JP2007174120A - Inter-road-vehicle communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inter road-vehicle communication method whereby high speed connection control applied to a plurality of communication channels can be attained by means of a control channel. <P>SOLUTION: A road side station 1 periodically informs each mobile station about channel information notice including a plurality of the communication channels communicable with the use of the control channel, information required for connection, and a degree of congestion of each communication channel, each mobile station discriminates a connection desirable channel on the basis of the degree of congestion in the channel information notice received through the control channel and informs the road side station about a communication channel connection request including the discriminated connection desirable channel through the control channel, the road side station discriminates connection permission of the notified connection desirable channel, executes connection processing for the permitted channel in accordance with the result of the discrimination, and informs the mobile station about the connection permission including a permitted channel identifier through the control channel, and the mobile station receiving the connection permission immediately executes the connection processing about the permitted channel without the need for an ordinary connection sequence, and starts communication through the instructed permission channel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to road-to-vehicle communication using wireless communication, and more particularly enables a roadside station and a mobile station to perform priority communication control / high-speed connection control using one control channel and a plurality of communication channels. The present invention relates to a road-vehicle communication method.

  In Patent Literature 1, in wireless communication between a radio base station and a mobile station, information on availability of communication channels and other information are reported from the radio base station to the mobile station through a control channel at a constant cycle. Based on the information, a connection request to the channel to be connected is made to the radio base station, and when the radio base station receives this connection request, it checks whether or not the communication channel is usable. It is disclosed that a communication channel is designated for a mobile station and communication is performed via the communication channel.

Japanese Patent Laid-Open No. 04-286432 (paragraph “0020”, FIG. 1)

  However, in Patent Document 1, it is disclosed that selection / request of a channel to be connected by a mobile station is performed through a control channel. However, a connection ID, etc., necessary for connection to the actually selected communication channel is disclosed. Since there is no disclosure of the connection process, it cannot be applied to road-to-vehicle communication, which is communication between a roadside station and a mobile station that require high speed. That is, in Patent Document 1, the aspect of speeding up the connection time required for road-to-vehicle communication where the mobile station is high-speed is not considered, and communication that requires priority between road vehicles such as rear-end collision information is not considered. There is also a problem that the responsiveness of priority communication when it occurs and the improvement of the arrival probability are out of scope.

  The present invention has been made in view of the above, and provides a road-to-vehicle communication method that enables high-speed connection control for a plurality of communication channels using a control channel and improves the responsiveness and arrival probability of priority communication when priority communication occurs. The purpose is to obtain.

  In order to solve the above-described problems and achieve the object, the present invention provides a roadside station connected to an upper network and capable of transmitting / receiving simultaneously on one control channel and a plurality of communication channels, one control channel and the plurality of the plurality of communication channels. In a road-to-vehicle communication method that includes a mobile station capable of transmitting and receiving simultaneously on at least one of the communication channels and performs wireless communication using a wireless LAN between the roadside station and the mobile station, the roadside station uses a control channel. A plurality of communication channels that can be communicated with each other, and channel information notification including a connection requirement information necessary for a mobile station to connect to a roadside station via each communication channel and a congestion degree of each communication channel Broadcast to the mobile station side, and the mobile station determines the desired connection channel based on the degree of congestion of the channel information broadcast received through the control channel, and the determination A communication channel connection request including the desired connection channel is notified to the roadside station through the control channel, and the roadside station performs connection permission determination of the notified connection desired channel, and is the connection desired channel according to the determination result. Executes connection processing for the permitted channel in the roadside station, notifies the mobile station through the control channel of connection permission information necessary for connection to the permitted channel and connection permission including the permitted channel identifier, and permits the connection through the control channel. The mobile station that has received the message immediately executes connection processing in the mobile station for the permitted channel without performing a normal connection sequence, and starts communication on the permitted channel indicated by the connection permission.

