JP2010028636A - Base station, mobile station, and method for controlling communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent reduction in the wireless resource utilization efficiency. <P>SOLUTION: A base station 10 transmits allotment information for wireless resources to use for a first communication that is communication between a mobile station 50. The mobile station 50 prohibits use of the wireless resources indicated by the received allotment information for a second communication that is a communication between the mobile stations 50 to perform transmission to other mobile stations, and permits use of a part or all of the wireless resources for the second communication, to perform transmission to the other mobile stations 50, while the allotment information is not received. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  This case relates to a base station, a mobile station, and a communication control method. This case may be used for an Intelligent Transport System (ITS).

  In recent years, ITS has been developed with the aim of reducing traffic accidents. As ITS, the traffic lights are equipped with radio equipment (roadside equipment) that functions as a base station, and information on traffic lights at intersections (whether red or blue, etc.) or information on the presence or absence of a right turn car, etc. are installed in vehicles approaching several hundred meters away. There is a form of road-to-vehicle communication that is transmitted to a wireless device (hereinafter also referred to as an in-vehicle device or a mobile station). There is also a form of inter-vehicle communication in which vehicle-mounted devices located at a short distance communicate with each other to notify vehicle information such as the traveling direction and the traveling speed.

  For this inter-vehicle communication, narrow area ad hoc communication based on general wireless LAN (Local Area Network) technology (IEEE802.11 series standard) can be considered. The said narrow area ad hoc communication in this nonpatent literature 1 is communication of the form with which mobile stations communicate directly, without going through central control apparatuses, such as a base station. Since there is no base station that allocates communication (wireless) resources to each mobile station, each mobile station manages the communication resources used, and the communication resources shared by each mobile station are autonomously distributed among the mobile stations. Communication while competing with each other.

At that time, each mobile station, for example, exchanges communication timing information of other mobile stations existing in the vicinity, and shifts the communication timing of each mobile station in an autonomous distributed manner, that is, uses communication resources in an autonomous distributed manner. By selecting, it is possible to avoid interference.
JP-A-5-307697 ANSI / IEEE Std 802.11, 1999 Edition F. Borgonovo et al., “ADHOC MAC: New MAC Architecture for Ad Hoc Networks Providing Efficient and Reliable Point-to-Point and Broadcast Services”, Wireless Networks 10, 359-366, 2004, Kluwer Academic Publishers, Netherlands

  In the prior art, regardless of whether the in-vehicle device is in the wireless area (service area) provided by the roadside device or outside the area, it is used for communication (road-to-vehicle communication) between the roadside device and the in-vehicle device. The radio resource can only be fixedly allocated.

One of the purposes of this case is to suppress a decrease in the utilization efficiency of radio resources.
Another object of the present invention is to prevent the first communication between the base station and the mobile station from receiving interference (interference) due to the second communication between the mobile stations.

  It should be noted that the present invention is not limited to these purposes, and is a function and effect derived from each configuration shown in the embodiments described later, and it can be positioned as one of the other purposes to exhibit a function and effect that cannot be obtained by conventional techniques. it can.

  For example, the following means are used.

  (1) Of the radio resource group that can be shared by the first communication that is communication between the base station and the mobile station and the second communication that is communication between the mobile stations, it is used for the first communication. An allocation information generating means for generating allocation information of radio resources; and the mobile station transmits the allocation information, and the mobile station uses the radio resource indicated by the received allocation information for the second communication to another mobile station. A control unit that prohibits transmission to another mobile station using a part or all of the radio resources for the second communication when the allocation information is not received. Can be used.

  (2) Of the radio resource group that can be shared by the first communication that is communication between the base station and the mobile station and the second communication that is communication between the mobile stations, it is used for the first communication. Receiving means for receiving radio resource allocation information from the base station, and when the allocation information is received by the receiving means, the radio resource indicated by the allocation information is used for the second communication to Transmission to a mobile station is prohibited, and if the allocation information is not received by the receiving means, a part or all of the radio resource is used for the second communication to transmit to another mobile station And a mobile station equipped with a control means that allows

  (3) A communication control method in a wireless communication system comprising a mobile station and a base station that communicates wirelessly with the mobile station, wherein the base station is communication with the mobile station. Of the radio resource group that can be shared for communication and second communication that is communication between mobile stations, the mobile station transmits radio resource allocation information used for the first communication, and the mobile station receives the allocation information received If the radio resource indicated by is used for the second communication to prohibit transmission to another mobile station, and if the allocation information is not received, a part or all of the radio resource is transmitted to the second communication. It is possible to use a communication control method that allows transmission to other mobile stations.

  According to the disclosed technology, since radio resources used for the first communication and the second communication are not fixed, it is possible to suppress a decrease in use efficiency of the radio resources. It is also possible to suppress the first communication from being disturbed (interfered) by the second communication.

  Hereinafter, embodiments will be described with reference to the drawings. However, the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described below. That is, the present embodiment can be implemented with various modifications (combining the examples) without departing from the spirit of the present embodiment.

[1] One Embodiment For the spread of ITS, it is desired that the cost of a radio device mounted on an in-vehicle device and a roadside device is reduced and that a user can easily introduce it. Therefore, road-to-vehicle communication (first communication) that is communication between the roadside device and the vehicle-mounted device is common to vehicle-to-vehicle communication (second communication) that is communication between the vehicle-mounted devices that do not pass through the roadside device. It is effective to implement with a radio.

  As an example of an ITS that satisfies this requirement, it is conceivable to perform communication between road vehicles and between vehicles using autonomous distributed CSMA (Carrier Sense Multiple Access). However, CSMA may be insufficient for communications that require high reliability. Therefore, in ITS, it is generally insufficient from the viewpoint of reliability to apply CSMA to road-to-vehicle communication that requires higher reliability than vehicle-to-vehicle communication.

  For example, as illustrated in FIG. 14, the in-vehicle device A that is performing road-to-vehicle communication with the roadside device receives interference (interference) due to vehicle-to-vehicle communication of the in-vehicle device B that is in a hidden terminal relationship with the roadside device. There is a case. Further, as illustrated in FIG. 15, interference may occur between in-vehicle devices that perform road-to-vehicle communication at the same timing. The occurrence of such interference may cause deterioration in communication quality.

  The former interference can be prevented by separating communication (wireless) resources such as time (timing) and frequency in road-to-vehicle communication and vehicle-to-vehicle communication. However, there is room for improvement from the viewpoint of utilization efficiency of communication resources because the time or frequency allocated for road-to-vehicle communication is not used in a place where there is no roadside device.

  The latter interference can be avoided by selecting the carrier sense time performed by each in-vehicle device according to a predetermined rule (using random numbers, etc.). Such a method is called CSMA / CA (CSMA / Collision Avoidance). However, interference cannot be guaranteed to be successful because interference is only avoided probabilistically.

  In the present embodiment, a communication method is proposed that can improve communication resource utilization efficiency and communication reliability (success rate). For example, communication resources used (allocated) for road-to-vehicle communication and vehicle-to-vehicle communication are not fixed. The outline is illustrated in FIG. The ITS shown in FIG. 1 is exemplarily mounted on a roadside device 10 as an example of a base station, a signal controller 20, a network 30, a server 40, and a vehicle or the like as an example of a mobile station. And a wireless device (hereinafter referred to as an in-vehicle device) 50.

