JP6390757B2 - Communication device, congestion control method, and program - Google Patents

Description

  The present invention relates to a communication device, a congestion control method, and a program, and more particularly, to a communication device, a congestion control method, and a program for controlling congestion.

  A vehicle-to-vehicle communication system in which vehicle-mounted communication devices mounted on a vehicle communicate with each other and a road-to-vehicle communication system in which a vehicle-mounted communication device mounted on a vehicle and a roadside communication device installed on a roadside communicate with each other are known.

  In inter-vehicle communication systems and road-to-vehicle communication systems, for example, DENM (Decentralized Environmental Notification Message) and CAM (Cooperative Awareness Message) are used.

  The DENM is a message for notifying a communication device within a predetermined range of occurrence of a predetermined event (for example, sudden braking or lighting of a hazard lamp). The DENM is repeatedly transmitted for a predetermined time as a predetermined event occurs. In DENM, transmission conditions (for example, necessary transmission distance and necessary transmission delay time) according to a predetermined event are set.

  On the other hand, the CAM is a message for informing surrounding communication devices of the position and speed of the vehicle. The CAM is repeatedly transmitted regardless of the occurrence of an event. A transmission condition corresponding to an event such as DENM is not set in the CAM.

  If messages such as DENM and CAM are frequently sent and received, congestion occurs.

  Patent Document 1 describes an in-vehicle communication device that can avoid congestion. The in-vehicle communication device described in Patent Literature 1 performs congestion control by controlling the message transmission period, the message transmission power, and the message reception sensitivity according to the utilization rate of the communication channel. Generally, the greater the transmission power of a message, the longer the message transmission distance.

International Publication No. 2009/133740

  The in-vehicle communication device described in Patent Document 1 performs congestion control regardless of the message type (for example, DENM, CAM).

  In this congestion control, there is no problem regarding the transmission condition for a message for which no transmission condition is set, such as CAM.

  However, in this congestion control, a transmission condition (for example, a necessary transmission distance) may not be satisfied because a transmission condition is not considered for a message in which a transmission condition such as DENM is set. When the transmission condition is not satisfied, a situation occurs in which the transmitted message does not reach the communication partner to be delivered properly.

  Therefore, the in-vehicle communication device described in Patent Document 1 has a problem that a message that does not properly reach the communication partner with congestion control occurs depending on the type of message.

  An object of the present invention is to provide a communication device, a congestion control method, and a program that can solve the above-described problems.

  The communication apparatus of the present invention includes a generation unit that generates a message and a control unit that controls transmission of the message. The message includes a plurality of types of messages including a first type of message that accompanies the occurrence of a specific event and a second type of message that accompanies the occurrence of the specific event. The control unit determines a type of a message to be transmitted, and when the message to be transmitted is the message of the first type, the control unit determines the degree of congestion of a communication channel used for transmitting the message of the first type. A communication channel that performs a first congestion control operation according to the first type message and uses the second type message transmission when the transmission target message is the second type message. The second congestion control operation according to the second type message is performed based on the congestion level of the communication and the transmission condition according to the specific event.

  The congestion control method of the present invention includes a generation process for generating a message and a control process for controlling transmission of the message. The message includes a plurality of types of messages including a first type of message that accompanies the occurrence of a specific event and a second type of message that accompanies the occurrence of the specific event. The control process determines the type of message to be transmitted, and determines the degree of congestion of a communication channel used for message transmission of the first type when the message to be transmitted is the message of the first type. A communication channel that performs a first congestion control operation according to the first type message and uses the second type message transmission when the transmission target message is the second type message. And a process of performing a second congestion control operation according to the second type message based on the congestion degree of the communication and the transmission condition according to the specific event.

  The program of the present invention causes a computer to execute a generation procedure for generating a message and a control procedure for controlling transmission of the message. The message includes a plurality of types of messages including a first type of message that accompanies the occurrence of a specific event and a second type of message that accompanies the occurrence of the specific event. The control procedure determines the type of message to be transmitted, and when the message to be transmitted is the message of the first type, determines the degree of congestion of the communication channel used for transmitting the message of the first type. A communication channel that performs a first congestion control operation according to the first type message and uses the second type message transmission when the transmission target message is the second type message. And a procedure for performing a second congestion control operation according to the second type message based on the congestion degree of the communication and the transmission condition according to the specific event.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to suppress that the message which does not reach a communicating party appropriately according to congestion control depending on the message type.