  According to the present invention, the channel information broadcast periodically transmitted from the roadside station to the mobile station includes in advance connection requirement information necessary for the mobile station to connect to the roadside station, and the roadside station transmits to the mobile station. The connection permission information such as connection ID is included in advance in the connection permission notification to be performed, and the roadside station permits communication on the desired connection channel included in the communication channel connection request when receiving the communication channel connection request from the mobile station Since the connection processing in the roadside station for this permission channel is executed in advance, the roadside station and the mobile station are moved during the communication channel selection processing procedure between the roadside station and the mobile station via the control channel. The connection requirement information necessary for the station connection is notified to the counterpart device in advance, and after this communication channel selection processing procedure is completed, the normal wireless LAN connection control is performed. Immediately it can start communication grant channel without performing sequence, a connection control of the road-to-vehicle communication and it is possible to speed as compared with general wireless LAN connection method.

  Embodiments of a road-vehicle communication method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a basic system configuration of a road-vehicle communication system according to the present invention. The road-to-vehicle communication system shown in FIG. 1 includes a roadside station 1 arranged on the roadside such as an intersection or an expressway, and a plurality of mobile stations 10A, 10B,. An upper network 2 connected to the station 1, a traffic information distribution server 3 connected to the upper network 2, and a telephone 4 are provided.

  The roadside station 1 constructs communication cells of the control channel (control CH) Q and channels A to E (CHA to CHE) at frequencies that do not interfere with each other. Channels A to E other than the control channel Q are hereinafter referred to as “communication channels”. Channels A and B are assigned to traffic information communication, channels C and D are assigned to telephones, and channel E is assigned to other applications. The mobile stations 10A and 10B are communication devices that can simultaneously transmit and receive at least two channels, that is, the control channel Q and at least one of the channels A to E. In this case, the control channel Q is a fixed channel having a fixed frequency, and the roadside station 1 and the mobile stations 10A and 10B are always in a state where the control channel Q can be transmitted and received.

  FIG. 2 shows the configuration of the roadside station 1. The roadside station 1 communicates with one control channel communication device 20 that communicates using a control channel Q of a predetermined frequency, and channels A to E communication that communicate using communication channels A to E of different frequencies different from the control channel Q. Channels 21 to 21E, channels A to E connection control units 22A to 22E for controlling connection of communication channels A to E, respectively, and channels A to E priority control units 23A to 23A for performing priority connection control of communication channels A to E, respectively. 23E and the channel A to E connection control units 22A to 22E based on the communication channel connection request transmitted from the mobile station through the control channel Q and the priority communication frame described in the second to fourth embodiments. Control channel control unit 24 for controlling channels A to E priority control units 23A to 23E and a higher level network for communication with the higher level network And a chromatography click communication device 25.

  FIG. 3 shows the configuration of the mobile stations 10A, 10B,. In this case, the mobile station performs communication using one control channel communication device 30 that performs communication using the control channel Q and one communication channel communication that performs communication using one communication channel selected from the communication channels A to E. The communication channel connection control unit 32 that controls connection of the communication channel communication device 31 using the device 31, one communication channel selected from the communication channels A to E, and one selected from the communication channels A to E A communication channel priority control unit 33 that performs priority connection control of the communication channel communication device 31 using two priority communication channels, and a communication channel connection control unit 32 based on a communication channel permission notification transmitted from the roadside station 1 through the control channel Q. In the case of the priority communication frame described in the second to fourth embodiments, the communication channel priority control unit 33 is controlled. A power sale control channel control unit 34, and a mobile station inside a communication device 35 for communicating with the interior equipment of a vehicle.

FIG. 4 shows a connection sequence between the mobile station 10A and the roadside station 1. The control channel control unit 24 of the roadside station 1 periodically transmits information on the communication channels A to E including the following contents on the control channel Q as channel information notification in the cell via the control channel communication device 20. (SQ401).
-Channel ID (frequency identifier) of communication channel among communication channels A to E
Connection required information (BSSID, SSID, supported transmission rate, etc.) necessary for the mobile station to connect to the roadside station 1 via each communication channel A to E (SSID (Service Set ID), BSSID in IEEE 802.11) (Roadside machine MAC address))
Support application identifier (traffic information / telephone / others) indicating the application type supported for each communication channel A to E, that is, the relationship between the communication channels A to E and the supported application types. Degree (average traffic)

