WO2013018318A1

WO2013018318A1 - Communication system, base station device, and wireless device

Info

Publication number: WO2013018318A1
Application number: PCT/JP2012/004731
Authority: WO
Inventors: 真琴永井; 児島　則章; 真佐哉奥村
Original assignee: 三洋電機株式会社
Priority date: 2011-07-29
Filing date: 2012-07-25
Publication date: 2013-02-07

Abstract

A first control base station device (110a) etc. broadcasts a packet signal in a first period in the frame, and is installed so as to be fixed. A first CSMA base station device (120a) etc. broadcasts a packet signal in a second period which is different from the first period, in the frame, and is installed so as to be fixed. A terminal device broadcasts a packet signal in the second period in the frame, and is movable. The first control base station device (110a) etc. or the first CSMA base station device (120a) etc. is installed at a single junction.

Description

COMMUNICATION SYSTEM, BASE STATION DEVICE, RADIO DEVICE

The present invention relates to a communication technique, and more particularly to a communication system, a base station apparatus, and a radio apparatus that transmit and receive a signal including predetermined information.

路 Road-to-vehicle communication is being studied to prevent collisions at intersections. In the road-to-vehicle communication, information on the situation of the intersection is communicated between the roadside device and the vehicle-mounted device. Further, in the case of a form in which vehicle-to-vehicle communication is performed, that is, information is communicated between on-vehicle devices, for example, the current position information is detected in real time by GPS (Global Positioning System), and the position information is exchanged between the on-vehicle devices. Thus, it is determined on which road the own vehicle and the other vehicle enter the intersection (see, for example, Patent Document 1).

JP 2005-202913 A

If the road-to-vehicle communication is executed in addition to the vehicle-to-vehicle communication, the communication forms are diversified. At that time, the amount of data broadcast by road-to-vehicle communication varies. In order to improve frequency reason efficiency, efficient communication is desired.

The present invention has been made in view of such a situation, and an object thereof is to provide a technique for efficiently executing broadcast transmission.

In order to solve the above problems, a communication system according to an aspect of the present invention includes a first type base station device and a second type base station device as base station devices. The first type base station apparatus reports a signal in the first period, and the second type base station apparatus is a period different from the first period, and the terminal apparatus can report the signal. Signals are broadcast during the specified second period, and the first type base station device and the second type base station device are installed at different intersections.

It should be noted that an arbitrary combination of the above-described components and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

According to the present invention, broadcast transmission can be executed efficiently.

It is a figure which shows the structure of the communication system which concerns on the Example of this invention. It is a figure which shows the structure of the control base station apparatus of FIG. FIGS. 3A to 3D are diagrams showing frame formats defined in the communication system of FIG. FIGS. 4A and 4B are diagrams showing the format of a packet signal defined in the communication system of FIG. It is a figure which shows the structure of the base station apparatus for CSMA of FIG. It is a figure which shows the structure of the terminal device mounted in the vehicle of FIG. It is a flowchart which shows the reception procedure in the terminal device of FIG. It is a figure which shows the format of the packet signal which concerns on the 1st modification of this invention. It is a figure which shows the structure of the communication system which concerns on the 2nd modification of this invention. It is a figure which shows another structure of the communication system which concerns on the 2nd modification of this invention. It is a figure which shows the structure of the base station apparatus for control and CSMA which concerns on the 2nd modification of this invention. It is a figure which shows another structure of the communication system which concerns on the 2nd modification of this invention. It is a figure which shows another structure of the communication system which concerns on the 2nd modification of this invention.

The knowledge that became the basis of the examples of the present invention is as follows. In a wireless LAN (Local Area Network) compliant with a standard such as IEEE 802.11, an access control function called CSMA / CA (Carrier Sense Multiple Access Avididance) is used. Therefore, in the wireless LAN, the same wireless channel is shared by a plurality of terminal devices. In such CSMA / CA, a packet signal is transmitted after confirming that no other packet signal is transmitted by carrier sense.

On the other hand, when a wireless LAN is applied to inter-vehicle communication such as ITS (Intelligent Transport Systems), it is necessary to transmit information to an unspecified number of terminal devices. . However, at an intersection or the like, an increase in the number of vehicles, that is, an increase in the number of terminal devices increases traffic, and therefore, an increase in packet signal collision is assumed. As a result, data included in the packet signal is not transmitted to other terminal devices. If such a situation occurs in vehicle-to-vehicle communication, the objective of preventing a collision accident at the intersection encounter will not be achieved. Furthermore, if the road-to-vehicle communication is executed in addition to the vehicle-to-vehicle communication, the communication forms are various. At that time, the amount of data broadcast by road-to-vehicle communication varies. In order to improve frequency reason efficiency, efficient communication is desired.

An outline will be given before concretely explaining the present invention. Embodiments of the present invention relate to a communication system that performs vehicle-to-vehicle communication between terminal devices mounted on a vehicle, and also executes road-to-vehicle communication from a base station device installed at an intersection or the like to a terminal device. As inter-vehicle communication, the terminal device broadcasts and transmits a packet signal storing information such as the speed and position of the vehicle (hereinafter referred to as “data”). Further, the other terminal device receives the packet signal and recognizes the approach of the vehicle based on the data. Here, the base station apparatus repeatedly defines a frame including a plurality of subframes. The base station apparatus selects any of a plurality of subframes for road-to-vehicle communication, and broadcasts a packet signal in which control information and the like are stored during the period of the head portion of the selected subframe.

The control information includes information related to a period (hereinafter referred to as “road vehicle transmission period”) for the base station apparatus to broadcast the packet signal. The terminal device specifies a road and vehicle transmission period based on the control information, and transmits a packet signal by the CSMA method in a period other than the road and vehicle transmission period (hereinafter referred to as “vehicle transmission period”). Thus, since the road-to-vehicle communication and the vehicle-to-vehicle communication are time-division multiplexed, the collision probability of packet signals between them is reduced. That is, when the terminal device recognizes the content of the control information, interference between road-vehicle communication and vehicle-to-vehicle communication is reduced. Note that a terminal device that cannot receive control information from the base station device, that is, a terminal device that exists outside the area formed by the base station device transmits a packet signal by the CSMA method regardless of the frame configuration.