It is the figure which showed the communication apparatus of 1st Embodiment of this invention. 4 is a flowchart for explaining the operation of the communication apparatus 1; It is the figure which showed the communication apparatus 10 of 2nd Embodiment of this invention. 3 is a flowchart for explaining the operation of the communication device 10;

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram illustrating a communication apparatus according to a first embodiment of the present invention.

  In FIG. 1, the communication device 1 includes a generation unit 2 and a control unit 3.

  For example, the communication device 1 is mounted on a vehicle and performs inter-vehicle communication or road-vehicle communication. The communication device 1 has a plurality of radio channels. The generation unit 2 generates a message to be transmitted. The control unit 3 controls congestion by controlling transmission of a message to be transmitted.

  The control unit 3 controls congestion by controlling transmission of a message to be transmitted on a predetermined radio channel (hereinafter referred to as “predetermined radio channel”) among a plurality of radio channels based on the degree of congestion of the predetermined radio channel. Can be performed. Hereinafter, this congestion control operation is referred to as a “first operation”.

  Further, the control unit 3 sets the transmission degree of the message to be transmitted on the wireless channel (hereinafter referred to as “specific wireless channel”) whose congestion level is equal to or less than the congestion level threshold among the plurality of wireless channels to the congestion level of the specific wireless channel. An operation for controlling congestion based on the control can be executed. Hereinafter, this congestion control operation is referred to as a “second operation”. The congestion level threshold is an example of a predetermined value.

  The control unit 3 switches between the first operation and the second operation according to the type of message to be transmitted.

  FIG. 2 is a flowchart for explaining the operation of the communication apparatus 1.

  When generating the transmission target message (step S1), the generation unit 2 outputs the transmission target message to the control unit 3.

  When receiving the message to be transmitted, the control unit 3 switches between the first operation and the second operation according to the type of the message to be transmitted (step S2).

  Next, the effect of this embodiment will be described.

  The generation unit 2 generates a message. The control unit 3 performs switching between the first operation and the second operation according to the type of message generated by the generation unit 2. In the first operation, a predetermined predetermined radio channel is used as the radio channel. For this reason, in the first operation, a predetermined radio channel is used regardless of the degree of congestion. On the other hand, in the second operation, a radio channel (specific radio channel) whose congestion level is equal to or less than the congestion level threshold is used as the radio channel. For this reason, the range which the radio channel congestion level can take is different between the first operation and the second operation.

  In both the first operation and the second operation, congestion control is executed based on the degree of congestion of the radio channel used for message transmission. For this reason, the difference in the range that the radio channel congestion can take causes a difference between the congestion control in the first operation and the congestion control in the second operation. Since the first operation and the second operation are switched according to the message type, the congestion control is switched according to the message type. Therefore, it is possible to suppress the occurrence of a message that does not reach the communication partner properly due to congestion control depending on the message type.

(Second Embodiment)
FIG. 3 is a diagram illustrating the communication device 10 according to the second embodiment of the present invention.

  In FIG. 3, the communication device 10 includes a receiving unit 11, an application unit 12, and a control unit 13. The control unit 13 includes a radio channel setting unit 13a, a transmission cycle setting unit 13b, a transmission power / transmission rate setting unit 13c, a congestion control unit 13d, and a transmission unit 13e.

  The communication device 10 is, for example, an in-vehicle communication device. The communication device 10 performs vehicle-to-vehicle communication or road-to-vehicle communication with another communication device (for example, another vehicle-mounted communication device or a roadside communication device) in a state where it is mounted on the vehicle.

  The communication device 10 performs vehicle-to-vehicle communication or road-to-vehicle communication using two wireless channels simultaneously.

  The communication device 10 uses a CCH (Control Channel) as one of the two radio channels (hereinafter referred to as “radio channel CH1”). The CCH is used in common by the communication device 10 that performs inter-vehicle communication or road-vehicle communication with the communication device 10. CCH is an example of a common radio channel set in advance for communication of the communication device 10. CCH is used for CAM communication. The CCH may be used for communication of a unicast message that is a message used in DENM communication or one-to-one communication.

  The communication device 10 uses any one of a plurality of SCHs (Service Channels) having different frequencies as the other of the two radio channels (hereinafter referred to as “radio channel CH2”). Each SCH is used for communication of DEMN and unicast messages. The frequency of each SCH is different from the frequency of CCH. The number of SCHs may be one or more.

  The radio channels CH1 and CH2 are examples of a plurality of radio channels. The number of radio channels simultaneously used by the communication device 10 is not limited to “2”, and may be plural. The radio channel used by the communication device 10 is not limited to CCH and SCH, and can be changed as appropriate.

