U.S. patent application number 16/167268 was filed with the patent office on 2019-02-21 for radio apparatus, processing apparatus and processing system.
The applicant listed for this patent is Panasonic Intellectual Property Management Co., Ltd.. Invention is credited to Teppei SHIBATA.
Application Number | 20190057607 16/167268 |
Document ID | / |
Family ID | 54191200 |
Filed Date | 2019-02-21 |
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United States Patent
Application |
20190057607 |
Kind Code |
A1 |
SHIBATA; Teppei |
February 21, 2019 |
RADIO APPARATUS, PROCESSING APPARATUS AND PROCESSING SYSTEM
Abstract
A first determination unit provisionally determines collision or
non-collision between a vehicle and another vehicle on the basis of
positional information of the vehicle and positional information of
the other vehicle. A second determination unit changes a
determination result to collision when the provisional
determination result has been collision N times in succession and
when the determination result was previously non-collision, and
changes the determination result to non-collision when the
provisional determination result has been non-collision M times in
succession and when the determination result was previously
collision. Here, N is smaller than M. N and M are positive integral
numbers.
Inventors: |
SHIBATA; Teppei; (Gifu,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Intellectual Property Management Co., Ltd. |
Osaka |
|
JP |
|
|
Family ID: |
54191200 |
Appl. No.: |
16/167268 |
Filed: |
October 22, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14662166 |
Mar 18, 2015 |
10140869 |
|
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16167268 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G08G 1/166 20130101;
B60Q 9/008 20130101 |
International
Class: |
G08G 1/16 20060101
G08G001/16; B60Q 9/00 20060101 B60Q009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2014 |
JP |
2014-069777 |
Oct 31, 2014 |
JP |
2014-223322 |
Claims
1. A radio apparatus configured to be mounted in a vehicle,
comprising: an acquirer configured to acquire at least one of first
positional data of the vehicle; a receiver configured to receive at
least packet signals from another radio apparatus, each of the at
least packet signals including at least one of second positional
data of another vehicle in which the another radio apparatus is
mounted, wherein the radio apparatus firstly determines each of
provisional collisions and each of provisional non-collisions
between the vehicle and the another vehicle on the basis of one of
the at least one of the first positional data and one of the at
least one of the second positional data, and the radio apparatus
secondly determines a collision or a non-collision between the
vehicle and the another vehicle based on at least two of the
provisional collisions and/or at least two of the provisional
non-collisions.
2. The radio apparatus according to claim 1, wherein after the
radio apparatus secondly determines the non-collision, the radio
apparatus changes the second determination result to the collision
when the radio apparatus determines the provisional collisions N
times in succession.
3. The radio apparatus according to claim 2, wherein after the
radio apparatus secondly determines the collision, the radio
apparatus changes the second determination result to non-collision
when the radio apparatus determines the provisional non-collisions
M times in succession, and N is smaller than M in the second
determiner.
4. The radio apparatus according to claim 3, wherein N and M are
positive integral numbers.
5. The radio apparatus according to claim 1, wherein after the
radio apparatus secondly determines the non-collision, the radio
apparatus changes the second determination result to the collision
when a ratio of the provisional collisions to the first
determination results exceeds a first threshold value.
6. The radio apparatus according to claim 5, wherein after the
radio apparatus secondly determines the collision, the radio
apparatus changes the second determination result to the
non-collision when a ratio of the provisional non-collisions in the
first determination results exceeds a second threshold value, and
the first threshold value is smaller than the second threshold
value in the second determiner.
7. A process apparatus, comprising: an acquirer that acquires a
first determination result regarding each of provisional collisions
or each of provisional non-collisions between a first vehicle and a
second vehicle, which are determined on the basis of i) one of at
least one of first positional data of a first vehicle in which a
first radio apparatus is mounted and ii) one of at least one of
second positional data of a second vehicle that is included in a
packet signal that is received from a second radio apparatus
mounted in the second vehicle by the first radio apparatus and that
at least includes at least one of second positional data of the
second vehicle, wherein the process apparatus secondly determines a
collision or a non-collision between the first vehicle and the
second vehicle based on at least two of the provisional collisions
and/or at least two of the provisional non-collisions.
8. The process apparatus according to claim 7, wherein the acquirer
includes an inputter that inputs the one of at least one of first
positional data and the one of at least one of second positional
data, and a provisional determiner that firstly determines each of
the provisional collisions or each of the provisional
non-collisions between the first vehicle and the second vehicle on
the basis of the one of at least one of first positional data and
the one of at least one of second positional data.
9. The process apparatus according to claim 7, wherein after the
process apparatus secondly determines the non-collision, the
process apparatus changes the second determination result to the
collision when the process apparatus determines the provisional
collisions N times in succession.
10. The process apparatus according to claim 9, wherein after the
radio apparatus secondly determines the collision, the process
apparatus changes the second determination result to non-collision
when the process apparatus determines the provisional
non-collisions M times in succession, and N is smaller than M in
the second determiner.
11. The process apparatus according to claim 10, wherein N and M
are positive integral numbers.
12. The process apparatus according to claim 7, wherein after the
process apparatus secondly determines the non-collision, the
process apparatus changes the second determination result to the
collision when a ratio of the provisional collisions to the first
determination results exceeds a first threshold value.
13. The process apparatus according to claim 12, wherein after the
process apparatus secondly determines the collision, the process
apparatus changes the second determination result to the
non-collision when a ratio of the provisional non-collisions in the
first determination results exceeds a second threshold value, and
the first threshold value is smaller than the second threshold
value in the second determiner.
14. A process system, comprising: a first radio apparatus that is
mounted in a first vehicle, and a process apparatus that is
connected to the first radio apparatus, wherein the radio apparatus
includes an acquirer configured to acquire at least one of first
positional data of the first vehicle; and a receiver configured to
receive at least packet signals from a second radio apparatus, each
of the at least packet signals including at least one of second
positional data of a second vehicle in which the second radio
apparatus is mounted, the radio or process apparatus firstly
determines each of provisional collisions and each of provisional
non-collisions between the first vehicle and the second vehicle on
the basis of one of the at least one of the first positional data
and one of the at least one of the second positional data, and the
radio or process apparatus secondly determines a collision or a
non-collision between the first vehicle and the second vehicle
based on at least two of the provisional collisions and/or at least
two of the provisional non-collisions.
15. The process system according to claim 14, wherein after the
radio or process apparatus secondly determines the non-collision,
the radio or process apparatus changes the second determination
result to the collision when the radio or process apparatus
determines the provisional collisions N times in succession.
16. The process system according to claim 15, wherein after the
radio apparatus secondly determines the collision, the radio or
process apparatus changes the second determination result to
non-collision when the radio or process apparatus determines the
provisional non-collisions M times in succession, and N is smaller
than M in the second determiner.
17. The process system according to claim 16, wherein N and M are
positive integral numbers.
