KR102151873B1 - Method and apparatus for transmitting and receiving signal using optical camera communication in communication access for land mobiles system - Google Patents

Abstract

A method of operating a roadside unit (RSU) belonging to an intelligent transportation system (ITS) supporting OCC (optical camera communication), wherein data to be transmitted to an onboard unit (OBU) belonging to the ITS is modulated by a preset modulation method Generating a converted data signal; And transmitting the modulated data signal to the OBU by blinking each of the light sources included in the RSU according to the modulated data signal, wherein the modulated data signal includes information on the preset modulation method, It further includes information about a modulation frequency and information about a dimming level of the light sources included in the RSU.

Description

Signal transmission/reception method and apparatus using optical camera communication in CALM system {METHOD AND APPARATUS FOR TRANSMITTING AND RECEIVING SIGNAL USING OPTICAL CAMERA COMMUNICATION IN COMMUNICATION ACCESS FOR LAND MOBILES SYSTEM}

The present invention relates to a method of transmitting and receiving a signal using an optical camera system (OCC), and more specifically, of a station supporting OCC (for example, an intelligent transportation system (ITS) station). It relates to a method of operation and an architecture of a station.

Recently, Visible Light Communication (VLC) technology, a technology that enables wireless communication by adding a communication function to the visible light wavelength, is being actively researched, and the IEEE 802.15.7 international standard has also been completed, thus pursuing the discovery of a business model for commercialization. have. However, since IEEE 802.15.7 is mainly limited to data transmission using a photo diode (PD), there is a problem in that a dedicated communication device such as a VLC dongle must be used. Accordingly, the international standardization of Optical Camera Communications (OCC), which mainly uses an image sensor such as a camera rather than a photodetector, and includes not only visible light but also infrared and ultraviolet wavelengths, is IEEE 802.15.7m OWC TG (Task Group). In progress. OCC can be used in various fields, and in particular, it can be used for vehicle to vehicle (V2V) communication and vehicle to everything (V2X) communication.

The CALM (communication access for land mobiles) system may provide communication services through various wireless communication protocols. To this end, the CALM system may be a system that utilizes various wireless communication protocols such as wireless Internet service (Wibro/Mobile WiMAX), wireless LAN (WLAN) service, and infrared (IR) communication service. In particular, research is underway to implement ITS (intelligent transportation system), an intelligent wireless integrated platform that enables continuous communication even in a moving vehicle environment by using the CALM system, and it has been standardized by ISO 21217 and ISO 21218 for commercialization. It is promoting business model discovery. However, there is a problem that the ITS system up to now does not support communication by the OCC protocol.

An object of the present invention for solving the above problems is to provide an architecture of an intelligent transportation system (ITS) station supporting an optical camera communication (OCC) method and a method of operating an ITS station.

In a method of operating a roadside unit (RSU) belonging to an intelligent transportation system (ITS) supporting optical camera communication (OCC) according to an embodiment of the present invention for achieving the above object, the onboard unit (OBU) belonging to the ITS Generating a modulated data signal by modulating the data to be transmitted in) according to a preset modulation method; And transmitting the modulated data signal to the OBU by blinking each of the light sources included in the RSU according to the modulated data signal, wherein the modulated data signal includes information on the preset modulation method, It may further include information on a frequency used for transmission of the modulated data signal and information on a dimming level of the light sources included in the RSU.

Here, the preset modulation scheme is a spatial 2-phase shift keying (S2-PSK) modulation scheme, and the modulated data signal further includes code rate information of run-length limited (RRL) coding. can do.

Here, the preset modulation scheme is a hybrid spatial phase shift keying (HS-PSK) modulation scheme including S2-PSK and dimmable spatial M-PSK (DSM-PSK) modulation schemes, and the modulated data signal is the It may further include information on the modulation order (M) of the DSM-PSK.

Here, the information on the frequency used for transmission of the modulated data signal is information on the frequency used for transmission of the data signal modulated by the S2-PSK method and the information on the frequency modulated by the DSM-PSK method. It further includes information on a modulation frequency used for transmission of a data signal, and information on a frequency used for transmission of a data signal modulated by the S2-PSK scheme and modulated by the DSM-PSK scheme. Frequency used for transmission of the data signal may be characterized in that different frequencies.

Here, the information on the dimming level further includes information on a high dimming level of the DSM-PSK and information on a low dimming level of the DSM-PSK, and the information on the high dimming level and the low dimming level The information may be characterized as having different values.

Here, the modulated data signal may further include coding rate information of RRL coding of the S2-PSK and information about forward error coding (FEC) of the DSM-PSK.