  The receiving unit 11 receives a message wirelessly transmitted from another communication device through the wireless channel CH1. The receiving unit 11 also receives a message wirelessly transmitted from another communication device through the wireless channel CH2.

  When receiving a message (for example, CAM, DENM, unicast message) wirelessly transmitted from another communication device via the wireless channel CH1 or CH2, the receiving unit 11 outputs the message to the application unit 12.

  Further, the receiving unit 11 specifies the degree of congestion of each of the radio channels CH1 and CH2 based on the message communication status. The receiving unit 11 notifies the congestion control unit 13d of the degree of congestion of each of the radio channels CH1 and CH2.

  The application unit 12 is an example of a generation unit.

  The application unit 12 has a positioning function for measuring a position. The positioning function of the application unit 12 is a function that performs positioning using, for example, GPS (Global Positioning System). Note that the positioning function of the application unit 12 is not limited to a function using GPS, but can be changed as appropriate.

  In addition, the application unit 12 detects an event (for example, sudden braking or lighting of a hazard lamp) that has occurred in a vehicle in which the communication device 10 is mounted (hereinafter simply referred to as “vehicle”).

  The application unit 12 detects an event that has occurred in the vehicle, for example, as follows. The application unit 12 receives event notification information representing an event that has occurred in the vehicle from the vehicle. The application part 12 detects the event which generate | occur | produced in the vehicle using event notification information. Note that the method for detecting an event that has occurred in the vehicle by the application unit 12 is not limited to the method using the event notification information, and can be changed as appropriate.

  In addition, the application unit 12 receives a message output from the receiving unit 11. For example, when the application unit 12 receives a CAM, the application unit 12 checks the position of another in-vehicle communication device indicated by the CAM.

  In addition, the application unit 12 generates a plurality of types of messages used in inter-vehicle communication and road-to-vehicle communication as messages to be transmitted.

  In the present embodiment, the application unit 12 generates a message (unicast message) used in CAM, DENM, and one-to-one communication as a plurality of types of messages.

  The application unit 12 generates, for example, a DENM indicating the occurrence of a specific event in association with the occurrence of an event such as sudden braking or lighting of a hazard lamp (hereinafter referred to as a “specific event”).

  The application unit 12 stores a transmission condition (for example, transmission distance or transmission delay time) corresponding to the specific event for each specific event.

  For example, the application unit 12 stores a communication distance A1 required for communication and a delay time B1 required for communication as transmission conditions corresponding to “sudden braking” which is an example of a specific event. Further, the application unit 12 stores a communication distance A2 required for communication and a delay time B2 required for communication as transmission conditions corresponding to “hazard lamp lighting” which is an example of a specific event.

  Hereinafter, the communication distance required for communication is referred to as “requested communication distance”. The requested communication distance is an example of a transmission distance that is a transmission condition. In this embodiment, it is assumed that the transmission power corresponding to the requested communication distance (hereinafter referred to as “requested transmission power”) is smaller than a predetermined maximum transmission power.

  The delay time required for communication is referred to as “request delay time”. The request delay time is an example of a transmission delay time that is a transmission condition. In the present embodiment, it is assumed that the request delay time is longer than the time indicated by a predetermined shortest transmission cycle.

  The requested communication distance A1 may be the same as or different from the requested communication distance A2. The request delay time B1 may be the same as or different from the request delay time B2.

  In addition, the application unit 12 intermittently generates a CAM that represents the position and speed of the vehicle. The application unit 12 does not store transmission conditions for CAM.

  In addition, the application unit 12 generates a unicast message when executing one-to-one communication. The application unit 12 stores transmission conditions according to the unicast message (for example, matters in which the distance to the communication partner is the requested communication distance and the requested delay time).

  The control unit 13 performs a congestion control operation for controlling congestion by controlling transmission of a transmission target message generated by the application unit 12.

  The control unit 13 can execute a first congestion control operation for controlling congestion by controlling transmission of a message to be transmitted on the radio channel CH1 (CCH) based on the congestion degree of the radio channel CH1. The first congestion control operation is an example of a first operation. The radio channel CH1 (CCH) is an example of a predetermined radio channel.

  The control unit 13 controls transmission of a message to be transmitted on a radio channel (hereinafter referred to as “corresponding radio channel”) having a congestion degree equal to or less than a congestion degree threshold among the radio channels CH1 and CH2 based on the congestion degree of the corresponding radio channel. Thus, a second congestion control operation for controlling congestion can also be executed. The second congestion control operation is an example of a second operation. The corresponding radio channel is an example of a specific radio channel.

  The control unit 13 executes the first congestion control operation and the second congestion control operation by switching according to the type of message to be transmitted.