18. The process system according to claim 14, wherein after the
radio or process apparatus secondly determines the non-collision,
the radio or process apparatus changes the second determination
result to the collision when a ratio of the provisional collisions
to the first determination results exceeds a first threshold
value.
19. The process system according to claim 18, wherein after the
radio or process apparatus secondly determines the collision, the
radio or process apparatus changes the second determination result
to the non-collision when a ratio of the provisional non-collisions
in the first determination results exceeds a second threshold
value, and the first threshold value is smaller than the second
threshold value in the second determiner.
Description
CROSS REFERENCE
[0001] This application is the Continuation Application of U.S.
application Ser. No. 14/662,166 filed Mar. 18, 2015, now allowed,
and claims the benefit of Japanese Application No. 2014-223322
filed Oct. 31, 2014 and 2014-069777 filed Mar. 28, 2014, the entire
contents of each are hereby incorporated by reference.
BACKGROUND
1. Technical Field
[0002] The present disclosure relates to a communication technique,
and particularly to a radio apparatus that receives a signal
including predetermined information, a process apparatus, and a
process system.
2. Description of the Related Art
[0003] Inter-vehicle radio communication apparatuses communicate
with one another between vehicles on the move to communicate
information on the vehicles such as driving conditions. The
inter-vehicle radio communication apparatus receives incoming
information signals and detects another vehicle which is predicted
to be in the vicinity of a position where the vehicle is
substantially heading at the same time as the other vehicle on the
basis of the information signal, and notifies the presence of the
detected other vehicle (see, for example, Japanese Unexamined
Patent Application Publication No. 2000-348299).
[0004] Further improvements of the invention of Japanese Unexamined
Patent Application Publication No. 2000-348299 are needed.
SUMMARY
[0005] In one general aspect, the techniques disclosed here feature
a radio apparatus that can be mounted in a vehicle. The radio
apparatus includes an acquirer that acquires first positional
information of a vehicle in which the radio apparatus is mounted; a
receiver that receives, from another radio apparatus, a packet
signal that includes at least second positional information of
another vehicle in which the other radio apparatus is mounted; a
first determiner that provisionally determines collision or
non-collision between the vehicle and the other vehicle on the
basis of the first positional information that is acquired by the
acquirer and the second positional information included in the
packet signal that is received by the receiver; and a second
determiner that collects a plurality of provisional determination
results from the first determiner and determines collision or
non-collision between the vehicle and the other vehicle based on
the collected plurality of the provisional determination
results.
[0006] According to one aspect, further improvement can be
achieved.
[0007] Additional benefits and advantages of the disclosed
embodiments will become apparent from the specification and
drawings. The benefits and/or advantages may be individually
obtained by the various embodiments and features of the
specification and drawings, which need not all be provided in order
to obtain one or more of such benefits and/or advantages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 illustrates a configuration of a communication system
according to Embodiment 1 of this disclosure;
[0009] FIG. 2 illustrates a configuration of a base station
apparatus illustrated in FIG. 1;
[0010] FIG. 3 illustrates a format of a frame specified in the
communication system illustrated in FIG. 1;
[0011] FIG. 4 illustrates a configuration of a terminal apparatus
illustrated in FIG. 1;
[0012] FIG. 5 illustrates a data structure of a management list
which is stored in a second determination unit illustrated in FIG.
4;
[0013] FIG. 6 illustrates a provisional determination result and a
determination result of the terminal apparatus illustrated in FIG.
4;
[0014] FIG. 7 is a flowchart of a determination process by the
terminal apparatus illustrated in FIG. 4;
[0015] FIG. 8 is a flowchart of an update process by the terminal
apparatus illustrated in FIG. 4;
[0016] FIG. 9 is a flowchart of another update process of the
terminal apparatus illustrated in FIG. 4;
[0017] FIG. 10 illustrates a configuration of a process system
according to Embodiment 3 of this disclosure;
[0018] FIG. 11 illustrates another configuration of a process
system according to Embodiment 3 of this disclosure; and
[0019] FIG. 12 illustrates another configuration of a process
system according to Embodiment 3 of this disclosure.
DETAILED DESCRIPTION
(Underlying Knowledge Forming the Basis of the Present
Disclosure)
[0020] In Japanese Unexamined Patent Application Publication No.
2000-348299, in a case where it is determined at predetermined
intervals whether or not a course of a vehicle and a course of
another vehicle will intersect, on the basis of a positional
relationship therebetween, determination of collision or
non-collision changes frequency. As a result, notification of a
driver changes frequently, which results in insufficient support to
the driver.
[0021] Therefore, the inventor has studied the following
improvement measure in order to solve the above problem.
[0022] A radio apparatus according to one aspect of this disclosure
is a radio apparatus that can be mounted in a vehicle. The radio
apparatus includes an acquirer that acquires first positional
information of a vehicle in which the radio apparatus is mounted; a
receiver that receives, from another radio apparatus, a packet
signal that includes at least second positional information of
another vehicle in which the other radio apparatus is mounted; a
first determiner that provisionally determines collision or
non-collision between the vehicle and the other vehicle on the
basis of the first positional information that is acquired by the
acquirer and the second positional information included in the
packet signal that is received by the receiver; and a second
determiner that collects a plurality of provisional determination
results from the first determiner and determines collision or
non-collision between the vehicle and the other vehicle based on
the collected plurality of the provisional determination
results.
[0023] According to this aspect, a determination result based on a
plurality of provisional determination results is obtained;
therefore, a stable support for a driver can be provided.
[0024] Another aspect of this disclosure relates to a process
apparatus. This process apparatus includes an acquirer that
acquires a provisional determination result regarding, collision or
non-collision between a first vehicle and a second vehicle, that is
determined on the basis of i) first positional information of the
first vehicle in which a first radio apparatus that is mounted in a
first vehicle is mounted and ii) second positional information of
the second vehicle that is included in a packet signal that is
received from a second radio apparatus by the first radio apparatus
and that at least includes the second positional information of the
second vehicle in which the second radio apparatus is mounted, and
a determiner that collects a plurality of provisional determination
results that is acquired by the acquirer over time and determines
collision or non-collision between the first vehicle and the second
vehicle based on the collected plurality of the provisional
determination results.
[0025] According to this aspect, a determination result based on a
plurality of provisional determination results is obtained;
therefore, a stable support for a driver can be provided.
[0026] Another aspect of this disclosure relates to a process
system. The process system includes a first radio apparatus that is
mounted in a first vehicle, and a process apparatus that is
connected to the first radio apparatus. The radio apparatus
includes an acquirer that acquires first positional information of
the first vehicle in which the first radio apparatus is mounted and
a receiver that receives, from a second radio apparatus, a packet
signal that includes at least second positional information of a
second vehicle in which the second radio apparatus is mounted. The
first radio apparatus or the process apparatus includes a first
determiner that provisionally determines collision or non-collision
between the first vehicle and the second vehicle on the basis of
the first positional information that is acquired by the acquirer
and the second positional information included in the packet signal
that is received by the receiver. The process apparatus includes a
second determiner that collects a plurality of provisional
determination results from the first determiner and determines
collision or non-collision between the first vehicle and the second
vehicle based on the collected plurality of the provisional
determination results.
