JP4381079B2 - Wireless communication system, wireless communication device, and wireless communication method - Google Patents

Wireless communication system, wireless communication device, and wireless communication method Download PDF

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JP4381079B2
JP4381079B2 JP2003335057A JP2003335057A JP4381079B2 JP 4381079 B2 JP4381079 B2 JP 4381079B2 JP 2003335057 A JP2003335057 A JP 2003335057A JP 2003335057 A JP2003335057 A JP 2003335057A JP 4381079 B2 JP4381079 B2 JP 4381079B2
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wireless communication
wireless
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information
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JP2005100231A (en
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健樹 岩崎
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クラリオン株式会社
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  The present invention relates to mobile radio communication technology, and more particularly, to a radio communication system that performs radio communication between vehicles (road vehicles), a radio communication device and a radio communication method used in the radio communication system.

2. Description of the Related Art A wireless communication system between vehicles is known in which a wireless communication device is mounted on each of a plurality of vehicles, and vehicle information that is useful information for traveling (operation) is transmitted and received between the wireless communication devices of each vehicle. (For example, refer to Patent Document 1). Examples of vehicle information include the following. That is, vehicle speed information, vehicle position information, brake information in chronic traffic jams on expressways and general roads, information on other vehicles that are out of sight at intersections with poor visibility, construction information, and information on faulty vehicles Etc. Furthermore, weather forecasts, information for the purpose of exchange between people riding on each vehicle aiming at the same destination, and the like are also useful information transmitted and received between vehicles. In recent years, the wireless communication system between vehicles is expected to be applied to a road traffic system, a railway vehicle system, and the like of wireless communication between vehicles due to advancement of the technology.
JP 2003-101457 A

However, the efficiency of communication deteriorates when a large number of vehicles are in a certain communication range (service area) due to traffic congestion and the amount of information transmitted / received within the communication range increases. There's a problem.

  The present invention has been made in view of the above-described circumstances, and a wireless communication system, a wireless communication device, and a wireless communication method capable of maintaining communication efficiency even when the amount of information transmitted and received increases. The purpose is to provide.

In order to achieve the above object, the present invention comprises a plurality of wireless communication devices, and these wireless communication devices send data to a wireless channel or receive data transmitted on the wireless channel and receive each other. In the wireless communication system that performs communication, each of the wireless communication devices includes a calculation unit that calculates an occupation time for occupying the wireless channel for transmitting the data, and the calculation is performed prior to transmitting the data. The occupied time calculated by the means is transmitted to a wireless channel different from the wireless channel for transmitting the data, and the occupied time is notified to another wireless communication device.

  The present invention also includes a plurality of wireless communication devices, and these wireless communication devices send data to any one of the plurality of wireless channels, or receive data transmitted on each wireless channel and In the wireless communication system that performs communication, each of the wireless communication devices includes a calculation unit that calculates an occupation time for occupying the wireless channel for transmitting the data, and the calculation is performed prior to transmitting the data. A wireless channel through which the occupied time calculated by the means and the identification information of the wireless channel used for transmitting the data are transmitted to a wireless channel different from the wireless channel indicated by the identification information and the data is transmitted And notifying other wireless communication devices of the occupied time of the wireless channel.

The present invention also occupies the wireless channel to transmit the data in a wireless communication device that transmits data to the wireless channel or receives data transmitted on the wireless channel to perform wireless communication. Calculation means for calculating the occupied time, and prior to sending the data, the occupied time calculated by the calculating means is sent to a wireless channel different from the wireless channel for sending the data, and the occupied time is Is notified to other wireless communication devices.

  In addition, the present invention is characterized in that the present invention further comprises storage means for storing the occupied time of the radio channel every time the occupied time of the wireless channel is received.

  In the present invention, when the data is transmitted to the wireless channel, the data is transmitted at a timing when the occupied time stored in the storage means has elapsed.

  Furthermore, the present invention transmits data to any one of a plurality of wireless channels, or transmits the data in a wireless communication device that receives data transmitted on each wireless channel and performs wireless communication. For this purpose, a calculation means for calculating an occupation time for occupying the radio channel is provided, and the occupancy time calculated by the calculation means and the identification information of the radio channel used for sending the data before sending the data. Are transmitted to a predetermined first wireless channel different from the wireless channel indicated by the identification information, and the wireless channel through which the data is transmitted and the occupied time of the wireless channel are notified to other wireless communication devices. It is characterized by that.

  In the present invention, the present invention further comprises storage means for storing an occupation time in which each radio channel except the first radio channel is occupied by another communication device, and the radio channel occupation time and the radio Each time channel identification information is received, the occupation time associated with the radio channel indicated in the identification information is updated to the received occupation time.

  Further, in the present invention, in the above invention, when the data is transmitted to any one of the plurality of wireless channels except the first wireless channel, the occupied time stored in the storage means has already elapsed. The selected wireless channel is selected, and the data is transmitted to the selected wireless channel.

  Further, in the present invention, when there is no wireless channel for which the occupation time stored in the storage means has already elapsed, the wireless channel with the shortest occupation time is selected, and at the timing when the occupation time has elapsed. The data is transmitted.

  Further, in the present invention, in the above invention, a basic assigned radio channel that specifies a radio channel to be mainly used for sending the data for each radio communication device is stored in the storage means in advance, and when the data is sent, When the occupied time of the radio channel corresponding to the basic assigned radio channel stored in the storage means has already passed, the data is transmitted to the radio channel corresponding to the basic assigned radio channel.