  The roadside device 10 is a wireless device installed at a traffic light on a road (such as an intersection), for example, and forms a wireless area (service area) where wireless communication is possible. In this wireless area, the vehicle-mounted device 50 can perform wireless road-to-vehicle communication with the roadside device 10 and wireless vehicle-to-vehicle communication with other vehicle-mounted devices 50. The in-vehicle device 50 located outside the wireless area can perform inter-vehicle communication with other in-vehicle devices 50.

  For road-to-vehicle communication, communication using the downlink (downlink: DL) radio channel, which is the direction from the roadside device 10 to the vehicle-mounted device 50, and uplink (uplink: UL), which is the direction from the vehicle-mounted device 50 to the roadside device 10. ) And / or communication via a wireless channel.

  Communication (wireless) resources (road-to-vehicle resources) used for this road-to-vehicle communication (wireless channel) can be centrally managed (schedule controlled) in the roadside device 10. The roadside device 10 can individually allocate road-to-vehicle resources to the in-vehicle device 50 by the schedule control.

  The allocation information can be notified, for example, using a DL control channel signal such as a broadcast channel. For example, MAP information can be used if a radio frame based on OFDM (Orthogonal Frequency Division Multiplex) or OFDMA (Orthogonal Frequency Division Multiple Access) is used. For example, the MAP information can be information or a set of information in which road-to-vehicle resource identification information is associated with identification information of the in-vehicle device 50 that is the allocation destination of the road-to-vehicle resource.

  When receiving the notification, the in-vehicle device 50 can perform wireless communication with the roadside device 10 using the road-to-vehicle resources allocated by the roadside device 10. In other words, the in-vehicle device 50 uses a road-to-vehicle resource that is individually assigned under schedule control by the road-side device 10 in a wireless area where road-to-vehicle communication with the road-side device 10 is possible. Car-to-vehicle communication.

  On the other hand, in an area where road-to-vehicle communication is possible, communication resources (vehicle-to-vehicle resources) other than the road-to-vehicle communication resources are used for communication between the in-vehicle devices 50 (vehicle-to-vehicle communication). That is, use of road-to-vehicle communication resources for vehicle-to-vehicle communication is restricted (prohibited). Therefore, it is possible to prevent the interference between the vehicle-mounted devices 50 and the interference (disturbance) due to the inter-vehicle communication with respect to the road-to-vehicle communication.

  Wireless resources other than road-to-vehicle resources (vehicle-to-vehicle resources) can be shared by a plurality of in-vehicle devices 50. The in-vehicle device 50 selects the inter-vehicle resources in an autonomous and distributed manner so as not to compete with the inter-vehicle resources used in other inter-vehicle communication. For example, ad hoc communication can be applied to the inter-vehicle communication, and CSMA / CA can be applied to the autonomous distributed resource selection, for example.

  Vehicle-to-vehicle resources that can be shared by a plurality of vehicle-mounted devices 50 can be explicitly specified (assigned) from the roadside device 10 to the vehicle-mounted device 50, and the vehicle-mounted devices are based on the explicit allocation of road-to-vehicle resources. It is also possible for 50 to recognize autonomously.

  On the other hand, in an area where the roadside device 10 does not exist and road-to-vehicle communication is unnecessary, the roadside device 10 allows the vehicle-mounted device 50 to use part or all of the road-to-vehicle resources for vehicle-to-vehicle communication. That is, the vehicle-to-vehicle resource amount that the in-vehicle device 50 can use for vehicle-to-vehicle communication can be increased or decreased depending on whether or not road-to-vehicle communication is possible. The in-vehicle device 50 can determine whether or not the vehicle-mounted device 50 is located in a wireless area that does not require road-to-vehicle communication based on whether or not the wireless signal transmitted from the roadside device 10 is received. This determination can be made additionally or alternatively by using GPS (Global Positioning System).

  Here, when a vehicle-mounted device 50 that performs vehicle-to-vehicle communication using a certain vehicle-to-vehicle resource enters a wireless area where the roadside device 10 exists and performs roadside-vehicle communication with the roadside device 10, the roadside device. The road-to-vehicle resource allocated from 10 and the vehicle-to-vehicle resource used for the vehicle-to-vehicle communication before the entry may overlap. In that case, the in-vehicle device 50 can continue the vehicle-to-vehicle communication by autonomously re-selecting the vehicle-to-vehicle resource from the communication resources other than the road-to-vehicle resource allocated from the roadside device 10.

  Road-to-vehicle communication may be described as “infrastructure communication”, and vehicle-to-vehicle communication may be described as “ad hoc communication”. In this example, communication (wireless) resources include time slot (timing) in time division multiplexing, frequency in frequency division multiplexing, code in code division multiplexing, burst in orthogonal frequency division multiplexing (frequency × time). ) Etc. are included.

  The radio resources between road vehicles and between vehicles may be the same (common) between road vehicles and between vehicles, for example, road-to-vehicle orthogonal frequency division multiplexing bursts, and vehicle-to-vehicle time slots called time division multiplexing time slots. Thus, it may be different between road vehicles and between vehicles.

  In this example, for the sake of convenience, it is assumed that each communication resource (radio channel) between road vehicles and between vehicles is a time slot according to a time division multiplexing system. FIG. 1 illustrates a state in which a preamble, an address, and data can be included per time slot.

  The preamble can include synchronization information indicating the start of a radio frame or time slot, and header information. The address may include data destination information, for example, the IP address or MAC (Media Access Control) address of the in-vehicle device 50 or the roadside device 10. The data may include various data such as characters, sounds, images, moving images, and the like.

  In FIG. 1, the signal controller 20 controls the display state (blue, yellow, red, etc.) of the signal. The signal controller 20 is connected to the roadside device 10 and a network 30 such as an IP (Internet Protocol) network or an ATM (Asynchronous Transfer Mode) network so that they can communicate with each other. As a result, the signal controller 20 transmits the data from the in-vehicle device 50 received by the roadside device 10 to the server 40 via the network 30, while the data addressed to the in-vehicle device 50 received from the server 40 via the network 30. It can be transmitted to the roadside machine 10.

  The server 40 generates and transmits / receives data (service information) according to the service provided to the roadside device 10 and the vehicle-mounted device 50. Examples of the service may include a navigation service to the destination of the in-vehicle device 50, an information service regarding road conditions, a probe service, and the like.

  Information on road conditions includes, for example, information such as vehicle congestion (congestion), presence of nearby emergency vehicles, road construction, road surface conditions (road surface temperature, pavement state, rainfall, snowfall, freezing) (Hereinafter collectively referred to as “road traffic information” together with the signal information of the traffic light). The road traffic information may include any one or a combination of text, voice, still image, and moving picture information.

  The probe service is, for example, a service that periodically notifies the roadside device 10 (signal controller 20) of vehicle travel information (position, speed, moving direction, etc.). The service information (probe information) is used, for example, for recognizing the number of vehicles traveling around the roadside machine 10 and performing appropriate traffic light control, or for determining the travel time of a specific road section.

  In FIG. 2, the example of a structure of each of the roadside machine 10 and the vehicle equipment 50 is shown. 2 includes, for example, a road-vehicle communication unit 11 for performing road-vehicle communication with the vehicle-mounted device 50. The road-vehicle communication unit 11 includes a transmission unit 111, a reception unit 112, and Slot management unit 113.