[0027] According to this aspect, a determination result based on a
plurality of provisional determination results is obtained;
therefore, a stable support for a driver can be provided.
Embodiment 1
[0028] Before specifically describing an embodiment of this
disclosure, a basic concept is described. Embodiment 1 of this
disclosure relates to a communication system for performing
inter-vehicle communication between terminal apparatuses mounted in
vehicles and also road-to-vehicle communication from a base station
apparatus installed at an intersection or the like to the terminal
apparatus. The communication system is also referred to as an
intelligent transport system (ITS). The communication system
employs an access control function called carrier sense multiple
access with collision avoidance (CSMA/CA) in a similar manner to a
wireless local area network (LAN) conforming to the standard of
IEEE802.11 or the like. Thus, a single radio channel is shared by a
plurality of terminal apparatuses. Additionally, in ITS,
information needs to be transmitted to an unspecified number of
terminal apparatuses. To efficiently perform such transmission, the
communication system transmits packet signals by broadcast.
[0029] In other words, in inter-vehicle communication, a terminal
apparatus transmits a packet signal including information on a
vehicle such as speed or position by broadcast. Another terminal
apparatus receives the packet signal and detects an approach of the
vehicle or the like on the basis of the aforementioned information.
In order to reduce an interference between road-to-vehicle
communication and inter-vehicle communication, the base station
apparatus repeatedly specifies a frame including a plurality of
subframes. For the road-to-vehicle communication, the base station
apparatus selects any of the subframes and transmits a packet
signal including control information or the like by broadcast at a
start portion of the selected subframe.
[0030] The control information includes information on a period in
which the base station apparatus transmits a packet signal by
broadcast (hereinafter, such a period is referred to as a
"road-to-vehicle transmission period"). The terminal apparatus
specifies the road-to-vehicle transmission period on the basis of
the control information, and transmits a packet signal in the CSMA
protocol by broadcast in a period other than the road-to-vehicle
transmission period (hereinafter, such a period is referred to as
an "inter-vehicle transmission period"). In this way, the
road-to-vehicle communication and the inter-vehicle communication
are time-multiplexed. Note that a terminal apparatus which cannot
receive the control information from the base station apparatus,
that is, a terminal apparatus which is outside of an area defined
by the base station apparatus, transmits a packet signal by
broadcast in the CSMA protocol regardless of a structure of
frames.
[0031] Depending on positions of one terminal apparatus and another
terminal apparatus, the determination result is frequently changed
between collision and non-collision, which results in inconsistent
driver support. To provide a solution to this problem, in a
terminal apparatus according to Embodiment 1, collision or
non-collision is determined in a conventional manner and the result
is defined as a provisional determination result. The terminal
apparatus identifies the provisional determination result as a
determination result when a provisional determination result which
is different from the previous determination result is obtained
repeatedly several times in succession. For example, when the
determination result was previously non-collision and the
provisional determination result turns out to be collision for a
plurality of times in succession, the terminal apparatus changes
the determination result to collision.
[0032] FIG. 1 illustrates a configuration of a communication system
100 according to Embodiment 1 of this disclosure. FIG. 1
illustrates a top view of an intersection. The communication system
100 includes a base station apparatus 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, a seventh vehicle 12g, and
an eighth vehicle 12h, which are collectively referred to as
vehicles 12, and a network 202. Each vehicle 12 is installed with a
terminal apparatus 14, which is illustrated only on the first
vehicle 12a in FIG. 1. An area 212 is formed around the base
station apparatus 10, and the area outside the area 212 is referred
to as an outer area 214.
[0033] As illustrated, a road in the left to right horizontal
direction and a road in the top to bottom vertical direction
intersect at the center. Here, the upper side of the drawing
corresponds to north, the left side corresponds to west, the lower
side corresponds to south, and the right side corresponds to east.
The point where the two roads intersect is an "intersection". The
first vehicle 12a and the second vehicle 12b travel from left to
right, and the third vehicle 12c and the fourth vehicle 12d travel
from right to left. The fifth vehicle 12e and the sixth vehicle 12f
travel from top to bottom, and the seventh vehicle 12g and the
eighth vehicle 12h travel from bottom to top.
[0034] In the communication system 100, the base station apparatus
10 is permanently positioned at the intersection. The base station
apparatus 10 controls communication between the terminal
apparatuses. The base station apparatus 10 repeatedly generates a
frame including a plurality of subframes on the basis of a signal
received from a global positioning system (GPS) satellite (not
illustrated) or a frame formed in another base station apparatus 10
(not illustrated). Here, the start portion of each subframe can be
set as the road-to-vehicle transmission period.
[0035] The base station apparatus 10 selects one of the subframes
in which the road-to-vehicle transmission period is not set by the
other base station apparatus 10. The base station apparatus 10 sets
the road-to-vehicle transmission period at the start portion of the
selected subframe. The base station apparatus 10 transmits a packet
signal in the set road-to-vehicle transmission period. In the
road-to-vehicle transmission period, a plurality of packet signals
may be transmitted. In addition, the packet signal includes, for
example, information about accidents, traffic jams, and traffic
lights. Note that the packet signal also includes information on
the timing at which the road-to-vehicle transmission period is set
and control information of the frame.
[0036] As described above, the terminal apparatus 14 is mounted in
the vehicle 12 and is mobile. When the terminal apparatus 14
receives a packet signal from the base station apparatus 10, the
terminal apparatus 14 is estimated to be inside the area 212. When
the terminal apparatus 14 is within the area 212, the terminal
apparatus 14 generates a frame on the basis of the control
information included in the received packet signal, specifically on
the basis of the information about the frame and the information on
the timing at which the road-to-vehicle transmission period is set.
Consequently, the frame generated in each terminal apparatus 14 is
synchronized with the frame generated in the base station apparatus
10. The terminal apparatus 14 transmits a packet signal in the
inter-vehicle transmission period, which is different from the
road-to-vehicle transmission period. In the inter-vehicle
transmission period, data transmission in the CSMA/CA protocol is
performed. On the other hand, when the terminal apparatus 14 is
estimated to be in the outer area 214, the terminal apparatus 14
performs data transmission in the CSMA/CA protocol irrespective of
the frame structure to transmit a packet signal. The terminal
apparatus 14 receives a packet signal from another terminal
apparatus 14, thereby detecting an approach of another vehicle 12
in which the other terminal apparatus 14 is mounted. Details of the
detection will be described later.
[0037] FIG. 2 illustrates a structure of the base station apparatus
10. The base station apparatus 10 includes an antenna 20, an RF
unit 22, a modulation/demodulation unit 24, a process unit 26, a
control unit 28, and a network communication unit 30. The process
unit 26 includes a frame specification unit 32, a selection unit
34, and a generation unit 36.