  The radio channel setting unit 13 a is set with a radio channel (hereinafter referred to as “scheduled radio channel to be used”) used for transmitting a message to be transmitted.

  In the transmission cycle setting unit 13b, the transmission cycle of the message to be transmitted is set.

  In the transmission power / transmission speed setting unit 13c, the transmission power and transmission speed of the message to be transmitted are set.

  The congestion control unit 13d determines the transmission of the transmission target message based on the type of the transmission target message and the congestion level notified from the reception unit 11 (for example, the scheduled radio channel, transmission cycle, transmission power, transmission rate). By controlling, the congestion control operation is executed.

  In addition, the congestion control unit 13d stores a correspondence table indicating a correspondence relationship between transmission power and transmission distance, and a congestion degree threshold value. In the correspondence table, the transmission power increases as the corresponding transmission distance increases.

  The transmission unit 13e sets the message to be transmitted in the scheduled use radio channel set in the radio channel setting unit 13a, the transmission cycle set in the transmission cycle setting unit 13b, and the transmission power / transmission rate setting unit 13c. Wireless transmission with the same transmission power and transmission speed.

  Next, the operation will be described.

  FIG. 4 is a flowchart for explaining the operation of the communication apparatus 10.

  When the scheduled radio channel to be used set in the radio channel setting unit 13a is CCH, the reception unit 11 uses the CCH as the radio channel CH1 and uses one of a plurality of SCHs (for example, a default SCH or a radio channel CH2). SCH) set by the user.

  On the other hand, when the scheduled radio channel set in the radio channel setting unit 13a is not CCH, the receiving unit 11 uses CCH as the radio channel CH1 and uses the scheduled radio channel as the radio channel CH2.

  The receiving unit 11 specifies the degree of congestion of each of the radio channels CH1 and CH2 based on the communication status of the message through each radio channel. The receiving unit 11 notifies the congestion control unit 13d of the degree of congestion of each of the radio channels CH1 and CH2.

  When the application unit 12 generates a message to be transmitted (step S101), the application unit 12 outputs the message to be transmitted to the transmission cycle setting unit 13b and sends message type information indicating the type of the message to be transmitted to the congestion control unit 13d. Output.

  When the message type to be transmitted is a DENM or unicast message, the application unit 12 also outputs the transmission condition of the message to be transmitted to the congestion control unit 13d. For example, when the message to be transmitted is DENM, the application unit 12 outputs a transmission condition corresponding to the specific event represented by the DENM to the congestion control unit 13d.

  The application unit 12 uses request communication distance information indicating the request communication distance and request delay time information indicating the request delay time as the transmission conditions of the transmission target message. When the type of message to be transmitted is a unicast message, the application unit 12 determines the distance between the communication partner position indicated in the CAM transmitted by the communication partner and the communication device 10 position measured by the application unit 12. Is used as the required communication distance.

  When the transmission cycle setting unit 13b accepts a transmission target message, the transmission cycle setting unit 13b holds the transmission target message.

  When receiving the message type information, the congestion control unit 13d determines whether the type of the message to be transmitted is CAM, DENM, or unicast message (step S102).

  When the type of the message to be transmitted is CAM, the congestion control unit 13d determines CCH as the scheduled radio channel (step S103).

  Subsequently, the congestion control unit 13d sets the use-scheduled radio channel determined in step S103 in the radio channel setting unit 13a.

  Subsequently, the congestion control unit 13d refers to the degree of congestion of the CCH (radio channel CH1) notified from the reception unit 11 (step S104).

  Subsequently, the congestion control unit 13d determines the transmission cycle of the message to be transmitted based on the CCH congestion degree (step S105).

  For example, when the CCH congestion level is equal to or less than the congestion level threshold, the congestion control unit 13d determines the shortest transmission cycle as the transmission cycle of the transmission target message.

  On the other hand, when the CCH congestion level is higher than the congestion level threshold, the congestion control unit 13d sets a cycle longer than the transmission cycle currently set in the transmission cycle setting unit 13b as the transmission cycle of the message to be transmitted. decide. In a situation where the transmission cycle is not set in the transmission cycle setting unit 13b, the congestion control unit 13d determines a cycle longer than the shortest transmission cycle by a specified time as the transmission cycle of the message to be transmitted.

  Subsequently, the congestion control unit 13d sets the transmission cycle determined in step S105 in the transmission cycle setting unit 13b as the transmission cycle of the message to be transmitted.

