WO2013042383A1

WO2013042383A1 - Wireless equipment

Info

Publication number: WO2013042383A1
Application number: PCT/JP2012/006033
Authority: WO
Inventors: 俊朗中莖; 土居　義晴; 真琴永井
Original assignee: 三洋電機株式会社
Priority date: 2011-09-22
Filing date: 2012-09-21
Publication date: 2013-03-28
Also published as: JPWO2013042383A1

Abstract

A generating section (36) divides data into a plurality of partial data items and generates a plurality of packet signals by including the partial data items in the packet signals. The plurality of packet signals generated in the generating section (36) may be of two different sizes. Specifically, the size of the packet signal generated in the generating section (36) may have a maximum value that is specified as the packet signal size, or a value smaller than the maximum value. A modem section (24) and an RF section (22) report the plurality of packet signals that are generated.

Description

Wireless device

The present invention relates to communication technology, and more particularly, to a radio apparatus that broadcasts 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. Road-to-vehicle communication requires the installation of roadside equipment, which increases labor and cost. On the other hand, if it is the form which communicates information between vehicle-to-vehicle communication, ie, onboard equipment, installation of a roadside machine will become unnecessary. In this case, for example, the current position information is detected in real time by GPS (Global Positioning System), etc., and the position information is exchanged between the vehicle-mounted devices so that the own vehicle and the other vehicle each enter the intersection. (See, for example, Patent Document 1).

JP 2005-202913 A

When the size of the data to be transmitted increases, it becomes necessary to divide the data. Even when data is divided to generate a plurality of packet signals, efficient processing 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 processing when a plurality of packet signals are generated.

In order to solve the above problems, a radio apparatus according to an aspect of the present invention includes a generation unit that generates a plurality of packet signals by dividing the data into a plurality of partial data and then including the partial data in the packet signal. And a notification unit for reporting a plurality of packet signals generated by the generation unit. There are two types of packet signals generated in the generation unit.

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, when a plurality of packet signals are generated, the processing 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 base station apparatus of FIG. FIGS. 3A to 3D are diagrams showing frame formats defined in the communication system of FIG. 4A and 4B are diagrams showing the format of a packet signal generated by the base station apparatus of FIG. FIGS. 5A and 5B are diagrams showing the configuration of layers defined in the communication system of FIG. FIGS. 6A and 6B are diagrams showing a configuration of a road and vehicle transmission period used by the base station apparatus of FIG. It is a figure which shows the structure of the terminal device mounted in the vehicle of FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to specific description of embodiments of the present invention, the knowledge that is the basis will be described. 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, ITS (Intelligent Transport Systems) is stipulated in, for example, 700 MHz band highway traffic system standards (General Electric Industries Association). When a wireless LAN is applied to inter-vehicle communication such as ITS, it is necessary to transmit information to an unspecified number of terminal devices, and therefore it is desirable that the signal be transmitted by broadcast. 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, if the data broadcasted by road-to-vehicle communication increases, it becomes necessary to divide the data in order to store it in the packet signal.

Next, the outline of the embodiment of the present invention will be described. 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 a packet signal that stores information such as the speed or position of the vehicle. In addition, the other terminal device receives the packet signal and recognizes the approach of the vehicle based on the above-described information. 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.

The base station apparatus broadcasts a packet signal during the road-to-vehicle transmission period, but a maximum value is determined for the size of data that can be stored in the packet signal. When the size of data to be broadcast exceeds the maximum value, the base station apparatus broadcasts a plurality of packet signals in the road and vehicle transmission period by dividing the data into a plurality of data. At this time, it is desired to suppress an increase in processing for a packet signal divided into a plurality of parts. In order to cope with this, the base station apparatus according to the present embodiment executes the following processing. The base station apparatus divides the data so that the size of the packet signal is limited to two types. Specifically, the base station apparatus sequentially divides the data so that the maximum value that can be stored in the packet signal is obtained, and finally acquires divided data having a size smaller than the maximum value.