  Further, the present invention is the above invention, wherein when the occupation time of the radio channel corresponding to the basic assigned radio channel stored in the storage means has not elapsed, the radio channel with the shortest occupation time is selected, and the occupation time The data is transmitted at the timing when elapses.

  Also, in the present invention, in the above invention, the transmission time and occupation time of the data are specified by the number of slots that define a time unit on the time axis, and in the storage means, as the occupation time of each radio channel, The number of slots is stored, and one slot is subtracted every time when the time corresponding to the slot has elapsed.

  Also, the present invention is characterized in that, in the above-mentioned invention, the occupied time of the radio channel and the identification information of the radio channel are transmitted as common channel information to the first radio channel in the slot unit.

  Also, the present invention is characterized in that, in the above-mentioned invention, the common channel information is received, and the slot timing is adjusted based on the reception timing of the common channel information.

  Further, the present invention is characterized in that, in the above-mentioned invention, information requiring urgent notification is included in the common channel information and transmitted to the first radio channel.

  Further, in the above invention, the present invention is mounted on a vehicle, and information on the running state of the vehicle is information that requires urgent notification, and the information on the running state of the vehicle includes vehicle position information, It includes at least one of vehicle speed information and vehicle brake information.

Further, according to the present invention, in the above invention, the data transmitted to another wireless channel different from the first wireless channel includes the weather forecast, the toll information of the road toll booth, and the will of each person who divides each vehicle. It is characterized in that at least any one of information sent out for the purpose of exchange and information concerning a route to a destination on traveling of the vehicle is included.

The present invention is also directed to a wireless communication method in which a wireless communication device transmits data to a wireless channel or receives data transmitted on the wireless channel to perform wireless communication. A first step of calculating an occupation time for occupying the wireless channel for transmitting the data, and a wireless channel for transmitting the data by using the occupation time calculated in the first step prior to transmitting the data. And a second process of notifying other wireless communication devices of the occupied time by transmitting to a different wireless channel.

  Further, the present invention provides a wireless communication method in which a wireless communication device transmits data to any one of a plurality of wireless channels or receives data transmitted on each wireless channel to perform wireless communication. A first step in which a wireless communication device calculates an occupation time for occupying the wireless channel to transmit the data; an occupation time calculated in the first step prior to transmitting the data; The wireless channel used to transmit the data and the wireless channel through which the data is transmitted by transmitting the wireless channel identification information to a predetermined first wireless channel different from the wireless channel indicated by the identification information And a second step of notifying the other wireless communication device of the occupation time.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where the information content transmitted / received increases, the radio | wireless communications system, the radio | wireless communication apparatus, and the radio | wireless communication method which can maintain the efficiency of communication are provided.

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

  FIG. 1 is a diagram showing a schematic configuration of a wireless communication system S according to the present embodiment. The wireless communication system S includes a wireless communication device 11a (see FIG. 2) mounted on each of a plurality of vehicles 1, and a wireless communication device 11b (see FIG. 3) provided on the roadside device 2 installed on the roadside of the road. ). The vehicle information of the mounted vehicle 1 is distributed to the outside from the wireless communication device 11 a of each vehicle 1, and the road traffic information is distributed to each vehicle 1 from the wireless communication device 11 b of the roadside device 2. Is done. The wireless communication devices 11a and 11b, which are wireless communication devices, have a predetermined range (service area) in which wireless communication is possible, but each of the vehicle 1 and the roadside device 2 is located within a wireless communication range. To do. Under such a configuration, the wireless communication device 11a of the vehicle 1 and the wireless communication device 11b of the roadside device 2 receive information from the other wireless communication devices 11a and 11b, while sending information to the other wireless communication devices 11a and 11b. By transmitting, wireless communication between vehicles and between road vehicles is performed.

  FIG. 2 is a block diagram illustrating a schematic configuration of the in-vehicle system Sa mounted on the vehicle 1. As shown in this figure, the in-vehicle system Sa includes a vehicle computer 12, the wireless communication device 11a, and an antenna 13a connected to the wireless communication device 11a.

  The vehicle computer 12 is obtained from, for example, vehicle position information obtained from a car navigation system (not shown) using GPS (Global Positioning System), vehicle speed information obtained from a vehicle speed meter (not shown), and a brake pedal (not shown). It is a device that manages various vehicle information such as brake information by acquiring and temporarily storing it.

  FIG. 3 is a block diagram illustrating a schematic configuration of the roadside device 2. As shown in this figure, the roadside device 2 includes the wireless communication device 11b, an antenna 13b connected to the wireless communication device 11b, and a roadside control device 14. The roadside control device 14 is a device that receives road traffic information from a roadside management device wirelessly or by wire and manages the road traffic information.

  Each of the wireless communication device 11a mounted on the vehicle 1 and the wireless communication device 11b provided on the roadside device 2 has substantially the same configuration, and the configuration of the wireless communication device 11a of the vehicle 1 is taken as an example. I will explain.

  FIG. 4 is a block diagram illustrating a configuration of the wireless communication device 11 a mounted on the vehicle 1. As shown in the figure, the wireless communication device 11 a includes a CPU 101, a memory 102, a data link unit 103, a modem unit 104, and an RF unit 105.