  On the other hand, the in-vehicle device 50 exemplarily includes a road-to-vehicle communication unit 51 for communicating with the roadside device 10, a vehicle-to-vehicle communication unit 52 for communicating with other on-vehicle devices 50, And an inter-vehicle communication switching control unit 53. The road-to-vehicle communication unit 51 illustratively includes a transmission unit 511, a reception unit 512, and a slot management unit 513. The inter-vehicle communication unit 52 includes, for example, a transmission unit 521 and a reception unit 522.

  In the road-vehicle communication unit 11 of the roadside machine 10, the transmission unit 111 performs DL transmission processing in road-vehicle communication. This transmission processing may include, for example, processing such as transmission signal encoding, modulation, DA conversion, frequency conversion (up-conversion) to radio frequency, and high output amplification. In this transmission process, a synchronization signal (synchronization information) used for establishing synchronization of road-to-vehicle communication, a radio frame synchronized with the synchronization signal, and communication resources for road-to-vehicle communication allocated to the in-vehicle device 50 (road-to-vehicle communication) Processing of generating and transmitting resource (allocation) information is also included.

  On the other hand, the receiving unit 112 of the road-vehicle communication unit 11 performs UL reception processing in road-vehicle communication. This reception process includes, for example, processes such as low noise amplification of a UL radio signal received by an antenna (not shown), frequency conversion to a baseband signal (down conversion), AD conversion, demodulation, and decoding. May be included.

  The slot management unit 113 manages time slots (road-to-vehicle slots) as an example of road-to-vehicle resources, and controls time slot allocation to the in-vehicle device 50. Therefore, the slot management unit 113 exemplarily includes a scheduler 114 and a slot management table (memory) 115. The slot management table 115 holds information regarding the air-blocking situation of the road-to-vehicle slot, and the scheduler 114 determines (schedules) the road-to-vehicle slot to be allocated to the in-vehicle device 50 based on the information about the air-fueling situation.

  The scheduling result (slot allocation information) is transmitted from the transmission unit 111. The in-vehicle device 50 that has received this slot allocation information (that is, time information) stops transmission of the inter-vehicle slot in the time slot (road-to-vehicle slot) indicated by the allocation information (at this time, reception may be continued). And may stop.) The in-vehicle device 50 that does not receive the slot allocation information is allowed to select all the time slots including the road-to-vehicle slot indicated by the slot allocation information as slots used for inter-vehicle communication (transmission of inter-vehicle slots). That is, part or all of the road-to-vehicle slot can be used for transmission of the vehicle-to-vehicle slot.

  Therefore, the slot management unit 113 is used as an example of an allocation information generating unit that generates allocation information for road-to-vehicle slots among time slot groups that can be shared for road-to-vehicle communication and vehicle-to-vehicle communication. Further, the transmission unit 111 transmits the allocation information in cooperation with, for example, the slot management unit 113, and the in-vehicle device 50 uses the road-to-vehicle slot indicated by the received allocation information for other vehicle-to-vehicle communication. Control means for prohibiting transmission to the in-vehicle device 50 and permitting transmission to another in-vehicle device 50 using part or all of the road-to-vehicle slot for inter-vehicle communication while the allocation information is not received. It is also used as an example.

(In-vehicle device 50)
On the other hand, in the in-vehicle device 50, the transmission unit 511 of the road-vehicle communication unit 51 performs UL transmission processing in road-vehicle communication. This transmission processing may include, for example, processing such as encoding, modulation, DA conversion, frequency conversion (up-conversion) to a radio frequency, and high output amplification of a transmission signal to the roadside device 10.

  The receiving unit 512 performs DL reception processing in road-to-vehicle communication. The receiving unit 512 receives slot allocation information scheduled by the roadside device 10. The reception processing includes, for example, low noise amplification of a DL radio signal from the roadside device 10 received by an antenna (not shown), frequency conversion (down conversion) to a baseband signal, AD conversion, demodulation, Processing such as decryption may be included.

  The slot management unit 513 manages DL and UL road-to-vehicle slots allocated from the roadside device 10 based on the slot allocation information received by the reception unit 512. Under the management, the transmission unit 511 and the reception unit 512 are managed. Controls transmission / reception frequency and transmission / reception timing.

  The transmission unit 521 of the inter-vehicle communication unit 52 performs transmission processing of a signal (data) to be transmitted to the other in-vehicle device 50 by ad hoc communication, and the reception unit 522 is received from the other in-vehicle device 50 by ad hoc communication. A signal (data) reception process is performed. Time slots (inter-vehicle slots) as an example of communication resources used for transmission and reception are managed and controlled by, for example, a road / vehicle / vehicle communication switching control unit 53.

  A road-to-vehicle / vehicle-to-vehicle communication switching control unit (hereinafter, also simply referred to as “control unit”) 53 enables communication by the road-to-vehicle communication unit 51 in a road-to-vehicle slot based on the slot allocation information (an inter-vehicle communication unit 52). And transmission by the inter-vehicle communication unit 52 is controlled in the inter-vehicle slot. When the in-vehicle device 50 does not receive the slot allocation information from the roadside device 10, it is permitted to select a part or all of the road-to-vehicle slots as the vehicle-to-vehicle slots. Prohibition of transmission by the vehicle-to-vehicle communication unit 52 is possible by controlling the vehicle-to-vehicle communication unit 52 to a busy state.

  That is, when the slot allocation information is received by the receiving unit 512, the control unit 53 prohibits transmission to another in-vehicle device 50 using the road-to-vehicle slot indicated by the allocation information for inter-vehicle communication. When the slot allocation information is not received by the receiving unit 512, it is possible to allow a part or all of the road-to-vehicle slots to be used for the second communication and to transmit to other mobile stations. However, reception of inter-vehicle communication can be continued without being prohibited (stopped).

  The road-to-vehicle slot and the vehicle-to-vehicle slot can be defined as an elapsed time (offset) from the top of the frame. The roadside device 10 can notify the in-vehicle device 50 of the slot allocation by including the offset value in the slot (bandwidth) allocation information.

  Hereinafter, operation examples of the roadside device 10 and the vehicle-mounted device 50 configured as described above will be described with reference to FIGS. 3 and 4. 3 shows an operation flowchart of the in-vehicle device 50, and FIG. 4 shows an operation flowchart of the roadside device 10.

(Operation example of in-vehicle device 50)
As illustrated in FIG. 3, when the vehicle-mounted device 50 is turned on (processing 1501), the vehicle-mounted device 50 ensures time synchronization based on the synchronization signal received from the GPS satellite or the roadside device 10 (processing 1502). And the vehicle equipment 50 checks whether the receiving part 512 of the road-vehicle communication part 51 has received the synchronous signal from the roadside machine 10 (process 1503).

  If not received (No in process 1503), the in-vehicle device 50 is not located in the wireless area of the roadside device 10, and therefore the control unit 53 allows communication by the inter-vehicle communication unit 52. The inter-vehicle communication unit 52 performs autonomous inter-vehicle communication by selecting any slot including slots that may be allocated to road-to-vehicle resources so as not to compete with other in-vehicle devices 50 (processing). 1504).

  On the other hand, if the synchronization signal is received from the roadside device 10 (Yes in processing 1503), the vehicle-mounted device 50 recognizes that it is located in the wireless area of the roadside device 10, and Car-to-vehicle communication with other in-vehicle devices 50 is performed using a slot other than the road-to-vehicle slot so as not to disturb the communication (process 1505).