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. Here, only the first vehicle 12 a is shown, but each vehicle 12 is equipped with a terminal device 14. 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. The base station device 10 controls communication between terminal devices. Base station apparatus 10 repeatedly generates a frame including a plurality of subframes based on a signal received from a GPS satellite (not shown) or a frame formed by another base station apparatus 10 (not shown). Here, the road vehicle transmission period can be set at the head of each subframe. The base station apparatus 10 selects a subframe in which the road and vehicle transmission period is not set by another base station apparatus 10 from among a plurality of subframes in the frame. The base station apparatus 10 sets a road and vehicle transmission period at the beginning of the selected subframe.

The base station apparatus 10 broadcasts a packet signal during the set road and vehicle transmission period. In the road and vehicle transmission period, a plurality of packet signals may be notified. In addition, as data to be included in the packet signal, for example, dynamic data and static data are defined. Dynamic data is data whose contents are frequently updated, and static data is data whose update frequency is lower than that of dynamic data. The former is data with high real-time property, and the latter can be said to be data with low real-time property. For example, dynamic data is sensor information and signal information, and static data is road alignment, area, information on obstacles, and sensor position. Note that the packet signal also includes information related to the timing at which the road and vehicle transmission period is set or control information related to the frame.

Since the terminal device 14 is mounted on the vehicle 12 as described above, the terminal device 14 is movable. When the terminal device 14 receives the packet signal from the base station device 10, the terminal device 14 generates a frame based on the control information included in the packet signal, in particular, the information on the timing when the road-to-vehicle transmission period is set or the information on the frame. To do. As a result, the frame generated in each of the plurality of terminal devices 14 is synchronized with the frame generated in the base station device 10. The terminal device 14 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 14 acquires data and stores the data in a packet signal. The data includes, for example, information related to the location. The terminal device 14 also stores control information received from the base station device 10 in the packet signal. That is, the control information transmitted from the base station device 10 is transferred by the terminal device 14. On the other hand, when it is estimated that the terminal apparatus 14 exists outside the area 214, the terminal apparatus 14 notifies the packet signal by executing CSMA / CA regardless of the frame configuration.

FIG. 2 shows the configuration of the base station apparatus 10. The base station apparatus 10 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 14 (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 processing corresponds to generating a frame synchronized with the timing of the frame formed by another base station apparatus 10.

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. This can be said that the terminal device 14 forms a frame by multiplexing a plurality of subframes that can be used for notification for a plurality of hours. 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. Here, an instruction regarding a subframe to be selected is received from the outside. Although details of this processing will be described later, the selection unit 34 selects a subframe in accordance with the instruction. Multiple subframes may be selected. In addition, the road and vehicle transmission period which can be used for alerting | reporting by the base station apparatus 10 can be set to each sub-frame contained in the frame.

Alternatively, the selection unit 34 may automatically select a subframe. At this time, the selection unit 34 inputs a demodulation result from another base station device 10 or the terminal device 14 (not shown) via the RF unit 22 and the modem unit 24. The selection part 34 extracts the demodulation result from the other base station apparatus 10 among 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 base station apparatus 10, 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 base station apparatus 10a. The first base station apparatus 10a sets a road and vehicle transmission period at the beginning of the first subframe. Moreover, the 1st base station apparatus 10a sets a vehicle transmission period following the road and vehicle transmission period in a 1st sub-frame. The vehicle transmission period is a period during which the terminal device 14 can notify the packet signal. That is, the first base station apparatus 10a can notify the packet signal in the road and vehicle transmission period which is the first period of the first subframe, and the terminal apparatus in the vehicle and vehicle transmission period other than the road and vehicle transmission period in the frame. It is specified that 14 can broadcast the packet signal. Furthermore, the first base station apparatus 10a 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 base station apparatus 10b. The second base station apparatus 10b sets a road and vehicle transmission period at the beginning of the second subframe. Also, the second base station apparatus 10b sets the vehicle transmission period from the first stage of the road and vehicle transmission period in the second subframe, from the first subframe and the third subframe to the Nth subframe. FIG. 3D shows a configuration of a frame generated by the third base station apparatus 10c. The third base station apparatus 10c sets a road and vehicle transmission period at the beginning of the third subframe. Also, the third base station apparatus 10c sets the vehicle transmission period from the first 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. As described above, the plurality of base station apparatuses 10 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 the road and vehicle transmission period in the subframe of the received subframe number. Moreover, the production | generation part 36 produces | generates the some packet signal which should be alert | reported in a road and vehicle transmission period by dividing the data used as alert | reporting object into several partial data, and including a partial data in a packet signal. Here, the generation unit 36 generates at least one partial data by dividing the data for each maximum value of data that can be stored in the packet signal. Such processing is repeated until data having a size smaller than the maximum value remains, and the generation unit 36 sets the remaining data as the last partial data.