Here, two types of base station devices are assumed. The first base station apparatus (hereinafter referred to as “control base station apparatus”) is a base station apparatus having the above-described functions. On the other hand, the second base station apparatus (hereinafter referred to as “CSMA base station apparatus”) is a base station apparatus that is intended to execute road-to-vehicle communication irregularly rather than controlling vehicle-to-vehicle communication. is there. The CSMA base station device requires a flexible change in the amount of communication instead of requiring regular and preferential notification during the road-to-vehicle transmission period. Therefore, the CSMA base station apparatus reports the packet signal by the CSMA method during the vehicle communication period, similarly to the terminal apparatus. As a result, a control base station apparatus, a CSMA base station apparatus, and a terminal apparatus are defined as notification sources of packet signals on the communication system. Depending on the application, it may be desirable to identify them. In order to cope with this, the present embodiment executes the following processing.

In the present embodiment, a control signal having a common format is included in the packet signal regardless of the type of the notification source. The control signal includes information indicating whether it is a base station device or a terminal device as the type of transmission source. Moreover, the information for showing whether the road and vehicle transmission period is used or the vehicle and vehicle transmission period is used is also contained. On the receiving side, by combining these, it is specified which of the three types of devices is the source of the packet signal.

FIG. 1 shows a configuration of a communication system 100 according to an embodiment of the present invention. This corresponds to a case where one intersection is viewed from above. The communication system 100 includes a base station device 10, a first vehicle 12a, a second vehicle 12b, a third vehicle 12c, a fourth vehicle 12d, a fifth vehicle 12e, a sixth vehicle 12f, and a seventh vehicle 12g, collectively referred to as a vehicle 12. , The eighth vehicle 12h, and the network 202. The base station apparatus 10 corresponds to the control base station apparatus 110 or the CSMA base station apparatus 120. Here, only the first vehicle 12 a is shown, but each vehicle 12 is equipped with a terminal device 130. An area 212 is formed around the base station apparatus 10, and an outside area 214 is formed outside the area 212.

As shown in the figure, the road that goes in the horizontal direction of the drawing, that is, the left and right direction, intersects the vertical direction of the drawing, that is, the road that goes in the up and down direction, at the central portion. Here, the upper side of the drawing corresponds to the direction “north”, the left side corresponds to the direction “west”, the lower side corresponds to the direction “south”, and the right side corresponds to the direction “east”. The intersection of the two roads is an “intersection”. The first vehicle 12a and the second vehicle 12b are traveling from left to right, and the third vehicle 12c and the fourth vehicle 12d are traveling from right to left. Further, the fifth vehicle 12e and the sixth vehicle 12f are traveling from the top to the bottom, and the seventh vehicle 12g and the eighth vehicle 12h are traveling from the bottom to the top.

In the communication system 100, the base station apparatus 10 is fixedly installed at an intersection. A case where the base station apparatus 10 is the control base station apparatus 110 will be described. The control base station apparatus 110 controls communication between terminal apparatuses. The control base station device 110 repeats a frame including a plurality of subframes based on a signal received from a GPS satellite (not shown) or a frame formed by another control base station device 110 (not shown). Generate. Here, the road vehicle transmission period can be set at the head of each subframe. Control base station apparatus 110 selects a subframe in which the road and vehicle transmission period is not set by another control base station apparatus 110 from among a plurality of subframes in the frame. Control base station apparatus 110 sets a road and vehicle transmission period at the beginning of the selected subframe. The control base station apparatus 110 broadcasts a packet signal in the set road and vehicle transmission period.

* Multiple types of data are assumed as data to be included in the packet signal. One is data such as traffic jam information and construction information, and the other is information related to the timing when the road and vehicle transmission period is set and information related to the frame. In particular, the latter corresponds to control information, but since it is generated in the control base station apparatus 110, it can be said that it is non-transfer information. The former is acquired from the network 202.

Since the terminal device 130 is mounted on the vehicle 12 as described above, the terminal device 130 is movable. When the terminal device 130 receives the packet signal from the control base station device 110, the terminal device 130 generates a frame based on the control information included in the packet signal, in particular, the information about the timing at which the road and vehicle transmission period is set and the information about the frame. Is generated. As a result, the frame generated in each of the plurality of terminal devices 130 is synchronized with the frame generated in the control base station device 110. The terminal device 130 notifies the packet signal during the vehicle transmission period. Although the vehicle transmission period will be described later, it can be said that this is a period different from the road and vehicle transmission period in the frame. Here, CSMA / CA is executed in the vehicle transmission period.

The terminal device 130 acquires data and stores the data in a packet signal. The data includes, for example, information related to the location. The terminal device 130 also stores the control information received from the control base station device 110 in the packet signal. That is, the control information transmitted from the control base station device 110 is transferred by the terminal device 130. On the other hand, when it is estimated that the terminal apparatus 130 exists outside the area 214, the terminal apparatus 130 notifies the packet signal by executing CSMA / CA regardless of the frame configuration.

Next, a case where the base station apparatus 10 is the CSMA base station apparatus 120 will be described. The CSMA base station apparatus 120 does not generate a frame by itself, but synchronizes with the frame generated by the control base station apparatus 110 in the same manner as the terminal apparatus 130. Similarly to the terminal device 130, the CSMA base station device 120 notifies the packet signal during the vehicle transmission period. Data to be included in the packet signal by the CSMA base station apparatus 120 is acquired from the network 202, for example. However, this is data having a size larger than the data that the control base station apparatus 110 should include in the packet signal. Also, the CSMA base station apparatus 120 stores the control information received from the control base station apparatus 110 in the packet signal in order to transfer the control information. In the following description, the base station device 10 may collectively refer to the control base station device 110 and the CSMA base station device 120, or one of the control base station device 110 and the CSMA base station device 120. May be indicated.