As an ITS (intelligent transportation system) station supporting optical camera communication (OCC) according to an embodiment of the present invention for achieving the above object, the ITS station is an access entity performing an access function. ); And a management entity performing a management function for vehicle communication, wherein the access entity transmits an MI-request message used to set an OCC interface between the management entity and the access entity. Generating and sending the MI request message to the management entity, the management entity receiving the MI request message from the access entity, and the OCC interface based on the OCC parameter included in the MI request message Can be run to set

An access entity included in an ITS (intelligent transportation system) station, including a processor and a memory in which at least one instruction executed through the processor is stored, and the at least one The command generates an MI-request message used to set an OCC interface between a management entity belonging to the ITS station and the access entity, and transmits the MI request message to the management entity. The MI request message may be characterized in that it includes a communication interface parameter related to the OCC.

Here, the OCC parameter further includes information on a modulation method of the OCC signal, information on a frequency used for transmission of the OCC signal, and information on a dimming level of an output unit included in the ITS station. can do.

Here, the OCC parameter may further include information on OCC protocol regulation information, OCC link data rate, and quality of service (QoS) requirements for transmission and reception of OCC signals. .

Here, the access entity is further executed to receive an MI-command message that is a response message to the MI request from the management entity, and the MI command message performs a monitoring operation of the OCC parameter. It may be characterized by including the requested information.

An access entity of an ITS (intelligent transpotation system) station supporting optical camera communication (OCC) according to the present invention can transmit and receive signals according to the OCC protocol, and transmit a signal including an OCC interface parameter. It can be created and delivered to the management entity of the ITS station.

The management entity of the ITS station supporting OCC according to the present invention may receive OCC interface parameters from the access entity and perform a management operation of the ITS station based on the received OCC interface parameters.

1 is a conceptual diagram illustrating an embodiment of an intelligent transportation system (ITS) based on optical camera communication (OCC).
2 is a conceptual diagram showing an embodiment of the configuration of an OCC system.
3 is a block diagram showing the architecture of an ITS station supporting CALM (communications access for land mobiles).
4 is a block diagram showing an embodiment of an OCC communication interface.
5 is a block diagram showing the architecture of the ITS-OCC communication interface.
6 is a conceptual diagram illustrating an embodiment of a physical (PHY) layer of an ITS-OCC communication interface.
7 is a conceptual diagram illustrating an embodiment of a media access control (MAC) layer of an ITS-OCC communication interface.
8 is a conceptual diagram showing an embodiment of the structure of a MAC frame (frame).
9 is a conceptual diagram illustrating an embodiment of a structure of a frame control field of a MAC frame.
10 is a flowchart illustrating an embodiment of a signaling operation between an access entity and a management entity of an ITS-OCC communication interface.
11 is a table showing the first embodiment of communication interface parameters included in the MI request message.
12 is a table showing a second embodiment of communication interface parameters included in the MI request message.
13 is a table showing an embodiment of request information included in an MI request message.
14 is a table showing an embodiment of command information included in an MI command message.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being "connected" or "connected" to another component, it is understood that it may be directly connected or connected to the other component, but other components may exist in the middle. Should be. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

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

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate an overall understanding, the same reference numerals are used for the same elements in the drawings, and duplicate descriptions for the same elements are omitted.

1 is a conceptual diagram illustrating an embodiment of an intelligent transportation system (ITS) based on optical camera communication (OCC).

Referring to FIG. 1, the ITS system may include a plurality of sub-systems. For example, the ITS system may include a central station 110, a roadside station 120, an onboard unit (OBU) station 130 and a personal station 140.

The central station 110 of the ITS may include an ITS application 111 and a network interface 112. The ITS application 111 may perform a function for maintaining the ITS. In addition, the network interface may support a network between ITS stations, and may further include a server.

The central station 110 of the ITS and the roadside station 120 of the ITS may be connected by a communication network 150. In addition, the communication network 150 may be connected to the personal station 140 of the ITS. The central station 110 of the ITS, the roadside station 120 of the ITS, and the personal station 140 of the ITS may transmit and receive data through the communication network 150.

The load side station 120 of the ITS may further include a transmission/reception module 121 and may be connected to the communication network 150 through the transmission/reception module 121. In addition, the load side station 120 of the ITS may support the OCC scheme. The load side station 120 of the ITS may include a plurality of light sources for transmitting the OCC signal, and may include an image sensor for receiving the OCC signal. The load side station 120 of the ITS may communicate with the OBU station 130 of the ITS through the OCC method.

The OBU stations 130-1 and 130-2 of the ITS may be stations provided in the vehicle. The first OBU station 130-1 may include an OBU 131-1, an antenna 132-1, a host computer 133-1, and a user interface 134-1. The OBU 131-1 may include devices mounted on a vehicle, and, for example, an infotainment device (eg, a display device, a navigation device, an around view monitoring device). monitoring) device), and the like. The OBU 131-1 may further include an antenna 132-1, and may transmit and receive data by accessing a preset network through the antenna 132-1.