As a result of such processing, the size of the packet signal generated by the generation unit 36 is limited to two types: a maximum value defined as the size of the packet signal and a value smaller than the maximum value. Each packet signal is composed of, for example, control information and a data payload. The control information includes a subframe number in which a road and vehicle transmission period is set. The partial data is stored in the data payload. Note that static data or dynamic data that is data before division is acquired from the network 202 (not shown) by the network communication unit 30.

4 (a)-(b) show the format of a packet signal generated by the base station apparatus 10. 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. A physical frame corresponds to the packet signal described above.

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.

FIG. 4B is a diagram illustrating a configuration of the RSU control header generated by the generation unit 36. In the RSU control header, “protocol version”, “transmission node type”, “transfer count / reuse count”, “reserve”, “TSF timer”, “RSU transmission period length”, and “reserve” are 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 14 are defined as types of transmission nodes.

The transfer count / reuse count indicates an index of validity when the RSU control header is transferred by the terminal device 14, and the TSF timer indicates the 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. Returning to FIG. The processing unit 26 causes the modem unit 24 and the RF unit 22 to broadcast-transmit a plurality of packet signals during the road and vehicle transmission period. Here, for example, a plurality of packet signals are broadcast at SIFS (Short Inter Frame Space) intervals. The control unit 28 controls processing of the entire base station device 10.

In the following, the processing related to setting of road and vehicle transmission period, static data and dynamic data will be described in detail. FIGS. 5A and 5B show layer configurations defined in the communication system 100. FIG. FIG. 5A shows a layer configuration for transmission processing, and FIG. 5B shows a layer configuration for reception processing. Therefore, in the case of road-to-vehicle communication, the former corresponds to the layer configuration in the base station device 10 and the latter corresponds to the layer configuration in the terminal device 14. Here, FIG. 5A will be described. The transmission control layer, the packet division / combination layer, the security layer, the MAC layer, and the PHY layer are included in the modem unit 24 and the processing unit 26 in FIG. 2, and radio signal transmission is included in the RF unit 22 in FIG. The packet division / combination layer, security layer, MAC layer, and PHY layer are grouped as baseband processing, and radio signal transmission is grouped as RF processing.

Furthermore, for concrete explanation, the size of the static data is 4 kB, the size of the dynamic data is 3 kB, the maximum size of the data payload is 1.5 kB, and can be transmitted in the road and vehicle transmission period. Assume that the maximum size is 4 kB. Note that the present invention is not limited to these values. In the above values, redundant bits generated by security processing or encoding are ignored, and they may be considered.

The transmission control layer accepts static data and dynamic data separately. This corresponds to accepting data for each application program. The transmission control layer divides each data so that the maximum is about 4 kB. As described above, if the size of static data is 4 kB and the size of dynamic data is 3 kB, no division is required. That is, the maximum size of data output from the transmission control layer is a size that can be transmitted in one road-vehicle transmission period. The transmission control layer outputs static data and dynamic data separately.

The packet division / combination layer divides data within the road and vehicle transmission period when the data size from the application exceeds the number of bytes that can be transmitted with one packet signal. That is, the packet division / combination layer performs division on the static data and the dynamic data so that the data size is smaller than 1.5 kB. This is because each data is stored in the data payload. At that time, a plurality of packet signals are generated. If the size of static data or dynamic data received from the transmission control layer does not exceed 1.5 kB, the packet division / combination layer does not have to execute division. The security layer executes security processing for each data. The MAC layer generates a MAC frame based on the data from the security layer, and the PHY layer generates a packet signal so as to store the MAC frame, and executes IFFT. As a result, a plurality of packet signals can be generated even for one road and vehicle transmission period. FIG. 5B will be described later.