FIG. 2 shows the configuration of the control base station apparatus 110. The control base station apparatus 110 includes an antenna 20, an RF unit 22, a modem unit 24, a processing unit 26, a control unit 28, and a network communication unit 30. Further, the processing unit 26 includes a frame defining unit 32, a selecting unit 34, and a generating unit 36.

The RF unit 22 receives a packet signal from the terminal device 130 (not shown) or another base station device 10 by the antenna 20 as a reception process. The RF unit 22 performs frequency conversion on the received radio frequency packet signal to generate a baseband packet signal. Further, the RF unit 22 outputs a baseband packet signal to the modem unit 24. In general, baseband packet signals are formed by in-phase and quadrature components, so two signal lines should be shown, but here only one signal line is shown for clarity. Shall be shown. The RF unit 22 also includes an LNA (Low Noise Amplifier), a mixer, an AGC, and an A / D conversion unit.

The RF unit 22 performs frequency conversion on the baseband packet signal input from the modem unit 24 as a transmission process, and generates a radio frequency packet signal. Further, the RF unit 22 transmits a radio frequency packet signal from the antenna 20 during the road-vehicle transmission period. The RF unit 22 also includes a PA (Power Amplifier), a mixer, and a D / A conversion unit.

The modem unit 24 demodulates the baseband packet signal from the RF unit 22 as a reception process. Further, the modem unit 24 outputs the demodulated result to the processing unit 26. The modem unit 24 also modulates the data from the processing unit 26 as a transmission process. Further, the modem unit 24 outputs the modulated result to the RF unit 22 as a baseband packet signal. Here, since the communication system 100 corresponds to the OFDM (Orthogonal Frequency Division Multiplexing) modulation method, the modem unit 24 also executes FFT (Fast Fourier Transform) as reception processing and IFFT (Inverse TransFastFast) as transmission processing. Also execute.

The frame defining unit 32 receives a signal from a GPS satellite (not shown), and acquires time information based on the received signal. In addition, since a well-known technique should just be used for acquisition of the information of time, description is abbreviate | omitted here. The frame defining unit 32 generates a plurality of frames based on the time information. For example, the frame defining unit 32 generates ten “100 msec” frames by dividing the “1 sec” period into ten on the basis of the timing indicated by the time information. By repeating such processing, the frame is defined to be repeated. The frame defining unit 32 may detect control information from the demodulation result and generate a frame based on the detected control information. Such a process corresponds to generating a frame synchronized with the timing of the frame formed by another control base station apparatus 110. FIGS. 3A to 3D show frame formats defined in the communication system 100. FIG. FIG. 3A shows the structure of the frame. The frame is formed of N subframes indicated as the first subframe to the Nth subframe. For example, when the frame length is 100 msec and N is 8, a subframe having a length of 12.5 msec is defined. N may be other than 8. The description of FIGS. 3B to 3D will be described later, and returns to FIG.

The selection unit 34 selects a subframe in which a road and vehicle transmission period is to be set from among a plurality of subframes included in the frame. More specifically, the selection unit 34 receives a frame defined by the frame defining unit 32. The selection unit 34 inputs a demodulation result from another base station device 10 or a terminal device 130 (not shown) via the RF unit 22 and the modem unit 24. The selection unit 34 extracts a demodulation result from another base station apparatus 10, particularly from another control base station apparatus 110, from the input demodulation results. The selection unit 34 specifies the subframe that has not received the demodulation result by specifying the subframe that has received the demodulation result. This corresponds to specifying a subframe in which the road and vehicle transmission period is not set by another control base station apparatus 110, that is, an unused subframe. When there are a plurality of unused subframes, the selection unit 34 selects one subframe at random. When there are no unused subframes, that is, when each of a plurality of subframes is used, the selection unit 34 acquires reception power corresponding to the demodulation result, and gives priority to subframes with low reception power. Select

FIG. 3B shows a configuration of a frame generated by the first control base station apparatus 110a. The first control base station apparatus 110a sets a road and vehicle transmission period at the beginning of the first subframe. In addition, the first control base station apparatus 110a sets the vehicle transmission period following the road and vehicle transmission period in the first subframe. The vehicle transmission period is a period during which the terminal device 130 can notify the packet signal. That is, the first control base station apparatus 110a can notify the packet signal in the road and vehicle transmission period that is the head period of the first subframe, and in the vehicle and vehicle transmission period other than the road and vehicle transmission period in the frame. It is defined that the terminal device 130 can broadcast the packet signal. Furthermore, the first control base station apparatus 110a sets only the vehicle transmission period from the second subframe to the Nth subframe.

FIG. 3C shows a configuration of a frame generated by the second control base station apparatus 110b. The second control base station apparatus 110b sets a road and vehicle transmission period at the beginning of the second subframe. Also, the second control base station apparatus 110b sets the vehicle transmission period from the first subframe and the third subframe to the Nth subframe after the road and vehicle transmission period in the second subframe. FIG. 3D shows a configuration of a frame generated by the third control base station apparatus 110c. The third control base station device 110c sets a road and vehicle transmission period at the beginning of the third subframe. Also, the third control base station apparatus 110c sets the vehicle transmission period in the subsequent stage of the road and vehicle transmission period in the third subframe, the first subframe, the second subframe, and the fourth subframe to the Nth subframe. To do. In this way, the plurality of control base station apparatuses 110 select different subframes, and set the road and vehicle transmission period at the head portion of the selected subframe. Returning to FIG. The selection unit 34 outputs the selected subframe number to the generation unit 36.

The generation unit 36 receives a subframe number from the selection unit 34. The generation unit 36 sets a road and vehicle transmission period in the subframe of the received subframe number, and generates a packet signal to be notified in the road and vehicle transmission period. In the road and vehicle transmission period, a plurality of packet signals to be notified may be generated. FIGS. 4A and 4B show packet signal formats defined in the communication system 100. FIG. FIG. 4A shows a physical frame format. In the physical frame, “PLCP preamble”, “signal”, “service”, “MAC header”, “RSU control header”, “payload”, “FCS”, and “tail bit” are arranged in order from the top.