  When the transmission cycle of the transmission target message is set, the transmission cycle setting unit 13b copies the held transmission target message at a time interval indicated by the transmission cycle, and copies the transmission target message (hereinafter, “ (Referred to as “transmission data”) (step S106).

  Subsequently, the transmission cycle setting unit 13b outputs the transmission data to the transmission unit 13e.

  On the other hand, when the transmission control unit 13d sets the transmission cycle to the transmission cycle setting unit 13b, the congestion control unit 13d determines the transmission power of the message to be transmitted based on the CCH congestion degree (step S107).

  For example, when the CCH congestion level is equal to or less than the congestion level threshold, the congestion control unit 13d determines the maximum transmission power as the transmission power of the transmission target message.

  On the other hand, when the CCH congestion level is higher than the congestion level threshold, the congestion control unit 13d transmits a transmission power smaller than the transmission power currently set in the transmission power / transmission speed setting unit 13c by a predetermined amount. Determined as the transmission power. Note that, in a situation where the transmission power is not set in the transmission power / transmission speed setting unit 13c, the congestion control unit 13d determines a transmission power smaller than the maximum transmission power by a specified amount as the transmission power of the message to be transmitted.

  Subsequently, the congestion control unit 13d sets the transmission power determined in step S107 in the transmission power / transmission rate setting unit 13c as the transmission power of the message to be transmitted.

  Subsequently, the congestion control unit 13d determines the transmission rate of the message to be transmitted based on the CCH congestion degree (step S108).

  For example, when the CCH congestion level is less than or equal to the congestion level threshold, the congestion control unit 13d uses a predetermined slowest transmission rate (hereinafter referred to as “latest transmission rate”) as the transmission rate of the message to be transmitted. decide.

  Also, when the CCH congestion level is higher than the congestion level threshold, the congestion control unit 13d sets a transmission rate that is faster than the transmission rate currently set in the transmission power / transmission rate setting unit 13c by a message to be transmitted. Determined as the transmission speed. Note that, in a situation where the transmission rate is not set in the transmission power / transmission rate setting unit 13c, the congestion control unit 13d determines a transmission rate that is faster than the latest transmission rate by a specified value as the transmission rate of the message to be transmitted. .

  Subsequently, the congestion control unit 13d sets the transmission rate determined in step S108 in the transmission power / transmission rate setting unit 13c as the transmission rate of the message to be transmitted.

  When receiving the transmission data from the transmission cycle setting unit 13b, the transmission unit 13e uses the transmission data set in the transmission power / transmission rate setting unit 13c using the scheduled radio channel set in the radio channel setting unit 13a. Transmission is performed at power and transmission speed (step S109). In step S109, CCH is used as the scheduled radio channel.

  When the transmission unit 13e receives transmission data from the transmission period setting unit 13b, the transmission power / transmission rate setting unit 13c does not set the transmission power and transmission rate, and the radio channel setting unit 13a uses the scheduled radio channel. If is not set, the transmission data is not transmitted.

  Subsequently, the transmission unit 13e outputs a transmission notification indicating that the transmission data has been transmitted to the congestion control unit 13d.

  When the congestion control unit 13d receives the transmission notification, the congestion control unit 13d determines whether the elapsed time from the reception of the message type information exceeds a predetermined transmission continuation time (step S110).

  If the elapsed time does not exceed the transmission duration in step S110, the congestion control unit 13d returns the process to step S104.

  If the elapsed time exceeds the transmission continuation time in step S110, the congestion control unit 13d deletes the transmission target message held by the transmission cycle setting unit 13b. Subsequently, the congestion control unit 13d deletes the transmission cycle, transmission power, and transmission rate set in the transmission cycle setting unit 13b and the transmission power / transmission rate setting unit 13c, respectively, and ends the first congestion control operation. To do.

  On the other hand, when the type of the message to be transmitted is DENM or unicast message in step S102, the congestion control unit 13d determines the congestion degree of the radio channels CH1 and CH2 and the transmission condition (requested communication distance information and requested delay time information). ) Are referred to (step S111).

  Subsequently, the congestion control unit 13d determines a scheduled radio channel (Step S112).

  For example, the congestion control unit 13d first identifies a corresponding radio channel whose congestion level is equal to or less than the congestion level threshold among the radio channels CH1 and CH2. When the congestion levels of the radio channels CH1 and CH2 exceed the congestion level threshold, the congestion control unit 13d selects the radio channel with the lowest congestion level among the radio channels CH1 and CH2 as the corresponding radio channel. Use instead.

  Subsequently, when the number of corresponding radio channels is 1, the congestion control unit 13d determines the corresponding radio channel as a scheduled radio channel.

