FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
“WIRELESS COMMUNICATION SYSTEM, CONTROL
METHOD THEREOF, AND PROGRAM”
MITSUBISHI HEAVY INDUSTRIES, LTD., a Japanese
Company of 16-5, Konan 2-chome, Minato-ku, Tokyo 1088215,
Japan
The following specification particularly describes the invention and the manner in which
it is to be performed.

DESCRIPTION
Title of Invention
WIRELESS COMMUNICATION SYSTEM, CONTROL METHOD THEREOF, AND PROGRAM
Technical Field
[0001]
The present invention relates to a wireless communication system in which
wireless communication with a vehicle traveling in a road is performed, a control method
thereof, and a program.
10 Priority is claimed on Japanese Patent Application No. 2012-035563, filed
February 21, 2012, the content of which is incorporated herein by reference.
Background Art
[0002]
In intelligent transport systems (ITS), there is a wireless access in vehicular
15 environments (WAVE) communication standard as a standard of a communication
system commonly used in various traffic-related services including road pricing.
In-vehicle devices according to the WAVE communication standard (hereinafter, referred
to as a "WAVE") perform road-to-vehicle communication or vehicle-to-vehicle
communication. Here, there is road pricing as an application example of the
20 road-to-vehicle communication. In this communication, a wireless communication
device installed on a road performs communication with an in-vehicle device equipped in
a vehicle using a control channel, and after the communication according to the control
channel is completed, communication with the in-vehicle device is performed on a
service channel. In other words, communication is performed such that a transmission
25 and reception control period between a wireless communication device installed on a
3
road and an in-vehicle device is divided into a transmission and reception control period
on the control channel and a transmission and reception control periodon the service
channel. A technique related to the WAVE is disclosed in PTL 1.
Citation List
5 Patent Literature
[0003]
[PTL 1] Japanese Unexamined Patent Application, First Publication No. 2010-239607
Summary of Invention
Technical Problem
10 [0004]
Meanwhile, each of the wireless communication devices performing
communication with the in-vehicle devices using the WAVE technique is installed
directly above a corresponding lane so as to be able to perform communication with
vehicles traveling thereon, for example, to correspond to a plurality of lanes formed on a
15 road, respectively. FIG. 6 is a diagram showing a wireless communication system using
a WAVE technique according to a related art. In FIG. 6, a reference numeral 1
represents a wireless communication device, and a wireless communication region 3
formed by radio waves transmitted from each wireless communication device 1 is present
in a lane corresponding to each wireless communication device 1. Here, when the
20 wireless communication devices 1 perform communication with vehicles 2 on a control
channel or a service channel at the same timing, a radio wave interference region is likely
to occur at a range in which the wireless communication regions 3 of the adjacent
wireless communication devices 1 overlap.
[0005]
25 It is an object of the invention to provide a wireless communication system, a
4
control method thereof, and a program, which are capable of reducing the occurrence of
the radio wave interference region.
Solution to Problem
[0006]
According to the present invention, provided is a wireless 5 communication
system that includes a plurality of wireless communication devices each of which
performs wireless communication with a vehicle traveling in one of a plurality of lanes
formed on a road, each of the plurality of wireless communication devices corresponding
to one of the plurality of lanes, wherein the wireless communication device performs
10 transmission and reception with the vehicle traveling in the corresponding lane such that
the timing of a transmission and reception control period in which transmission and
reception with the vehicle is performed on a control channel which is a first frequency
and the timing of a transmission and reception control period in which transmission and
reception with the vehicle is performed through a service channel which is a frequency
15 different from the first frequency are shifted from the timings of another wireless
communication device.
[0007]
Further, according to the present invention, in the wireless communication
system, the wireless communication device may perform transmission and reception with
20 the vehicle traveling in the corresponding lane such that the timing of the transmission
and reception control period in which transmission and reception with the vehicle is
performed on the control channel and the timing of the transmission and reception
control period in which transmission and reception with the vehicle is performed through
the service channel are shifted from the timings of another adjacent wireless
25 communication device.
5
[0008]
Further, according to the present invention, in the wireless communication
system, the wireless communication device may perform transmission and reception with
the vehicle traveling in the corresponding lane such that the timing of the transmission
and reception control period in which transmission and reception 5 with the vehicle is
performed on the control channel and the timing of the transmission and reception
control period in which transmission and reception with the vehicle is performed through
a service channel of the same frequency among the service channels of a plurality of
frequencies are shifted from the timings of another first adjacent wireless communication
10 device adjacent thereto and the timings of a second adjacent wireless communication
device adjacent to the first adjacent wireless communication device.