10 A of mobile stations receive channel information alerting | reporting via the control channel Q by the control channel communication apparatus 30. FIG. The control channel control device 34 of the mobile station 10A corresponds to a desired application based on the channel information notification included in the control channel Q received from the roadside station 1, that is, from the support application type and the congestion level included in the channel information notification. A communication channel to be selected or not included is selected (SQ402). For example, when the mobile station 10A selects an application corresponding to a telephone, the mobile station 10A selects the channels C and D corresponding to the telephone, and selects the non-intrusive channel among the channels C and D. Then, the mobile station 10A operates the control channel communication device 30 to transmit a communication channel connection request including the following information on the control channel Q to the roadside station 1 (SQ403). In this case, it is assumed that a connection request to channel A is issued.
-MAC address of the mobile station as necessary connection information necessary for connection-Connection request channel ID (in this case, channel A channel ID)

The roadside station 1 receives the connection request via the control channel Q by the control channel communication device 20. The control channel control unit 24 of the roadside station 1 performs connection permission determination based on the degree of congestion, the number of connections, and the like for the channel corresponding to the connection request channel ID included in the connection request (SQ404). The corresponding channel connection control unit (in this case, since the connection request channel is channel A, the channel A connection control unit 22A) is instructed to control connection with the mobile station 10A (SQ405). When this connection control is finished, the control channel control unit 24 of the roadside station 1 sends a connection permission notification including the following information to the connection request source mobile station (in this case, the mobile station A) by the control channel communication device 20. Transmit on the control channel (SQ406).
-Connection ID as connection requirement information necessary for connection (unique ID assigned to mobile stations permitted to connect)
Connection permission communication channel ID (identifier of permitted frequency, in this case, channel A channel ID)

  The mobile station 10 </ b> A receives the connection permission notification on the control channel Q via the control channel communication device 30. Based on the connection permission notification included in the control channel Q received from the roadside station 1, the control channel control device 34 of the mobile station 10A performs a normal wireless LAN connection control sequence on the channel permitted to connect (channel A in this case). Data communication is started immediately without any communication (SQ407). That is, the control channel control device 34 notifies the communication channel connection control unit 32 of the connection permission communication channel ID (in this case, channel A) and the connection ID included in the received connection permission notification. The communication channel connection control unit 32 causes the communication channel communication device 31 to select a communication channel (in this case, channel A) corresponding to the connection-permitted communication channel from the plurality of communication channels, and uses the selected communication channel and notified the connection. Data communication using the ID is immediately started by the communication channel communication device 31.

  As described above, according to the first embodiment, connection requirement information necessary for the mobile station to connect to the roadside station, such as BSSID, SSID, and transmission rate, for channel information notification periodically transmitted from the roadside station to the mobile station. Is included in advance, the communication channel connection request transmitted from the mobile station to the roadside station includes connection required information such as the MAC address of the mobile station in advance, and the connection permission notification transmitted from the roadside station to the mobile station is permitted. The connection requirement information such as a connection ID that is a unique ID assigned to the mobile station is included in advance, and the roadside station uses the connection desired channel included in the communication channel connection request when receiving the communication channel connection request from the mobile station. Since the connection process in the roadside station for this permission channel is executed in advance when the communication of the roadside is permitted, the roadside via the control channel In the communication channel selection processing procedure between the mobile station and the mobile station (steps SQ401 to S406 in FIG. 4), connection requirement information necessary for connection between the roadside station and the mobile station is notified in advance to the counterpart device, As a result, after completing this communication channel selection processing procedure, communication can be started immediately with the permission channel indicated by the connection permission without performing a normal wireless LAN connection control sequence, and compared with a general wireless LAN connection method. As a result, the speed of connection control for road-to-vehicle communication can be increased.

  In the first embodiment, the roadside station includes the relationship between the communication channel and the supported application type in the channel information notification, and the mobile station selects the communication channel corresponding to the desired application type, Since the communication channel connection request is notified to the roadside station using the selected communication channel as a connection desired channel, it is possible to suppress a decrease in throughput due to communication of different applications on the same channel, and to improve the throughput. be able to.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. The system configuration to which the second embodiment is applied is the same as that shown in FIG. 1, and the configurations of the roadside station 1 and the mobile stations 10A and 10B are the same as those shown in FIGS. Suppose there is.

  In the second embodiment, the above-mentioned channel information broadcast that the roadside station 1 transmits in the cell using the control channel Q indicates the status information indicating the status such as the occurrence of priority communication in the control channel Q and the communication channels A to E. Try to add a field. That is, the channel information notification status information field is separated for each of the control channel Q and each of the communication channels A to E. The status information field of the control channel Q and the status information field of the communication channels A to E are respectively in each channel. A priority communication occurrence identifier K indicating whether or not priority communication has occurred is included.