The host computer 133-1 may include a processor and a memory. The processor may include control logic for controlling an OBU, a user interface, and a memory. The memory may store signals processed by the processor and may output the stored signals according to the request of the processor. The memory may refer to a volatile memory (eg, random access memory (RAM)) that temporarily stores data necessary for the operation of the processor. Alternatively, the memory is a nonvolatile memory in which operating system code (eg, kernel and device driver) and application program code for performing a function of a processor are stored. It can mean.

The user interface 134-1 may be an interface that provides a service to a user. The user interface 134-1 may include an input unit, an output unit, and a display unit, and may provide a service according to commands of the OBU 131-1 and the host computer 133-1.

The OBU stations 130-1 and 130-2 of the ITS may support the OCC scheme. The OBU stations 130-1 and 130-2 of the ITS may include a plurality of light sources for transmitting the OCC signal, and may include an image sensor for receiving the OCC signal. For example, the first OBU station 130-1 of the ITS may receive an OCC signal from the ITS roadside station 120 and transmit a signal to the second OBU station 130-2.

Each station (110, 120, 130-1, 130-2, etc.) included in the ITS system may be configured as a single network node. Alternatively, each station (110, 120, 130-1, 130-2, etc.) included in the ITS system may be composed of a plurality of network nodes (eg, routers and hosts). A router included in the stations 110, 120, 130-1, 130-2, etc. may perform a function of transmitting packets between ITS stations. In addition, a host included in the stations 110, 120, 130-1, 130-2, etc. may perform functions related to the ITS service.

2 is a conceptual diagram showing an embodiment of the configuration of an OCC system.

Referring to FIG. 2, an OCC system according to an embodiment of the present invention may include an optical wireless transmission device 210 and an optical wireless reception device 220. The optical wireless transmission device 210 may include a modulator 211 and a transmitter 212. The transmitter 212 may include at least one or more light sources 212-1 and 212-2, and the light sources 212-1 and 212-2 may be LEDs. The optical wireless reception device 220 may include a receiver 221 and a demodulator 223, and may further include a light source detector 222. The receiver 221 may include an image sensor 221-1 such as a camera.

The modulator 211 can receive a binary data signal D[i], which is a bit sequence to be transmitted, and can generate binary data signals S1(t) and S2(t) having a modulated pulse waveform. have. S1 and S2 may be continuous signals or discrete signals.

The transmitter 212 may transmit data by blinking each of the plurality of light sources 212-1 and 212-2 according to the binary data signals S1(t) and S2(t). Flashing here does not necessarily indicate the way the light sources 212-1 and 212-2 are completely turned on and completely turned off, but two states of binary values of 0 and 1 using the change in brightness of the light sources 212-1 and 212-2. It can include any way of representing. When the blinking frequency of the light sources 212-1 and 212-2 is equal to or higher than a predetermined value (eg, 200 Hz), a person may not feel the blinking of the light sources 212-1 and 212-2.

The receiver 221 may receive an image sequence obtained by continuously photographing (sampling) the light sources 212-1 and 212-2 by the image sensor 221-1. The light source detector 222 may detect the positions of the light sources 212-1 and 212-2 in the received image. The demodulator 223 may demodulate the data signal from the blinking states of the light sources 212-1 and 212-2.

3 is a block diagram illustrating an architecture of an intelligent transportation system (ITS) station supporting communications access for land mobiles (CALM).

Referring to FIG. 3, a communication interface (CI) of an intelligent transport system station (ITS) may include an application layer 310 and a communication layer 320. The application layer 310 of the ITS station may support a plurality of functions. For example, the application layer 310 may be a layer that supports functions related to road safety, functions related to traffic congestion, and other functions. The application layer 310 may be connected to the communication layer 320 and a plurality of entities included in the communication layer 320 through an application programming interface (API).

The communication layer 320 may include a plurality of entities. For example, the communication layer includes a management entity 321, a security entity 322, a facility entity 323, a network and transport entity 324, and an access ( access) entity 325 may be included.

The management entity 321 may perform a function of managing an ITS station. The management entity 321 may manage a plurality of ITS management objects, and the ITS management object may include information on a plurality of protocols and communication interfaces supported by the ITS station.

The security entity 322 may perform security-related functions of the ITS station. For example, the security entity 322 may manage firewalls and intrusions. The security entity 322 may further include a hardware security module (HSM) and a security management information base (SMIB). SMIB can manage the authentication procedure and encryption key (crypto-key).