[0009]
Further, according to the present invention, in the wireless communication
system, the wireless communication device may perform transmission and reception with
15 the vehicle on a service channel of a frequency different from a frequency of the service
channel used by the another adjacent wireless communication device.
[0010]
Further, according to the present invention, provided is a control method of a
wireless communication system including a plurality of wireless communication devices
20 each of which performs wireless communication with a vehicle traveling in one of a
plurality of lanes formed on a road, each of the plurality of wireless communication
devices corresponding to the one of plurality of lanes, and the control method includes
performing, by the wireless communication device, transmission and reception with the
vehicle traveling in the corresponding lane such that the timing of a transmission and
25 reception control period in which transmission and reception with the vehicle is
6
performed on a control channel which a first frequency is and the timing of a
transmission and reception control period in which transmission and reception with the
vehicle is performed on a service channel which is a frequency different from the first
frequency are shifted from the timings of another wireless communication device.
5 [0011]
Further, according to the present invention, in the control method, the wireless
communication device may perform transmission and reception with the vehicle
traveling in the corresponding lane such that the timing of the transmission and reception
control period in which transmission and reception with the vehicle is performed on a
10 control channel and the timing of the transmission and reception control period in which
transmission and reception with the vehicle is performed on a service channel are shifted
from the timings of another adjacent wireless communication device.
[0012]
Further, according to the present invention, in the control method, the wireless
15 communication device may perform transmission and reception with the vehicle
traveling in the corresponding lane such that a timing of the transmission and reception
control period in which transmission and reception with the vehicle is performed on a
control channel and a timing of the transmission and reception control period in which
transmission and reception with the vehicle is performed on a service channel of the
20 same frequency among the service channels of a plurality of frequencies are shifted from
the timings of another first adjacent wireless communication device adjacent thereto and
a timing of a second adjacent wireless communication device adjacent to the first
adjacent wireless communication device.
[0013]
25 Further, according to the present invention, in the control method, the wireless
7
communication device may perform transmission and reception with the vehicle on a
service channel of a frequency different from a frequency of the service channel used by
the another adjacent wireless communication device.
[0014]
Further, according to the present invention, provided is 5 a program causing a
computer of each of a plurality of wireless communication devices that performs wireless
communication with a vehicle traveling in one of a plurality of lanes formed on a road,
each of the plurality of wireless communication devices corresponding to one of the
plurality of lanes, to function as a unit configured to perform transmission and reception
10 with the vehicle traveling in the corresponding lane such that a timing of a transmission
and reception control period in which transmission and reception with the vehicle is
performed on a control channel which is a first frequency and a timing of a transmission
and reception control period in which transmission and reception with the vehicle is
performed on a service channel which is a frequency different from the first frequency
15 are shifted from the timings of another wireless communication device.
Advantageous Effects of Invention
[0015]
According to the present invention, adjacent wireless communication devices
alternately transmit wireless signals on different frequencies, and thus it is possible to
20 reduce the occurrence of a radio wave interference region in a range in which the
wireless communication regions overlap.
Brief Description of Drawings
[0016]
FIG. 1 is a schematic diagram of a wireless communication system.
25 FIG. 2A is a first diagram showing transmission control of wireless signals of
8
wireless communication devices.
FIG. 2B is a first diagram showing transmission control of wireless signals of
wireless communication devices.
FIG. 3 is a second diagram showing transmission control of wireless signals of
wireless communication 5 devices.
FIG. 4 is a diagram showing an overview of a synchronous operation of
communication between a wireless communication device and a vehicle.
FIG. 5 is a diagram showing an overview of a communication process between a
wireless communication device and a vehicle.
10 FIG. 6 is a diagram showing a wireless communication system using a WAVE
technique according to a related art.
Description of Embodiments
[0017]
Hereinafter, a wireless communication device according to an embodiment of
15 the present invention will be described with reference to the appended drawings.
FIG. 1 is a schematic diagram of a wireless communication system according to
the embodiment.