  At that time, for example, the in-vehicle device 50 can recognize a slot determined in advance based on the pattern of the synchronization signal received from the roadside device 10 as a road-to-vehicle slot, and recognize other slots as inter-vehicle slots. . As an alternative example, it is possible to make the in-vehicle device 50 explicitly recognize the road-to-vehicle slot or the inter-vehicle slot by using a broadcast signal or the like instead of using the pattern of the synchronization signal.

  Thereafter, the in-vehicle device 50 checks whether or not the communication resource allocation information (slot allocation information) transmitted by the roadside device 10 is received by the reception unit 512 of the road-to-vehicle communication unit 51 (process 1506). If not received (No in process 1506), the process returns to process 1503. If it has been received (Yes route of processing 1506), the in-vehicle device 50 holds and manages the received slot allocation information in the slot management unit 513. This slot allocation information includes DL and UL slot allocation information.

  Then, the in-vehicle device 50 determines the presence / absence of DL information (control information, service information, etc.) that the on-vehicle device 50 should receive based on the slot allocation information of the slot management unit 513, and receives necessary information. (Processing 1507). The in-vehicle device 50 (road-to-vehicle communication unit 51) checks whether or not UL link establishment is necessary to start road-to-vehicle communication with the roadside device 10 (processing 1508). If link establishment is necessary (Yes in processing 1508), the in-vehicle device 50 generates a UL link establishment request by the transmission unit 511 and transmits it to the roadside device 10 (processing 1509).

  This link establishment request can be transmitted using, for example, a random access channel (RACH) slot. The RACH slot is designated by the allocation information, for example. An example of this is shown by the hatched portion in FIG. The link establishment request can use a signal of a predetermined pattern called a preamble or a signature. The in-vehicle device 50 autonomously selects one of a plurality (for example, 64 types) of preambles prepared for random access and transmits it to the roadside device 10. For the selection, a predetermined selection criterion such as using a random number can be applied. According to this, the contention rate with the preamble transmitted by the other in-vehicle device 50 can be lowered.

  When the link establishment request is correctly received by the roadside device 10 and a slot (bandwidth) used for UL communication is assigned to the in-vehicle device 50 by a predetermined random access procedure, the in-vehicle device 50 uses the slot to use the roadside device 10. And road-to-vehicle communication.

  When UL link establishment is not necessary (No in processing 1508), or when UL link establishment is performed and UL communication is started, the in-vehicle device 50 (road-to-vehicle communication unit 51) communicates with the roadside device 10. It is checked whether or not UL link disconnection is necessary (process 1510).

  As a result, if UL link disconnection is necessary due to completion of road-to-vehicle communication, the in-vehicle device 50 (road-to-vehicle communication unit 51) generates a link disconnection request by the transmission unit 511, and the roadside device 10 The message is transmitted to the destination (from the Yes route of process 1510 to process 1511). This link disconnection request can also be transmitted using RACH, for example. The link disconnection request is generated, for example, when UL communication ends or when the power source of the in-vehicle device 50 is turned off.

  The link disconnection request may not be transmitted. In that case, the link of the corresponding UL can be disconnected when the time during which the roadside device 10 does not receive the UL data from the in-vehicle device 50 of the communication partner continues for a predetermined time. Further, the roadside device 10 can also perform link disconnection of the UL by not receiving an established UL link disconnection request within a predetermined time.

  Thereafter, the in-vehicle device 50 (road-to-vehicle communication unit 51) generates data (service information or the like) to be transmitted to the roadside device 10 in the transmission unit 511 (process 1512). At that time, the transmission unit 511 checks whether or not an additional UL band (slot allocation) is necessary for data transmission (process 1513).

  If an additional bandwidth is necessary (Yes in processing 1513), the transmission unit 511 generates a UL bandwidth request and transmits it to the roadside device 10 (processing 1514). This bandwidth request can also be transmitted using, for example, a RACH slot (see, for example, FIG. 12). On the other hand, if the UL allocation sufficient for UL data transmission has already been allocated based on the slot allocation information received in the above-described processing 1506, and no additional UL bandwidth request is required, the transmission unit 511 receives the bandwidth request. Is not transmitted (No route of processing 1513).

  Thereafter, the in-vehicle device 50 (the road-to-vehicle communication unit 51) checks whether a UL band sufficient for UL data transmission has been secured (process 1515). If secured, the transmission unit 511 transmits the UL transmission data generated in the process 1512 to the roadside device 10 (from the Yes route of the process 1515 to the process 1516).

  Thereafter, the in-vehicle device 50 (road-to-vehicle communication unit 51) performs processing after processing 1503. If the UL bandwidth sufficient for the UL data transmission is not secured, the UL data transmission is not performed by the transmission unit 511, and the processing returns to the processing 1503 (No route of the processing 1515). Even if the UL bandwidth sufficient for UL data transmission is not secured, it is possible to partially transmit the UL transmission data using the secured bandwidth.

(Operation example of roadside machine 10)
On the other hand, as illustrated in FIG. 4, the roadside device 10 (road-to-vehicle communication unit 11) receives some signal (information) from the external device such as the server 40 and the signal controller 20 or the vehicle-mounted device 50 at the receiving unit 112. Whether or not the received information (data) has been received, the type of the received information (data) is confirmed, and processing corresponding to the type is performed. When a plurality of pieces of information are received during a certain period, the processes exemplified below can be processed in parallel according to each type.

  For example, when the received information is DL data (service information or the like) from the server 40 or the signal controller 20 (processing 1102), the roadside device 10 wirelessly transmits the received data to the in-vehicle device in the transmission unit 111. Processing for transmission to 50 is performed (processing 1103). This processing may include, for example, addition of a header necessary for wireless transmission, an error correction code, and the like. In addition, a process of requesting the scheduler 114 to allocate a DL radio band (slot) used for the radio transmission may be included.

  When the received information is a UL link establishment request from the in-vehicle device 50 (process 1104), the roadside device 10 (road-to-vehicle communication unit 11) performs the requested UL link establishment processing. In this link establishment process, for example, the identification information (ID) of the in-vehicle device 50 of the link establishment request source included in the link establishment request and the requested band information (transmission capacity, allowable delay time, etc.) Processing such as holding (registering) in the slot management table 115 of the slot management unit 113 is included. Further, a process of generating a response indicating that a link establishment request has been accepted, and a process of requesting the scheduler 114 of the slot management unit 113 to allocate a DL band used for transmitting the response may be included.

  Furthermore, when the received information is a UL link disconnection request from the in-vehicle device 50 (process 1106), the road-vehicle communication unit 11 of the roadside device 10 performs the requested UL link disconnection process (process 1107). ). This link disconnection process includes, for example, a process of deleting the ID of the in-vehicle device 50 that is the link disconnection request source, the requested bandwidth information, and the like from the slot management table 115. In addition, a process for generating a response indicating that a link disconnection request has been accepted, and a process for requesting the scheduler 114 of the slot management unit 113 to allocate a DL band used for transmitting the response may be included.

  When the received information is a UL bandwidth request from the in-vehicle device 50 (process 1108), the roadside device 10 (road-to-vehicle communication unit 11) recognizes the requested UL bandwidth, and the UL bandwidth Is requested to the scheduler 114 of the slot management unit 113 (process 1109).

  When the scheduler 114 is requested to perform scheduling of the DL radio band through any of the processes 1102 to 1109, for example, the scheduler 114 allocates the DL frame in the next frame based on the request. Determine the bandwidth. At this time, the number of slots to be allocated to UL / DL data transmission is determined based on the UL and / or DL data amount and the like. Note that for data to which no band is allocated in the next radio frame, the band can be allocated by scheduling performed in the subsequent radio frame.