The facility entity 323 may support the operation of entities included in the ITS station. For example, the facility entity 323 may perform an application support operation, may perform an information support operation, and may perform a session/communication support operation. have.

The network and transport entity 324 may include a network layer and a transport layer of an OSI communication protocol stack. The network layer may support a network based on an internet protocol (IP) (eg, IPv6) and a network based on a non-IP (non-IP).

The access entity 325 may access the network through a plurality of communication protocols. For example, the access entity 325 may perform communication with the outside of the ITS station through long term evolution (LTE) and 5G new radio (NR) protocols, and the inside of the ITS station through a protocol such as Ethernet. Communication can be performed.

A plurality of entities included in the communication layer 320 may be connected through a service access point (SAP). For example, the management entity 321 may be connected to the security entity 322 through MS SAP. The management entity 321 may be connected to the facility entity 323 through MF SAP. In addition, the management entity 321 may be connected to the network communication entity 324 through the MN SAP, and may be connected to the access entity 325 through the MI SAP.

In addition, the security entity 322 may be connected to the facility entity 323 through SF SAP. In addition, the security entity 322 may be connected to the network and transmission entity 324 through SN SAP, and may be connected to the access entity 325 through SI SAP. The facility entity 323 may be connected with the network and transmission entity 324 through NF SAP, and the network and transmission entity 324 may be connected with the access entity 325 through IN SAP.

The ITS station according to the present invention may include one or more processors. For example, the ITS station may include one processor, and one processor may perform functions of a plurality of entities 321, 322, 323, 324, 325, etc. included in the ITS station. Also, the ITS station may include a plurality of processors, and each of the plurality of processors may perform a function of a plurality of entities 321, 322, 323, 324, 325, etc. included in the ITS station.

The ITS station communication interface according to the present invention may be a communication interface supporting OCC. ITS communication interface supporting OCC can be defined as ITS-OCC communication interface. The ITS-OCC communication interface may specify a protocol for performing communication by a preset medium type (MedType), a CI class, and a CI access class as OCC.

4 is a block diagram showing an embodiment of an OCC communication interface.

Referring to FIG. 4, the ITS-OCC communication interface may further include functions and layers for supporting OCC in some entities of the existing ITS communication interface. For example, the ITS-OCC communication interface may include a management entity 410, a security entity 420, a facility entity 430, a network and transmission entity 440, and an access entity 450.

The ITS-OCC communication interface can support one-to-many communication by a base station. Alternatively, the ITS-OCC communication interface may be an interface that supports one-to-many communication between ITS stations without support by a separate base station. The management entity 410 of the ITS-OCC communication interface may further include a function for supporting OCC to the management entity 321 of the existing ITS station. The MIIB of the management entity of the ITS-OCC communication interface may further perform functions to support OCC, and may perform functions to support OCC so that coexistence with other communication interfaces is possible.

For example, the management entity 410 of the ITS-OCC communication interface may perform a relay function of transmitting data to another node through an optical channel. And the management entity 410 of the ITS-OCC communication interface performs a handover function that supports handover from one node to another node in a vehicle to vehicle (V2V) topology or a vehicle to everything (V2X) topology. can do. The management entity 410 of the ITS-OCC communication interface may perform a relay function and a handover function using an OCC communication interface and other communication interfaces (eg, LTE, 5G, Wi-Fi, etc.).

The management entity 410 of the ITS-OCC communication interface may perform a function of measuring a distance between vehicles. Specifically, the management entity 410 of the ITS-OCC communication interface may measure a distance to an adjacent vehicle through an OCC interface, a hybrid OCC interface, and a radio frequency (RF) interface.

The management entity 410 of the ITS-OCC communication interface may perform a dimming management function of changing the illuminance level of a transmitter of a node supporting OCC. In addition, the management entity 410 of the ITS-OCC communication interface may perform a function of managing location information of a node. The management entity 410 of the ITS-OCC communication interface may manage the location information of the node by interworking with the OCC communication interface or a separate communication interface. The location information management function of the management entity can enhance the function of the CPS interface in a specific scenario.

The security entity 420 of the ITS-OCC communication interface may include the same layer as the security entity 322 of the existing IDS stage, and may perform the same function. In addition, the facility entity 430 of the ITS-OCC communication interface may include the same layer as the facility entity 323 of the existing IDS stay line, and may perform the same function.

The network and transmission entity 440 of the ITS-OCC communication interface may further include a function for supporting OCC to the network and transmission entity 324 of the existing ITS station. The network and transmission entity 440 of the ITS-OCC communication interface may adjust the transmission delay and the size of the packet header in order to shorten the transmission time in performing OCC.