FIG. 1 is shown wireless communication devices 1a to 1d, a vehicle 2, a
transmission control device 10, a road 50, and lanes 60a to 60d. Further, in the
20 following description, the wireless communication devices 1a to 1d are referred to
collectively as a “wireless communication device 1” and the lanes 60a to 60d are referred
to collectively as a “lane 60.” In the wireless communication system according to the
present embodiment, each of the wireless communication devices 1a to 1d correspond to
and are installed directly above one of the plurality of lanes 60a to 60d formed on road 50.
25 The wireless communication devices 1a to 1d are connected to the transmission control
9
device 10 so that communication can be performed therebetween, and transmit wireless
signals specified in the WAVE communication standard on the lanes formed at
corresponding positions on the road 50 based on control of the transmission control
device 10.
5 [0018]
The transmission control device 10 includes a communication unit 11, a
transmission control unit 12, and a storage unit 13 as shown in FIG. 1. The
communication unit 11 is a processing unit that performs communication with the
wireless communication devices 1a to 1d. The transmission control unit 12 is a
10 processing unit that controls transmission timings of wireless signals that are transmitted
on the control channel or the service channel by the wireless communication devices 1a
to 1d. The storage unit 13 stores various types of information for processing.
[0019]
Further, in the wireless communication system according to the present
15 embodiment, based on control of the transmission control device 10, the wireless
communication device 1 performs transmission and reception with the in-vehicle device
of the vehicle 2 traveling in a corresponding lane such that a timing of a transmission and
reception control period in which transmission and reception with the in-vehicle device
of the vehicle 2 is performed on the control channel which is a first frequency and a
20 timing of a transmission and reception control period in which transmission and
reception with the in-vehicle device of the vehicle 2 is performed on the service channel
which is a frequency different from the first frequency are shifted from the timings of the
another wireless communication devices.
Accordingly, a wireless communication system capable of reducing the
25 occurrence of the radio wave interference region is provided.
10
[0020]
FIGS. 2A and 2B are first diagrams showing transmission control of wireless
signals of the wireless communication devices.
The transmission control of the wireless signal shown in FIG. 2A is an example
in which the wireless communication device 1 performs transmission 5 and reception with
the in-vehicle device of the vehicle 2 traveling in a corresponding lane such that a timing
of a transmission and reception control period in which transmission and reception with
the in-vehicle device of the vehicle 2 is performed on the control channel and a timing of
a transmission and reception control period in which transmission and reception with the
10 in-vehicle device of the vehicle 2 is performed on the service channel are shifted from the
timings of the other adjacent wireless communication devices 1.
[0021]
In other words, in the example of FIG. 2A, the wireless communication device
1a causes the timings of the transmission and reception control periods according to the
15 control channel and the service channel to be different from those of the adjacent
wireless communication device 1b.
Further, in the example of FIG. 2A, the wireless communication device 1b
causes the timings of the transmission and reception control periods on the control
channel and the service channel to not overlap those of the adjacent wireless
20 communication devices 1a and 1c.
Further, in the example of FIG. 2A, the wireless communication device 1c
causes the timings of the transmission and reception control periods on the control
channel and the service channel to not overlap those of the adjacent wireless
communication devices 1b and 1d.
25 Further, in the example of FIG. 2A, the wireless communication device 1d
11
causes the timings of the transmission and reception control periods according to the
control channel and the service channel not to overlap that of the adjacent wireless
communication device 1c.
[0022]
When such transmission control is performed, the transmission 5 control unit 12
of the transmission control device 10 reads network addresses of the wireless
communication devices 1a to 1d connected via communication from the storage unit 13,
and transmits a communication start request signal to give an instruction to start
communication control with the vehicle 2 to the wireless communication devices 1a to
10 1d.
[0023]
Here, in the wireless communication device 1a and the wireless communication
device 1c, information to instruct transmission of a wireless signal on the control channel
when the count is an odd number and instruct transmission of a wireless signal on the
15 service channel when the count is an even number is recorded in a memory or the like in
advance. Meanwhile, in the wireless communication device 1b and the wireless
communication device 1d, information to instruct transmission of a wireless signal on the
control channel when the count is an even number and instruct transmission of a wireless
signal on the service channel when the count is an odd number is recorded in a memory
20 or the like in advance.