  The CPU 101 performs overall control of the wireless communication device 11a. For example, the CPU 101 stores received data in the memory 102, calls transmission data from the memory 102, and determines carrier wave detection. The CPU 101 also executes processing such as acquiring various data such as vehicle information (for example, vehicle position information, vehicle speed information, and brake information) from the vehicle computer 12 via an input / output port (not shown) and storing the data in the memory 102. . In the wireless communication device 11 b provided in the roadside device 2, the CPU 101 acquires various data such as road information and traffic information from the roadside control device 14 through an input / output port (not shown) and stores it in the memory 102. To do.

  The memory 102 stores a control program executed by the CPU 101 and various data. These data include data received by wireless communication, data such as vehicle information from the vehicle computer 12, and the like. In the wireless communication device 11 b provided in the roadside device 2, the memory 102 also functions as a communication buffer that stores data such as road information and traffic information from the roadside control device 14.

  The data link unit 103 is controlled according to a communication protocol between vehicles (including road vehicles). The modem unit 104 modulates a transmission data signal or demodulates a reception data signal. The RF unit 105 transmits and receives data signals, and includes, for example, a PLL (Phase Locked Loop) circuit, an AGC (Auto Gain Control) circuit, an amplifier circuit, and the like.

  Under such a configuration, the wireless communication device 11a performs bidirectional communication in which data is transmitted to the other wireless communication devices 11a and 11b, and at the same time, data is received from the other wireless communication devices 11a and 11b. In this bidirectional communication, a plurality of wireless channels obtained by dividing a certain frequency band are used, and when a certain wireless channel is used for data transmission, another wireless channel is used as a data receiving channel. It is done.

  In the wireless communication system S of the present embodiment, each of the plurality of wireless channels is assigned to either the common channel C or the individual channel I. Specifically, as shown in FIG. 5, n wireless channels f0,..., Fn-1 are provided in advance as available wireless channels, and the first wireless channel f0 is the common channel C and the second to The (n-1) -th n-1 radio channels f1, ..., fn-1 are assigned to the individual channel I.

  The common channel C is used for transmission / reception of highly important information (common channel information) such as information related to safe driving of the vehicle and information that requires urgent notification, and the individual channel I is other information such as each It is used for transmission / reception of information (individual channel information) for exchange between vehicles. That is, the common channel information transmitted / received in the common channel C is information that should be used by all the vehicles 1 and the roadside devices 2, and is information that is more important than the individual channel information. This is information that only needs to be received by a vehicle that has a low degree of contribution to the safety of traveling of the vehicle 1 or a specific vehicle 1 or roadside device 2. When this individual channel information is transmitted / received by the wireless communication device 11a of the vehicle 1 or the wireless communication device 11b of the roadside device 2, it transmits and receives one wireless channel belonging to the individual channel I.

  FIG. 6 is a diagram schematically showing a specific example of the common channel information and the individual channel information. FIG. 6A shows the common channel information, and FIG. 6B shows the individual channel information.

  As shown in FIG. 6A, the common channel information includes ID information, common information, individual channel identification information, and individual channel occupation information. The ID information is identification information for uniquely specifying each of the wireless communication devices 11a and 11b of the vehicle 1 and the roadside device 2. The common information is information related to driving safety or information that should be notified to all vehicles in an urgent need. For example, vehicle position information managed by the vehicle computer 12, vehicle speed information, brake information, etc. There are vehicle information and breakdown / emergency information. The failure / emergency information is information indicating a failure of the vehicle or an abnormality occurring in the vehicle, information to be urgently notified to each vehicle, or the like. Further, as the common information from the wireless communication device 11b of the roadside device 2, there is progress / route information, which is so-called road traffic information such as construction information on the travel route of the vehicle 1 and traffic congestion. In the common information, an appropriate number of pieces of information are stored, and “NULL” is stored when no valid information is stored in the common information.

  The individual channel identification information is transmitted when the wireless communication devices 11a and 11b transmit the individual channel information using any one of the (n-1) wireless channels f1, ..., fn belonging to the individual channel I. This is information specifying a radio channel, and “NULL” is stored when the individual channel I is not used (that is, when the individual channel information is not transmitted). The individual channel occupancy information designates a period during which the wireless communication devices 11a and 11b occupy the radio channel designated by the individual channel identification information for data transmission. In this embodiment, this designation is the number of slots ( (Described later). When the individual channel I is not used, “NULL” is stored in the individual channel occupation information.

  Under such a configuration, each wireless communication device 11a, 11b stores its own ID in the ID information of the common channel information, and when notifying each vehicle 1 of important information for traveling of the vehicle 1, In the case where the appropriate information described above is stored and communication using the individual channel I is performed, a valid radio channel is designated in the individual channel identification information and transmitted using the common channel C. Accordingly, each wireless communication device 11a, 11b receives the common channel information of the common channel C, which vehicle 1 or roadside device 2 is transmitting common information, or which vehicle 1 or roadside device 2 is which. It is possible to identify how long a radio channel is used and how long individual channel information is transmitted.

  On the other hand, as shown in FIG. 6B, the individual channel information stores information that is not so important in traveling of the vehicle 1 and that only the specific vehicle 1 or the roadside device 2 needs to receive. Examples of such information include toll information, destination road information, weather forecast information, and inter-vehicle communication information. The toll information is information indicating the toll of a toll road such as an expressway, and the destination road information is road information (construction information, traffic regulation information, etc.) along the route to the destination set in the car navigation system (not shown). ) And traffic information (congestion information, etc.). The weather forecast information is information indicating the weather at the destination. The inter-vehicle communication information is, for example, information for exchanging the will of the people who share the vehicle. Among these pieces of information, fee information, destination road information, and weather forecast information are information transmitted from the roadside device 2, and inter-vehicle communication information is information transmitted / received between the vehicles.