The “PLCP preamble” is a known signal defined in the physical layer, the “signal” is a control signal defined in the physical layer, and the “MAC header” is a control signal defined in the MAC layer. It is. The “RSU control header” is a control signal commonly used in road-to-vehicle communication and vehicle-to-vehicle communication, and details will be described later. A “payload” is a data signal. Therefore, it can be said that a data signal is arranged in the packet signal following the control signal. Further, when receiving data such as traffic jam information and construction information from the network communication unit 30, the generation unit 36 includes them in the data payload. Here, the network communication unit 30 is connected to a network 202 (not shown).

FIG. 4B is a diagram illustrating a configuration of the RSU control header generated by the generation unit 36. The RSU control header includes “protocol version”, “transmission node type”, “transfer count / reuse count”, “reserve”, “TSF timer”, “RSU transmission period length”, “use period information”, “reserve” Is arranged. The protocol version indicates the version of the corresponding protocol. The transmission node type indicates the type of the transmission node. Base station apparatus 10 and terminal apparatus 130 are defined as types of transmission nodes. This can be said to indicate whether the transmission node is fixedly installed or movable. In the case of the control base station apparatus 110, the transmission node type is the base station apparatus 10.

The transfer count / reuse count indicates an index of validity when the RSU control header is transferred by the terminal device 130, and the TSF timer indicates a transmission time. The RSU transmission period length indicates the length of the road and vehicle transmission period, and can be said to be information relating to the road and vehicle transmission period. The usage period information indicates whether to use a road and vehicle transmission period or a vehicle and vehicle transmission period when transmitting a packet signal. In the case of the control base station apparatus 110, the usage period information is a road and vehicle transmission period. Returning to FIG. The processing unit 26 broadcasts the packet signal to the modem unit 24 and the RF unit 22 during the road and vehicle transmission period. The control unit 28 controls processing of the entire control base station apparatus 110.

This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of any computer, and in terms of software, it can be realized by a program loaded in the memory, but here it is realized by their cooperation. Draw functional blocks. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms only by hardware, or by a combination of hardware and software.

FIG. 5 shows the configuration of the CSMA base station apparatus 120. The CSMA base station apparatus 120 includes an antenna 40, an RF unit 42, a modem unit 44, a processing unit 46, a control unit 48, and a network communication unit 50. The processing unit 46 includes a timing specifying unit 52, a transfer determining unit 54, and a generating unit 56. The timing specifying unit 52 includes an extracting unit 58 and a carrier sense unit 60. This corresponds to the case where the base station apparatus 10 shown in FIG. 1 is the CSMA base station apparatus 120. The antenna 40, the RF unit 42, and the modem unit 44 perform the same processing as the antenna 20, the RF unit 22, and the modem unit 24 in FIG. Therefore, here, the difference will be mainly described.

The modem unit 44 and the processing unit 46 receive packet signals from the terminal device 130 and other base station devices 10 (not shown). As described above, the modem unit 44 and the processing unit 46 receive the packet signal from the control base station apparatus 110 during the road and vehicle transmission period. Further, as described above, the modem unit 44 and the processing unit 46 receive packet signals from the terminal device 130 and other CSMA base station devices 120 during the vehicle transmission period.

When the demodulation result from the modem unit 44 is a packet signal from the control base station device 110 (not shown), the extracting unit 58 specifies the timing of the subframe in which the road and vehicle transmission period is arranged. Specifically, the extracting unit 58 determines whether the packet signal is from the control base station apparatus 110 based on the transmission node type and the usage period information in the RSU control header. Here, when the transmission node type indicates the base station apparatus 10 and the usage period information indicates the road and vehicle transmission period, the extraction unit 58 determines that the packet signal notification source is the control base station apparatus 110. decide. Further, the extraction unit 58 generates a frame based on the subframe timing and the content of the RSU transmission period length in the RSU control header of the packet signal. As a result, the extraction unit 58 generates a frame synchronized with the frame formed in the control base station apparatus 110. When the notification source of the packet signal is the other CSMA base station apparatus 120 or the terminal apparatus 130, the extraction unit 58 omits the synchronized frame generation process.

The extraction unit 58 specifies the remaining vehicle transmission period after specifying the road and vehicle transmission period in use. The extraction unit 58 outputs information regarding the timing of the frames and subframes and the vehicle transmission period to the carrier sense unit 60. On the other hand, when the extraction unit 58 has not received a packet signal from the control base station apparatus 110, that is, when a frame synchronized with the control base station apparatus 110 is not generated, the extraction unit 58 selects a timing unrelated to the frame configuration. To do. When the extraction unit 58 selects a timing unrelated to the frame configuration, the extraction unit 58 instructs the carrier sense unit 60 to perform carrier sense unrelated to the frame configuration.

The carrier sense unit 60 receives information on the timing of frames and subframes and the vehicle transmission period from the extraction unit 58. The carrier sense unit 60 measures the interference power by performing carrier sense during the vehicle transmission period. Also, the carrier sense unit 60 determines transmission timing based on the interference power. More specifically, the carrier sense unit 60 stores a predetermined threshold value in advance, and compares the interference power with the threshold value. If the interference power is smaller than the threshold value, the carrier sense unit 60 determines the transmission timing. When the carrier sense unit 60 is instructed to perform carrier sense from the extraction unit 58, the carrier sense unit 60 determines the transmission timing by executing CSMA without considering the frame configuration. The carrier sense unit 60 notifies the generation unit 56 of the determined transmission timing.

The transfer determination unit 54 controls the transfer of the RSU control header. The transfer determination unit 54 extracts the RSU control header from the packet signal. When the packet signal is directly transmitted from the control base station apparatus 110, the reuse count is set to “0”, but the packet signal is transmitted from the terminal apparatus 130 or another CSMA base station apparatus 120. In the case where it is set, the reuse count is set to a value of “1 or more”. The transfer determination unit 54 selects an RSU control header to be transferred from the extracted RSU control header. Here, for example, the RSU control header with the smallest number of reuses is selected. Further, the transfer determination unit 54 may generate a new RSU control header by combining the contents included in the plurality of RSU control headers. The transfer determination unit 54 outputs the RSU control header to be selected to the generation unit 56. At that time, the transfer determination unit 54 increases the reuse count by “1”.