  Next, the scheduler 114 transmits the scheduled (determined) bandwidth (slot) allocation information from the transmission unit 111. For example, the allocation information is broadcast to a wireless area for road-to-vehicle communication (processing 1113). Then, the scheduler 114 transmits DL data (control information and service information) from the transmission unit 111 in accordance with the determined slot allocation information (processing 1114). At that time, the DL data can be broadcast or unicast to each in-vehicle device 50 according to the data type.

  When the roadside device 10 receives UL data (service information or the like) transmitted by the in-vehicle device 50 based on the slot allocation information transmitted in the above processing 1113 (processing 1110), the roadside device 10 (road-to-vehicle communication unit 11) Then, a process for transmitting the received UL data to an external device such as the server 40 or the signal controller 20 is performed (process 1111). This processing may include, for example, removal of a header necessary for wireless transmission, error correction code, and the like. Further, a process of requesting the scheduler 114 to allocate a UL wired band used for transmitting the UL data may be included.

  The scheduler 114 requested to schedule the UL wired band performs the allocation of the UL wired band used to transmit the UL data received from the in-vehicle device 50 to the external device (process 1115). This bandwidth allocation is illustratively performed for each UL data based on the connection line speed with the external device, the priority of the UL data, and the like.

  Thereafter, the roadside device 10 transmits the UL data received from the in-vehicle device 50 using the assigned UL wired band (processing 1116).

(Example)
Hereinafter, specific examples of the ITS will be described with reference to FIGS. 5 to 13 based on the configurations and operations of the roadside device 10 and the vehicle-mounted device 50 described above.
FIG. 5 shows that in ITS, the first vehicle-mounted device 50-1 moves (runs) in the order of point A, point B, and point C, approaches the roadside device 10, and The situation which 2 onboard equipment 50-2 follows is illustrated typically.

  Each of the in-vehicle devices 50-1 and 50-2 has the above-described configuration and can perform the above-described operation. Further, FIG. 5 clearly shows that there is a GPS satellite 60 used for GPS. The roadside device 10 and the vehicle-mounted device 50 can ensure time synchronization based on the radio waves received from the GPS satellite 60, respectively. However, the means for ensuring time synchronization is not limited to this.

(Road-to-vehicle communication)
First, an explanation will be given focusing on road-to-vehicle communication based on FIGS.
(Processing 2001) As illustrated in FIG. 6, the roadside device 10, the vehicle-mounted device 50-1, and the vehicle-mounted device 50-2 ensure time synchronization based on the radio wave (synchronization information) received from the GPS satellite 60, and transmit / receive Define and recognize radio frames and slots to be used.

  (Processing 2002) In addition, the signal controller 20 periodically transmits information related to the traffic signal (signal information provision service information such as signal display change timing) to the roadside device 10.

  (Processing 2003) The roadside device 10 transmits a signal to a predetermined wireless area (service area). The signal includes, for example, synchronization information (also called a preamble) indicating the start position of the radio frame, road-to-vehicle slot information, band allocation information, information on the traffic signal, and other provided service information types (for example, described later) Probe services, navigation information services, etc.).

  For example, as shown in FIG. 7, the road-to-vehicle slot information is a slot (slot number = 1) that can be used for road-to-vehicle communication among a plurality of time slots (for example, 20 slots shown in FIG. 9) constituting one radio frame. To 15: for example, see FIG. 10).

  The bandwidth allocation information is information indicating which time slot is used to transmit what information as shown in FIG. 8, for example. In FIG. 8, for example, slot numbers = 1 to 7 are assigned to DL road-to-vehicle communication, slot numbers = 8 to 15 are assigned to UL road-to-vehicle communication, and slot numbers = 16 to 20 are between vehicles. The state assigned to communication is shown.

  For example, among the slots # 1 to # 7 for DL road-to-vehicle communication, slots # 1 and # 2 transmit control information such as frame header information (preamble and road-to-vehicle slot information) (broadcast). Assigned as a slot. Slot # 3 is assigned as a slot for transmitting (broadcasting) the service information type, and slot # 4 is assigned as a slot for transmitting (broadcasting) information regarding the traffic signal. The remaining slots # 5 to # 7 are empty slots.

  Further, among the slots # 8 to # 15 for UL communication, the slots # 8 to # 12 are exemplarily empty slots, and the slots # 13 to # 15 indicate that the in-vehicle device 50 has a UL link establishment request or the like. It is assigned as a random access slot used for making a bandwidth request (for example, see the shaded area in FIG. 12).

The slot configuration (allocation) described above is an example and can be changed as appropriate.
The in-vehicle device 50-1 does not reach the point B in FIG. 5 (does not enter the wireless area of the roadside device 10), and no other in-vehicle device 50 exists in the wireless area of the roadside device 10. As illustrated in FIG. 9, there is no slot assigned to a specific in-vehicle device 50. The bandwidth allocation policy in such a state can be set by an operator of the roadside device 10 or the like.

  For example, since the allocation (ratio) between the road-to-vehicle slot and the vehicle-to-vehicle slot and the information related to the signal information providing service are information that should be received by all the in-vehicle devices 50 existing in the wireless area of the roadside device 10, For example, a broadcast address is given to a destination address of a wireless packet).

  In this example, the roadside device 10 can transmit information on the traffic signal in slot # 4. Further, the roadside device 10 can increase the transmission power at the timing of the slot # 1 for transmitting the control information and / or transmit (broadcast) the control information using a robust modulation method.

  According to this, it is possible to make control information reach farther than information transmitted in other slots. That is, the roadside device 10 (for example, the slot management unit 113) controls the transmission conditions (transmission power, modulation method, etc.) of the slot allocation information so that the reception quality at the in-vehicle device 50 is higher than other transmission information. be able to. Therefore, the vehicle-mounted device 50 that has received the control information can control the vehicle-to-vehicle communication so as not to interfere with the road-to-vehicle communication in the service area of the roadside device 10 (the phenomenon described above with reference to FIG. 14 can be avoided). .

  Now, since the vehicle-mounted device 50-1 existing at the point A shown in FIG. 5 exists outside the service area of the roadside device 10, it does not receive any information transmitted from the roadside device 10. Therefore, as illustrated in FIG. 9, the in-vehicle device 50-1 performs inter-vehicle communication on all slots # 2 to # 20 except for a slot (frame recognition slot) # 1 for transmitting frame header information (preamble). It is allowed to be used for. The same applies to the in-vehicle device 50-2.

  (Processing 2004, Process 2005) Accordingly, the in-vehicle devices 50-1 and 50-2 can perform inter-vehicle communication with each other using any of the slots # 2 to # 20.

  If the frame recognition slot # 1 is divided by, for example, a frequency or a code, a part or all of the slot # 1 can be used for inter-vehicle communication. Further, by changing the preamble between the road-to-vehicle slot and the inter-vehicle slot, it is possible to allow the entire slot # 1 to be used for inter-vehicle communication. In other words, even if the in-vehicle device 50 uses the slot format that can detect the frame header information or information corresponding thereto even during the inter-vehicle communication using the slot # 1, the slot # 1 can also be used for the inter-vehicle communication. Is possible.