Hereinafter, the configuration of the road and vehicle transmission period set by the base station apparatus 10 will be described. FIGS. 6A to 6B show the configuration of the road and vehicle transmission period used by the base station apparatus 10. FIG. 6A shows that the first to M-th packet signals are broadcast at SIFS intervals during the road and vehicle transmission period. Here, the size of the first to M−1th packet signals is a maximum value, and the size of the Mth packet signal is a value smaller than the maximum value, that is, a fraction. The advantage of such division is that the size of partial data other than the partial data to be stored in the last packet signal is fixed, so that the division processing is simplified. In addition, the number of packet signals after division is minimized, and the addition and processing of control information necessary for each packet signal is reduced.

Further, as a modification of FIG. 6A, a variable-length packet signal (hereinafter referred to as “the 0th packet signal”) may be notified before the first packet signal. The size of the 0th packet signal is variable depending on the header contents. The advantage of such division is that the portion whose size varies depending on the header content and the large data portion are processed separately, so that even if the size changes depending on the header content, the processing becomes simple.

Up to now, a plurality of packet signals having two types of sizes have been generated, but a plurality of packet signals having one type may be generated as shown in FIG. 6B. At that time, the generation unit 36 equally divides the data into a plurality of partial data, and then includes the partial data in the packet signal. As a result, a plurality of packet signals of one kind of size are generated. Here, the size of the packet signal is determined according to the number of packet signals that can be notified during the road and vehicle transmission period. That is, a plurality of minimum-size packet signals are generated under the condition that the sizes are uniform. An advantage of such division is that the influence of frequency fluctuations in the packet signal is reduced by reducing the size.

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. 7 shows the configuration of the terminal device 14 mounted on the vehicle 12. The terminal device 14 includes an antenna 50, an RF unit 52, a modem unit 54, a processing unit 56, and a control unit 58. The processing unit 56 includes a timing specifying unit 60, a transfer determination unit 62, an acquisition unit 64, a generation unit 66, and a notification unit 70. The timing identification unit 60 includes an extraction unit 72 and a carrier sense unit 74. The antenna 50, the RF unit 52, and the modem unit 54 execute the same processing as the antenna 20, the RF unit 22, and the modem unit 24 in FIG. Here, the difference will be mainly described.

The modem unit 54 and the processing unit 56 receive a packet signal from another terminal device 14 or the base station device 10 (not shown) in the reception process. As described above, the modem unit 54 and the processing unit 56 receive a packet signal from the base station apparatus 10 during the road-to-vehicle transmission period, and receive packet signals from other terminal apparatuses 14 during the vehicle-to-vehicle transmission period. To do.

The extraction unit 72 specifies the timing of the subframe in which the road and vehicle transmission period is arranged when the demodulation result from the modem unit 54 is a packet signal from the base station device 10 (not shown). Specifically, the extraction unit 72 determines whether or not the packet signal is from the base station apparatus 10 based on the control information included in the packet signal. In addition, the extraction unit 72 generates a frame based on the subframe timing and the timing information included in the control information. As a result, the extraction unit 72 generates a frame synchronized with the frame formed in the base station device 10. When the notification source of the packet signal is another terminal device 14, the extraction unit 72 omits the synchronized frame generation process.

The extraction unit 72 specifies the remaining vehicle transmission period after specifying the road and vehicle transmission period in use based on the control information. The extraction unit 72 outputs information on frame and subframe timing and vehicle transmission period to the carrier sense unit 74. On the other hand, when the extraction unit 72 does not receive a packet signal from the base station apparatus 10, that is, when a frame synchronized with the base station apparatus 10 is not generated, the extraction unit 72 selects a timing unrelated to the frame configuration. When the extraction unit 72 selects a timing unrelated to the frame configuration, the extraction unit 72 instructs the carrier sense unit 74 to perform carrier sensing unrelated to the frame configuration. This corresponds to the operation outside the area 214 in FIG.