The network communication unit 50 is connected to a network 202 (not shown) in the same manner as the network communication unit 30 in FIG. The network communication unit 50 receives predetermined information via the network 202. The network communication unit 50 outputs predetermined information to the generation unit 56. The generation unit 56 receives predetermined information from the network communication unit 50 and also receives an RSU control header from the transfer determination unit 54. The predetermined information is information that occurs irregularly, for example, image information, video information, or entertainment information including these. Such information may not be related to the traveling of the vehicle 12. The generation unit 56 uses the physical frame shown in FIGS. 4A to 4B and stores predetermined information in the payload. Here, the generation unit 56 sets the transmission node type to the base station device 10 and sets the usage period information to the vehicle transmission period. The generation unit 56 generates a packet signal having a physical frame configuration, and transmits the generated packet signal via the modulation / demodulation unit 44, the RF unit 42, and the antenna 40 at the transmission timing determined by the carrier sense unit 60. Broadcast transmission. The control unit 48 controls the overall operation of the CSMA base station apparatus 120.

FIG. 6 shows the configuration of the terminal device 130 mounted on the vehicle 12. The terminal device 130 includes an antenna 70, an RF unit 72, a modem unit 74, a processing unit 76, and a control unit 78. The processing unit 76 includes a timing specifying unit 80, a transfer determining unit 82, an acquiring unit 84, a generating unit 86, and a notifying unit 88. The timing specifying unit 80 includes an extracting unit 90 and a carrier sense unit 92. The antenna 70, the RF unit 72, the modem unit 74, the timing specifying unit 80, and the transfer determining unit 82 perform the same processing as the antenna 40, the RF unit 42, the modem unit 44, the timing specifying unit 52, and the transfer determining unit 54 in FIG. Execute. Therefore, here, the difference will be mainly described.

The acquisition unit 84 includes a GPS receiver (not shown), a gyroscope, a vehicle speed sensor, and the like. Based on data supplied from these, the location of the vehicle 12 (not shown), that is, the position of the vehicle 12 on which the terminal device 130 is mounted, the progress The direction, the moving speed, etc. (hereinafter collectively referred to as “position information”) are acquired. The existence position is indicated by latitude and longitude. Since a known technique may be used for these acquisitions, description thereof is omitted here. The acquisition unit 84 outputs the position information to the generation unit 86.

The generation unit 86 receives position information from the acquisition unit 84 and receives an RSU control header from the transfer determination unit 82. The generation unit 86 uses the physical frame shown in FIGS. 4A to 4B and stores the position information in the payload. Furthermore, the generation unit 86 sets the transmission node type in the terminal device 130 and sets the usage period information to the vehicle transmission period. The generation unit 86 generates a packet signal having a physical frame configuration, and transmits the generated packet signal via the modem unit 74, the RF unit 72, and the antenna 70 at the transmission timing determined by the carrier sense unit 92. Broadcast transmission.

The notification unit 88 acquires a packet signal from the control base station device 110 (not shown) during the road and vehicle transmission period, and from the CSMA base station device 120 and other terminal devices 130 (not shown) during the vehicle transmission period. Get packet signal. As a process for the acquired packet signal, the notification unit 88 notifies the driver of the approach of another vehicle 12 (not shown) or the like via a monitor or a speaker according to the content of the data stored in the packet signal. The control unit 78 controls the overall operation of the terminal device 130.

The operation of the communication system 100 configured as above will be described. FIG. 7 is a flowchart showing a reception procedure in the terminal device 130. If the transmission node type indicates the base station device 10 (Y in S10) and the road and vehicle transmission period is used (Y in S12), the extraction unit 90 executes timing synchronization (S14). When the transmission node type does not indicate the base station device 10 (N in S10), or when the road and vehicle transmission period is not used (N in S12), step 14 is skipped. The notification unit 88 extracts information included in the packet signal (S16) and notifies it (S18).

Next, a first modification of the present invention will be described. The first modification also relates to the communication system 100 including the control base station device 110, the CSMA base station device 120, and the terminal device 130, as in the embodiment. In the first modification, the format of the physical frame for notifying the type of the notification source is different from that in the embodiment. The communication system 100, the control base station device 110, the CSMA base station device 120, and the terminal device 130 according to the modification are of the same type as those shown in FIG. 1, FIG. 2, FIG. Here, the difference will be mainly described.

FIG. 8 shows a packet signal format according to the first modification. In the RSU control header, “protocol version”, “transfer count / reuse count”, “reserve”, “TSF timer”, “RSU transmission period length”, “reserve” are arranged, and in the payload, “transmission node” "Type" is included. The “transfer count / reuse count” is set to “0” when directly transmitted from the control base station apparatus 110, and is “1 or more” when transmitted from the CSMA base station apparatus 120 or the terminal apparatus 130. "Is set. The former corresponds to the processing in the generation unit 36, and the latter corresponds to the processing in the generation unit 56 and the generation unit 86. The transmission node type indicates the type of the transmission node. This is similar to the embodiment. Therefore, the processing unit 26 includes, in the payload, a transmission node type indicating whether the transmission node is fixedly installed or movable.

Next, a second modification of the present invention will be described. The second modification also relates to the communication system 100 including the control base station apparatus 110, the CSMA base station apparatus 120, and the terminal apparatus 130, as before. In the second modification, installation of the control base station apparatus 110 and the CSMA base station apparatus 120 will be described. The control base station apparatus 110, the CSMA base station apparatus 120, and the terminal apparatus 130 according to the modification are of the same type as those shown in FIGS. Here, the difference will be mainly described.

FIG. 9 shows a configuration of a communication system 100 according to the second modification. In FIG. 9, roads are shown in the left and right directions, and as an example, five intersections are arranged side by side. From the leftmost intersection to the rightmost intersection, the first control base station device 110a, the first CSMA base station device 120a, the second control base station device 110b, and the second CSMA base station device 120b are respectively connected to the intersections. The third control base station apparatus 110c is installed in order. That is, one of the control base station apparatus 110 and the CSMA base station apparatus 120 is installed at one intersection.