[0038] The RF unit 22 receives a packet signal from a terminal
apparatus 14 (not illustrated) or another base station apparatus 10
(not illustrated) by the antenna 20 as a reception process. The RF
unit 22 converts the frequency of the received wireless frequency
packet signal and generates a baseband packet signal. The RF unit
22 outputs the baseband packet signal to the
modulation/demodulation unit 24. Typically, the baseband packet
signal includes an in-phase component and a quadrature component
and thus should be indicated by two signal lines, but only one
signal line is illustrated herein for the purpose of simplifying
the drawing. The RF unit 22 includes a low-noise amplifier (LNA), a
mixer, an AGC, and an A/D conversion unit.
[0039] The RF unit 22 converts the frequency of the baseband packet
signal accepted from the modulation/demodulation unit 24 and
generates a wireless frequency packet signal as a transmission
process. The RF unit 22 transmits the wireless frequency packet
signal from the antenna 20 in the road-to-vehicle transmission
period. The RF unit 22 includes a power amplifier (PA), a mixer,
and a D/A conversion unit.
[0040] The modulation/demodulation unit 24 demodulates the baseband
packet signal accepted from the RF unit 22 as a reception process.
The modulation/demodulation unit 24 outputs a demodulation result
to the process unit 26. The modulation/demodulation unit 24
modulates the data from the process unit 26 as a transmission
process. The modulation/demodulation unit 24 outputs a modulation
result as a baseband packet signal to the RF unit 22. Here, the
communication system 100 is compatible with an orthogonal frequency
division multiplexing (OFDM) modulation system, and thus the
modulation/demodulation unit 24 both performs fast fourier
transform (FFT) as a reception process and inverse fast fourier
transform (IFFT) as a transmission process.
[0041] The frame specification unit 32 accepts a signal from a GPS
satellite (not illustrated) and acquires time information from the
accepted signal. A known technique may be used for acquiring the
time information, and an explanation thereof is omitted here. The
frame specification unit 32 generates a plurality of frames on the
basis of the time information. For example, the frame specification
unit 32 divides a period of "1 sec" into 10 with reference to the
timings indicated by the time information to generate 10 "100-msec"
frames. The process is repeated and thus the frames are defined as
repeated. Note that the frame specification unit 32 may detect the
control information from the demodulation result and generate a
frame on the basis of the detected control information. Such a
process corresponds to a generation process of a frame synchronized
with a timing of a frame formed by another base station apparatus
10.
[0042] FIG. 3 illustrates a format of frames specified in the
communication system 100. Part (a) of FIG. 3 illustrates a
structure of a frame. The frame includes N subframes from the first
to the N-th subframes. The subframes which the terminal apparatus
14 uses for broadcasting are time multiplexed to form a frame. For
example, when a length of the frame is 100 msec and N is 8, a
subframe with a length of 12.5 msec is defined. N may be a number
other than 8. The description of part (b) to (d) of FIG. 3 will be
made later, and the description returns to FIG. 2.
[0043] The selection unit 34 selects, from among the subframes
included in the frame, a subframe in which the road-to-vehicle
transmission period is to be set. Specifically, the selection unit
34 accepts the frame defined in the frame specification unit 32.
The selection unit 34 also accepts an instruction of the subframe
to be selected via an interface (not illustrated) and selects a
subframe corresponding to the instruction. The selection unit 34
may alternatively select a subframe automatically. In that case,
the selection unit 34 accepts demodulation results of another base
station apparatus 10 (not illustrated) or another terminal
apparatus 14 (not illustrated) via the RF unit 22 and the
modulation/demodulation unit 24. The selection unit 34 extracts a
demodulation result from the other base station apparatus 10 from
among the accepted demodulation results. The selection unit 34
specifies subframes, the demodulation result of which has been
accepted, to specify the subframe, the demodulation result of which
has not been accepted.
[0044] This process specifies an unused subframe, or a subframe in
which any road-to-vehicle transmission period is not set by another
base station apparatus 10. When there are a plurality of unused
subframes, the selection unit 34 randomly selects one subframe.
When there is no unused subframe, that is, when all subframes are
used, the selection unit 34 acquires reception power of the
demodulation results and preferentially selects a subframe with low
reception power.
[0045] Part (b) of FIG. 3 illustrates a structure of a frame
generated by a first base station apparatus 10a (not illustrated).
The first base station apparatus 10a sets a road-to-vehicle
transmission period at a start portion of the first subframe. The
first base station apparatus 10a sets a period other than the
road-to-vehicle transmission period in the first subframe and the
second to the N-th subframes as an inter-vehicle transmission
period. The inter-vehicle transmission period is a period in which
the terminal apparatus 14 can transmit a packet signal. That is,
the first base station apparatus 10a can transmit a packet signal
in the road-to-vehicle transmission period at the start portion of
the first subframe while the terminal apparatus 14 can transmit a
packet signal in the inter-vehicle transmission period other than
the road-to-vehicle transmission period in the frame.
[0046] Part (c) of FIG. 3 illustrates a structure of a frame
generated by a second base station apparatus 10b (not illustrated).
The second base station apparatus 10b sets the road-to-vehicle
transmission period at the start portion of the second subframe.
The second base station apparatus 10b sets a period other than the
road-to-vehicle transmission period in the second subframe and the
first and third to the N-th subframes as the inter-vehicle
transmission period. Part (d) of FIG. 3 illustrates a structure of
a frame generated by a third base station apparatus 10c (not
illustrated). The third base station apparatus 10c sets the
road-to-vehicle transmission period at a start portion of the third
subframe. The third base station apparatus 10c sets a period other
than the road-to-vehicle transmission period in the third subframe
and the first, second, and fourth to the N-th subframes as the
inter-vehicle transmission period. In this way, the base station
apparatuses 10 select subframes different from one another, and
sets the road-to-vehicle transmission period at the start portion
of the selected subframes. The description returns to FIG. 2. The
selection unit 34 outputs a selected subframe number to the
generation unit 36.
[0047] The generation unit 36 accepts the subframe number from the
selection unit 34. The generation unit 36 sets the road-to-vehicle
transmission period in the subframe of the accepted number and
generates a packet signal which is to be transmitted in the
road-to-vehicle transmission period. When a plurality of packet
signals are to be transmitted in a single road-to-vehicle
transmission period, the generation unit 36 generates the plurality
of packet signals. A packet signal includes control information and
payload. The control information includes the subframe number in
which the road-to-vehicle transmission period is set, for example.
The payload includes information about accidents, traffic jams, and
traffic lights, for example. These kinds of data are obtained by
the network communication unit 30 via the network 202 (not
illustrated). The process unit 26 causes the
modulation/demodulation unit 24 and the RF unit 22 to transmit the
packet signal by broadcast in the road-to-vehicle transmission
period. The control unit 28 controls the entire process in the base
station apparatus 10.
[0048] This structure can be realized by including hardware such as
a CPU, a memory, or other LSI in any computer, or software such as
a program loaded into a memory. Here, the functional blocks
realized in their association are illustrated. Thus, those skilled
in the art should understand that the functional blocks can be
realized in any form such as hardware only, software only, or a
combination thereof.