[0024]
Upon receiving the communication start request signal from the transmission
control device 10, control units of the wireless communication devices 1a to 1d start
counting. For example, a count interval is 20 msec. Further, the control units of the
25 wireless communication device 1a and the wireless communication device 1c perform
12
control such that the wireless signal on the control channel is transmitted when a count is
an odd number.
Further, the control units of the wireless communication device 1a and the
wireless communication device 1c perform control such that the wireless signal on the
service channel is transmitted when a count 5 is an even number.
[0025]
Meanwhile, the control units of the wireless communication device 1b and the
wireless communication device 1d perform control such that the wireless signal on the
service channel is transmitted when a count is an odd number. Further, the control units
10 of the wireless communication device 1b and the wireless communication device 1d
perform control such that the wireless signal on the control channel is transmitted when a
count is an even number.
[0026]
Through such processing, the adjacent wireless communication devices 1
15 alternately transmit wireless signals of different frequencies, and thus it is possible to
reduce the occurrence of the radio wave interference region in the range in which the
wireless communication regions 3 overlap.
[0027]
Further, the transmission control unit 12 of the transmission control device 10
20 may determine the transmission timing of the wireless signal on the control channel and
the transmission timing of the wireless signal on the service channel in each of the
wireless communication devices 1 based on counting and transmit each timing to the
wireless communication device 1 each time. In this case, each of the wireless
communication devices 1 sequentially transmits the wireless signal on the control
25 channel and the wireless signal on the service channel based on the transmission timing
13
received from the transmission control device 10.
[0028]
The wireless communication device 1 may perform the transmission control of
the wireless signal shown in FIG. 2B instead of the transmission control of the wireless
signal 5 shown in FIG. 2A.
The transmission control of the wireless signal shown in FIG. 2B is an example
in which the wireless communication device 1 performs transmission and reception with
the in-vehicle device of the vehicle 2 traveling in a corresponding lane such that the
timing of a transmission and reception control period in which transmission and
10 reception with the in-vehicle device of the vehicle 2 is performed on a control channel
and a timing of a transmission and reception control period in which transmission and
reception with the in-vehicle device of the vehicle 2 is performed on a service channel
are shifted from timings of the other adjacent wireless communication devices 1.
Further, in the example of the transmission control of the wireless signal shown in FIG.
15 2B, the two adjacent wireless communication devices 1 perform transmission and
reception with the in-vehicle devices of the vehicles 2 traveling in corresponding lanes on
the service channels of different frequencies.
[0029]
In other words, in the example of FIG. 2B, the wireless communication device
20 1a cause the timings of the transmission and reception control periods on the control
channel and on the service channel to not overlap those of the adjacent wireless
communication device 1b, and performs transmission and reception with the in-vehicle
device of the vehicle 2 on a service channel of a frequency different from a frequency on
the service channel used by the wireless communication device 1b.
25 Further, in the example of FIG. 2B, the wireless communication device 1b
14
causes the timings of the transmission and reception control periods on the control
channel and on the service channel to not overlap those of the adjacent wireless
communication devices 1a and 1c, and performs transmission and reception with the
in-vehicle device of the vehicle 2 on the service channel of a frequency different from
frequencies of the service channels used by the wireless communication 5 devices 1a and
1c.
Further, in the example of FIG. 2B, the wireless communication device 1c
causes the timings of the transmission and reception control periods on the control
channel and on the service channel to not overlap those of the adjacent wireless
10 communication devices 1b and 1d, and performs transmission and reception with the
in-vehicle device of the vehicle 2 on the service channel of a frequency different from the
frequencies of the service channels used by the wireless communication devices 1b and
1d.
Further, in the example of FIG. 2B, the wireless communication device 1d
15 causes the timings of the transmission and reception control periods on the control
channel and on the service channel to not overlap those of the adjacent wireless
communication device 1c, and performs transmission and reception with the in-vehicle
device of the vehicle 2 on the service channel of a frequency different from a frequency
of the service channel used by the wireless communication device 1c.
20 [0030]
When such transmission control is performed, the transmission control unit 12
of the transmission control device 10 reads network addresses of the wireless
communication devices 1a to 1d connected via communication from the storage unit 13,
and transmits a communication start request signal to give an instruction to start
25 communication control with the vehicle 2 to the wireless communication devices 1a to 1d,
15
similarly to the process of the example shown in FIG. 2A.