Also, the control base station apparatus 110 is installed at one of the adjacent intersections, and the CSMA base station apparatus 120 is installed at the other of the adjacent intersections. Here, the adjacent intersection may be only the intersection where the base station apparatus 10 is installed. That is, when three intersections are arranged and the base station apparatus 10 is not installed at the central intersection, the control base station apparatus 110 and the CSMA base station apparatus 120 are installed at the intersections at both ends, respectively. Is also included in the neighborhood. Also, installation is performed such that the number of control base station apparatuses 110 and the number of CSMA base station apparatuses 120 are close to each other within a predetermined range.

FIG. 10 shows another configuration of the communication system 100 according to the second modification. A first control base station apparatus 110a and a first CSMA base station apparatus 120a are installed at the leftmost intersection. Similarly, for other intersections, the control base station apparatus 110 and the CSMA base station apparatus 120 are installed at one intersection.

FIG. 11 shows the configuration of the control / CSMA base station apparatus 140 according to the second modification. The control / CSMA base station apparatus 140 includes an antenna 150, an RF unit 152, a processing unit 156, and a control unit 158. The processing unit 156 includes a control processing unit 162, a CSMA processing unit 164, and a setting unit 166. . The antenna 150, the RF unit 152, the modem unit 154, and the network communication unit 160 execute the same processing as the antenna 20, the RF unit 22, the modem unit 24, and the network communication unit 30 in FIG. Further, the control processing unit 162 executes the same processing as the processing unit 26 in FIG. 2, and the CSMA processing unit 164 executes the same processing as the processing unit 46 in FIG.

The control / CSMA base station apparatus 140 is disposed at each intersection and has the function of the control base station apparatus 110 and the function of the CSMA base station apparatus 120. These functions are switched by the setting unit 166. The provider inputs the setting to the setting unit 166 so that only one of the functions is operated when the control / CSMA base station apparatus 140 is installed at the intersection. The setting unit 166 operates the control processing unit 162 or the CSMA processing unit 164 based on the input setting.

Alternatively, the setting unit 166 may switch the operation of the control processing unit 162 and the CSMA processing unit 164 at a predetermined frequency. For example, the setting unit 166 operates the control processing unit 162 in the daytime and operates the CSMA processing unit 164 at nighttime. Therefore, although it is time division, the control base station apparatus 110 and the CSMA base station apparatus 120 are installed at one intersection.

FIG. 12 shows still another configuration of the communication system 100 according to the second modification. The communication system 100 includes a control base station apparatus usage area 170 and a CSMA base station apparatus usage area 180. These are regions having an area such as 1 square kilometer. The area of the region is not limited to 1 square kilometer. The control base station apparatus use area 170 includes a plurality of intersections (not shown), and the CSMA base station apparatus use area 180 also includes a plurality of intersections (not shown). At the intersection included in the control base station device usage area 170, only the control base station device 110 is installed, and the CSMA base station device 120 is not installed. On the other hand, at the intersection included in the CSMA base station apparatus usage area 180, only the CSMA base station apparatus 120 is disposed, and the control base station apparatus 110 is not disposed.

That is, the control base station device 110 is arranged at each of a plurality of consecutive intersections in the control base station device use area 170, and is defined without overlapping with the control base station device use area 170. The CSMA base station apparatus 120 is arranged at each of a plurality of continuous intersections in the CSMA base station apparatus use area 180. Therefore, in these areas, one of the control base station apparatus 110 and the CSMA base station apparatus 120 is installed in common at a plurality of intersections.

FIG. 13 shows still another configuration of the communication system 100 according to the second modification. In the communication system 100, the first area 190a and the second area 190b collectively referred to as the area 190 are defined so as not to overlap each other. In the first area 190a, the first control base station device 110a, the second control base station device 110b, the third control base station device 110c, the fourth control base station device 110d, and the first CSMA base station device 120a are provided. Is installed. Further, in the second region 190b, the second CSMA base station apparatus 120b, the third CSMA base station apparatus 120c, the fifth control base station apparatus 110e, the sixth control base station apparatus 110f, and the seventh control base station apparatus. 110 g is installed.

Area 190 is an area such as a prefecture, city, or police station jurisdiction. FIG. 13 shows that a control base station apparatus 110 and a CSMA base station apparatus 120 are installed at intersections (not shown) of the respective areas 190. Here, for the sake of simplicity, it is assumed that the total number of control base station devices 110 and CSMA base station devices 120 is “5”, but the actual number is larger than that. Thus, in each area 190, the control base station apparatus 110 and the CSMA base station apparatus 120 are mixed.

Here, the installation ratio between the control base station apparatus 110 and the CSMA base station apparatus 120 (hereinafter simply referred to as “installation ratio”) will be described. Here, the installation ratio in the first region 190a is 80%: 20%. On the other hand, the installation ratio in the second region 192 is 60%: 40%. Therefore, although the installation ratio differs for each area 190, the control base station apparatus 110 is higher in any area 190.

Of these installation ratios, focusing on the value of the CSMA base station apparatus 120, the value is 20% in the

first area

190a and 40% in the second area 190b. Here, it is assumed that the population density of the second region 190b is higher than the population density of the first region 190a. That is, the value of the CSMA base station apparatus 120 in the installation ratio is designed to be higher in a region with a higher population density when different regions 190 are compared with each other.

According to the embodiment of the present invention, since the transmission node type and the usage period information can be included in the RSU control header, it is possible to distinguish which of the three types of devices the notification source of the packet signal corresponds to. As a result, processing corresponding to the type of device can be executed. Further, since it is possible to specify that the notification source of the packet signal is the control base station apparatus, timing synchronization can be executed in that case. Moreover, since the format of the RSU control header can be made common regardless of the type of the device that is the packet signal notification source, the processing can be simplified. In addition, since information regarding the number of transfers can be inserted into the RSU control header and the transmission node type can be inserted into the payload, it is possible to distinguish which of the three types of devices the notification source of the packet signal corresponds to. In addition, since the transmission node type can be inserted into the payload, information can be expanded as necessary.