[0049] FIG. 4 illustrates a structure of the terminal apparatus 14.
The terminal apparatus 14 includes an antenna 50, an RF unit 52, a
modulation/demodulation unit 54, a process unit 56, and a control
unit 58. The process unit 56 includes a timing specification unit
60, a transfer determination unit 62, a positional information
acquisition unit 64, a generation unit 66, a first determination
unit 76, a second determination unit 78, and a notification unit
70. The timing specification unit 60 includes an extraction unit 72
and a carrier sense unit 74. As described above, the terminal
apparatus 14 can be mounted in the vehicle 12. The antenna 50, the
RF unit 52, and the modulation/demodulation unit 54 execute a
similar process to the antenna 20, the RF unit 22, and the
modulation/demodulation unit 24 in FIG. 2. Thus, mainly differences
will be described herein.
[0050] The modulation/demodulation unit 54 and the process unit 56
receive a packet signal from the other terminal apparatus 14 or a
base station apparatus 10 (not illustrated) as a reception process.
As described above, the modulation/demodulation unit 54 and the
process unit 56 receive a packet signal from the base station
apparatus 10 in the road-to-vehicle transmission period and receive
a packet signal from another terminal apparatus 14 in the
inter-vehicle transmission period. A packet signal from the other
terminal apparatus 14 includes at least a position, a travelling
direction, a moving speed, and the like (which will be collectively
referred to as "position information" hereinafter) of another
vehicle 12 in which the other terminal apparatus 14 is mounted. A
known technique may be used for the acquisition of the positional
information of the other terminal apparatus 14, and thus an
explanation thereof is omitted here.
[0051] When a demodulation result from the modulation/demodulation
unit 54 represents a packet signal from the base station apparatus
10 (not illustrated), the extraction unit 72 specifies a timing of
a subframe in which the road-to-vehicle transmission period is set.
At this time, the extraction unit 72 is estimated to be within the
area 212 of FIG. 1. The extraction unit 72 generates a frame on the
basis of the timing of the subframe and message header content of
the packet signal, specifically, the length of time of the
road-to-vehicle transmission period. The frame may be generated in
a manner similar to that in the frame specification unit 32, and
thus an explanation thereof is omitted here. The extraction unit 72
generates a frame synchronized with the frame which is formed in
the base station apparatus 10. When the packet signal is
transmitted from the other terminal apparatus 14, the extraction
unit 72 omits a generation process of a synchronized frame, but
extracts positional information in the packet signal and outputs
the positional information to the first determination unit 76.
[0052] On the other hand, if a packet signal from the base station
apparatus 10 is not received, the extraction unit 72 estimates that
the terminal apparatus 14 is in the outer area 214 of FIG. 1. When
the terminal apparatus 14 is estimated to be within the area 212,
the extraction unit 72 selects the inter-vehicle transmission
period. When the terminal apparatus 14 is estimated to be in the
outer area 214, the extraction unit 72 selects a timing
irrespective of the frame structure. When the inter-vehicle
transmission period is selected, the extraction unit 72 outputs the
information on the timings of the frame and the subframe and the
inter-vehicle transmission period to the carrier sense unit 74.
When a timing irrespective of the frame structure is selected, the
extraction unit 72 instructs the carrier sense unit 74 to perform
carrier sensing.
[0053] The carrier sense unit 74 accepts the information on the
timings of the frame and the subframe and the inter-vehicle
transmission period from the extraction unit 72. The carrier sense
unit 74 determines a transmission timing by starting the CSMA/CA in
the inter-vehicle transmission period. On the other hand, when the
carrier sense unit 74 is instructed to perform carrier sensing
irrespective of the frame structure from the extraction unit 72,
the carrier sense unit 74 performs CSMA/CA to determine a
transmission timing irrespective of the frame structure. The
carrier sense unit 74 notifies the determined transmission timing
to the modulation/demodulation unit 54 and the RF unit 52 to
transmit a packet signal by broadcast.
[0054] The transfer determination unit 62 controls transmission of
the control information. The transfer determination unit 62
extracts information to be transmitted from the control
information. The transfer determination unit 62 generates
information to be transmitted on the basis of the extracted
information. An explanation of this process is omitted here. The
transfer determination unit 62 outputs the information to be
transmitted, that is, a part of the control information to the
generation unit 66.
[0055] The positional information acquisition unit 64 includes a
GPS receiver, a gyroscope, a vehicle speed sensor, and the like
(not illustrated), with which the positional information
acquisition unit 64 obtains data to acquire information of a
position, a travelling direction, a moving speed, and the like (as
mentioned above, which will be collectively referred to as
"positional information") of the vehicle 12 (not illustrated), that
is, the vehicle 12 in which the terminal apparatus 14 is mounted.
Note that the position is indicated by latitude and longitude
coordinates. A known technique may be used for the acquisition, and
thus an explanation thereof is omitted here. The positional
information acquisition unit 64 outputs the positional information
to the generation unit 66 and the first determination unit 76.
[0056] The generation unit 66 accepts the positional information
from the positional information acquisition unit 64 and accepts a
part of the control information from the transfer determination
unit 62. The generation unit 66 generates a packet signal including
the information and transmits the generated packet signal by
broadcast via the modulation/demodulation unit 54, the RF unit 52,
and the antenna 50 at the transmission timing determined in the
carrier sense unit 74. This process corresponds to inter-vehicle
communication.
[0057] The positional information is accepted from the positional
information acquisition unit 64 and the extraction unit 72 to the
first determination unit 76. The positional information accepted
from the positional information acquisition unit 64 corresponds to
the positional information of another vehicle 12, while the
positional information accepted from the extraction unit 72
corresponds to the positional information of the vehicle 12 in
which the first determination unit 76 is mounted. The first
determination unit 76 provisionally determines collision or
non-collision of the vehicle 12 with the other vehicle 12 on the
basis of the positional information of the vehicle 12 and the other
vehicle 12. A known technique may be used to provisionally
determine collision or non-collision. For example, a future
position of the vehicle 12 in which the first determination unit 76
is mounted is estimated in accordance with the present position,
the travelling direction, and the moving speed of the vehicle 12 in
which the first determination unit 76 is mounted, while a future
position of the other vehicle 12 is estimated in accordance with
the present position, the travelling direction, and the moving
speed of the other vehicle 12; a provisional determination result
of the first determination unit 76 is collision when the two future
positions are close to each other, and non-collision if not. The
two future positions are determined to be close to each other when
the proximity therebetween exceeds a threshold value. Otherwise,
they are determined not to be approximate to each other. Such
provisional determination is performed periodically, for example
every 100 msec, which is equal to a frame cycle. The first
determination unit 76 outputs the provisional determination result
to the second determination unit 78.