  On the other hand, when the number of corresponding radio channels is two or more, the congestion control unit 13d determines one corresponding radio channel from among a plurality of corresponding radio channels as a scheduled radio channel.

  Here, an example of a technique for determining one corresponding radio channel as a scheduled radio channel from a plurality of corresponding radio channels will be described.

  In this example, priorities are assigned in advance to each of the plurality of SCHs and the CCH. For example, the highest priority is assigned to the CCH, and a priority other than the highest priority is assigned to each SCH. As an example of assigning a priority other than the highest priority to each SCH, an example in which a higher priority is assigned to a SCH having a higher importance or usage frequency can be given. The priority assignment is not limited to the above, and can be changed as appropriate. The congestion control unit 13d holds the priority assignment result for the CCH and the plurality of SCHs. Then, the congestion control unit 13d determines the radio channel with the highest priority among the radio channels as the scheduled radio channel.

  Subsequently, the congestion control unit 13d sets the use-scheduled radio channel determined in step S112 in the radio channel setting unit 13a.

  Subsequently, the congestion control unit 13d determines the transmission cycle of the message to be transmitted based on the congestion level of the scheduled radio channel and the transmission condition (Step S113).

  For example, when the congestion level of the scheduled radio channel is equal to or less than the congestion level threshold, the congestion control unit 13d determines the shortest transmission cycle as the transmission cycle of the message to be transmitted.

  On the other hand, when the congestion level of the scheduled radio channel is higher than the congestion level threshold, the congestion control unit 13d firstly has a cycle longer than the transmission cycle currently set in the transmission cycle setting unit 13b (hereinafter referred to as “transmission cycle”). Identified as "candidate").

  Subsequently, when the time (cycle) represented by the transmission cycle candidate is shorter than the request delay time represented by the request delay time information, the congestion control unit 13d sets the transmission cycle candidate as the transmission cycle of the message to be transmitted. decide. On the other hand, when the time (cycle) represented by the transmission cycle candidate is equal to or greater than the request delay time, the congestion control unit 13d determines the request delay time as the transmission cycle of the message to be transmitted. This means that the maximum value of the transmission cycle is limited by the request delay time.

  In the present embodiment, the required delay time, the time represented by the shortest transmission cycle, and the specified time have a relationship of “requested delay time”> “time represented by the shortest transmission cycle” + “specified time”.

  In a situation where the transmission cycle is not set in the transmission cycle setting unit 13b, the congestion control unit 13d determines a cycle longer than the shortest transmission cycle by a specified time as the transmission cycle of the message to be transmitted.

  Subsequently, the congestion control unit 13d sets the transmission cycle determined in step S113 in the transmission cycle setting unit 13b as the transmission cycle of the message to be transmitted.

  When the transmission cycle of the message to be transmitted is set, the transmission cycle setting unit 13b executes Step S114. The process in step S114 is the same as the process in step S106. For this reason, the detailed description about the process in step S114 is omitted.

  When the congestion control unit 13d sets the transmission cycle to the transmission cycle setting unit 13b, the congestion control unit 13d determines the transmission power of the message to be transmitted based on the congestion level of the scheduled radio channel and the transmission condition (step S115).

  For example, when the congestion level of the scheduled radio channel is equal to or less than the congestion level threshold, the congestion control unit 13d determines the maximum transmission power as the transmission power of the message to be transmitted.

  On the other hand, when the congestion level of the wireless channel to be used is higher than the congestion level threshold, the congestion control unit 13d first transmits a transmission power (a specified amount smaller than the transmission power currently set in the transmission power / transmission speed setting unit 13c). (Hereinafter referred to as “transmission power candidates”).

  Subsequently, the congestion control unit 13d refers to the correspondence table and identifies the requested transmission power corresponding to the requested communication distance represented by the requested communication distance information.

  Subsequently, when the transmission power represented by the transmission power candidate is larger than the requested transmission power, the congestion control unit 13d determines the transmission power candidate as the transmission power of the message to be transmitted. On the other hand, when the transmission power represented by the transmission power candidate is equal to or less than the requested transmission power, the congestion control unit 13d determines the requested transmission power as the transmission power of the message to be transmitted. This means that the minimum value of the transmission power is limited by the required communication distance.

  In the present embodiment, the required transmission power, the maximum transmission power, and the specified amount have a relationship of “requested transmission power” <“maximum transmission power” − “specified amount”.

  In a situation where the transmission power is not set in the transmission power / transmission speed setting unit 13c, the congestion control unit 13d determines the transmission power obtained by subtracting the specified amount from the maximum transmission power as the transmission power of the message to be transmitted.

