducted at CEN in Europe, ARIB in Japan and ASTM in the United States, and internationally at ITU-R SG8 and ISO / TC204.

The main characteristics of the physical layer will be described in detail as follows.

DSRC wireless packet network provides half-duplex bidirectional communication between RSE and OBE. The frequency used is the ISM band of 5.8 GHz and has a bandwidth of 10 MHz for Manchester coded 2 Mbps data transmission. The bandwidth of the transmission signal is allocated to 10MHz including a spare of 2MHz. The modulation method uses the Amplitude Shift Key (ASK) method. This makes the DSRC system inexpensive because the circuit is simpler than the frequency shift key (FSK) and phase shift key (PSK) methods. The wireless communication method uses time division duplex (TDD) that allocates the same frequency to uplink and downlink and separates transmission and reception in time. The TDD communication scheme has an advantage that the frequency bandwidth can be efficiently used and the packet frame length can vary according to the number of OBEs, compared to the frequency division duplex (FDD) scheme that separates transmission and reception frequencies at the same time. . The transceiver in the vehicle terminal employs an active method incorporating a frequency oscillator in the terminal. The active method has a disadvantage in that the circuit is slightly complicated, but since the base station can transmit with low power, the frequency reuse rate is higher than that of the passive method used as an internal frequency oscillator signal by using a carrier wave continuously transmitted from the base station. . In addition, a scrambling scheme using LID LSB 16 bits is used as a default key.

The MAC layer controls transmission on a packet frame basis.

FIG. 1 is a diagram illustrating a structure of a packet frame, that is, a DSRC slot, used in a MAC layer in a conventional DSRC scheme.

As shown in FIG. 1, the DSRC slot is composed of a frame control message slot (FCMS), a message data slot (MDS) and an activation slot (ACTS) slot. The number of MDS and ACTS slots is repeated in the FCMS packet. The RSE periodically sends FCMS, and each OBE receives the FCMS to determine the structure of the slot. The size of the DSRC slot may vary within the range of 2 to 9 depending on the number of OBEs in the communication area.

If the vehicle equipped with the OBE enters the communication area of the RSE, the MAC layer of the RSE controls the radio link between the RSE and another OBE in the TDD communication mode. The downlink-only FCMS slot transmits information about channel allocation and communication profile. Although not shown, an MDS slot capable of bidirectional communication includes a message data channel (MDC) and an acknowledgment channel (ACKC).

In order for a vehicle equipped with an OBE to enter a wireless communication area of an RSE installed on a roadside and the OBE performs communication with the RSE, it must first be authorized to communicate with the RSE through an association. The association sends an OBE to the RSE with a 13-byte request message containing its link identifier (LID) in the ACTS slot. The RSE that receives the ACTS determines whether to permit communication by referring to the ACTS information such as the LID value and the application ID. If communication is allowed then the LID value of the requested OBE is included in the LID field of the FCMS.

In this case, when there are multiple OBEs for one RSE, a collision may occur due to the limited number of ACTS slots. That is, if multiple OBEs send a request message in the same ACTS slot at the same time, the RSE will not receive the message normally.

In the conventional DSRC standard, in order to avoid such a collision, a value called an activation probability (AP) is included in the FCMS and transmitted.

OBEs receiving the AP value of the FCMS determine whether to transmit a request message with a probability according to the AP value when the UE tries to use the ACTS slot.

The disadvantage of using this probabilistic method, however, is that ACTS can occur without any OBEs.

For example, suppose a DSRC slot consists of one FCMS, six MDSs, and two ACTS slots. In this case, there are six ACTS mini-slots in one ACTS, so the two ACTSs have a total of 12 activation attempts. OBEs attempting to communicate with the RSE attempt uplink transmission at the probability of AP in each ACTS minislot. And suppose 24 OBEs try to communicate at the same time and AP is 25%.

With this setup, all OBEs have a 25% chance of trying to transmit to the first ACTS slot. Since 24 OBEs are assumed, on average 6 OBEs will attempt to communicate in the first slot and the remaining OBEs will attempt to transmit in the next slot. On average, about six OBEs will attempt to communicate in the second slot. The reason why the expression is about 6 units is because there is a case where communication is successful by only one OBE attempt in the first slot, and thus it may be expected to have similar probability in the second slot.

Thus, using this probabilistic approach creates the possibility that there is an ACTS that does not use any OBEs.

Applicants have found that the present invention is based on the idea that activating with LID or other values simultaneously or alone with this probabilistic method may reduce the probability of using the same slot at the same time as the respective slot numbers are distributed so as not to overlap. I came to mind.

An object of the present invention is to improve the inefficiency of the ACTS allocation that occurs when attempting activation by using the activation probability in the conventional DSRC standard used in intelligent transportation system, through a plurality of activations using unique data such as LID The present invention provides a distributed activation method and apparatus for a DSRC that reduces collisions when an OBE transmits a request message to a limited ACTS slot and efficiently distributes the use of the ACTS slot.

Another object of the present invention is to provide a computer readable recording medium having recorded thereon a program for realizing the function of implementing the distributed activation method for the DSRC.