[0031]
Here, in the wireless communication device 1a and the wireless communication
device 1c, information to instruct transmission of a wireless signal on the control channel
when the count is an odd number and instruct transmission of a wireless 5 signal on the
service channel when the count is an even number is recorded in a memory or the like in
advance. Further, in the wireless communication device 1a and the wireless
communication device 1c, information to give an instruction to use a frequency F1 as the
service channel is recorded in a memory or the like. Meanwhile, in the wireless
10 communication device 1b and the wireless communication device 1d, information to
instruct transmission of a wireless signal on the control channel when the count is an
even number and instruct transmission of a wireless signal on the service channel when
the count is an odd number is recorded in a memory or the like in advance. Further, in
the wireless communication device 1b and the wireless communication device 1d,
15 information to give an instruction to use a frequency F2 as the service channel is
recorded in a memory or the like.
[0032]
Upon receiving the communication start request signal from the transmission
control device 10, control units of the wireless communication devices 1a to 1d start
20 counting. For example, a count interval is 20 msec. Further, the control units of the
wireless communication device 1a and the wireless communication device 1c perform
control such that the wireless signal on the control channel is transmitted when the count
is an odd number.
Further, the control units of the wireless communication device 1a and the
25 wireless communication device 1c perform control such that the wireless signal on the
16
service channel which is the frequency F1 is transmitted when the count is an even
number.
[0033]
Meanwhile, the control units of the wireless communication device 1b and the
wireless communication device 1d perform control such that the 5 wireless signal on the
service channel which is the frequency F2 is transmitted when the count is an odd
number. Further, the control units of the wireless communication device 1b and the
wireless communication device 1d perform control such that the wireless signal on the
control channel is transmitted when the count is an even number.
10 [0034]
Through such processing, the adjacent wireless communication devices 1
alternately transmit wireless signals on different frequencies, and thus it is possible to
reduce the occurrence of the radio wave interference region in the range in which the
wireless communication regions 3 overlap.
15 [0035]
FIG. 3 is a second diagram showing transmission control of wireless signals of
the wireless communication devices.
The transmission control of the wireless signal shown in FIG. 3 is an example in
which the wireless communication device 1 performs transmission and reception with the
in-vehicle device of the vehicle 2 traveling in a corresponding lane such that the timing
of a transmission and reception control period in which transmission and reception with
the in-vehicle device of the vehicle 2 is performed on the control channel and the timing
of a transmission and reception control period in which transmission and reception with
the in-vehicle device of the vehicle 2 is performed on the service channel which is the
same as the service channels of each of a plurality of frequencies are shifted from the
timing of a first adjacent wireless communication device adjacent thereto and a timing of
a second adjacent wireless communication device that is another wireless communication
device adjacent to the first adjacent wireless communication device.
[0036]
In other words, in the example of FIG. 3, the wireless communication 5 device 1a
performs transmission and reception with the in-vehicle device of the vehicle 2 such that
timings of the transmission and reception control periods by a control channel and a
service channel of the same frequency among service channels of a plurality of
frequencies do not overlap those of the wireless communication device 1b (the first
adjacent wireless communication device) and the wireless communication device 1c (the
second adjacent wireless communication device).
Further, in the example of FIG. 3, the wireless communication device 1b
performs transmission and reception with the in-vehicle device of the vehicle 2 such that
timings of the transmission and reception control periods on a control channel and a
service channel of the same frequency among service channels of a plurality of
frequencies do not overlap those of the adjacent wireless communication device 1a (the
first adjacent wireless communication device), the wireless communication device 1c
(the first adjacent wireless communication device), and the wireless communication
device 1d (the second adjacent wireless communication device).
Further, in the example of FIG. 3, the wireless communication device 1c
performs transmission and reception with the in-vehicle device of the vehicle 2 such that
timings of the transmission and reception control periods on a control channel and a
service channel of the same frequency among service channels of a plurality of
frequencies do not overlap those of the adjacent wireless communication device 1b (the
first adjacent wireless communication device), the wireless communication device 1d
(the first adjacent wireless communication device), and the wireless communication
device 1a (the second adjacent wireless communication device).
Further, in the example of FIG. 3, the wireless communication device 1d
performs transmission and reception with the in-vehicle device of the vehicle 2 such that
timings of the transmission and reception control periods by a control 5 channel and a
service channel of the same frequency among service channels of a plurality of
frequencies do not overlap those of the adjacent wireless communication device 1c (the
first adjacent wireless communication device) and the wireless communication device 1b
(the second adjacent wireless communication device).