[0058] A provisional determination result of the first
determination unit 76 is accepted to the second determination unit
78. The second determination unit 78 collects plural provisional
determination results over time to determine whether or not the
vehicle 12 and the other vehicle 12 will collide. Specifically,
when the determination result was previously "non-collision" and
when the provisional determination result turns out to be
"collision" N times in succession, the second determination unit 78
changes the determination result to "collision". On the other hand,
when the preceding determination result was previously "collision"
and when the provisional determination result turns out to be
"non-collision" M times in succession, the second determination
unit 78 changes the determination result to "non-collision". Here,
N is smaller than M. N and M are positive integral numbers. For
example, N may be 3 and M may be 4. Thus, a result which requires
caution, that is, the determination of collision, is more easily
obtained for the purpose of fail-safe operation.
[0059] In order to perform such determination, the second
determination unit 78 summarizes the provisional determination
results in a table (hereinafter referred to as a "management
list"). In other words, when a provisional determination result is
accepted, the second determination unit 78 updates the management
list. When the management list satisfies the above condition, the
second determination unit 78 changes the determination result.
[0060] FIG. 5 illustrates a data structure of the management list
stored in the second determination unit 78. An "ID" indicates an
identification number to identify other vehicles 12, an "update
flag" indicates whether update with 100 msec intervals is finished
or not. An "immediate determination result" indicates the latest
provisional determination result in the first determination unit
76, which is either "collision" or "non-collision". Further, the
"number of collision provisional determinations in succession"
indicates the number of times the provisional determination result
is "collision" in succession, while the "number of non-collision
provisional determinations in succession" indicates the number of
times the provisional determination result is "non-collision" in
succession. The "stabilized determination result" indicates a
determination result.
[0061] FIG. 6 illustrates provisional determination results and
determination results in the terminal apparatus 14. Part (a) of
FIG. 6 illustrates provisional determination results in the first
determination unit 76 and part (b) of FIG. 6 illustrates
determination results in the second determination unit 78 in a case
where N is 3 and M is 4. The description returns to FIG. 4. The
second determination unit 78 outputs the determination result to
the notification unit 70.
[0062] The notification unit 70 displays a content of a received
packet signal on a display or the like (not illustrated). The
determination result is accepted from the second determination unit
78 to the notification unit 70. The notification unit 70 notifies
the determination result to a driver via a monitor or a speaker.
Further, the notification unit 70 also notifies the information in
the packet signal received from the base station apparatus 10 to
the driver via a monitor or a speaker.
[0063] An operation of the communication system 100 with the above
structure will be described. FIG. 7 is a flowchart of a
determination process of the terminal apparatus 14. The positional
information acquisition unit 64 obtains information (a position, a
speed, and a travelling direction) of the vehicle in which the
terminal apparatus 14 is mounted (S10), the extraction unit 72
obtains another vehicle information (a position, a speed, and a
travelling direction) (S12). The first determination unit 76
provisionally determines collision or non-collision between the
vehicles (S14). If the information of the other vehicle is given in
the management list (Yes in S16), the second determination unit 78
updates the information of the other vehicle in the management list
(S18). On the other hand, if the information of the other vehicle
is not given in the management list (No in S16), the second
determination unit 78 adds the information of the other vehicle to
the management list (S20). In other word, the second determination
unit 78 sets the immediate determination result to a provisional
determination result, the number of collision provisional
determinations in succession to "0", the number of non-collision
provisional determinations in succession to "0", the stabilized
determination result to "non-collision", and the update flag column
to "finished". Further, the second determination unit 78 updates
information of a vehicle which is in the management list but the
packet signal of which is not received, that is data of a vehicle
whose update flag is "unfinished" (S22). The second determination
unit 78 updates all update flags in the management list to
"unfinished" (S24). When the process is selected to continue, the
process returns to Step 10 (Yes in S26). When the process is
selected not to continue (No in S26), the process ends.
[0064] FIG. 8 is a flowchart of an update process of the terminal
apparatus 14. The flowchart of FIG. 8 corresponds to Step 18 in
FIG. 7. When the provisional determination result is equal to the
stabilized determination result (Yes in S50), the second
determination unit 78 updates the management list by setting the
provisional determination result as a determination result and
changing the update flag to "finished" (S52). The stabilized
determination result obtained is the same as the preceding
determination result. When the provisional determination result is
not equal to a stabilized determination result (No in S50), if the
provisional determination result is "collision" (Yes in S54), and
the number of collision provisional determinations in succession
+1>N is satisfied (Yes in S56), the second determination unit 78
updates the management list (S58). Specifically, the second
determination unit 78 sets the number of collision provisional
determinations in succession to "0", the number of non-collision
provisional determinations in succession to "0", the stabilized
determination result to "collision", and the update flag to
"finished". If the number of collision provisional determinations
in succession +1>N is not satisfied (No in S56), the second
determination unit 78 updates the management list by adding 1 to
the number of collision provisional determinations in succession
and changing the update flag to "finished" (S60).
[0065] If the provisional determination result is not "collision"
(No in S54), and the number of non-collision provisional
determinations in succession +1>M is satisfied (Yes in S62), the
second determination unit 78 updates the management list (S64).
Specifically, the second determination unit 78 sets the number of
collision provisional determinations in succession to "0", the
number of non-collision provisional determinations in succession to
"0", the stabilized determination result to "non-collision", and
the update flag to "finished". If the number of non-collision
provisional determinations in succession +1>M is not satisfied
(No in S62), the second determination unit 78 updates the
management list by adding 1 to the number of non-collision
provisional determinations in succession and changing the update
flag to "finished" (S66).
[0066] FIG. 9 is a flowchart of another update process of the
terminal apparatus 14. The flowchart of FIG. 9 corresponds to Step
22 in FIG. 7 where the management list is updated for a vehicle of
which update flag is "unfinished". If the stabilized determination
result is "collision" (Yes in S80), and the number of non-collision
provisional determinations in succession +1>M is satisfied (Yes
in S82), the second determination unit 78 updates the management
list (S84). Specifically, the second determination unit 78 sets the
number of collision provisional determinations in succession to
"0", the number of non-collision provisional determinations in
succession to "0", the stabilized determination result to
"non-collision", and the update flag to "finished". If the number
of non-collision provisional determinations in succession +1>M
is not satisfied (No in S82), the second determination unit 78
updates the management list by adding 1 to the number of
non-collision provisional determinations in succession and changing
the update flag to "finished" (S86). If the stabilized
determination result is not "collision" (No in S80), the second
determination unit 78 updates the management list by deleting the
data of the vehicle (S88).
[0067] According to an embodiment of this disclosure, a
determination result is changed when the same provisional
determination result is obtained plural times in succession;
therefore, frequent changes of the determination result can be
avoided, which leads to stable support for a driver. In addition,
since N is set to be smaller than M, false determination of
non-collision can be suppressed, which suppresses collision
accidents of vehicles.