  (Processing 2006) After that, when the in-vehicle device 50-1 moves to the point B shown in FIG. 5 and can receive the frame header information transmitted by the roadside device 10, the in-vehicle device 50-1 becomes the slot # 2. The transmitted road-to-vehicle slot information is received, and slots (# 2 to # 15) used in road-to-vehicle communication are recognized as illustrated in FIG.

  (Processing 2007) The in-vehicle device 50-1 performs inter-vehicle communication (transmission) with respect to the in-vehicle device 50-2 using any of slots # 16 to # 20 other than the recognized road-to-vehicle slots # 2 to # 15. In the road-vehicle slots # 2 to # 15, wireless packets for vehicle-to-vehicle communication are not transmitted. As a result, it is possible to stop (prohibit) vehicle-to-vehicle communication using the road-to-vehicle slot, and to avoid interference with road-to-vehicle communication.

  (Processing 2008) On the other hand, since the in-vehicle device 50-2 has not received the frame header information from the roadside device 10 at this time, the on-vehicle device 50-2 uses any of the slots # 2 to # 20 other than the slot # 1. A wireless packet for communication is transmitted to the in-vehicle device 50-1. At this time, the in-vehicle device 50-1 stops the transmission of the wireless packet in the road-to-vehicle slots # 2 to # 15, but may receive the wireless packet continuously in the slots # 2 to # 15. Therefore, even if the in-vehicle device 50-2 transmits a wireless packet using any of the road-to-vehicle slots # 2 to # 15 as the inter-vehicle slot, the on-vehicle device 50-1 may receive the wireless packet. it can.

  (Processing 2009) Thereafter, when the in-vehicle device 50-1 enters the service area of the roadside device 10 (point C shown in FIG. 5), all information transmitted from the roadside device 10 can be received. When receiving the band allocation information (for example, see FIG. 11) transmitted in the slot # 2, the in-vehicle device 50-1 recognizes the slot configuration as illustrated in FIG.

  Note that the bandwidth allocation information illustrated in FIG. 11 is shown as static information for simplification, but in actuality, the slot allocation state is dynamically changed in units of radio frames by scheduling of the scheduler 114 in the subsequent processing. Since it changes, it is generated and transmitted dynamically according to the change.

  Then, for example, when the in-vehicle device 50-1 recognizes that the probe service is provided by the roadside device 10 based on the provided service information received in the slot # 3, the vehicle-mounted device 50-1 determines the route based on the received band allocation information. Recognize random access slots (slots # 13 to # 15) for inter-vehicle communication.

  (Processing 2010) Next, the in-vehicle device 50-1 selects any one of the recognized random access slots and transmits a link establishment request including the ID of the in-vehicle device 50-1 to the roadside device 10. The in-vehicle device 50-1 can also receive the broadcast signal information providing service information transmitted from the roadside device 10 in slot # 4 by entering the service area.

  (Process 2011) Upon receiving the link establishment request from the in-vehicle device 50-1, the roadside device 10 generates a link establishment response including the in-vehicle device ID included in the request, if the request can be permitted. To the in-vehicle device 50-1. The link establishment response is unicasted to the in-vehicle device 50-1 in slot # 5, for example.

  When the in-vehicle device 50-1 further receives the band allocation information periodically transmitted from the roadside device 10, as illustrated in FIG. 11, the presence of the information addressed to the in-vehicle device 50-1 is present in the slot # 5. Recognize and receive the link establishment response transmitted from the roadside device 10 in the slot # 5.

  (Processing 2012) When the roadside device 10 wants to collect probe information [vehicle travel information (position, speed, moving direction, etc.)] from the vehicle-mounted device 50-1, for example, a UL road-to-vehicle distance with respect to the vehicle-mounted device 50-1. Slot # 10 is allocated, and information indicating that is set in the band allocation information. Thereafter, the roadside device 10 periodically assigns UL road-to-vehicle slots to the vehicle-mounted device 50-1 in order to collect probe information.

  (Process 2013) When the in-vehicle device 50-1 recognizes that the UL band has been allocated from the roadside device 10 by receiving the band allocation information, the in-vehicle device 50-1 in the allocated slot # 10. Probe information is transmitted to the roadside device 10.

  (Process 2014) When the roadside device 10 receives the probe information from the in-vehicle device 50-1, the roadside device 10 transfers the probe information to, for example, the signal controller 20 (may be transferred to the server 40 together). At that time, the roadside device 10 may aggregate the probe information collected from the other in-vehicle devices 50 to reduce the amount of probe information transmitted to the signal controller 20 (and / or the server 40). Based on the received probe information, the signal controller 20 can recognize the number of surrounding vehicles and the like, and can optimize the signal control.

  (Processing 2015) When the vehicle-mounted device 50-1 requests a navigation (optimum route) information service from a driver, for example, it uses one of the random access slots # 13 to # 15 to set a UL road-to-vehicle slot (bandwidth). The allocation is requested to the roadside device 10.

  (Processing 2016) The roadside device 10 transmits a response to the UL bandwidth request to the roadside device 50-1 in the same manner as the processing 2011 described above.

  (Process 2017) The roadside device 10 assigns, for example, slot # 11 as a UL road-to-vehicle slot to the in-vehicle device 50-1, sets that in the band assignment information, and transmits it.

  (Process 2018) Upon receiving the band allocation information, the vehicle-mounted device 501 recognizes that the UL road-to-vehicle slot # 11 has been allocated, and in the slot # 11, for example, the current vehicle-mounted device 50-1 A request for a navigation information providing service including the position and the target position is transmitted to the roadside device 10.

  (Processing 2019) The roadside device 10 transfers the received service request to the server 40.

  (Processing 2020) The server 40 searches for one or a plurality of routes from the current position of the in-vehicle device 50-1 to the destination based on the received service request, and sends a response (service information) including the search result to the roadside device. Send to 10 address.

  (Processing 2021) When the roadside device 10 receives the response, the roadside device 10 allocates a DL road-to-vehicle slot to the in-vehicle device 50-1 that is the service request source, sets that in the band allocation information, and transmits it. Upon receiving the bandwidth allocation information, the vehicle-mounted device 50-1 recognizes that there is information addressed to the vehicle-mounted device 50-1 in the DL road-to-vehicle slot, receives the information in the slot, To provide.

(Vehicle-to-vehicle communication)
Next, an explanation will be given focusing on inter-vehicle communication based on FIG.
(1) As described above, the in-vehicle device 50-1 and the in-vehicle device 50-2 receive the synchronization information from the GPS satellite 60 and define the radio frame and the slot based on the synchronization information in the process 2001. .

  (2) The in-vehicle device 50-1 and the in-vehicle device 50-2 located at the point A in FIG. 5 exist outside the service area of the roadside device 10, and do not receive any information transmitted from the roadside device 10. . Therefore, as described in the processing 2014, it is allowed to use all of the slots # 2 to # 20 for inter-vehicle communication except the slot (frame recognition slot) # 1 for transmitting the frame header information (preamble). The Thereby, the in-vehicle device 50-1 and the in-vehicle device 50-2 can perform inter-vehicle communication using any of slots # 2 to # 20 that are allowed to be used.

  (3) Each of the in-vehicle device 50-1 and the in-vehicle device 50-2 (vehicle-to-vehicle communication unit 52) monitors the slot usage status (blocking status) after the power is turned on. This monitoring is performed, for example, for a time (for example, 100 msec) according to the data (packet) transmission cycle.