The carrier sense unit 74 receives information on frame and subframe timing and vehicle transmission period from the extraction unit 72. The carrier sense unit 74 determines the transmission timing by starting CSMA / CA within the vehicle transmission period. On the other hand, when the carrier sense unit 74 is instructed to perform carrier sense from the extraction unit 72, the carrier sense unit 74 determines the transmission timing by executing CSMA / CA without considering the frame configuration. The carrier sense unit 74 notifies the modem unit 54 and the RF unit 52 of the determined transmission timing, and broadcasts the packet signal.

The transfer determination unit 62 controls transfer of control information. The transfer determination unit 62 extracts information to be transferred from the control information. The transfer determination unit 62 generates information to be transferred based on the extracted information. Here, the description of this process is omitted. The transfer determination unit 62 outputs information to be transferred, that is, a part of the control information, to the generation unit 66. The acquisition unit 64 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 14 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 GPS receiver, gyroscope, vehicle speed sensor, and the like may be outside the terminal device 14. The acquisition unit 64 outputs the position information to the generation unit 66.

The generation unit 66 receives position information from the acquisition unit 64 and receives a part of control information from the transfer determination unit 62. The generation unit 66 generates a packet signal by storing part of the control information in the control information and storing the position information in the payload. The notification unit 70 acquires a packet signal from the base station device 10 (not shown) in the road and vehicle transmission period, and acquires a packet signal from another terminal device 14 (not shown) in the vehicle and vehicle transmission period. As a process for the acquired packet signal, the notification unit 70 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 58 controls the operation of the terminal device 14.

FIG. 5B shows the layer structure of the reception process as described above. The reception control layer, the packet division / combination layer, the security layer, the MAC layer, and the PHY layer are included in the modulation / demodulation unit 54 and the processing unit 56 in FIG. 7, and radio signal reception is included in the RF unit 52 in FIG. The packet division / combination layer, security layer, MAC layer, and PHY layer are grouped as baseband processing, and reception of radio signals is grouped as RF processing. These execute processing corresponding to each layer shown in FIG.

According to the embodiment of the present invention, since the data is divided so that there are two types of packet signal sizes, the processing can be simplified. Further, since the division is repeated at the maximum value and the remaining partial data has a different size, the division can be executed mechanically. Further, since the maximum value is used as a unit of division, the size of the packet signal after division can be increased. Further, since the size of the packet signal is increased, the ratio of redundant components is reduced, and the frequency utilization efficiency can be improved. Moreover, since the size of the packet signal is increased, the number of packet signals can be reduced. Note that the packet signal size may be one type instead of two. In this case, since the data is divided so that the size of the packet signal becomes one type, the processing can be simplified. Further, since the size of the packet signal is reduced, the influence of fluctuations in the propagation environment can be reduced.

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 each of those constituent elements or combinations of processing processes, and such modifications are also within the scope of the present invention. .

In the embodiment of the present invention, the generation unit 36 divides data on the basis of the data size. However, the present invention is not limited to this. For example, when the communication speed of the packet signal notified from the modem unit 24 and the RF unit 22 is variable, the generation unit 36 determines the size of the packet signal according to the communication speed of the packet signal. May be. The communication speed is defined by a combination of modulation scheme, coding rate, and the like. Here, the division is performed so that the size of the packet signal becomes smaller as the communication speed becomes higher. For example, in the case of an error-prone parameter such as 16QAM and a coding rate of 3/4, division is performed so that the size of the packet signal is reduced. In the case of QPSK and a coding rate of 1/2, the packet is The division is performed so that the size of the signal is increased. According to this modification, frequency use efficiency can be reduced while reducing the occurrence of errors. Even when packet signals of the same size are transmitted, the transmission time varies depending on whether 16QAM and coding rate 1/2 or QPSK and coding rate 1/2. Since the road-vehicle transmission period is defined by time, the size of the division may be determined in consideration of the packet size to be transmitted during the road-vehicle transmission period.