The access entity 450 of the ITS-OCC communication interface may further include functions and layers for supporting OCC in the access entity 325 of the ITS station shown in FIG. 2. The access entity 450 of the ITS-OCC communication interface may include an OCC module and may support the OCC protocol.

The access entity 450 of the ITS-OCC communication interface may include a plurality of sub-layers. Specifically, the access entity of the ITS-OCC communication interface includes a physical (PHY) layer 451, a media access control (MAC) sublayer 452, a logical link control (LLC) sublayer 453, and a management sublayer. I can. The LLC sublayer 453 may further include a communication adaptation sublayer (CAL) 454 connected to the network and transmission entity 440. The CAL 454 may generate a signal according to a protocol defined in an ITS related standard by converting a signal according to the OCC protocol received from a lower layer. The CAL 454 may transmit the generated signal to the network and transmission entity 440.

The management sublayer included in the access entity 450 is a management adaptation entity (MAE) 455 connected to the management entity 410 of the ITS communication interface and a security access (SAE) connected to the security entity 420 of the ITS communication interface. entity) 456 may be further included. The MAE 455 converts a signal according to the OCC protocol received from the lower layer, and may generate a signal according to the protocol defined in the ITS related standard. The MAE 455 may transmit the generated signal to the management entity 410. In addition, the SAE 455 may convert a signal according to the OCC protocol received from the lower layer to generate a signal according to the protocol defined in the ITS related standard. The SAE 455 may transmit the generated signal to the security entity 420.

The access entity 450 of the ITS-OCC communication interface may be connected to other entities of the ITS communication interface through SAP. The access entity 450 of the ITS-OCC communication interface may support SAPs defined in the ISO standard, and each of the SAPs supported by the access entity 450 of the ITS-OCC communication interface performs functions defined in the ISO standard. I can.

The access entity 450 of the ITS-OCC communication interface may support IN SAP defined in the ISO standard. The CA sublayer of the access entity of the ITS-OCC communication interface may be connected to the network and the transmission entity 440 of the ITS communication interface through IN SAP. IN SAP of the access entity 450 of the ITS-OCC communication interface may perform a function defined in the ISO standard.

The access entity 450 of the ITS-OCC communication interface may support SI SAP defined in the ISO standard. The SAE 452 of the access entity 450 of the ITS-OCC communication interface may be connected with the security entity 420 of the ITS communication interface through SI SAP. SI SAP can perform the functions defined in the ISO standard.

The access entity 450 of the ITS-OCC communication interface may support MI SAP defined in the ISO standard. The MAE 451 of the access entity 450 of the ITS-OCC communication interface may be connected to the management entity 410 of the ITS-OCC communication interface through MI SAP. MI SAP can perform the functions defined in the ISO standard.

5 is a block diagram illustrating an architecture including MAC and PHY of an ITS-OCC communication interface.

Referring to FIG. 5, the ITS-OCC communication interface may include an access entity. The architecture of the access entity may include a plurality of layers as defined in the IEEE standard. The access entity of the ITS-OCC communication interface may include an optical SAP (optical SAP), a PHY layer 520, a MAC layer 530, an LLC layer 540, an SSCS layer 550, and an upper layer 560. . The ITS-OCC communication interface may include a management entity 570 connected with an access entity. In addition, the ITS-OCC communication interface may further include a dimmer 580.

The optical SAP 510 may support communication by optical media. The optical medium may include a plurality of cells, and may receive a signal through the plurality of cells. The optical SAP 510 may be connected to the PHY layer 520 through a PHY switch of the PHY layer 520.

6 is a conceptual diagram illustrating an embodiment of a PHY layer of an ITS-OCC communication interface.

Referring to FIG. 6, the PHY layer 520 may receive a signal from the optical SAP 510. The PHY layer 520 may support a physical data (PD)-SAP function 521 for processing data and a PHY layer management entity (PLME)-SAP function 522 for connection with a management entity.

The PHY layer 520 may generate a protocol data unit (PDU). The PHY layer 520 may generate PDUs having different formats according to the modulation scheme of the OCC. For example, the PHY layer 520 of the OCC-ITS architecture that transmits and receives a signal modulated by the spatial 2-phase shift keying (S2-PSK) method can generate a PDU having an S2-PSK physical PDU (PPDU) format. have. In addition, the PHY layer 520 of the OCC-ITS architecture that transmits and receives a signal modulated by the hybrid spatial phase shift keying (HS-PSK) method may generate a PDU having an HS-PSK PPDU format.

The PHY layer 520 of the OCC-ITS architecture that transmits and receives a signal modulated in the S2-PSK scheme may generate an S2-PSK PPDU, and the S2-PSK PPDU may include a frame as shown in Table 1.