Embodiment 2
[0068] Then, Embodiment 2 of this disclosure will be described. As
in Embodiment 1, Embodiment 2 relates to a terminal apparatus that
determines collision or non-collision with another vehicle on the
basis of a packet signal received from another terminal apparatus
which is mounted in the other vehicle. In a terminal apparatus
according to Embodiment 1, when the same provisional determination
result comes out in succession, the provisional determination
result is identified as a determination result. On the other hand,
in a terminal apparatus according to Embodiment 2, when a rate of
either provisional determination result exceeds a threshold value
in a predetermined number of provisional determination results, the
provisional determination result is identified as a determination
result. The communication system 100 in Embodiment 2 is of a type
similar to that in FIG. 1, the base station apparatus 10 in
Embodiment 2 is of a type similar to that in FIG. 2, and the
terminal apparatus 14 in Embodiment 2 is of a type similar to that
in FIG. 4. Thus, differences will be mainly described herein.
[0069] In FIG. 4, the provisional determination result of the first
determination unit 76 is accepted to the second determination unit
78. The second determination unit 78, as in Embodiment 1, collects
plural provisional determination results over time to determine
whether or not the vehicle 12 and another vehicle 12 will collide.
Specifically, when the preceding determination result was
"non-collision" and when the rate of the collision provisional
determination result in plural provisional determination results
exceeds a first threshold value, the second determination unit 78
changes the determination result to "collision". Here, the plural
provisional determination results means the latest provisional
determination results of the predetermined number. For example, the
predetermined number may be 10. On the other hand, when the
preceding determination result was "collision" and the rate of the
non-collision provisional determination result in plural
provisional determination results exceeds a second threshold value,
the second determination unit 78 changes the determination result
to "non-collision". Here, the first threshold value is smaller than
the second threshold value.
[0070] According to an embodiment of this disclosure, a
determination result is changed when the rate of the same
provisional determination result in a predetermined number of
provisional determination results is high; therefore, frequent
changes of the determination result can be avoided. In addition,
since the first threshold value is smaller than the second
threshold value, false determination of non-collision can be
suppressed.
Embodiment 3
[0071] Then, Embodiment 3 of this disclosure will be described. As
in Embodiments 1 and 2, Embodiment 3 relates to a terminal
apparatus that receives a packet signal from another terminal
apparatus. In Embodiments 1 and 2, the terminal apparatus
determines and communicates collision or non-collision between a
vehicle and another vehicle in which another terminal apparatus is
mounted. On the other hand, in Embodiment 3, a process apparatus
which is provided separately from the terminal apparatus performs
such a function. The communication system 100 in Embodiment 3 is of
a type similar to that in FIG. 1 and the base station apparatus 10
in Embodiment 3 is of a type similar to that in FIG. 2. Thus,
differences will be mainly described herein.
[0072] FIG. 10 illustrates a configuration of a process system 300
according to Embodiment 3 of this disclosure. The process system
300 includes the terminal apparatus 14 and a process apparatus 310.
The terminal apparatus 14 includes the antenna 50, the RF unit 52,
the modulation/demodulation unit 54, the process unit 56, and the
control unit 58. The process unit 56 includes an output unit 320.
The process apparatus 310 includes an acquisition unit 330, the
second determination unit 78, and the notification unit 70. The
acquisition unit 330 includes an input unit 332 and the first
determination unit 76.
[0073] The terminal apparatus 14 and the process apparatus 310 are
linked by wired or wireless connection or the like. Such a
connection may be formed by a known technique and an explanation
thereof is omitted here. As compared to the terminal apparatus 14
of FIG. 4, the terminal apparatus 14 of FIG. 10 does not include
the first determination unit 76, the second determination unit 78,
and the notification unit 70. The process unit 56 includes the
output unit 320. The output unit 320 outputs information extracted
by the extraction unit 72, for example, positional information
included in a packet signal to the process apparatus 310. In
addition, the output unit 320 also outputs positional information
of the vehicle 12 to the process apparatus 310.
[0074] The process apparatus 310 is, for example, an on-vehicle
apparatus such as a car navigation apparatus and is mounted in the
vehicle 12. The input unit 332 accepts information from the output
unit 320 and outputs the accepted information to the first
determination unit 76. The first determination unit 76 may also be
referred to as a provisional determination unit. The process in the
first determination unit 76, the second determination unit 78, and
the notification unit 70 is similar to that has been described
above and an explanation thereof is omitted here.
[0075] FIG. 11 illustrates another configuration of the process
system 300 according to Embodiment 3 of this disclosure. The
process system 300 includes the terminal apparatus 14 and the
process apparatus 310. The terminal apparatus 14 includes the
antenna 50, the RF unit 52, the modulation/demodulation unit 54,
the process unit 56, and the control unit 58. The process unit 56
includes the first determination unit 76 and the output unit 320.
The process apparatus 310 includes the acquisition unit 330, the
second determination unit 78, and the notification unit 70.
[0076] As compared to the terminal apparatus 14 of FIG. 4, the
terminal apparatus 14 of FIG. 11 does not include the second
determination unit 78 and the notification unit 70. The process
unit 56 includes the first determination unit 76 and the output
unit 320. The first determination unit 76 performs provisional
determination as described above and outputs the provisional
determination result to the output unit 320. The output unit 320
outputs the provisional determination result to the process
apparatus 310. The acquisition unit 330 accepts the output unit 320
and outputs the provisional determination result to the second
determination unit 78. The process in the second determination unit
78 and the notification unit 70 is similar to that has been
described above and an explanation thereof is omitted here.
[0077] FIG. 12 illustrates another configuration of the process
system 300 according to Embodiment 3 of this disclosure. The
process system 300 includes the terminal apparatus 14 and the
process apparatus 310. The terminal apparatus 14 includes the
antenna 50, the RF unit 52, the modulation/demodulation unit 54,
the process unit 56, and the control unit 58. The process unit 56
includes the first determination unit 76, the second determination
unit 78, and the output unit 320. The process apparatus 310
includes the notification unit 70.
[0078] As compared to the terminal apparatus 14 of FIG. 4, the
terminal apparatus 14 of FIG. 12 does not include the notification
unit 70. The process unit 56 includes the first determination unit
76, the second determination unit 78, and the output unit 320. The
first determination unit 76 and the second determination unit 78
perform processes as described above and output the determination
result to the output unit 320. The output unit 320 outputs the
determination result to the process apparatus 310. The notification
unit 70 accepts the determination result from the output unit 320
and performs notification as described above.
[0079] According to an embodiment of this disclosure, the
configuration of the terminal apparatus can be simplified in a case
where the first determination unit, the second determination unit,
and the notification unit are provided in an outer process
apparatus. Also, the configuration of the terminal apparatus can be
simplified in a case where the second determination unit and the
notification unit are provided in the outer process apparatus.
Further alternatively, flexibility in the configuration can be
improved in a case where the notification unit is provided in the
outer process apparatus.
[0080] This disclosure has been described above by way of the
embodiment. The embodiments are exemplary, and those skilled in the
art may understand that various modifications of combination of the
components and the processes are possible and such modifications
are also encompassed in the scope of this disclosure.