  Next, the frame transmitted on the common channel C or the individual channel I will be described.

  In the present embodiment, when the wireless communication devices 11a and 11b transmit data to the individual channel I, first, the common channel information is transmitted using the common channel C, and the wireless channel used in the individual channel I and The occupation time of the wireless channel is notified to each vehicle 1.

  Therefore, each wireless communication device 11a, 11b generates a frame divided into individual channel information to be transmitted on the individual channel I and common channel information to be transmitted on the common channel C, as shown in FIG. To do. Specifically, the CPU 101 sends transmission information to the data link unit 103, and the data link unit 103 divides the transmission information into individual channel information and common channel information.

  Next, the data link unit 103 first sends the common channel information portion of the frame to the common channel C, and after sending the common channel information, the individual channel information portion is added to the radio channel of the individual channel I specified by the individual channel identification information. Sent out.

  Here, the transmission time of the common channel information to the common channel C is defined by a slot set on the time axis. More specifically, in this embodiment, the time width T of one slot is fixed to a predetermined time (for example, 500 μsec), and the common channel information is transmitted in the time of one slot. .

  As described above, since the transmission time on the common channel C is common to the wireless communication devices 11a and 11b of each vehicle 1 and the roadside device 2, the CPU 101 of the wireless communication devices 11a and 11b on the side of receiving the frame It is possible to achieve slot synchronization based on the reception timing of common channel information at C. Specifically, the reception start timing or the reception end timing of the common channel information is detected to synchronize the slot timing of the own device. As a result, the slots can be synchronized between the vehicles. The common channel information may include a synchronization signal and detect the synchronization signal to synchronize the slot timing.

  By the way, as described above, individual channel information has more types and larger data amount than common channel information. In particular, in recent years, transmission / reception of a large amount of data including multimedia data such as images (including still images and moving images) and music is required between vehicles or between the vehicle 1 and the roadside device 2. . As described above, the amount of information transmitted through the individual channel I increases day by day, and the communication time for one time tends to be longer. Therefore, when each of the vehicle 1 and the roadside device 2 performs wireless communication, if no measures are taken, the vehicle 1 and the roadside device 2 randomly occupy the wireless channel of the individual channel I, and the vehicle 1 or the roadside device 2 However, if the radio channel of the individual channel I is occupied for a long time, there is a possibility that the vehicle 1 that cannot communicate can be generated.

  In addition, if different wireless channels belonging to the individual channel I are statically assigned to the wireless communication devices 11a and 11b of all the vehicles 1 and the roadside devices 2, each of the vehicles 1 and the roadside devices 2 Although communication is possible regardless of the occupation of the radio channel, the frequency band that can be allocated to the individual channel I and the number of radio channels that can be secured in the frequency band are both finite, and thus are not realistic.

  Therefore, in the wireless communication system S of the present embodiment, the wireless channels f1,..., Fn-1 belonging to the individual channel I are dynamically allocated to the vehicles 1 and the roadside devices 2, and in this allocation, The wireless channel that is not used (not occupied) is preferentially assigned to the wireless communication devices 11a and 11b of each vehicle 1 and the roadside device 2, and further, the wireless communication of each vehicle 1 and the roadside device 2 is performed. The wireless communication devices 11a and 11b are configured to notify the other wireless communication devices 11a and 11b of the period during which the devices 11a and 11b occupy the assigned wireless channel, and each wireless communication device 11a and 11b can use the wireless channel more reliably. Wireless channels belonging to the individual channel I can be identified by identifying the timing of channel use start. Le f1, ..., thereby achieving effective use of the fn-1.

  Specifically, the memory 102 of each of the wireless communication devices 11a and 11b according to the present embodiment manages the usage status (occupation status) of the radio channels f1, ..., fn-1 belonging to the individual channel I. An individual channel management table TA is stored.

  FIG. 8 is a diagram schematically showing the configuration of the individual channel management table TA. As shown in this figure, one record of the individual channel management table TA includes an identification number (serial number in the illustrated example) for identifying each radio channel f1,..., Fn-1 belonging to the individual channel I, a radio The name of the channel (the center frequency of the wireless channel in the illustrated example) and the number of remaining slots are included.

  The occupied slot number indicates the remaining period when the radio channel is occupied. In the present embodiment, the remaining period is indicated by the slot. Yes. More specifically, the transmission time of the individual channel information, that is, the time for occupying the radio channel is determined by the data amount of the individual channel information, the transmission capacity per radio channel of the individual channel I, and the time width T of the slot. Based on the number of slots, the converted value is stored in the individual channel occupancy information of the common channel information, and each radio communication device together with individual channel identification information indicating which radio channel is occupied 11a and 11b are notified. When each of the wireless communication devices 11a and 11b receives the common channel information, the wireless communication devices 11a and 11b update the individual channel management table TA and record which wireless channel is occupied by how many slots. Thereafter, each time the time corresponding to the slot time width T elapses, each wireless communication device 11a, 11b decrements the number of slots recorded in the number of remaining slots in the individual channel management table TA by one. This makes it possible to identify the remaining period in which each radio channel is occupied, and whether or not the corresponding radio channel has been vacated based on whether or not the number of remaining slots has become zero. It becomes possible.

  Hereinafter, as an operation of the present embodiment, a frame transmission / reception operation in the wireless communication devices 11a and 11b configured as described above will be described.