Referring to Table 1, the S2-PSK PPDU may include a preamble and a physical service data unit (PSDU). The preamble of the S2-PSK PPDU may include a header (SDU header, SHR), and may include a frame as shown in Table 2. Referring to Table 2, the duration of the preamble of the S2-PSK PPDU may be 2 bit time. In addition, the S2-PSK PPDU may include 4 bits.

The PSDU of the S2-PSK PPDU may include a PHY payload, and the PSDU of the S2-PSK PPDU may include a frame indicating information about line codes. A frame related to the line code included in the PSDU may be defined as shown in Table 3.

Referring to Table 3, the PHY payload of the S2-PSK PSDU may include information on bit input and line code output according to bit input.

The PHY layer 520 of the OCC-ITS architecture that transmits and receives a signal modulated by the HS-PSK method may generate an HS-PSK PPDU, and the HS-PSK PPDU may include a frame as shown in Table 4.

Referring to Table 4, the HS-PSK PPDU may include a preamble, a PHY header, and a PHY payload. The PHY header may further include a header check sequence (HCS).

The preamble of the HS-PSK may include information on a signal modulation method. The preamble of HS-PSK may include a frame as shown in Table 5. Referring to Table 5, the duration time of the preamble part of the HS-PSK PPDU may be 2 bit time. The S2-PSK PPDU may include 4 bits.

Referring to Table 5, the preamble of the PDU including the signal modulated by the S2-PSK method may be set to '1111', and the preamble of the PDU including the signal modulated by the DS8-PSK method is '0000'. Can be set to

The PSDU of the HS-PSK PPDU may include a PHY payload, and the PSDU of the S2-PSK PPDU may include a frame as shown in Table 6.

The PSDU of the HS-PSK PPDU may include a low dimming frame and a high dimming frame. The low dimming frame may include information on a plurality of symbols, and the high dimming frame may include information on a plurality of symbols.

The PHY layer 520 of the OCC-ITS architecture may further include a PHY physical layer information base (PIB) 523, and the PHY PIB 523 may be a database including information on properties of the OCC signal. The PHY PIB 523 may include attribute information as shown in Table 7, and the PHY layer 520 may generate a PDU including the attribute information in Table 7.

phyOccMcsID may be attribute information defining a modulation method of an OCC signal. For example, phyOccMcsID may be defined as a signal modulated by the S2-PSK or HS-PSK scheme. phyOccOpticalClockRate may define an attribute related to an optical clock rate or symbol rate applied to each of the S2-PSK and DSM-PSK modulation schemes. phyDim may define a property of the dimming level of the OCC signal.

phyOccRLLCode may define an RLL coding scheme according to a modulation scheme of an OCC signal. phyOccRLLCode may define an RLL coding method according to a modulation method of an OCC signal according to phyOccMcsID.

phyOccFec can define FEC according to the modulation method of the OCC signal. phyOccFEC can define FEC according to the modulation method of the OCC signal according to phyOccMcsID. For example, when phyOccMcsID indicates HS-PSK and phyOccFEC is 0, the PHY layer may modulate the signal without performing FEC. In addition, when phyOccMcsID indicates HS-PSK and phyOccFEC is 1, the PHY layer may further perform FEC when performing DS8-PSK modulation.

The PHY layer 520 of the OCC-ITS architecture may set OCC information based on PHY physical layer information base (PIB) attribute information, and may further set additional attribute information according to a modulation method of the OCC signal. For example, when the OCC signal is modulated by the S2-PSK method, the PHY PIB 523 may further define the attributes shown in [Table 8], and the PHY layer 520 includes the attribute information of Table 8. It is possible to create a PDU.

phyS2pskNoLightSources may be attribute information defining the number of light sources used to transmit the OCC signal. In addition, phyS2pskModulationRate may be attribute information defining a frequency of a signal for performing S2-PSK modulation.

And when the OCC signal is modulated by the HS-PSK method, the PHY PIB 523 can further define the attributes shown in [Table 9], and the PHY layer 520 generates a PDU including the attribute information of Table 9. can do.

phyHSpskHighStreamMode can set the modulation order (M) of the DSM-PSK modulation method among the HS-PSK modulation methods. For example, when the value of phyHSpskHighStreamMode is 0, the OCC signal may be modulated in the HS-PSK scheme including the S2-PSK scheme and the DS8-PSK scheme. In addition, when the value of phyHSpskHighStreamMode is 1, the OCC signal may be modulated in the HS-PSK scheme including the S2-PSK scheme and the DS10-PSK scheme.

phyHSpskModulationRate can set the modulation frequency of the S2-PSK modulation method and the DSM-PSK modulation method. For example, when the value of phyHSpskModulationRate is 0, the modulation frequency of the S2-PSK modulation method may be set to 200Hz, and the modulation frequency of the DS8-PSK modulation method may be set to 80KHz. In addition, when the value of phyHSpskModulationRate is 1, the modulation frequency of the S2-PSK modulation method may be set to 200Hz, and the modulation frequency of the DS8-PSK modulation method may be set to 400KHz.