  In addition to the above-described channel information notification used in the control channel Q, the frame used in the control channel Q and the communication channels A to E has priority indicating whether or not the frame is in priority communication within the frame format. A communication identification field Y is provided, and each mobile station and the roadside station 1 can determine whether or not the frame is a priority communication according to the state of the priority communication identification field Y.

  Under such a premise, the roadside station 1 and the mobile station 10A perform normal communication on the communication channel A, and the roadside station 1 and the mobile station 10B perform normal communication on the communication channel C. FIG. 5 shows a sequence in the case where the roadside station 1 notifies all mobile stations of the highest priority broadcast communication indicating, for example, “occurrence of a collision accident at the next intersection” from the traffic information distribution server 3 shown in FIG.

  The roadside station 1 receives the frame from the traffic information distribution server 3 by the host network communication device 25 shown in FIG. When the control channel control unit 24 of the roadside station 1 determines that the frame has the highest priority from the priority communication identification field Y of the received frame and determines that the destination address is a broadcast address (SQ501), the roadside station 1 sets the identifier K of “priority communication occurrence” in the status information fields of all the communication channels (that is, the control channel Q and the communication channels A to E) of channel information notification transmitted using the control channel Q (SQ502). ), Channel information is broadcast via the control channel Q (SQ503).

  In all the mobile stations 10A and 10B, the control channel communication device 30 shown in FIG. 3 is a channel in which the priority communication occurrence identifier K is set in the status information field of all the communication channels A to E via the control channel Q. Receive information alerts. When the control channel control unit 34 of all the mobile stations 10A and 10B detects that the communication channel used by the control channel control unit 34 of the channel information notification is in the “priority communication occurrence” state ( SQ504, 505), the control channel communication device 30 that immediately transmits / receives the control channel Q is set in the reception state (SQ506), and the communication channel in use is received via the communication channel priority control unit 33 in FIG. The communication channel communication device 31 is controlled to switch to the state (SQ507). If the mobile station is communicating on the communication channel at that time, as soon as “highest priority communication occurs” is detected, the transmission is stopped and the mobile station shifts to the reception state. As a result, all mobile stations shift to a reception state in all channels.

  Thereafter, the roadside station 1 copies the priority communication frame from the traffic information distribution server 3, assigns the same sequence number (SQ508), and transmits the priority communication frame in parallel from all channels including the control channel Q (SQ509). ). At this time, the roadside station 1 distributes the priority communication frame through the control channel Q and all the communication channels A to E with transmission power higher than usual. These priority communication frames have a priority communication identification field Y, and the priority communication identification field Y indicates a priority communication state.

  Thereby, the mobile station 10A receives the priority communication frame from the roadside station 1 via the control channel Q and the communication channel A, and the mobile station B receives the control channel Q and the communication channel B. The mobile stations 10A and 10B determine that the frame is a priority communication frame based on the priority communication identification field Y in the received priority communication frame. At this time, since each mobile station receives frames with the same content on two channels, the sequence numbers of the received frames are compared, and if the frames have already been received, the frames are discarded. If it is assumed that both the mobile stations 10A and 10B received on the communication channel early, the frame with the same sequence number received on the control channel Q side is discarded, and the frame received via the communication channel is distributed to the in-vehicle application. (SQ510).

  The end of the priority communication is performed for all channels in the channel information notification transmitted from the roadside station 1 on the control channel Q after a certain time after the roadside station 1 no longer receives the priority communication frame from the traffic information distribution server 3. By setting the corresponding status information field to “normal”, it is transmitted to all the mobile stations (SQ511), whereby each mobile station returns to the normal communication state (SQ512).

  If a mobile station waiting for communication receives a channel information notification in which the priority communication occurrence identifier K is set to priority in the status information field, until the end of priority communication by channel information notification by the control channel Q is notified, The transmission operation is stopped, and the reception state of the control channel Q and the channel waiting for communication is held.