  As described above, the wireless communication devices 11a and 11b according to the present embodiment grasp the usage status of the individual channel I and specify the wireless channel that can be used for sending the individual channel information. , 11b sequentially receives the common channel information sent to the common channel C, and executes table update processing for updating the individual channel management table TA every time the time corresponding to the time width T of the slot elapses. This table update process is a process executed regardless of the transmission of the common channel information and the individual channel information after the wireless communication devices 11a and 11b are powered on. In the following description, it is assumed that the wireless communication devices 11a and 11b have already synchronized slots by receiving common channel information when the power is turned on.

  FIG. 9 is a flowchart showing the procedure of the table update process. As shown in this figure, the CPU 101 of the wireless communication devices 11a and 11b first has a timing at which the common channel information can be received, that is, when a slot start timing has arrived (step S1: YES). The RF unit 105 is controlled to execute common channel information reception processing that attempts to receive common channel information transmitted on the common channel C (step S2). Next, the CPU 101 determines whether or not the common channel information is received by this reception process, and further, the number of valid occupied slots is stored in the individual channel occupation information of the common channel information (step S3). If YES, the number of occupied slots is registered in the individual channel management table TA (step S4).

  Specifically, the CPU 101 refers to the individual channel identification information (see FIG. 6A) included in the common channel information received in step S2, and records the record corresponding to the individual channel identification information in the individual channel management table TA. Search from. Then, the CPU 101 registers the occupied slot number indicated by the individual channel occupation information included in the previously received common channel information as the occupied remaining slot number of the retrieved record. As a result, which radio channel of the individual channel I is occupied for which period is registered. Note that the initial value of the number of occupied slots in the individual channel management table TA (for example, the value when the power is turned on) is “0”.

  If the determination result in step S3 is NO, and after step S4 is processed, the CPU 101 performs an occupied slot number update process for updating the occupied slot number of each wireless channel registered in the individual channel management table TA. Execute. More specifically, the CPU 101 initializes the value of the counter N indicating what number record is processed in the individual channel management table TA to “1” (step S5).

  Next, the CPU 101 reads out the Nth record registered in the individual channel management table TA from the memory 102, and decrements the value of the occupied slot number registered in this record by “1” (step S6). It is determined whether or not the number of occupied slots has become a negative value (step S7). If the determination result is YES, the dedicated channel management table TA indicates that the occupied time of the wireless channel notified in the dedicated channel occupation information of the common channel information has elapsed and that the wireless channel is empty. The number of occupied slots is “0”.

  On the other hand, if the determination result in step S7 is NO, or after processing step S8, the CPU 101 increments the value of the counter N by “1” (step S9). As a result, the value of the counter N is individually set. It is determined whether or not the number of radio channels belonging to channel I is larger than N-1, which is the number of records registered in the individual channel management table TA (step S10). When the determination result is NO, the CPU 101 returns the processing procedure to step S6 and decrements the occupied slot number of the next record. That is, the number of occupied slots of all records registered in the individual channel management table TA is updated by the processing from step S5 to step S10.

  Next, the CPU 101 determines whether the start timing of the next slot has arrived (step S11). If the determination result is YES, the CPU 101 returns the processing procedure to step S2, and at the start timing of the next slot. Common channel information sent from other wireless communication devices 11a and 11b is received.

  With the above table update process, when the slot start timing arrives, the common channel information transmitted at the start timing is sequentially received, and the individual channel occupation information is sequentially registered in the individual channel management table TA. The number of occupied slots of each radio channel registered in the individual channel management table TA is updated each time the time width of each slot elapses. As a result, each of the wireless communication devices 11a and 11b can identify which wireless channel of the individual channel I is currently vacant or occupied, and can also identify the remaining occupied time.

  Next, operations when the wireless communication devices 11a and 11b transmit data will be described.

  The CPU 101 of each of the wireless communication devices 11a and 11b outputs the transmission data to the data link unit 103, and causes the data link unit 103 to generate a data transmission frame. Here, when the data to be transmitted is only common information, a frame including only common channel information is generated, and when the individual channel information is also included, common channel information and individual channel information are included. A frame (see FIG. 7) will be generated.

  When sending the individual channel information, the CPU 101 refers to the individual channel management table TA, searches for a radio channel indicating the number of occupied slots “0”, that is, an empty state, and sets the corresponding radio channel as an individual channel of the common channel information. Store in identification information. Then, the CPU 101 converts the transmission time of the individual channel information to be transmitted into the number of slots, and stores the converted value in the individual channel identification information of the common channel information.

  Here, if each wireless communication device 11a, 11b searches in order from the record with the identification number 1 to the last record in the individual channel management table TA to find an empty wireless channel, the wireless communication devices 11a, 11b In some cases, each of the wireless communication channels finds a wireless channel having the same identification number as an empty wireless channel, and transmits individual channel information using this wireless channel. In this case, a plurality of frames are about to be transmitted to one radio channel, so that the frames collide.

  Therefore, in the present embodiment, a radio channel fs (where fs is any one of f1 to fn-1) that each radio communication device 11a, 11b mainly uses when sending individual channel information is assigned in advance, and each radio communication device When searching for radio channels f1 to fn-1 in which 11a and 11b are vacant, search is performed from radio channels fs assigned in advance (hereinafter referred to as “basic assigned radio channels fs”) in the individual channel management table TA. It is configured. This basic assigned radio channel fs is assigned when each of the radio communication devices 11 a and 11 b is manufactured, and is stored in the memory 102. The basic assigned radio channel fs may be assigned not only at the time of manufacture, but also after the radio channel is selected, the radio channel may be stored in the memory 102 and assigned as a new basic assigned radio channel fs.