[0037]
When such transmission control is performed, the transmission control unit 12
of the transmission control device 10 reads network addresses of the wireless
communication devices 1a to 1d connected via communication from the storage unit 13,
and transmits a communication start request signal to give an instruction to start
communication control with the vehicle 2 to the wireless communication devices 1a to 1d,
similarly to the processes of the examples shown in FIGS. 2A and 2B.
[0038]
In the wireless communication devices 1a and 1d, information to give an
instruction to transmit the wireless signal on the control channel at a first count, transmit
20 the wireless signal on the service channel of the frequency F1 on a second count, and
transmit the wireless signal on the service channel of the frequency F2 on a third count is
recorded in a memory or the like in advance.
Further, in the wireless communication device 1b, information to give an
instruction to transmit the wireless signal on the service channel of the frequency F2 on a
first count, transmit the wireless signal on the control channel on a second count, and
transmit the wireless signal on the service channel of the frequency F1 on a third count is
recorded in a memory or the like in advance.
Further, in the wireless communication device 1c, information to give an
instruction to transmit the wireless signal on the service channel of the frequency F1 on a
first count, transmit the wireless signal on the service channel of the 5 frequency F2 on a
second count, and transmit the wireless signal on the control channel on a third count is
recorded in a memory or the like in advance.
[0039]
Upon receiving the communication start request signal from the transmission
10 control device 10, control units of the wireless communication devices 1a to 1d start
counting. For example, the count interval is 20 msec. Further, the control units of the
wireless communication devices 1a and 1d perform control such that the wireless signal
on the control channel is transmitted when the count is a first count. Further, the control
units of the wireless communication devices 1a and 1d perform control such that the
wireless signal on the service channel of the frequency F1 is transmitted when the count
is a second count. Further, the control units of the wireless communication devices 1a
and 1d perform control such that the wireless signal of the service channel of the
frequency F2 is transmitted when the count is a third count. Further, the control units of
the wireless communication devices 1a and 1d repeatedly perform the transmission
control of the first to third counts at each count.
[0040]
Further, the control unit of the wireless communication device 1b performs
control such that the wireless signal of the service channel of the frequency F2 is
transmitted when the count is the first count. Further, the control unit of the wireless
communication device 1b performs control such that the wireless signal of the control
channel is transmitted when the count is the second count. Further, the control unit of
the wireless communication device 1b performs control such that the wireless signal on
the service channel of the frequency F1 is transmitted when the count is the third count.
Further, the control unit of the wireless communication device 1b repeatedly performs
the transmission control of the first to third counts 5 at each count.
[0041]
Further, the control unit of the wireless communication device 1c performs
control such that the wireless signal on the service channel of the frequency F1 is
transmitted when the count is the first count. Further, the control unit of the wireless
communication device 1c performs control such that the wireless signal on the service
channel of the frequency F2 is transmitted when the count is the second count. Further,
the control unit of the wireless communication device 1c performs control such that the
wireless signal on the control channel is transmitted when the count is the third count.
Further, the control unit of the wireless communication device 1c repeatedly performs the
transmission control of the first to third counts at each count.
[0042]
Further, the wireless communication device 1 may perform transmission and
reception with the in-vehicle device of the vehicle 2 traveling in a corresponding lane
such that the timing of a transmission and reception control period in which transmission
and reception with the in-vehicle device of the vehicle 2 is performed on a control
channel and a timing of a transmission and reception control period in which
transmission and reception with the in-vehicle device of the vehicle 2 is performed
through a service channel of the same frequency among service channels of a plurality of
frequencies are shifted from the timings of other adjacent wireless communication
devices that are sequentially adjacent and equal in number to frequencies.
For example, the wireless communication device 1a may perform transmission
and reception with the in-vehicle device of the vehicle 2 traveling in a corresponding lane
such that a timing of a transmission and reception control period in which transmission
and reception with the in-vehicle device of the vehicle 2 is performed on a control
channel and a timing of a transmission and reception control 5 period in which
transmission and reception with the in-vehicle device of the vehicle 2 is performed
through a service channel of the same frequency among service channels of a plurality of
frequencies (three frequencies F1, F2, and F3) are shifted from the timings of (3) other
adjacent wireless communication devices (the wireless communication devices 1b, 1c,
10 and 1d) that are sequentially adjacent and equal in number to frequencies.