In order to achieve the above technical problem, the present invention provides a distributed activation method for DSRC, the method comprising: acquiring an ACTS slot number using unique data, and using the obtained ACTS slot number, an activation probability for each ACTS slot; It provides a distributed activation method for the DSRC including the step of modifying, and attempting communication using the modified activation probability.

The present invention also provides a distributed activation apparatus for DSRC, comprising: an FCMS receiver for receiving FCMS to obtain ACTS slot information and an activation probability, a unique data extractor for extracting unique data, and ACTS slot information obtained from the FCMS receiver; An ACTS slot number acquisition unit for selecting an ACTS slot number using the unique data, an activation probability correction unit for modifying the activation probability for each ACTS slot using the selected ACTS slot number, the ACTS slot information, and the Provided is a distributed activation apparatus for a DSRC including an association attempting communication using a modified activation probability.

In addition, the present invention is a computer-readable recording medium recording a program for realizing the function of implementing a distributed activation method for DSRC, the function of acquiring an ACTS slot number using unique data and the obtained ACTS slot number And a function for modifying an activation probability for each ACTS slot, and a program for realizing a function of attempting communication using the modified activation probability.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a computer-readable recording medium recording a program for realizing a distributed activation method and apparatus for a DSRC of the present invention and a function for implementing the same will be described in more detail with reference to the accompanying drawings.

2 is a flowchart of a distributed activation method for DSRC according to the present invention.

When the OBE according to the DSRC standard attempts to communicate with the RSE, the OBE first acquires an ACTS slot number to attempt communication using unique data of the OBE, for example, an LID value (S110). The unique data is described based on the LID value, but other data unique to the OBE may be used.

In addition, acquiring the ACTS slot number using the unique data may be performed by using a hash function. That is, the purpose is to distribute ACTS slot numbers as much as possible in each OBE, so various hashing functions can be used.

Thereafter, the activation probability is modified using the obtained ACTS slot number (S130).

That is, at the position corresponding to the ACTS slot number acquired in step S110, the corresponding OBE is activated at a higher probability than the existing AP or at the same probability as the conventional AP, and at the remaining slots at a lower probability than the existing AP or in the conventional AP. The activation probability is modified to perform activation with the same probability as the AP.

Thereafter, communication is attempted using the modified activation probability (S150).

In this case, the OBE can attempt activation at a higher probability than the existing AP at the position corresponding to the acquired ACTS slot number.

3 is a view comparing a distributed activation method for a DSRC and an activation method of a conventional DSRC according to the present invention, FIG. 3 (a) is a view showing an activation method of a conventional DSRC, and FIG. A distributed activation method for DSRC according to the invention is shown.

As shown in FIG. 3, in the conventional DSRC activation method, all OBEs attempt to activate each ACTS using the same activation probability (AP). That is, all eight OBEs marked with O0 to O7 attempt to activate with the same activation probability, for example, 25% of AP.

On the other hand, in the distributed activation method for the DSRC according to the present invention, each OBE attempts to activate the AP differently for each ACTS slot.

For example, as shown, OBE (O0) obtains the first ACTS slot number by using its LID hashing function, OBE (O1) obtains the second ACTS slot number, and both OBE (O2) and OBE (O5) Assume that OBEs have acquired the third ACTS slot number. In this case, each OBE attempts at a higher probability than the AP set in the FCMS, for example, the AP of 25% in the ACTS slot acquired. As shown, there is a 50% chance of activation. In the remaining slots, it attempts to activate the 25% AP or lower AP set by FCMS. In Fig. 3, for example, a 10% probability is shown to try.

Through such adjustment of the activation probability (AP), each OBE can attempt to activate by distributing to each ACTS slot while avoiding collision.

4 is a block diagram of a distributed activation device for DSRC according to the present invention.

As shown, a distributed activation apparatus for DSRC according to the present invention includes an FCMS receiver 110, a unique data extractor 120, an ACTS slot number obtainer 130, an activation probability correction unit 140, The association part 150 is included. In addition, the distributed activation apparatus for DSRC according to the present invention includes components such as a data transmitter and receiver for transmitting and receiving data, but these components are the same as in the prior art, and thus description thereof will be omitted.

The FCMS receiver 110 receives a frame control message slot (FCMS) to obtain activation slot (ACTS) slot information and an activation probability (AP).

That is, an FCMS including information on channel allocation and communication profile is received from the RSE, and acquiring an activation slot (ACTS) slot information and an activation probability (AP) based on the FCMS.

The unique data extraction unit 120 extracts unique data. For example, LID can be used as the unique data, but other data unique to the OBE can be used.

The ACTS slot number obtaining unit 130 selects an ACTS slot number using the ACTS slot information obtained from the FCMS receiving unit 110 and the unique data of the unique data extracting unit 120.

This choice may, for example, use a hash function. Since the purpose of the ACTS slot number obtaining unit 130 is to distribute ACTS slot numbers as much as possible for each OBE, various hashing functions may be used.

5 is a diagram illustrating an example of a hashing function used in a distributed activation device for DSRC according to the present invention. As shown in the figure, it is configured to select an ACTS slot number by performing hashing such as an XOR operation based on the LID.