  As described above, since each wireless communication device 11a, 11b mainly uses the basic assigned wireless channel fs for sending the individual channel information, each wireless communication device 11a, 11b may use the same wireless channel. The data is transmitted more reliably.

  If the number of vehicles in the communicable range increases due to traffic jams on the road and there is no free wireless channel of the individual channel I, the CPU 101 stores the data in the individual channel management table TA in order to send data as soon as possible. Thus, the wireless channel with the smallest occupied slot number, that is, the wireless channel with the shortest remaining occupied time is stored in the individual channel identification information.

  Next, the common channel information is not transmitted to the common channel C, and the CPU 101 sends the common channel information to the RF unit 105 during one slot period at a timing at which the information can be transmitted. For example, the transmission of the common channel information is performed when the common channel information is not received in step S2 of FIG.

  When the individual channel information is transmitted by the transmission of the common channel information, it is determined which wireless channel of the individual channel I is used for transmission, and how long the wireless channel is occupied. The communication devices 11a and 11b are notified. On the other hand, in the case of sending only common information, for example, vehicle speed information, vehicle position information, and the like are notified to other vehicles 1 and roadside equipment 2 together with ID information of the own device.

  The individual channel identification information and the individual channel occupation information are the individual channel management table TA updated at the timing immediately before the common channel information is transmitted (specifically, between step S10 and step S11 in FIG. 9). It is desirable to set based on By doing so, it is possible to avoid a situation in which the wireless channel is already occupied by other wireless communication devices 11a and 11b when the individual channel information is actually transmitted.

  Now, when sending the individual channel information, the CPU 101 designates the radio channel designated by the individual channel identification information of the common channel information in the individual channel occupation time following the transmission of the common channel information to the common channel C. The individual channel information constituting the frame data is transmitted between the number of slots.

  By the above processing, for example, as shown in FIG. 10, the wireless communication devices 11a and 11b mounted on the vehicles 1a to 1c (for convenience, different signs from the vehicle 1) are different from each other. The common channel information is transmitted to the common channel C at the slot timing, and if necessary, the individual channel information is transmitted to the radio channel belonging to the individual channel I after the transmission of the common channel information.

  Here, as shown in FIG. 10, the same radio channel f2 is assigned to each of the vehicle 1b and the vehicle 1c as the basic assigned radio channel fs. Therefore, as described above, when one of the vehicles 1b and 1c occupies the radio channel of the basic assigned radio channel fs, the individual channel information is transmitted using another empty radio channel. It will be. Specifically, since the vehicle 1c occupies the radio channel f2, which is a basic assigned radio channel, for a period of slots n + 2 to n + 3, when the vehicle 1b sends individual channel information from the slot n + 3, A radio channel (radio channel f3 in the illustrated example) different from the assigned radio channel fs is occupied and transmitted. When the vehicle 1c does not occupy the radio channel f2, which is the basic assigned radio channel fs, for example, as shown in the period from slot n + 9, individual channel information is transmitted using the radio channel f2. become.

  Next, the operation when each wireless communication device 11a, 11b receives a frame will be described.

  When each wireless communication device 11a, 11b receives a frame, the following processing is performed. That is, when the common channel information is received in step S2 of FIG. 9, the CPU 101 determines that the common channel information is only common information, or the individual channel identification information and the individual channel occupation information are other than “NULL”. It is determined whether or not valid information is stored.

  Then, when valid information other than “NULL” is stored in the individual channel identification information and the individual channel occupancy information, the CPU 101 uses the radio channel specified in the individual channel identification information as the individual channel occupancy information. The RF unit 105 is controlled so as to receive data for the number of slots specified in the above. As a result, the frame is received by the RF unit 105 via the antenna 13, demodulated by the modem unit 104, the data link unit 103 takes in data according to the communication protocol, and receives individual channel information. Become.

  In particular, the CPU 101 selectively acquires the common information or the individual channel information of the common channel information from the split-destination vehicle 1 based on the ID information of the common channel information, thereby ensuring communication with the sales destination vehicle 1. Can be performed. In the present embodiment, the data captured by the data link unit 103 is sequentially stored in the memory 102 by the CPU 101, but the data of one frame is temporarily stored in the data link unit 103. The received data may be stored in the memory 102 by the CPU 101 after the reception operation is completed.

  In the present embodiment, since an unspecified number of nearby vehicles 1 and roadside devices 2 are used as communication partners, normal reception response confirmation is not performed. Also, re-transmission is not performed in the event of a communication collision. In addition, the time width of the frame is a time width necessary to reliably notify other vehicles 1 of common information such as brake information during high-speed movement on an expressway, etc., and to prevent rear-end collisions, etc. The time width is set in consideration of the number of vehicles 1 equipped with the wireless communication device 11a in the area (for example, a time width with an upper limit of 100 msec).

  As described above, according to the present embodiment, the following effects can be obtained.

  The wireless communication devices 11a and 11b of each vehicle (including roadside devices) send out common channel information through a common channel C, which is a common wireless channel, and are individually transmitted through an individual channel I including a wireless channel different from the common channel C. Since the channel information is transmitted, each channel information can be transmitted more reliably, and the wireless channel can be effectively used.