  According to the second embodiment, when broadcast priority communication from the roadside station 1 side occurs, all mobile stations shift the control channel and the communication channel in communication to the reception state to suppress non-priority communication. Broadcast priority communication information is distributed using a plurality of channels, the delay of the priority communication frame is reduced, and the responsiveness and the arrival probability of the priority communication frame can be improved. Also, since the broadcast priority communication frame has higher transmission power than usual, the arrival probability can be further improved.

  In the above description, the roadside station 1 sets the priority communication occurrence identifier K with priority in the status information fields of all communication channels when performing broadcast priority communication. The priority communication occurrence identifier K with priority may be set in the status information field of only the communication channel, and the broadcast priority communication frame may be transmitted in parallel to the plurality of communication channels and control channels used.

Embodiment 3 FIG.
Next, Embodiment 3 of the present invention will be described with reference to FIG. The system configuration to which the third embodiment is applied is the same as that shown in FIG. 1, and the configurations of the roadside station 1 and the mobile stations 10A and 10B are the same as those shown in FIGS. Suppose there is.

  In this case, it is assumed that the roadside station 1 and the mobile station 10A perform normal communication on the communication channel A, and the roadside station 1 and the mobile station 10B perform normal communication on the communication channel C. FIG. 6 shows a sequence when unicast priority communication occurs from the traffic information distribution server 3 shown in FIG. 1 to the mobile station 10A.

  The roadside station 1 receives the priority communication frame from the traffic information distribution server 3 by the host network communication device 25 shown in FIG. When the control channel control unit 24 of the roadside station 1 determines that the frame has the highest priority from the priority communication identification field Y of the received frame and determines that the destination address is addressed to the mobile station 10A (SQ601), The roadside station 1 searches for a communication channel (in this case, channel A) currently used by the mobile station 10A (obtained during connection control using the control channel Q described in the first embodiment) (SQ602), and performs control. In the channel information broadcast on channel Q, the channel information is set to “priority communication occurrence” for the control channel Q, “priority communication occurrence” for the channel A status information, and “normal” for the channel C status information field. Status notification is performed (SQ603).

  The mobile station 10A communicating with the channel A shifts the control channel Q and the channel A to the receiving state by the channel information notification on the control channel Q (SQ604). On the other hand, the mobile station 10B communicating on the channel C shifts the control channel Q to the receiving state by the channel information notification on the control channel Q (SQ605), and the communication on the channel C continues normal communication as it is. (SQ606).

  Thereafter, as in the second embodiment, the roadside station 1 copies the unicast priority communication frame addressed to the mobile station 10A, assigns the same sequence number (SQ608), and sends the control channel Q and channel to the mobile station 10A. A unicast priority communication frame is transmitted from A (SQ609). At this time, the roadside station 1 distributes the priority communication frame through the control channel and channel A with higher transmission power than usual.

  The mobile station 10A receives the priority communication frame from the roadside station 1 on the control channel Q and channel A. Since frames with the same contents are received by two channels, the sequence numbers of received frames are compared as in the second embodiment, and if the frame has already been received, that frame is discarded. Assuming that the mobile station 10A received the communication channel A early, the frame with the same sequence number received on the control channel Q side is discarded, and the frame received via the communication channel A is distributed to the in-vehicle application. (SQ610).

  The end of the priority communication on the control channel Q and the channel A is transmitted from the roadside station 1 on the control channel Q after a certain time after the roadside station 1 does not receive the priority communication frame from the traffic information distribution server 3. By setting the status information field corresponding to all channels in the channel information broadcast to “normal”, it is transmitted to all mobile stations (SQ 611), whereby each mobile station returns to the normal communication state (SQ 612).

  Thus, according to the third embodiment, when performing unicast priority communication from the roadside station 1 side, only the mobile station corresponding to the destination of unicast priority communication sets the control channel and the communication channel in communication to the reception state. Since non-priority communication is suppressed by shifting, the unicast priority communication frame is delivered only to the corresponding destination mobile station without interfering with the communication of other communication channels. As a result, the responsiveness and arrival probability of the priority communication frame can be improved. In addition, since the transmission power of the unicast priority communication frame is higher than usual, the arrival probability can be further improved.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIG. The system configuration to which the fourth embodiment is applied is the same as that shown in FIG. 1, and the configurations of the roadside station 1 and the mobile stations 10A and 10B are the same as those shown in FIGS. Suppose there is.