Moreover, since not only the control base station apparatus but also the CSMA base station apparatus can be provided, it is possible to notify information that occurs irregularly with a packet signal that can be broadcast as necessary, and An efficient notification can be made. Further, in the CSMA base station apparatus, since the vehicle transmission period can be used without using the road and vehicle transmission period, it is unnecessary to periodically notify the packet signal, and as a result, the use of the frequency Efficiency can be improved. In addition, since it is possible to perform control so that information generated periodically is reported from the control base station apparatus and information generated irregularly is reported from the CSMA base station apparatus, a flexible service can be provided. In addition, since less important information can be reported from the CSMA base station apparatus, it is possible to avoid occupying a band, and as a result, it is possible to improve frequency utilization efficiency. Also, since highly important information can be reported from the control base station apparatus, the reliability of transmission can be improved.

In addition, since one of the control base station apparatus and the CSMA base station apparatus can be installed at one intersection, the installation cost can be suppressed even when installing base stations at a plurality of intersections. Notification can be executed efficiently. In addition, since the control base station apparatus and the CSMA base station apparatus can be installed at adjacent intersections, the CSMA base station apparatus operates in synchronization with the frame generated by the control base station apparatus. Can be made. Further, since the CSMA base station apparatus can be operated so as to be synchronized with the frame generated by the control base station apparatus, the collision probability of the packet signal can be reduced.

In addition, since both the control base station device and the CSMA base station device can be installed at one intersection, the information from each of the control base station device and the CSMA base station device can be reliably received by the terminal device. Can be transmitted. In addition, since the functions of the control base station device and the CSMA base station device can be integrated into one base station device, any one of the functions can be flexibly realized. In addition, since only one of the control base station apparatus and the CSMA base station apparatus can be installed in a predetermined area, the processing in a plurality of base station apparatuses can be shared.

In addition, although an arbitrary installation ratio is set for each area, since the control base station apparatus is larger than the CSMA base station apparatus in the installation ratio, safety and security can be improved. Also, entertainment information such as video can be broadcast from the CSMA base station device, but the higher the population density, the higher the installation ratio of the CSMA base station device, so that it is in line with user demand. Satisfaction can be provided.

The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

The outline of one embodiment of the present invention is as follows. A communication system according to an aspect of the present invention includes a first type of base station apparatus and a second type of base station apparatus. The first type base station apparatus reports a signal in the first period, and the second type base station apparatus is a period different from the first period, and the terminal apparatus can report the signal. Signals are broadcast during the specified second period, and the first type base station device and the second type base station device are installed at different intersections.

According to this aspect, since the second type base station apparatus broadcasts the signal in a period in which the terminal apparatus can broadcast the signal, the frequency utilization efficiency can be improved without occupying the band.

The first type base station apparatus may be installed at one of the adjacent intersections, and the second type base station apparatus may be installed at the other of the adjacent intersections. Since the first type base station device and the second type base station device are installed at adjacent intersections, it becomes easier to establish timing synchronization with each other, and the probability of signal collision can be reduced.

The first type base station apparatus and the second type base station apparatus may be mixed and installed in a predetermined area.

The first type base station apparatus is higher in the installation ratio of the first type base station apparatus and the second type base station apparatus in a predetermined area. Since there are more first type base station apparatuses that should be notified of signals in the first period, the signal transmission probability is improved, and safety and security can be improved.

The value (a) of the second type base station device at the installation ratio of the first type base station device and the second type base station device in the first region, and the population density of the first region In the value (b) of the second type base station apparatus at the installation ratio of the first type base station apparatus and the second type base station apparatus in the higher second region, the latter is higher (a <B). As the population density increases, the installation ratio of the second type base station apparatus that can control the communication volume is increased, so that the satisfaction can be improved in accordance with the user demand.

A first type of base station apparatus is arranged at each of a plurality of continuous intersections, and is different from a plurality of intersections at which each of the first type of base station apparatuses is arranged, and at each of a plurality of continuous intersections. The second type base station apparatus may be arranged. In a section surrounded by a plurality of continuous intersections, a signal from any of the base station devices can be preferentially transmitted.

Another aspect of the present invention is also a communication system. This communication system includes a first type base station apparatus and a second type base station apparatus. The first type base station apparatus reports a signal in the first period, and the second type base station apparatus is a period different from the first period, and the terminal apparatus can report the signal. The signal is broadcast during the specified second period, and the first type base station device and the second type base station device are installed at the same intersection.

According to this aspect, the information from each of the first type base station device and the second type base station device can be reliably transmitted by the terminal device.

In the communication system, the first period and the second period are time-division multiplexed in the frame, and the first period is a period for the first type base station apparatus to broadcast and transmit the packet signal.

The first type base station apparatus and the second type base station apparatus may be used for ITS (Intelligent Transport Systems).

Still another aspect of the present invention is a base station apparatus. The apparatus includes a first communication unit that notifies a signal in the first period, and a signal that is different from the first period and that is defined in a period in which the terminal apparatus can notify the signal. And a setting unit for setting the operation of one of the first communication unit and the second communication unit.

According to this aspect, since two types of communication functions are implemented, either function can be flexibly realized.

In the base station apparatus, the first period and the second period are time-division multiplexed in a frame, and the first period is a period for the base station apparatus to broadcast-transmit a packet signal.

The first communication unit and the second communication unit may be applied to ITS (Intelligent Transport Systems).

Still another aspect of the present invention is a wireless device. This device broadcasts a packet signal in a first period in a frame, and broadcasts a packet signal in a second period different from the first period in a frame, a first type wireless device installed fixedly And a wireless device corresponding to any of the second type of wireless device that is fixedly installed and the third type of wireless device that reports a packet signal in the second period in the frame and is movable. A generation unit that generates a packet signal in which a data signal is arranged following the control signal, and a notification unit that notifies the packet signal generated in the generation unit. The generation unit includes first information indicating whether the wireless device is fixedly installed or movable, and the wireless device uses the first period or uses the second period. The control signal is generated so as to include the second information indicating whether or not to do so.