[0081] Although Embodiments 1 and 3 in this disclosure describe the
procedure for provisionally determining collision or non-collision
between vehicles, the procedure is not limited to those described
above. Any procedure may be employed as long as it performs
hysteresis determination where M successive "collision" provisional
determination results make the determination result "collision",
while N successive "non-collision" provisional determination
results make the determination result "non-collision".
[0082] In Embodiments 1 and 3 of this disclosure, N is defined as a
threshold value for changing a determination result from
"non-collision" to "collision". N is a positive integral number.
Note that N may be 1. According to this modification, collision can
be notified immediately.
[0083] In Embodiments 1 to 3 of this disclosure, the second
determination unit 78 determines a determination result on the
basis of a plurality of provisional determination results. However,
this disclosure is not limited thereto. For example, at a start
portion of the process when a plurality of provisional
determination results have not been collected, the second
determination unit 78 may output a provisional determination result
as a determination result as it is. According to this modification,
the determination result can be early notified.
[0084] In Embodiments 1 to 3 of this disclosure, the communication
system 100 is used in a system for preventing collision with
oncoming vehicles. However, this disclosure is not limited thereto.
For example, the communication system 100 may be used for service
in/out determination or route determination in an emergency vehicle
transport support. According to this modification, the application
range of the communication system 100 can be widened.
[0085] An outline of one aspect of this disclosure is described
below. A radio apparatus according to one aspect of this disclosure
is a radio apparatus that can be mounted in a vehicle. The radio
apparatus includes an acquirer that acquires positional information
of a vehicle in which the radio apparatus is mounted; a receiver
that receives, from another radio apparatus, a packet signal that
includes at least second positional information of another vehicle
in which the other radio apparatus is mounted; a first determiner
that provisionally determines collision or non-collision between
the vehicle and the other vehicle on the basis of the first
positional information that is acquired by the acquirer and the
second positional information included in the packet signal that is
received by the receiver; and a second determiner that collects a
plurality of provisional determination results from the first
determiner and determines collision or non-collision between the
vehicle and the other vehicle based on the collected plurality of
the provisional determination results.
[0086] According to this aspect, a determination result based on a
plurality of provisional determination results is obtained;
therefore, a stable support for a driver can be provided.
[0087] The second determiner may change a determination result to
collision when the provisional determination result has been
collision N times in succession and when the determination result
was previously non-collision, and change the determination result
to non-collision when the provisional determination result has been
non-collision M times in succession and when the determination
result was previously collision. N is smaller than M in the second
determiner. N and M are positive integral numbers. In this case,
since N is set to be smaller than M, false determination of
non-collision can be suppressed.
[0088] The second determiner may change a determination result to
collision when a rate of collision in a plurality of provisional
determination results exceeds a first threshold value and when the
determination result was previously non-collision and the second
determiner change a determination result to non-collision when a
rate of non-collision in a plurality of provisional determination
results exceeds a second threshold value and when the determination
result was previously collision. The first threshold value is
smaller than the second threshold value in the second determiner.
In this case, since the first threshold value is set to be smaller
than the second threshold value, false determination of
non-collision can be suppressed.
[0089] Another aspect of this disclosure relates to a process
apparatus. This process apparatus includes an acquirer that
acquires a provisional determination result regarding collision or
non-collision between a first vehicle and a second vehicle, that is
determined on the basis of i) first positional information of the
first vehicle in which a first radio apparatus that is mounted in a
vehicle is mounted and ii) second positional information of the
second vehicle that is included in a packet signal that is received
from a second radio apparatus by the first radio apparatus and that
at least includes the second positional information of the second
vehicle in which the second radio apparatus is mounted, and a
determiner that collects a plurality of provisional determination
results that is acquired by the acquirer and determines collision
or non-collision between the first vehicle and the second vehicle
based on the collected plurality of the provisional determination
results.
[0090] According to this aspect, a determination result based on a
plurality of provisional determination results is obtained;
therefore, a stable support for a driver can be provided.
[0091] The acquirer may include an inputter that inputs the first
positional information and the second positional information and a
provisional determiner that provisionally determines collision or
non-collision between the first vehicle and the second vehicle on
the basis of the positional information included in the packet
signal and the first positional information and the second
positional information. N and M are positive integral numbers. In
this case, since the process apparatus performs provisional
determination, a process in the radio apparatus can be
simplified.
[0092] The determiner may change a determination result to
collision when the provisional determination result has been
collision N times in succession and when the determination result
was previously non-collision, and change the determination result
to non-collision when the provisional determination result has been
non-collision M times in succession and when the determination
result was previously collision. N is smaller than M in the
determiner. In this case, since N is set to be smaller than M,
false determination of non-collision can be suppressed.
[0093] The determiner may change a determination result to
collision when a rate of collision in a plurality of provisional
determination results exceeds a first threshold value and when the
determination result was previously non-collision, and change a
determination result to non-collision when a rate of non-collision
in a plurality of provisional determination results exceeds a
second threshold value and when the determination result was
previously collision. The first threshold value is smaller than the
second threshold value in the determiner. In this case, since the
first threshold value is set to be smaller than the second
threshold value, false determination of non-collision can be
suppressed.
[0094] Another aspect of this disclosure relates to a process
system. The process system includes a first radio apparatus that is
mounted in a first vehicle, and a process apparatus that is
connected to the first radio apparatus. The radio apparatus
includes an acquirer that acquires first positional information of
the first vehicle in which the first radio apparatus is mounted and
a receiver that receives, from a second radio apparatus, a packet
signal that includes at least second positional information of a
second vehicle in which the second radio apparatus is mounted. The
first radio apparatus or the process apparatus includes a first
determiner that provisionally determines collision or non-collision
between the first vehicle and the second vehicle on the basis of
the first positional information that is acquired by the acquirer
and the second positional information included in the packet signal
that is received by the receiver. The process apparatus includes a
second determiner that collects a plurality of provisional
determination results from the first determiner and determines
collision or non-collision between the first vehicle and the second
vehicle based on the collected plurality of the provisional
determination results.
[0095] According to this aspect, a determination result based on a
plurality of provisional determination results is obtained;
therefore, a stable support for a driver can be provided.
[0096] The second determiner may change a determination result to
collision when the provisional determination result has been
collision N times in succession and when the determination result
was previously non-collision, and change the determination result
to non-collision when the provisional determination result has been
non-collision M times in succession and when the determination
result was previously collision. N is smaller than M in the second
determiner. N and M are positive integral numbers. In this case,
since N is set to be smaller than M, false determination of
non-collision can be suppressed.
[0097] The second determiner may change a determination result to
collision when a rate of collision in a plurality of provisional
determination results exceeds a first threshold value and when the
determination result was previously non-collision and the second
determiner change a determination result to non-collision when a
rate of non-collision in a plurality of provisional determination
results exceeds a second threshold value and when the determination
result was previously collision. The first threshold value is
smaller than the second threshold value in the second determiner.
In this case, since the first threshold value is set to be smaller
than the second threshold value, false determination of
non-collision can be suppressed.
* * * * *