  In the fourth embodiment, a situation is assumed in which the mobile stations 10A and 10B communicate with the traffic information distribution server 3 via the roadside station 1 using the channel A. FIG. 7 shows a sequence when the mobile station 10A transmits unicast priority communication to the traffic information distribution server 3 under such a premise.

  The mobile station 10A communicates with the roadside station 1 through the control channel Q using the connection ID acquired during the connection process described in the first embodiment (the connection ID of the mobile station 10A is α) and the channel ID (preferably to perform priority communication). In this case, a priority communication permission request including channel A) is transmitted to the roadside station 1 (SQ701). The roadside station 1 that has received this priority communication permission request transmits a priority communication permission frame including the connection ID: α and the channel ID: channel A of the requesting mobile station 10A through the control channel Q (SQ702). This priority communication permission frame is received by the mobile station 10A through the control channel Q.

  On the other hand, the mobile station 10B detects a priority communication permission frame from the roadside station 1 to the mobile station 10A on the control channel Q (SQ703), and shifts the control channel Q to the reception state (SQ704). If the channel ID (channel A) included in the detected priority communication permission frame is the same as the channel ID used by itself, the transmission on channel A is immediately stopped and the state shifts to the reception state (SQ705).

  The mobile station 10A that has received the priority communication permission frame on the control channel Q copies the unicast priority communication frame to be transmitted, which is acquired from the in-vehicle application, and assigns the same sequence number (SQ706). These unicast priority communication frames are transmitted in parallel via A (SQ707). At this time, the mobile station 10A delivers the priority communication frame to the roadside station 1 through the control channel Q and the channel A with higher transmission power than usual.

  The roadside station 1 receives the unicast priority communication frame from the mobile station 10A via the control channel Q and the channel A. Since the roadside station 1 receives frames with the same contents on the two channels Q and A, the sequence numbers of the received frames are compared, and if the frames have already been received, the frames are discarded. Assuming that the reception on channel A was early, the frame of the same sequence number received on the control channel Q side is discarded, and the frame received on channel A is distributed by the upper network communication device 25 to the traffic information of the upper network 2. It is transmitted to the server 3 (SQ708).

  When the mobile station 10A ends the unicast priority communication, the mobile station 10A notifies the roadside station 1 of the completion of the priority communication including the connection ID and the channel ID that has performed the priority communication through the control channel Q (step SQ709).

  The roadside station 1 receives the completion of priority communication from the mobile station 10A, or when a certain period of time elapses after the priority communication frame from the mobile station 10A is not received (this is because the mobile station communicates with the roadside station). Detecting the end of this priority communication (assuming that the cell goes out of the cell range). When the end of the priority communication is detected, the roadside station 1 transmits a channel information notification via the control channel Q with the status information fields corresponding to the control channel Q and the communication channel A set to “normal” (SQ710). By receiving this channel information notification, the mobile stations 10A and 10B using the control channel Q and the communication channel A return to the normal communication state (SQ711).

  As described above, in the fourth embodiment, when a mobile station other than the mobile station that has transmitted the priority communication request receives the priority communication permission, if the mobile station uses the communication channel in which the priority communication is permitted, the mobile station immediately transmits. Since it is stopped and the permitted channel is shifted to the reception state, it is possible to improve the responsiveness and arrival probability of the priority communication on the mobile station side.

  As described above, the road-to-vehicle communication method according to the present invention is useful for a road-to-vehicle communication system in which a roadside station and a mobile station perform wireless communication using one control channel and a plurality of communication channels.

It is a figure which shows the basic system structure of the road-to-vehicle communication system to which this invention is applied. It is a block diagram which shows the internal structure of a roadside station. It is a block diagram which shows the internal structure of a mobile station. It is a figure which shows the connection sequence of a roadside station and a mobile station about Embodiment 1 of this invention. It is a figure which shows the priority communication sequence from the roadside station to all the mobile stations about Embodiment 2 of this invention. It is a figure which shows the unicast priority communication sequence from the roadside station to a mobile station about Embodiment 3 of this invention. It is a figure which shows the unicast priority communication sequence from a mobile station to a roadside station about Embodiment 4 of this invention.