  (4) Each of the in-vehicle device 50-1 and the in-vehicle device 50-2 (vehicle-to-vehicle communication unit 52) selects carrier sense times Tcs1 and Tcs2 within the range of the maximum carrier sense time Tmax_cs or less. For this selection, for example, a predetermined selection criterion such as using a random number can be applied. FIG. 13 illustrates a state in which the in-vehicle device 50-1 selects a shorter carrier sense time (Tcs1 <Tcs2).

  (5) Each of the in-vehicle device 50-1 and the in-vehicle device 50-2 (the inter-vehicle communication unit 52) selects a slot used for packet transmission from the empty slots recognized by the monitor. For this selection, for example, a predetermined selection criterion such as using a random number can be applied. FIG. 13 illustrates a state where the in-vehicle device 50-1 selects the empty slot # 3 and the in-vehicle device 50-2 also selects the empty slot # 3.

  (6) The in-vehicle device 50-1 and the in-vehicle device 50-2 (vehicle-to-vehicle communication unit 52) are carriers for the carrier sense time selected in (4) from the head of the empty slot # 3 selected in (5). Sense. That is, the in-vehicle device 50-1 performs carrier sense for Tsc1, and the in-vehicle device 50-2 performs carrier sense for Tsc2.

  (7) If the vehicle-mounted device 50-1 and the vehicle-mounted device 50-2 (vehicle-to-vehicle communication unit 52) do not receive a transmission packet of another vehicle-mounted device 50 during each carrier sense, the packet is transmitted. In the example of FIG. 13, there is no other vehicle-mounted device 50, and the carrier sense time Tcs1 of the vehicle-mounted device 50-1 is shorter than the carrier sense time Tcs2 of the vehicle-mounted device 50-2. Therefore, the in-vehicle device 50-1 transmits the packet before the in-vehicle device 50-2.

  (8) In the example of FIG. 13, the in-vehicle device 50-2 (the inter-vehicle communication unit 52) detects the packet transmission of the in-vehicle device 50-1 at the carrier sense time Tcs1, so that slot # 3 is recognized as being busy. Packet transmission in slot # 3 is not performed. Instead, the in-vehicle device 50-2 retries the packet transmission for the subsequent slots in the same manner as in the above (3) to (5).

  (9) The in-vehicle device 50-2 (the inter-vehicle communication unit 52) retries transmission of a packet in the slot # 4 next to the slot # 3, for example. The carrier sense time Tcs2 ′ at this time can be set shorter than the carrier sense time Tcs2 selected in the above (4). For example, the time (Tcs2 ′ = Tcs2−Tcs1) obtained by subtracting the time for performing the carrier sense until the transmission packet of the other vehicle-mounted device 50-1 is detected in the slot # 3 from the carrier sense time Tcs2 selected in the above (4). ). Thereby, the success rate of subsequent packet transmission of the vehicle equipment 50-2 which failed in packet transmission once can be raised.

  In addition, when the roadside machine 10 (road-vehicle communication part 11) and the vehicle equipment 50 (road-vehicle communication part 51) transmit a packet in a road-vehicle slot, it is preferable to transmit a packet from the head of a slot. According to this, even if the in-vehicle device 50 fails to receive the slot allocation information, the above-mentioned carrier sense during the vehicle-to-vehicle communication makes the road-to-vehicle communication a high priority and does not disturb the road-to-vehicle communication. be able to.

  As described above, according to this example, the in-vehicle device 50 is allowed to use all slots including some or all of the road-to-vehicle slots in the radio frame outside the service area of the roadside device 10 for inter-vehicle communication. Therefore, it is possible to suppress a decrease in utilization efficiency of communication resources (frequency).

  Further, the roadside device 10 can notify the in-vehicle device 50 of the allocation information of the road-to-vehicle slot, and can stop (inhibit) the vehicle-to-vehicle communication using the road-to-vehicle slot. Therefore, it is possible to suppress the road-to-vehicle communication from being disturbed (interference) by the vehicle-to-vehicle communication.

  Furthermore, since a common communication method based on a time slot as an example of a radio resource is applied to each road-to-vehicle and vehicle-to-vehicle communication, both communication can be performed by the shared radio 50 for each communication. It is.

  Regarding road-to-vehicle communication, since the roadside device 10 individually assigns the road and vehicle slots to the vehicle-mounted devices 50 by scheduling control, interference between the vehicle-mounted devices 50 can also be prevented.

[2] Others In the example described above, in the drawings, the slot size is shown to be the same in road-to-vehicle communication and vehicle-to-vehicle communication, but the slot size may be different in both communications. . For example, communication resources of different sizes are defined by defining communication resources (slots) of smaller units and combining a plurality of them. In this case, a vehicle-to-vehicle resource (slot) for transmitting fixed-length data can be set to a fixed length.

  Further, when transmitting large data that cannot be transmitted in one slot, a plurality of slots sufficient to transmit the data can be allocated by the band allocation information. In this case, overhead such as preamble (synchronization information) and destination information may be shared by a plurality of slots to reduce the overhead amount. According to this, the amount of transmission data can be increased (throughput can be improved).

  In each of the embodiments described above, the number of resources (number of slots) to be allocated and released is not specified, but the number of resources to be allocated to the resource allocation request transmitted from the in-vehicle device 50 to the roadside device 10. By including (number of slots), a plurality of resources may be allocated simultaneously. Similarly, by including the resource ID (slot number) that you want to release in the release request that is sent from the in-vehicle device 50 to the roadside device 10, some necessary resources remain allocated and unnecessary resources. You may make it release only.

  In the above-described embodiment, the first slot of the frame is defined as a frame header, and the synchronization information and the inter-vehicle slot information can be transmitted farther than the service area of the roadside device 10 using the slot. . As an alternative example, a plurality of types of synchronization information may be defined, an inter-vehicle slot may be defined corresponding to each type, and only the synchronization information may be transmitted far away. At this time, band allocation information may be transmitted as data in slot # 1 into the service area, and the functions of slot # 1 and slot # 2 may be realized in one slot.

  A time gap (guard time) may be provided between the slots to absorb time (transmission / reception timing) errors of the roadside device 10 and the vehicle-mounted device 50.

Furthermore, the installation location of the base station 10 and the radio device 50 can be changed as appropriate. For example, when a railway network is assumed as one of the transportation systems, the base station 10 is installed on the traffic signal of the circuit breaker, the radio device 50 is installed on the railway vehicle, It is also possible to provide a service for providing information related to the situation of the surroundings, and notifying each other of vehicle information such as vehicle speed between the railway vehicles or between the railway vehicle and the vehicle-mounted device 50.
Regarding the above embodiment, the following additional notes are disclosed.

[3] Appendix (Appendix 1)
Of the radio resource group that can be shared by the first communication that is communication between the base station and the mobile station and the second communication that is communication between the mobile stations, the radio resource used for the first communication Allocation information generating means for generating allocation information;
Transmitting the allocation information, prohibiting the mobile station from transmitting to another mobile station using the radio resource indicated by the received allocation information for the second communication, and receiving the allocation information Control means for permitting transmission to another mobile station using part or all of the radio resources for the second communication while not performing,
A base station characterized by having

(Appendix 2)
The mobile station that receives the allocation information is allowed to perform transmission to the other mobile station using radio resources other than the radio resource indicated by the allocation information in the radio communication group in the second communication. The base station according to supplementary note 1, characterized in that:

(Appendix 3)
The radio resource indicated by the allocation information includes a plurality of time slots that are time-division multiplexed.
The allocation information is time information corresponding to one or a plurality of the time slots.
The base station according to appendix 1 or 2, characterized in that.