OCC attribute information may include information on a dimming level. phyHSpskLowDim can set the low dimming level, and phyHSpskHighDim can set the high dimming level. In addition, phyHSpskPsduLength may set the length of a high speed link (or high speed message) in a signal generated by the HS-SPK method.

The PHY layer 520 may generate a PDU including OCC attribute information, and may transmit the generated PDU to the MAC layer 530 and the management entity 570.

7 is a conceptual diagram showing an embodiment of the MAC layer of the ITS-OCC communication interface.

Referring to FIG. 7, the MAC layer 530 may receive a signal from the PHY layer. The MAC layer 530 may support a MAC common part sublayer (MCPS)-SAP function 531 for processing data and a MAC layer management entity (MLME)-SAP 532 function for connection with a management entity.

The MLME 532 of the MAC layer may further include a MAC layer information base (MAC PIB) 533, and the MAC PIB 533 may be a database including information on the properties of the MAC frame. The MAC layer 530 may generate a MAC frame based on MAC frame property information included in the MAC PIB 533.

8 is a conceptual diagram showing an embodiment of the structure of a MAC frame.

Referring to FIG. 8, the MAC layer 530 may generate a MAC frame including a MAC header (MHR), a MAC SDU (MSDU), and a MAC footer (MFR). The MHR of the MAC frame may include a frame control field, a sequence field, and an address field. The fields of the MAC frame may be set in octet units, and an octet may include 8 bits.

9 is a conceptual diagram illustrating an embodiment of a structure of a frame control field of a MAC frame.

9, the frame control field indicates a frame version field indicating a version of a MAC frame, a frame type field indicating a frame type, a security enabled field indicating whether or not a security function is supported, and whether or not frame pending is supported. A field indicating whether an ACK message is requested, a field indicating whether to request an ACK message, a destination addressing mode of a signal, and a field indicating a source addressing mode of a signal may be included.

The receive address designation method field and the transmission address designation method field of a signal may be allocated to different bits of the MAC frame control field. For example, the receive address designation method field may be allocated to bits 12-13 of the MAC frame control field, and the transmission address designation method field of a signal may be allocated to bits 14 to 15 of the MAC frame control field.

According to another embodiment of the present invention, the MAC frame may include a field indicating an address assignment method. The field indicating the address designation method may be allocated to one bit of the MAC control field, and may indicate the address designation method as shown in Table 10.

Referring to Table 10, when the address designation method indicator is 0, the MAC frame may support a destination address designation method, and when the address designation method indicator is 1, the MAC frame may support a transmission address designation method.

Referring back to FIG. 8, the MHR of the MAC frame may include an address field. The address field of the MHR may include a field indicating a wireless personal access network (WPAN) indicator of a receiving node and a field indicating a receiving address. The address field of the MHR may include a field indicating a WPAN indicator of a transmitting node and a field indicating a transmission address. In addition, the MHR may further include an auxiliary security header (ASH) for securing the security of the MAC frame.

The MSDU may include a PDU received from the PHY layer, and the MFR may include a frame check sequence (FCS). The MAC layer may generate a MAC frame including MHR, MSDU and MFR, and may transmit the generated MAC frame to a management entity and an upper layer.

10 is a flowchart illustrating an embodiment of a signal transmission operation between an access entity and a management entity of an ITS-OCC communication interface.

Referring to FIG. 10, the access entity 450 may generate an MI request message. The MI request message may include a communication interface parameter (I-parameter). The communication interface parameter may include a standard defined by ISO, and may further include parameters related to OCC.

11 is a table showing a first embodiment of communication interface parameters included in the MI request message, and FIG. 12 is a table showing a second embodiment of the communication interface parameters included in the MI request message.

First, referring to FIG. 11, the communication interface parameter may further include parameters related to an OCC modulation scheme. For example, the communication interface parameter may include a parameter indicating a modulation method of an OCC signal, a parameter indicating a clock speed, a parameter indicating a dimming level, a parameter related to RLL coding, and a parameter related to FEC.

A parameter related to RLL coding may indicate an RLL coding method according to a parameter value indicating a modulation method of a signal. In addition, the FEC-related parameter may indicate an FEC coding method according to a value of a parameter indicating a signal modulation method.