  Subsequently, the congestion control unit 13d sets the transmission power determined in step S115 in the transmission power / transmission rate setting unit 13c as the transmission power of the message to be transmitted.

  Subsequently, the congestion control unit 13d determines the transmission rate of the message to be transmitted based on the degree of congestion of the scheduled radio channel (Step S116). The process in step S116 is the same as the process in step S108, except that the congestion level of the scheduled radio channel is used instead of the CCH congestion level. For this reason, the detailed description about the process in step S116 is omitted.

  Subsequently, the congestion control unit 13d sets the transmission rate determined in step S116 in the transmission power / transmission rate setting unit 13c as the transmission rate of the message to be transmitted.

  The transmission part 13e will perform step S117, if transmission data is received from the transmission period setting part 13b. The process in step S117 is the same as the process in step S109 except that the scheduled radio channel is not limited to CCH. For this reason, the detailed description about the process in step S117 is omitted.

  Subsequently, the transmission unit 13e outputs a transmission notification to the congestion control unit 13d.

  When the congestion control unit 13d receives the transmission notification, the congestion control unit 13d executes Step S118. The process in step S118 is the same as the process in step S110. For this reason, the detailed description of the process in step S118 is omitted.

  If the elapsed time does not exceed the transmission continuation time in step S118, the congestion control unit 13d returns the process to step S111.

  On the other hand, when the elapsed time exceeds the transmission continuation time in step S118, the congestion control unit 13d deletes the transmission target message held by the transmission cycle setting unit 13b. Subsequently, the congestion control unit 13d deletes the transmission cycle set in the transmission cycle setting unit 13b and the transmission power and transmission rate set in the transmission power / transmission rate setting unit 13c, and performs the congestion control operation. finish.

  Next, the effect of this embodiment will be described.

  The control unit 13 transmits a first congestion control operation that uses CCH as a radio channel regardless of the congestion level, and a second congestion control operation that uses a corresponding radio channel whose congestion level is less than or equal to a congestion level threshold as a radio channel. Switch according to the target message type. For this reason, the range in which the radio channel congestion level can be different between the first congestion control operation and the second congestion control operation. Each congestion control operation is controlled according to the degree of congestion of the radio channel to be used. For this reason, the difference in the range that the radio channel congestion can take causes a difference between the congestion control in the first congestion control operation and the congestion control in the second congestion control operation. The first congestion control operation and the second congestion control operation are switched according to the message type. Therefore, the congestion control operation is switched according to the message type. Therefore, it is possible to suppress the occurrence of a message that does not reach the communication partner properly due to congestion control depending on the message type.

  For messages with transmission conditions, the control unit 13 performs congestion control by controlling the transmission of messages on the corresponding radio channel based on the congestion level of the scheduled radio channel and the transmission conditions. Further, the control unit 13 performs congestion control by controlling message transmission on the CCH based on the congestion level of the scheduled radio channel for messages that do not involve transmission conditions. For this reason, it is possible to perform congestion control in consideration of transmission conditions for messages with transmission conditions, and to perform congestion control in consideration of transmission conditions for messages without transmission conditions.

  Next, a modification of this embodiment will be described.

  In the present embodiment, both the transmission distance and the transmission delay time are used as the transmission conditions. However, the transmission condition may be any one of the transmission distance and the transmission delay time, and can be changed as appropriate.

  The order of determining the transmission period, determining the transmission power, and determining the transmission rate can be changed as appropriate.

  In order to simplify the congestion control operation, the transmission rate control may be omitted. Further, in order to simplify the congestion control operation, either one of the transmission cycle control and the transmission power control may be omitted.

  As a method for determining one corresponding radio channel as a scheduled radio channel from a plurality of corresponding radio channels, the following modified method may be used instead of the method using priority.

<Modification 1>
The congestion control unit 13d determines the radio channel with the lowest congestion level among the plurality of radio channels as the scheduled radio channel.

<Modification 2>
The congestion control unit 13d confirms the radio channel used by the receiving unit 11. When the congestion control unit 13d confirms the radio channel used by the reception unit 11, the congestion control unit 13d causes the transmission unit 13e to transmit radio channel information indicating the radio channel used by the reception unit 11.

  Further, the congestion control unit 13d receives wireless channel information indicating a wireless channel used by another communication device. The radio channel information is transmitted from another communication device, for example. The congestion control unit 13d determines a radio channel used by another communication device among a plurality of corresponding radio channels as a scheduled radio channel. In this case, since the radio channel used by another communication device is used as the scheduled radio channel, communication with the other communication device can be executed with high probability.