Explanation of symbols

1 Roadside station 2 Host network 3 Traffic information distribution server 4 Telephone 10A, 10B Mobile station

Claims (9)

A roadside station connected to an upper network and capable of transmitting and receiving simultaneously through one control channel and a plurality of communication channels, and a mobile station capable of transmitting and receiving simultaneously through one control channel and at least one of the plurality of communication channels In the road-to-vehicle communication method for performing wireless communication using wireless LAN between the roadside station and the mobile station,
The roadside station determines a plurality of communication channels that can communicate using the control channel, connection requirement information necessary for the mobile station to connect to the roadside station via each communication channel, and the degree of congestion of each communication channel. Including the channel information broadcast to the mobile station periodically,
The mobile station determines a connection desired channel based on the degree of congestion of the channel information broadcast received through the control channel, notifies the roadside station through the control channel of a communication channel connection request including the determined connection desired channel,
The roadside station performs connection permission determination of the notified connection desired channel, executes connection processing in the roadside station for the permission channel that is the connection desired channel according to the determination result, and connects to the permission channel To notify the mobile station through the control channel of the connection permission including the necessary connection information and permission channel identifier,
The mobile station that has received the connection permission through the control channel immediately executes connection processing within the mobile station for the permitted channel without performing a normal connection sequence, and starts communication on the permitted channel indicated by the connection permission. A road-vehicle communication method characterized by the above. The roadside station includes a relationship between a communication channel and a supported application type in the channel information broadcast,
The mobile station selects a communication channel corresponding to a desired application type, and notifies the roadside station of the communication channel connection request including the selected communication channel as the connection desired channel. The road-to-vehicle communication method described. When the roadside station receives a broadcast priority communication frame from the upper network to the mobile station, the channel information broadcast includes state information including occurrence of priority communication for the control channel and a plurality of communication channels.
When the mobile station receives a channel information broadcast having state information including priority communication occurrence, the mobile station sets the control channel and the communication channel specified by the state information to a reception state,
The road-to-vehicle communication method according to claim 1, wherein the roadside station transmits broadcast priority communication frames in parallel to a plurality of communication channels including a control channel. When the roadside station receives a unicast priority communication frame from the upper network to the mobile station, the channel information notification includes generation of priority communication for the communication channel used by the destination mobile station of the control channel and unicast priority communication. Include state information,
When the destination mobile station of the unicast priority communication frame receives the channel information notification having the state information including the priority communication occurrence, the control channel and the use communication channel specified by the state information are set to the reception state,
The road-to-vehicle communication method according to claim 1, wherein the roadside station transmits a unicast priority communication frame in parallel to a control channel and a communication channel in communication with the destination mobile station.   5. The road-to-vehicle communication method according to claim 3, wherein the roadside station increases transmission power from normal when transmitting a priority communication frame in parallel. The roadside station gives the same sequence number to the priority communication frame transmitted in parallel,
The path according to any one of claims 3 to 5, wherein the mobile station discards packets other than the packet that has arrived first when there is the same sequence number among packets received from a plurality of channels. Inter-vehicle communication method. When transmitting the priority communication frame, the mobile station transmits a priority communication request including a connection identifier and a communication channel identifier for performing priority communication to the roadside station,
In response to the priority communication request, the roadside station transmits a priority communication permission including a connection identifier and a communication channel identifier that permits priority communication,
Upon receiving the priority communication permission, the mobile station that has transmitted the priority communication request transmits a priority communication frame to the roadside station in parallel to the permitted communication channel and the control channel, and transmits a priority communication request other than the mobile station that has transmitted the priority communication request. When the mobile station receives the priority communication permission, if the mobile station is using a communication channel for which priority communication is permitted, the mobile station immediately stops transmission, shifts the permitted channel to the reception state,
The mobile station that has transmitted the priority communication request, when finishing the priority communication, notifies the roadside station of the completion of priority communication including the connection identifier and the channel identifier that has performed priority communication through the control channel. The road-to-vehicle communication method described.   The road-to-vehicle communication method according to claim 7, wherein the mobile station increases transmission power from normal when transmitting a priority communication frame in parallel. The mobile station gives the same sequence number to the priority communication frames transmitted in parallel,
9. The road-to-vehicle communication method according to claim 7, wherein the roadside station discards packets other than the packet that has arrived first when there is the same sequence number among packets received from a plurality of channels.

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