[0043]
Through such processing, a plurality of wireless communication devices 1 that
are sequentially adjacent alternately transmit wireless signals on different frequencies,
and thus it is possible to reduce the occurrence of the radio wave interference regions in
the range in which the wireless communication regions 3 of the plurality of wireless
communication devices 1 overlap.
[0044]
FIG. 4 is a diagram showing an overview of a synchronous operation of
communication between the wireless communication device and the vehicle.
As shwon in FIG. 4, the wireless communication device 1 repeatedly performs
transmission of the wireless signal on the control channel (CCH) and transmission of the
wireless signal on the service channel (SCH) at certain count intervals. The count
interval is referred to as an interval, and a wireless signal non-transmission period called
a guard band is set during a certain period from a start timing of the interval in the
interval of the wireless signal in each of the control channel and the service channel.
Meanwhile, the vehicle 2 repeats a control channel reception mode at intervals equal to
those of the wireless communication device 1 until the wireless signal on the control
channel transmitted from the wireless communication device 1 is received. Then, when
the vehicle enters the wireless communication region 3 of the wireless signal transmitted
from the wireless communication device 1, the in-vehicle device of the 5 vehicle 2 receives
the wireless signal on the control channel in the control channel reception mode, and
repeats transmission and reception of the wireless signals on the service channel and the
control channel in a subsequent interval.
[0045]
10 FIG. 5 is a diagram showing an overview of a communication process between
the wireless communication device and the vehicle.
When the period of time of the guard band of the interval elapses, the wireless
communication device 1 transmits timing notification information to the vehicle 2 as
shown in FIG. 5. The timing notification information is information used to
synchronize the in-vehicle device mounted in the vehicle 2 with the wireless
communication. Further, the wireless communication device 1 transmits service
channel (SCH) designation information and position correction information using the
control channel. The service channel designation information is information used to
designate necessary in-vehicle device data.
The position correction information is data used to correct the position of the
in-vehicle device.
[0046]
Then, upon receiving the timing notification information, the service channel
designation information, and the position correction information, the in-vehicle device of
the vehicle 2 transmits in-vehicle device information on the service channel after the
guard band of the transmission and reception control period on the service channel
elapses. When an acknowledge response (ACK) is not received from the wireless
communication device 1 before the transmission and reception control period on the
service channel elapses, the in-vehicle device transmits the in-vehicle device information
again within the same transmission and reception control period on 5 the service channel.
[0047]
Here, when the length of the interval is too short, the ratio of the period of the
guard band of the interval (the transmission and reception control period) is increased,
and a communication rate (a data transmission/reception amount per unit time) between
the wireless communication device 1 and the vehicle 2 is lowered. Thus, it is necessary
to set the length of the interval so that transmission and reception of certain information
based on wireless communication on the service channel can be completed in the
wireless communication region 3 after the in-vehicle device of the vehicle 2 receives the
wireless communication on the control channel from the wireless communication device
15 1.
[0048]
Further, each of the wireless communication device 1, the transmission control
device 10, and the in-vehicle device equipped in the vehicle 2 includes an internal
computer system. Further, the above-described processes are stored in a computer
readable recording medium in a program form, and are performed as the program is read
and executed by a computer. Here, examples of the computer readable recording
medium include a magnetic disk, a magneto optical disk, a CD-ROM, a DVD-ROM, and
a semiconductor memory. The computer program may be delivered to a computer via a
communication line and executed by the computer that received the delivery.
25 [0049]
Further, the program may implement some of the above-described functions.
In addition, the program may be a so-called differential file (a differential
program) that can be implemented in combination with a program having the
above-described functions that are already recorded in a computer system.
Industrial 5 Applicability
[0050]
According to an aspect of the present invention, it is possible to provide a
wireless communication system capable of reducing the occurrence of radio wave
interference regions.