  When there is no radio channel used by another communication device among the plurality of corresponding radio channels, the congestion control unit 13d refers to the radio channel information and the reception unit 11 currently uses as the radio channel CH2. The SCH being used is changed to the SCH used by another communication device. Subsequently, the congestion control unit 13d determines the changed SCH as a scheduled radio channel regardless of the degree of congestion of the changed SCH.

  In addition, when each of a plurality of radio channels used by other communication devices is a corresponding radio channel, the congestion control unit 13d selects one of the plurality of radio channels (for example, one selected at random). Is determined as the scheduled radio channel.

<Modification 3>
In the second modification, the congestion control unit 13d may use the above-described priority order. For example, when each of a plurality of radio channels used by other communication devices is a corresponding radio channel, the congestion control unit 13d uses the radio channel to which the highest priority is assigned among the plurality of radio channels. Is determined as the scheduled radio channel.

<Modification 4>
In the second modification, when each of a plurality of radio channels used by other communication devices is a corresponding radio channel, the congestion control unit 13d selects a radio channel having the lowest congestion degree among the plurality of radio channels. It is determined as a scheduled radio channel.

  In each of the above embodiments, the communication device may be realized by a computer. In this case, the computer reads and executes a program recorded on a recording medium such as a CD-ROM (Compact Disk Read Only Memory) readable by the computer, and executes a function of the communication device. The recording medium is not limited to the CD-ROM and can be changed as appropriate.

  In each embodiment described above, the illustrated configuration is merely an example, and the present invention is not limited to the configuration.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above-described embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2014-41311 for which it applied on March 4, 2014, and takes in those the indications of all here.

DESCRIPTION OF SYMBOLS 1,10 Communication apparatus 2 Generation | occurrence | production part 3 Control part 11 Reception part 12 Application part 13 Control part 13a Radio channel setting part 13b Transmission period setting part 13c Transmission power / transmission speed setting part 13d Congestion control part 13e Transmission part

Claims (7)

A communication device having a generation unit that generates a message and a control unit that controls transmission of the message,
The message includes:
A first type of message that does not accompany the occurrence of a specific event;
There are multiple types of messages including a second type of message associated with the occurrence of the specific event,
The control unit determines the type of message to be transmitted, and when the message to be transmitted is the message of the first type, based on the degree of congestion of the communication channel used for transmitting the message of the first type. When a first congestion control operation is performed according to the first type message, and the message to be transmitted is the second type message, a communication channel used for transmitting the second type message A communication apparatus that performs a second congestion control operation according to the second type of message based on a communication congestion level and a transmission condition according to the specific event. The first type of message that does not accompany the occurrence of the event is a CAM,
The communication device according to claim 1, wherein the second type message accompanied by the occurrence of the event is a message of DENM or one-to-one communication.   The communication channel for transmitting the second type message is a wireless channel having a congestion degree of a predetermined value or less among wireless channels usable by the communication device. Communication equipment.   The communication channel for transmitting the second type of message is a wireless channel having the lowest congestion degree among wireless channels that can be used by the communication device. The communication apparatus as described in.   The communication channel for transmitting the second type of message is a radio channel to which the highest priority is given among radio channels that can be used by the communication device. The communication device according to any one of the above. A generation process for generating a message;
Control processing for controlling transmission of the message,
The message includes a plurality of types of messages including a first type message that does not accompany the occurrence of a specific event and a second type message that accompanies the occurrence of the specific event,
The control process is
The type of the message to be transmitted is determined, and when the message to be transmitted is the message of the first type, the first type is based on the degree of congestion of the communication channel used for transmitting the message of the first type. When the first congestion control operation is performed according to the type message, and the message to be transmitted is the second type message, the communication congestion level of the communication channel used for transmitting the second type message And a congestion control method including a process of performing a second congestion control operation according to the second type message based on a transmission condition according to the specific event. A program for causing a computer to execute a generation procedure for generating a message and a control procedure for controlling transmission of the message,
The message includes a plurality of types of messages including a first type message that does not accompany the occurrence of a specific event and a second type message that accompanies the occurrence of the specific event,
The control procedure is:
The type of the message to be transmitted is determined, and when the message to be transmitted is the message of the first type, the first type is based on the degree of congestion of the communication channel used for transmitting the message of the first type. When the first congestion control operation is performed according to the type message, and the message to be transmitted is the second type message, the communication congestion level of the communication channel used for transmitting the second type message And a program for performing a second congestion control operation according to the second type message based on a transmission condition according to the specific event.

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