In the embodiment of the present invention, the generation unit 36 divides data on the basis of the data size. However, the present invention is not limited to this. For example, when the partial data in the generation unit 36 is generated by dividing the encrypted data into a plurality of pieces, the generation unit 36 responds to a multiple of the block size of the encryption processing. Thus, the size of the packet signal may be determined. When it is necessary on the receiving side to combine partial packets before and after security processing, if the encryption processing block size, for example, AES (Advanced Encryption Standard), it is divided by a multiple of 16 bytes. According to this modification, security block processing can be executed in units of packet signals, and it is not necessary to hold fractional data, and processing can be simplified.

The outline of one embodiment of the present invention is as follows. A wireless device according to an aspect of the present invention includes: a generation unit configured to generate a plurality of packet signals by dividing the data into a plurality of partial data and then including the partial data in the packet signal; An informing unit for informing the packet signal. There are two types of packet signals generated in the generation unit.

According to this aspect, since the data is divided so that there are two types of packet signal sizes, the processing can be simplified.

The size of the packet signal generated in the generation unit may be a maximum value defined as the size of the packet signal and a value smaller than the maximum value. In this case, since the maximum value is set as a unit of division, the size of the divided packet signal can be increased.

Another aspect of the present invention is also a wireless device. This apparatus divides data into a plurality of partial data, and then includes the partial data in the packet signal, thereby generating a plurality of packet signals and a notification for reporting the plurality of packet signals generated in the generation unit A part. The size of the plurality of packet signals generated in the generation unit is one type.

According to this aspect, since the data is divided so that the size of the packet signal becomes one type, the processing can be simplified.

The notification unit reports a plurality of packet signals in a predetermined period, and the size of the packet signal generated in the generation unit may be determined according to the number of packet signals that can be notified in the predetermined period. Good.

The communication speed of the packet signal notified from the notification section is variable, and the size of the packet signal generated in the generation section may be determined according to the communication speed of the packet signal notified from the notification section. In this case, the frequency utilization efficiency can be reduced while reducing the occurrence of errors.

The partial data in the generation unit is generated by dividing the encrypted data into a plurality of pieces, and the size of the packet signal generated in the generation unit is determined according to a multiple of the block size of the encryption process. May be. In this case, security block processing can be executed in packet signal units, and it is no longer necessary to hold fractional data, thereby simplifying the processing.

10 base station devices, 12 vehicles, 14 terminal devices, 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, 50 Antenna, 52 RF section, 54 modulation / demodulation section, 56 processing section, 58 control section, 60 timing identification section, 62 transfer determination section, 64 acquisition section, 66 generation section, 70 notification section, 72 extraction section, 74 carrier sense section, 100 Communications system.

Claims

A generator that generates a plurality of packet signals by dividing the data into a plurality of partial data and then including the partial data in the packet signal;
A notification unit for reporting a plurality of packet signals generated in the generation unit,
The wireless device characterized in that the plurality of packet signals generated in the generation unit are of two types.
The radio apparatus according to claim 1, wherein the size of the packet signal generated by the generation unit is a maximum value defined as the size of the packet signal and a value smaller than the maximum value.
A generator that generates a plurality of packet signals by dividing the data into a plurality of partial data and then including the partial data in the packet signal;
A notification unit for reporting a plurality of packet signals generated in the generation unit,
The radio apparatus according to claim 1, wherein the plurality of packet signals generated by the generation unit have one size.
The notification unit broadcasts a plurality of packet signals in a predetermined period,
The size of the packet signal produced | generated in the said production | generation part is defined according to the number of packet signals which the said alerting | reporting part can alert | report in a predetermined period, The radio | wireless apparatus in any one of Claim 1 to 3 characterized by the above-mentioned. .
The communication speed of the packet signal notified from the notification unit is variable,
The size of the packet signal produced | generated in the said production | generation part is defined according to the communication speed of the packet signal alert | reported from the said alerting | reporting part, The radio | wireless apparatus in any one of Claim 1 to 3 characterized by the above-mentioned.
The partial data in the generation unit is generated by dividing the encrypted data into a plurality of pieces,
The radio apparatus according to claim 1, wherein the size of the packet signal generated by the generation unit is determined according to a multiple of a block size of encryption processing.