And referring to FIG. 12, the communication interface parameter may further include parameters related to communication based on the OCC protocol. For example, the communication interface parameter is a low-level (LL) address parameter, a parameter related to regulatory information, a parameter related to transmission and reception, a parameter related to a link data rate, a parameter related to PCI. , A parameter related to an operation mode and a parameter related to QoS may be further included.

The regulation information parameter may indicate information on regulation for the OCC protocol when performing OCC communication. The parameters related to transmission and reception may indicate information on the operation of a node when transmitting or receiving an OCC signal. For example, a parameter related to reception may indicate information about a reception sensitivity of a node that receives an OCC signal. The transmission parameters may indicate information on transmission power, maximum transmission power, and peer transmission power of the OCC signal.

The parameter related to the link data rate may indicate the data rate of the OCC link. The PCI parameter can indicate the physical channel of the OCC protocol. In addition, the QoS parameter may indicate information on the QoS requirements of the OCC signal.

The access entity 450 may generate an MI request message including communication parameters related to the OCC illustrated in FIGS. 11 to 12, and the MI request message may further include messages requesting an operation of the management entity.

13 is a table showing an embodiment of request information included in an MI request message.

Referring to FIG. 13, the MI request message may include a communication interface registration request, event indication information, and location information update request.

The access entity 450 may generate an MI request message including the communication interface shown in FIGS. 11 to 12 and the request information shown in FIG. 13, and transmit the generated MI request message to the management entity 410. Yes (S1010).

The management entity 410 may receive the MI request message from the access entity 450 (S1010), and may perform operations indicated by an indicator included in the MI request message. For example, the management entity 410 may register a communication interface based on communication interface registration request information included in the MI request message. Upon receiving the MI request message, the management entity 410 may generate an MI command message.

14 is a table showing an embodiment of command information included in an MI command message.

Referring to FIG. 14, the MI command message may include an MI echo test command, a CI state change command, a communication interface parameter monitoring command, a pseudo MAC address change command, and a VCI management (vehicle communication interface) command.

The management entity 410 may perform a communication interface registration operation based on the MI request message, and may generate a CI state change command indicating that the communication interface has been changed. The management entity 410 may generate a command for requesting management of a virtual communication interface (VCI), and the VCI management request command may be a command for requesting generation, reset, and deletion of a VCI. The management entity 410 may generate a command requesting monitoring of a communication parameter.

The management entity 410 may generate an MI command message including command information shown in FIG. 13 and may transmit the generated MI command message to the access entity 450 (S1020). The access entity 450 may receive the MI command message (S1020), and may perform an operation indicated by the received MI command message.

The methods according to the invention may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like alone or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the present invention, or may be known and usable to those skilled in computer software.

Examples of computer-readable media include hardware devices specially configured to store and execute program instructions, such as rom, ram, flash memory, and the like. Examples of program instructions include not only machine language codes such as those produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The above-described hardware device may be configured to operate as at least one software module to perform the operation of the present invention, and vice versa.

Although described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention described in the following claims. I will be able to.

Claims (10)

In the operation method of a roadside unit (RSU) belonging to an intelligent transportation system (ITS) supporting optical camera communication (OCC),
Hybrid spatial phase shift keying (HS-PSK) including spatial 2-phase shift keying (S2-PSK) and dimmable spatial M-PSK (DSM-PSK) modulation schemes for data to be transmitted to an onboard unit (OBU) belonging to the ITS ) Generating a modulated data signal by modulating by a modulation method; And
And transmitting the modulated data signal to the OBU by blinking each of the light sources included in the RSU according to the modulated data signal,
The modulated data signal,
Information on the HS-PSK modulation scheme, information on a frequency used for transmission of the modulated data signal, and information on dimming levels of the light sources included in the RSU. How the RSU works. In claim 1,
The modulated data signal,
The operating method of the RSU, characterized in that it further comprises code rate information of the RRL (run-length limited) coding of the S2-PSK. In claim 1,
The modulated data signal further includes information on a modulation order (M) of the DSM-PSK. In claim 3,
Information on the frequency used for transmission of the modulated data signal,
Further comprising information on a frequency used for transmission of the data signal modulated by the S2-PSK scheme and information on a frequency used for transmission of the data signal modulated by the DSM-PSK scheme,
A method of operating an RSU, characterized in that a frequency used for transmission of a data signal modulated by the S2-PSK method and a frequency used for transmission of a data signal modulated by the DSM-PSK method are different frequencies . In claim 3,
Information on the dimming level,
Further including information on the high dimming level of the DSM-PSK and information on the low dimming level of the DSM-PSK,
The information on the high dimming level and the information on the low dimming level have different values. In claim 3,
The modulated data signal,
The method of operating an RSU, further comprising information on forward error coding (FEC) of the DSM-PSK. delete delete delete delete

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