According to this aspect, since the first information and the second information are included, it is possible to specify which type of wireless device is based on the combination thereof.

Still another aspect of the present invention is also a wireless device. This apparatus broadcasts a packet signal including non-transfer information in a first period in a frame, and is a first type of wireless apparatus that is fixedly installed, and a first type different from the first period in a frame Informing the packet signal including the transfer information in the two periods, and informing the packet signal including the transfer information in the second period in the frame, the second type wireless device fixedly installed, And a wireless device corresponding to one of the movable third-type wireless devices, which generates a packet signal in which a data signal is arranged following a control signal, and is generated in the generating unit An informing unit for informing the packet signal. The generation unit generates a control signal so as to include first information related to the number of transfers, and includes data so as to include second information indicating whether the wireless apparatus is fixedly installed or movable. Generate a signal.

In the wireless device, the first period and the second period are time-division multiplexed in the frame, and the first period is a period for the first type wireless device to broadcast the packet signal.

10 base station devices, 12 vehicles, 20 antennas, 22 RF units, 24 modulation / demodulation units, 26 processing units, 28 control units, 30 network communication units, 32 frame definition units, 34 selection units, 36 generation units, 40 antennas, 42 RF Unit, 44 modulation / demodulation unit, 46 processing unit, 48 control unit, 50 network communication unit, 52 timing identification unit, 54 transfer determination unit, 56 generation unit, 58 extraction unit, 60 carrier sense unit, 70 antenna, 72 RF unit, 74 Modulation / demodulation unit, 76 processing unit, 78 control unit, 80 timing identification unit, 82 transfer determination unit, 84 acquisition unit, 86 generation unit, 88 notification unit, 90 extraction unit, 92 carrier sense unit, 100 communication system, 1 0 control base station apparatus, 120 CSMA base station apparatus 130 terminal.

Claims

A first type base station apparatus and a second type base station apparatus;
The first type base station apparatus broadcasts a signal in a first period,
The second type base station apparatus broadcasts a signal in a second period that is different from the first period and that is defined as a period in which the terminal apparatus can broadcast the signal,
The communication system, wherein the first type base station apparatus and the second type base station apparatus are installed at different intersections.
2. The communication according to claim 1, wherein the first type base station apparatus is installed at one of adjacent intersections, and the second type base station apparatus is installed at the other of the adjacent intersections. system.
The communication system according to claim 1 or 2, wherein the first type base station apparatus and the second type base station apparatus are installed in a mixed manner in a predetermined area.
4. The installation ratio of the first type base station apparatus and the second type base station apparatus in a predetermined area is higher in the first type base station apparatus. Communication system.
The value (a) of the second type base station apparatus at the installation ratio of the first type base station apparatus and the second type base station apparatus in the first area, and more than the first area The value (b) of the second type base station apparatus at the installation ratio of the first type base station apparatus and the second type base station apparatus in the second region having a high population density is the latter. The communication system according to claim 3, wherein is higher (a <b).
The first type of base station apparatus is arranged at each of a plurality of continuous intersections, and is different from the plurality of intersections at which the first type of base station apparatuses are respectively arranged, and a plurality of continuous intersections. The communication system according to claim 1, wherein each of the second type base station apparatuses is arranged.
A first type base station apparatus and a second type base station apparatus;
The first type base station apparatus broadcasts a signal in a first period,
The second type base station apparatus broadcasts a signal in a second period that is different from the first period and that is defined as a period in which the terminal apparatus can broadcast the signal,
The communication system characterized in that the first type base station apparatus and the second type base station apparatus are installed at the same intersection.
The first period and the second period are time-division multiplexed in a frame, and the first period is a period for the first type base station apparatus to broadcast-transmit a packet signal. Item 8. The communication system according to any one of Items 1 to 7.
The communication system according to any one of claims 1 to 8, wherein the first type base station apparatus and the second type base station apparatus are used for ITS (Intelligent Transport Systems).
A first communication unit for reporting a signal in the first period;
A second communication unit that reports a signal in a second period that is different from the first period and that is defined as a period in which the terminal device can report the signal;
A setting unit for setting the operation of one of the first communication unit and the second communication unit;
A base station apparatus comprising:
The first period and the second period are time-division multiplexed in a frame, and the first period is a period for the base station apparatus to broadcast and transmit a packet signal. Base station equipment.
The base station apparatus according to claim 10 or 11, wherein the first communication unit and the second communication unit are applied to ITS (Intelligent Transport Systems).
A packet signal is broadcast in the first period in the frame, and the first type wireless device is fixedly installed. The packet signal is broadcast and fixed in a second period different from the first period in the frame. A wireless device corresponding to any one of the second type wireless devices installed in the frame, the third type wireless device that broadcasts the packet signal in the second period in the frame and is movable,
A generation unit for generating a packet signal in which a data signal is arranged following the control signal;
A notification unit for reporting the packet signal generated in the generation unit,
The generating unit includes first information indicating whether the wireless device is fixedly installed or movable, and whether the wireless device uses the first period or the second period. A radio apparatus that generates a control signal so as to include second information indicating whether to use the second information.
A packet signal that contains non-transfer information in the first period in the frame, and is transmitted in a second period that is different from the first period in the frame. A second type of wireless device installed in a fixed manner, a packet signal containing transfer information in the second period in the frame, and movable. A wireless device corresponding to any one of the third type wireless devices,
A generation unit for generating a packet signal in which a data signal is arranged following the control signal;
A notification unit for reporting the packet signal generated in the generation unit,
The generation unit generates a control signal so as to include first information regarding the number of transfers, and includes second information indicating whether the wireless apparatus is fixedly installed or movable. A wireless device for generating a data signal.
The first period and the second period are time-division multiplexed in a frame, and the first period is a period for the first type wireless device to broadcast and transmit a packet signal. The wireless device according to 13 or 14.