The activation probability correction unit 140 modifies the activation probability for each ACTS slot using the ACTS slot number selected by the ACTS slot number obtaining unit 130. That is, the activation probability acquired by the FCMS receiver 110 is not used as it is for the plurality of ACTS slots obtained through the ACTS slot information. For example, the activation probability is calculated for the ACTS slot corresponding to the selected ACTS slot number. It is to modify higher than the activation probability obtained from. In addition, for an ACTS slot that does not correspond to the selected ACTS slot number, the activation probability may be modified to be lower than the activation probability obtained by the FCMS receiver 110, or the activation probability obtained by the FCMS receiver 110 may be used as it is.

This modification of the activation probability allows each OBE to attempt activation by distributing to each ACTS slot while avoiding collisions.

The association unit 150 attempts to communicate using the ACTS slot information and the activation probability modified by the activation probability correction unit 140. For example, the association unit 150 receives information such as when an ACTS slot is transmitted through the FCMS receiver 110, and when an MLME-ASSOCIATE.request request is issued, the input value, that is, each ACTS slot and its corresponding modification, is received. It is determined whether to transmit data to the ACTS slot with reference to the activated activation probability.

The distributed activation apparatus for DSRC according to the present invention includes an FCMS receiver 110, a unique data extractor 120, an ACTS slot number obtainer 130, an activation probability correction unit 140, Although described separately by the association unit 150, each of these components can be implemented integrally. For example, the function of the activation probability correction unit 140 may be implemented in the association unit 150 or one-chip may be implemented.

The present invention also provides a computer-readable recording medium having recorded thereon a program for realizing the function of implementing the distributed activation method for the DSRC, but the description thereof is distributed activation for the DSRC described with reference to Figs. Since the method and apparatus overlap, the description is omitted.

Although the present invention has been described in detail, this is for illustrative purposes only, and the protection scope of the present invention is not limited thereto, and the protection scope of the present invention is defined through the description of the claims.

As described above, according to the present invention, it is possible to reduce the occurrence of collision when a plurality of OBEs transmit a request message to a limited ACTS slot through activation using unique data such as an LID and to efficiently distribute the use of the ACTS slot.

Claims (15)

delete As a distributed activation method for Dedicated Short Range Communication (DSRC), Acquiring a slot number of an active slot (ACTS) using unique data; Modifying an activation probability for each ACTS slot using the obtained ACTS slot number; Attempting to communicate using the modified activation probability Including, The unique data is a link identifier (LID: Link Identification). The method of claim 2, Acquiring an ACTS slot number using the unique data, The method of claim 1, wherein an ACTS slot number is obtained from the unique data using a hashing function. The method of claim 2, Modifying the activation probability for each ACTS slot using the obtained ACTS slot number, And modifying an activation probability higher than a predetermined activation probability for the ACTS slot corresponding to the obtained ACTS slot number. The method of claim 2, Modifying the activation probability for each ACTS slot using the obtained ACTS slot number, And modifying an activation probability lower than a predetermined activation probability for an ACTS slot that does not correspond to the obtained ACTS slot number. delete As a distributed activation device for DSRC, An FCMS receiver configured to receive a frame control message slot (FCMS) to obtain ACTS slot information and an activation probability; Unique data extraction unit for extracting unique data, An ACTS slot number obtaining unit selecting an ACTS slot number using the ACTS slot information obtained from the FCMS receiving unit and the unique data; An activation probability correction unit for modifying the activation probability for each ACTS slot using the selected ACTS slot number; An association unit attempting communication using the ACTS slot information and the modified activation probability Including, And wherein the unique data is an LID. The method of claim 7, wherein The ACTS slot number obtaining unit obtains an ACTS slot number from the unique data by using a hashing function. The method of claim 7, wherein The activation probability correction unit, And for the ACTS slot corresponding to the selected ACTS slot number, modifying an activation probability higher than an activation probability obtained by the FCMS receiver. The method of claim 7, wherein The activation probability correction unit, And for an ACTS slot not corresponding to the selected ACTS slot number, modifying an activation probability lower than an activation probability obtained by the FCMS receiver. delete A computer-readable recording medium having recorded thereon a program for realizing a function of implementing a distributed activation method for a DSRC, Acquiring the ACTS slot number using the unique data; Modifying an activation probability for each ACTS slot using the obtained ACTS slot number; Attempt to communicate using the modified activation probability A computer-readable recording medium having recorded thereon a program for realizing And the unique data is an LID. The method of claim 12, The function of acquiring an ACTS slot number using the unique data may include: And obtain an ACTS slot number from said unique data using a hashing function. The method of claim 12, The function of modifying the activation probability for each ACTS slot using the obtained ACTS slot number is And modifying an activation probability higher than a predetermined activation probability for an ACTS slot corresponding to the obtained ACTS slot number. The method of claim 12, The function of modifying the activation probability for each ACTS slot using the obtained ACTS slot number is And modifying an activation probability lower than a predetermined activation probability for an ACTS slot not corresponding to the obtained ACTS slot number.

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