(Appendix 4)
The base station according to supplementary note 3, wherein a radio resource other than the radio resource indicated by the allocation information includes a plurality of time slots multiplexed in time division.

(Appendix 5)
The plurality of time slots indicated by the allocation information includes a time slot used for transmission of control information addressed to the mobile station and a time slot used for transmission of information related to a service provided to the mobile station. The base station according to Appendix 3, wherein

(Appendix 6)
The base station according to appendix 1, wherein the allocation information includes radio resource allocation information used by the mobile station to request the base station to start the first communication. .

(Appendix 7)
The control means includes
The base station according to supplementary note 1, wherein a transmission condition of the allocation information to be transmitted is controlled so that reception quality at the mobile station is higher than other transmission information.

(Appendix 8)
Of the radio resource group that can be shared by the first communication that is communication between the base station and the mobile station and the second communication that is communication between the mobile stations, the radio resource used for the first communication Receiving means for receiving allocation information from the base station;
When the allocation information is received by the reception unit, the radio resource indicated by the allocation information is prohibited from being transmitted to another mobile station using the second communication, and the reception unit A control means for permitting transmission to another mobile station using part or all of the radio resources in the second communication when allocation information is not received;
A mobile station characterized by having

(Appendix 9)
The control means includes
Supplementary note 8, wherein a radio resource other than the radio resource indicated by the allocation information in the radio resource group is allowed to be transmitted to the other mobile station using the second communication. The listed mobile station.

(Appendix 10)
The radio resource indicated by the allocation information includes a plurality of time slots that are time-division multiplexed.
The allocation information is time information corresponding to one or a plurality of the time slots.
The mobile station according to appendix 8 or 9, characterized in that.

(Appendix 11)
The mobile station according to appendix 8, wherein the radio resources other than the radio resource indicated by the allocation information include a plurality of time slots multiplexed in time division.

(Appendix 12)
The plurality of time slots indicated by the allocation information includes a time slot used for transmission of control information addressed to the mobile station and a time slot used for transmission of information related to a service provided to the mobile station. The mobile station according to appendix 10, wherein

(Appendix 13)
The allocation information includes radio resource allocation information used by the mobile station to request the base station to start the first communication,
The control means includes
The mobile station according to appendix 8, wherein the base station is requested to start the first communication using a radio resource used for the request included in the allocation information.

(Appendix 14)
The control means includes
The mobile station according to appendix 10, wherein transmission to the base station during the first communication is performed from the beginning of any of the plurality of time slots indicated by the allocation information.

(Appendix 15)
The control means includes
15. The mobile station according to appendix 14, wherein in the second communication, carrier sense is performed for a time selected according to a predetermined selection criterion from the beginning of the time slot.

(Appendix 16)
A communication control method in a radio communication system comprising a mobile station and a base station that communicates with the mobile station by radio,
The base station
Of radio resource groups that can be shared by the first communication that is communication with the mobile station and the second communication that is communication between the mobile stations, allocation information of radio resources used for the first communication Send
The mobile station
Prohibiting transmission to another mobile station using the radio resource indicated by the received allocation information for the second communication, and part or all of the radio resource is not received while the allocation information is not received. Allowing transmission to another mobile station using the second communication;
A communication control method.

(Appendix 17)
The base station is a roadside device in ITS (Intelligent Transport System), the mobile station is an in-vehicle device in the ITS, and the first communication is road-to-vehicle communication, and the second communication The communication control method according to supplementary note 16, wherein the communication is vehicle-to-vehicle communication.

It is a schematic diagram which shows an example of ITS which concerns on embodiment. It is a block diagram which shows the structural example of the roadside machine illustrated in FIG. 1, and vehicle equipment. 3 is a flowchart illustrating an operation example of the in-vehicle device illustrated in FIG. 2. It is a flowchart explaining the operation example of the roadside machine illustrated in FIG. It is a schematic diagram which shows a mode that a vehicle-mounted apparatus moves in order to demonstrate the operation example of ITS illustrated in FIG. FIG. 6 is a sequence diagram illustrating an operation example of the ITS illustrated in FIG. 5. It is a figure which shows an example of the road and vehicle slot information which concerns on this embodiment. It is a figure which shows an example of the slot (bandwidth) allocation information which concerns on this embodiment. It is a figure which shows an example of the radio | wireless frame format in A point of FIG. It is a figure which shows an example of the radio | wireless frame format in the B point of FIG. It is a figure which shows an example of the slot (bandwidth) allocation information which concerns on this embodiment. It is a figure which shows an example of the radio | wireless frame format in the C point of FIG. It is a schematic diagram explaining the carrier sense at the time of the vehicle-to-vehicle communication in ITS illustrated in FIG. It is a schematic diagram which illustrates a mode that road-to-vehicle communication receives the interference by vehicle-to-vehicle communication. It is a schematic diagram which illustrates a mode that the interference of road-to-vehicle communication generate | occur | produces.

Explanation of symbols

10 Roadside aircraft (base station)
DESCRIPTION OF SYMBOLS 11 Road-to-vehicle communication part 111 Transmission part 112 Reception part 113 Slot management part 114 Scheduler 115 Slot management table 20 Signal controller 30 Network 40 Server 50, 50-1, 50-2 Radio | wireless machine (vehicle equipment, mobile station)
51 Road-to-vehicle communication unit 511 Transmission unit 512 Reception unit 52 Vehicle-to-vehicle communication unit 521 Transmission unit 522 Reception unit 53 Road-to-vehicle / vehicle-to-vehicle communication switching control unit 60 GPS satellite

Claims (5)

Of the radio resource group that can be shared by the first communication that is communication between the base station and the mobile station and the second communication that is communication between the mobile stations, the radio resource used for the first communication Allocation information generating means for generating allocation information;
Transmitting the allocation information, prohibiting the mobile station from transmitting to another mobile station using the radio resource indicated by the received allocation information for the second communication, Control means for allowing transmission to other mobile stations using part or all of the radio resources for the second communication if not received;
A base station characterized by having   The mobile station that receives the allocation information is allowed to perform transmission to the other mobile station using radio resources other than the radio resource indicated by the allocation information in the radio communication group in the second communication. The base station according to claim 1, wherein: The control means includes
The base station according to claim 1, wherein the transmission condition of the allocation information to be transmitted is controlled to a condition that the reception quality at the mobile station is higher than other information addressed to the mobile station. Of the radio resource group that can be shared by the first communication that is communication between the base station and the mobile station and the second communication that is communication between the mobile stations, the radio resource used for the first communication Receiving means for receiving allocation information from the base station;
When the allocation information is received by the reception unit, the radio resource indicated by the allocation information is prohibited from being transmitted to another mobile station using the second communication, and the reception unit A control means for permitting transmission to another mobile station using part or all of the radio resources in the second communication when allocation information is not received;
A mobile station characterized by having A communication control method in a radio communication system comprising a mobile station and a base station that communicates with the mobile station by radio,
The base station
Of radio resource groups that can be shared by the first communication that is communication with the mobile station and the second communication that is communication between the mobile stations, allocation information of radio resources used for the first communication Send
The mobile station
Prohibiting transmission to another mobile station using the radio resource indicated by the received allocation information for the second communication, and if not receiving the allocation information, part or all of the radio resource is Allowing transmission to another mobile station using the second communication;
A communication control method.

Images