10 Reference Signs List
[0051]
1, 1a, 1b, 1c, 1d Wireless communication device
2 Vehicle
10 Transmission control device
15 11 Communication unit
12 Transmission control unit
13 Storage unit
50 Road
60, 60a, 60b, 60c, 60d Lane
CLAIMS
[Claim 1]
A wireless communication system, comprising:
a plurality of wireless communication devices each of which 5 performs wireless
communication with a vehicle traveling in one of a plurality of lanes formed on a road,
each of the plurality of wireless communication devices corresponding to one of the
plurality of lanes,
wherein the wireless communication device performs transmission and reception
with the vehicle traveling in the corresponding lane such that a timing of a transmission
and reception control period in which transmission and reception with the vehicle is
performed on a control channel which a first frequency is and a timing of a transmission
and reception control period in which transmission and reception with the vehicle is
performed through a service channel which is a frequency different from the first
frequency are shifted from a timing of another wireless communication device.
[Claim 2]
The wireless communication system according to claim 1,
wherein the wireless communication device performs transmission and reception
with the vehicle traveling in the corresponding lane such that a timing of the transmission
and reception control period in which transmission and reception with the vehicle is
performed on the control channel and a timing of the transmission and reception control
period in which transmission and reception with the vehicle is performed on the service
channel are shifted from a timing of another adjacent wireless communication device.
[Claim 3]
The wireless communication system according to claim 1,
wherein the wireless communication device performs transmission and reception
with the vehicle traveling in the corresponding lane such that a timing of the transmission
and reception control period in which transmission and reception with the vehicle is
performed through the control channel and a timing of the transmission and reception
control period in which transmission and reception with the vehicle 5 is performed on a
service channel which is the same as the service frequency of each of plurality of
wireless communication devices are shifted from a timing of another first adjacent
wireless communication device adjacent to the wireless communication device and a
timing of a second adjacent wireless communication device adjacent to the first adjacent
wireless communication device.
[Claim 4]
The wireless communication system according to claim 2 or 3,
wherein the wireless communication device performs transmission and reception
with the vehicle on a service channel of a frequency different from a frequency of the
service channel used by the another adjacent wireless communication device.
[Claim 5]
A control method of a wireless communication system including a plurality of
wireless communication devices each of which performs wireless communication with a
vehicle traveling in one of a plurality of lanes formed on a road, each of the plurality of
wireless communication devices corresponding to one of the plurality of lanes, the
control method comprising:
performing, by the wireless communication device, transmission and reception
with the vehicle traveling in the corresponding lane such that a timing of a transmission
and reception control period in which transmission and reception with the vehicle is
performed through a control channel which a first frequency is and a timing of a
transmission and reception control period in which transmission and reception with the
vehicle is performed on a service channel which is a frequency different from the first
frequency are shifted from a timing of another wireless communication device.
[Claim 6]
The control method 5 according to claim 5,
wherein the wireless communication device performs transmission and reception
with the vehicle traveling in the corresponding lane such that a timing of the transmission
and reception control period in which transmission and reception with the vehicle is
performed on the control channel and a timing of the transmission and reception control
period in which transmission and reception with the vehicle is performed on the service
channel are shifted from a timing of another adjacent wireless communication device.
[Claim 7]
The control method according to claim 5,
wherein the wireless communication device performs transmission and reception
with the vehicle traveling in the corresponding lane such that a timing of the transmission
and reception control period in which transmission and reception with the vehicle is
performed on the control channel and a timing of the transmission and reception control
period in which transmission and reception with the vehicle is performed on a service
channel which is the same as the service frequency of each of plurality of wireless
communication devices are shifted from a timing of another first adjacent wireless
communication device adjacent thereto and a timing of a second adjacent wireless
communication device adjacent to the first adjacent wireless communication device.
[Claim 8]
The control method according to claim 6 or 7,
wherein the wireless communication device performs transmission and reception
with the vehicle on a service channel of a frequency different from a frequency of the
service channel used by the another adjacent wireless communication device.
[Claim 9]
A program causing a computer of each of a plurality of wireless communication
devices each of which performs wireless communication with a vehicle 5 traveling in one
of a plurality of lanes formed on a road, each of the plurality of wireless communication
devices corresponding to one of the plurality of lanes, to function as:
a unit configured to perform transmission and reception with the vehicle
traveling in the corresponding lane such that a timing of a transmission and reception
control period in which transmission and reception with the vehicle is performed on a
control channel which is a first frequency and a timing of a transmission and reception
control period in which transmission and reception with the vehicle is performed on a
service channel which is a frequency different from the first frequency are shifted from a
timing of another wireless communication device.