  In particular, vehicle channel information, vehicle speed information, brake information, failure / emergency information, progress / course information, and other information that is important for the safe driving of vehicles are common channel information, and other information is individual channel information. As a result, the radio channel to be used is divided according to the importance of the information to be transmitted. Therefore, the occupation time of the common channel C for transmitting the common channel information having higher importance compared to the individual channel information is shortened, and communication is performed. The compression of the communication channel capacity due to the increase in the amount of communication information due to the increase in vehicles in the area is reduced, and the communication efficiency is improved.

  This also ensures a sufficient frequency band for the wireless channel (common channel C) for transmitting highly important information, and can reliably transmit this highly important information to other wireless communication devices. Become.

  Further, since the type of information stored in the common channel information and the amount of information transmitted in the common channel information are smaller than the individual channel information, the amount of information to be transmitted in the common channel C is the individual channel I. Less than Therefore, as shown in the present embodiment, the frequency band used in the radio communication system S can be efficiently used by making the number of radio channels allocated to the common channel C smaller than the individual channels I. It becomes possible.

  In addition, since the transmission timing of information is defined by the slot and the common channel information is transmitted by one slot, each wireless communication device 11a, 11b receives the common channel information and can share the common channel information. The slot start timing can be acquired from the reception start timing or the reception end timing of the channel information, and the slot can be synchronized. This eliminates the need for a base station or the like that centrally controls communication between the wireless communication devices 11a and 11b. Further, for example, as in Bluetooth (registered trademark) communication, a complicated procedure of dividing communication devices into groups and dividing each communication device into a master that controls communication and other slaves in the group becomes unnecessary. That is, even when communication is performed between an unspecified number of wireless communication devices 11a and 11b, simple and efficient communication can be realized.

  Further, since each wireless communication device 11a, 11b has an individual channel management table TA and the occupation status and the occupation period of each radio channel f1 to fn-1 belonging to the individual channel I can be identified, the wireless communication devices 11a, 11b Even if the number is larger than the number of the wireless channels f1 to fn-1, it is possible to secure the wireless channels necessary for sending the individual channel information only for the period corresponding to the data capacity of the individual channel information. As a result, even when the amount of information increases with the increase in the number of vehicles 1 and roadside devices 2 within the communication range, each wireless communication device 11a, 11b is efficiently connected according to the communication status (occupation status). Communication efficiency is improved.

  In addition, since the wireless channel mainly used by the wireless communication devices 11a and 11b is determined in advance, the same wireless channel is found when searching for a free wireless channel from the record registered in the individual channel management table TA. It can be avoided that individual channel information (frame) is transmitted using a wireless channel. That is, the collision of frames in the radio channel is reduced, and the communication quality can be improved.

  In addition, since each wireless communication device 11a, 11b notifies the wireless channel used in the individual channel I and the period for which the wireless channel is occupied by the common channel information, each wireless communication device 11a, 11b receives this common channel information. The reception status (occupation status) of each radio channel of the individual channel I can be identified simply by receiving the. Therefore, the carrier sense operation for detecting the use state of each wireless channel and the configuration necessary for this operation are not required, and the wireless communication devices 11a and 11b can be reduced in size and cost.

  As mentioned above, although this invention was demonstrated based on one Embodiment, this invention is not limited to this.

  For example, in the above embodiment, the case where the frequency band used for wireless communication is divided into a plurality of wireless channels having different frequencies by frequency division has been described. Alternatively, a configuration may be used in which the code is divided by different spreading codes by code division using a spread spectrum method.

  Further, for example, the number of radio channels allocated to the common channel C is set to “1”. However, the present invention is not limited to this, and the transmission capacity is insufficient in consideration of the information amount of the common channel information transmitted on the common channel C. In such a case, a configuration may be adopted in which more radio channels are assigned to the common channel C.

It is a figure which shows roughly the structure of the radio | wireless communications system concerning embodiment of this invention. It is a block diagram which shows schematic structure of the vehicle-mounted system mounted in a vehicle. It is a block diagram which shows schematic structure of a roadside apparatus. It is a block diagram which shows the functional structure of a radio | wireless communication apparatus. It is a figure which shows allocation with the common channel of a radio channel of a radio | wireless communications system, and an individual channel. It is a figure which shows the information transmitted to a radio channel, (a) shows the structure of common channel information typically, (b) is a figure which shows the structure of individual channel information typically. It is a figure which shows typically the format of the flame | frame transmitted to a radio channel. It is a figure which shows typically the structure of an individual channel management table. It is a flowchart which shows the procedure of the table update process which is an update process of an individual channel management table. It is a figure for demonstrating the communication procedure between each vehicle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Roadside apparatus 11a, 11b Wireless communication apparatus 101 CPU
DESCRIPTION OF SYMBOLS 102 Memory 103 Data link part 104 Modulation / demodulation part 105 RF part C Common channel I Dedicated channel fs Basic allocation radio channel S Line communication system TA Dedicated channel management table

Claims (19)

  1. In a wireless communication system comprising a plurality of wireless communication devices, these wireless communication devices send data to a wireless channel, or receive data transmitted on the wireless channel and communicate with each other,
    Each of the wireless communication devices
    Calculating means for calculating an occupation time for occupying the wireless channel to transmit the data;
    Prior to sending the data, sending the occupied time calculated by the calculating means to a wireless channel different from the wireless channel sending the data and notifying the other wireless communication device of the occupied time. A wireless communication system.
  2. A wireless communication system that includes a plurality of wireless communication devices, and these wireless communication devices send data to any one of a plurality of wireless channels, or receive data transmitted on each wireless channel and communicate with each other In
    Each of the wireless communication devices
    Calculating means for calculating an occupation time for occupying the wireless channel to transmit the data;
    Prior to sending the data, the occupied time calculated by the calculating means and the identification information of the radio channel used for sending the data are sent to a radio channel different from the radio channel indicated by the identification information. Then, the wireless communication system characterized by notifying other wireless communication devices of the wireless channel through which the data is transmitted and the occupied time of the wireless channel.
  3. In a wireless communication device that transmits data to a wireless channel or receives data transmitted on the wireless channel and performs wireless communication,
    Calculating means for calculating an occupation time for occupying the wireless channel to transmit the data;
    Prior to sending the data, sending the occupied time calculated by the calculating means to a wireless channel different from the wireless channel sending the data and notifying the other wireless communication device of the occupied time. A featured wireless communication device.
  4. The wireless communication device according to claim 3, further comprising storage means for storing the occupied time of the wireless channel every time the occupied time of the wireless channel is received.
  5. The wireless communication device according to claim 4, wherein when the data is transmitted to the wireless channel, the data is transmitted at a timing when the occupation time stored in the storage unit has elapsed.
  6. In a wireless communication device that transmits data to any one of a plurality of wireless channels, or receives data transmitted on each wireless channel and performs wireless communication,
    Calculating means for calculating an occupation time for occupying the wireless channel to transmit the data;
    Prior to transmitting the data, the occupation time calculated by the calculating means and the identification information of the wireless channel used for transmitting the data are different from the wireless channel indicated by the identification information. A wireless communication device, wherein the wireless channel is transmitted to the wireless channel to notify the wireless channel on which the data is transmitted and the occupied time of the wireless channel to another wireless communication device.
  7. Storage means for storing an occupation time in which each wireless channel except the first wireless channel is occupied by another communication device;
    The occupancy time associated with the radio channel indicated in the identification information is updated to the received occupancy time each time the radio channel occupation time and the radio channel identification information are received. Item 7. The wireless communication device according to Item 6.
  8. When the data is transmitted to any one of the plurality of wireless channels except the first wireless channel, the wireless channel for which the occupied time stored in the storage means has already passed is selected and selected. The wireless communication device according to claim 7, wherein the data is transmitted to a wireless channel.
  9. When there is no radio channel for which the occupation time stored in the storage means has already elapsed, the radio channel with the shortest occupation time is selected, and the data is transmitted when the occupation time has elapsed. The wireless communication device according to claim 8.
  10. A basic assigned radio channel that designates a radio channel to be mainly used for sending the data for each radio communication device is stored in advance in the storage means,
    When transmitting the data, if the occupation time of the radio channel corresponding to the basic allocated radio channel stored in the storage means has already passed, the data is transmitted to the radio channel corresponding to the basic allocated radio channel. The wireless communication device according to claim 7.
  11. When the occupation time of the radio channel corresponding to the basic assigned radio channel stored in the storage means has not elapsed, the radio channel with the shortest occupation time is selected, and the data is transmitted when the occupation time has elapsed. The wireless communication device according to claim 10.
  12. The transmission time and occupation time of the data are specified by the number of slots that define a time unit on the time axis,
    The number of slots is stored in the storage means as the occupied time of each radio channel, and one slot is subtracted each time the time corresponding to the slot elapses. The wireless communication device according to any one of 11.
  13. The wireless communication device according to claim 12, wherein the radio channel occupancy time and identification information of the radio channel are transmitted as common channel information to the first radio channel in the slot unit.
  14. The wireless communication device according to claim 13, wherein the common channel information is received, and the slot timing is adjusted based on the reception timing of the common channel information.
  15. The wireless communication device according to claim 13 or 14, wherein information that requires urgent notification is included in the common channel information and transmitted to the first wireless channel.
  16. The information on the running state of the vehicle, which is mounted on the vehicle, is information that requires urgent notification, and the information on the running state of the vehicle includes vehicle position information, vehicle speed information, and vehicle brake information. The wireless communication device according to claim 15, wherein at least one of the information is included.
  17. For data transmitted to another wireless channel different from the first wireless channel,
    At least one of weather forecasts, toll information at road toll booths, information sent for the purpose of exchanging wills among people who divide each vehicle, and information on the route to the destination on the vehicle The wireless communication device according to claim 16, further comprising:
  18. In a wireless communication method in which a wireless communication device transmits data to a wireless channel or receives data transmitted through the wireless channel to perform wireless communication,
    A first step of calculating an occupation time for the wireless communication device to occupy the wireless channel in order to transmit the data;
    Prior to sending the data, the occupied time calculated in the first step is sent to a wireless channel different from the wireless channel that sends the data, and the occupied time is notified to another wireless communication device. A wireless communication method comprising the steps of 2.
  19. In a wireless communication method in which a wireless communication device transmits data to any one of a plurality of wireless channels, or receives data transmitted on each wireless channel and performs wireless communication,
    A first step in which the wireless communication device calculates an occupation time for occupying the wireless channel to transmit the data;
    Prior to transmitting the data, the occupation time calculated in the first step and the identification information of the wireless channel used for transmitting the data are set to a predetermined number of times different from the wireless channel indicated by the identification information. A wireless communication method comprising: a second step of transmitting to one wireless channel and notifying another wireless communication device of the wireless channel through which the data is transmitted and the occupied time of the wireless channel.
JP2003335057A 2003-09-26 2003-09-26 Wireless communication system, wireless communication device, and wireless communication method Expired - Fee Related JP4381079B2 (en)

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