Description
Title of Invention
TERMTNAL DEVICE, BASE STATION, AND PROGRAM
5
Technical Field
[OOOl]
The present disclosure relates to a terminal device, a base station, and a
program.
10
Background Art
[0002]
In a wireless communication system, carrier sense is performed as one of
technologies for avoiding collision. The carrier sense is processing to confirm that
15 another terminal does not perform transmission in a frequency channel used. A
terminal performs wireless transmission when another terminal does not perform
transmission, while it suppresses wireless transmission when another terminal
performs transmission. The wireless communication system uses the carrier sense
to avoid interference due to wireless transmission performed by a plurality of
20 terminals using the same wireless resource (frequency, time).
[0003]
When the interference occurs, a terminal on the reception side receives
desired signals and interference signals at the same time, and a signal-to-noise (SN)
ratio is reduced. When the SN ratio is reduced excessively, the reception of desired
25 signals becomes difficult and, consequently, wireless communication becomes
difficult. Then, the technology of avoiding interference using carrier sense is
developed.
[0004]
For example, the following Patent Literature 1 discloses a technology in
30 which a base station in a wireless local area network (LAN) controls signal detection
thresholds of belonging teiminals so that the belonging terminals detect each other to
avoid a hidden terminal problem.
Citation List
Patent Literature
5 [0005]
Patent Literature 1 : JP 2008-17337A
Summary of Invention
Technical Problem
10 [0006]
However, the technology in the above-described Patent Literature 1 does not
consider the existence of networks other than a network formed by the base station.
In today's spread and concentration of wireless communication systems, it is
assumed that another network adjacent to or overlapping the own network exists.
15 Thus, it is desirable to provide a mechanism of carrier sensc considering the
influence of not only the own network but also other networks.
Solution to Problem
[0007]
20 According to the present disclosure, there is provided a terminal device,
including: a wirelcss communication unit that performs communication with a base
station that forms a first wireless network; a carrier sense unit that performs carrier
sensc with another device; and a control unit that controls a signal detection
threshold so that another terminal device belonging to a second wireless network
25 different from the first wireless network is outside a signal detection range, based on
a carrier scnse result by the carrier sense unit.
[0008]
According to the present disclosure, there is provided a base station,
including: a wireless communication unit that forms a first wireless network and
30 performs communication with a terminal devicc, and a control unit that transmits as a
reply, through the wireless communication unit, a threshold change response for
changing a signal detection threshold so that a second terminal dcvice belonging to a
second wireless network different from the first wirelcss network is outside a signal
detection range of a first terminal device, bascd on a threshold change request
rece~vedf rom the first terminal device belonging to the first wireless network.
5 [0009]
According to the present disclosure, there is provided a program that causes
a computer to function as: a wireless communication unit that performs
communication with a base station that forms a first wireless network; a carrier sense
unit that performs carrier sense with another device; and a control unit that controls a
10 signal detection threshold so that another terminal device belonging to a second
wireless network different from the first wireless network is outside a signal
detection range, based on a carrier sense result by the carrier sense unit.
[OO lo]
According to the present disclosure, there is provided a program that causes
15 a computer to function as: a wireless communication unit that forms a first wireless
network and performs communication with a terminal device; and a control unit that
transmits as a reply, through the wireless communication unit, a threshold change
response for changing a signal detection threshold so that a second terminal device
belonging to a second wireless network different from the first wireless network is
20 outside a signal detection range of a first terminal device, based on a threshold
change request received from the first terminal device belonging to the lirst wireless
network.
Advantageous Effects of Invention
25 [OOll]
As described above, the present disclosure enables carrier sense considering
the influence of not only the own network but also other networks.
Note that the effects described above are not necessarily limitative. With
or in the place of the above effects, there may be achieved any one of the effects
30 described in this specification or other effects that may be grasped from this
specification.
Brief Description of Drawings
[00 121
[FIG. 11 FIG. 1 is an explanatory diagram for explaining the outline of a
5 communication system according to an embodiment of the present disclosure.
[FIG. 21 FIG. 2 is a block diagram showing an example of a logical configuration of a
terminal device according to a first embodiment.
[FIG. 31 FIG. 3 is an explanatory diagram for explaining an example of the change of
a signal detection threshold in a communication system according to the first
10 embodiment.
[FIG. 41 FIG. 4 is a block diagram showing an example of a logical configuration of a
base station according to the first embodiment.
[FIG. 51 FIG. 5 is an explanatory diagram for explaining an example of the change of
a signal detection threshold in a communication system according to the first
15 embodiment.
[FIG. 61 FIG. 6 is an explanatory diagram for explaining an example of the change of
a signal detection threshold in a communication -system according to the first
embodiment.
[FIG. 71 FIG. 7 is an explanatory diagram for explaining an example of the change of
20 a signal detection threshold in a communication system according to the first
embodiment.
[FIG. 81 FIG. 8 is a sequence diagram showing an example of a flow of signal
detection threshold change processing performed in the communication system
according to the first embodiment.
25 [FIG. 91 FIG. 9 is a flowchart showing an example of a flow of carrier sense
processing performed in the terminal device according to the first embodiment.
[FIG. 101 FIG. 10 is a flowchart showing an example of a flow of change request
determination processing performed in the base station according to the first
embodiment.
30 [FIG. 1 I] FIG. 11 is a sequence diagram showing an example of a flow of threshold
change cancellation processing performed in a conmlunication system according to a
second embodiment.
[FIG. 121 FIG. 12 is a block diagram showing an example of a schematic
configuration of a smartphone.
[FIG. 131 FIG. 13 is a block diagram showing an example of a schematic
5 configuration of a car navigation device.
[FIG. 141 FIG. 14 is a block diagram showing an example of a schematic
configuration of a wireless access point.
Description of Embodiment(s)
10
[00 131
Hereinafter, (a) preferred embodiment(s) of the present disclosure will be
described in detail with reference to the appended drawings. In this specification
and the appended drawings, structural elements that have substantially the same
15 function and structure are denoted with the same reference numerals, and repeated
explanation of these structural elements is omitted.
[OO 141
Moreover, in this specification and the appended drawings, structural
elements that have substantially the, same function and structure may be
20 distinguished with different alphabets following the same reference numeral For
example, a plurality of structural elements that have substantially the same function
and structure are distinguished as tenninal devices 100A, 100B, and IOOC, if
necessary. However, when it is unnecessary to distinguish each of a plurality of
structural elements that have substantially the same function and structure, they are
25 denoted with only the same reference numeral. For example, when it is
unnecessary to particularly distinguish the terminal devices 100A, 100B, and 100C,
the terminal devices are simply referred to as the tenninal device(s) 100.
[00 151
The description will be given in the following order.
30 1. Overview
2. First embodiment
2-1. Configuration example of terminal device
2-2. Configuration example of base station
2-3. Example of operation processing
3. Second embodiment
5 3-1. Configuration example of terminal device
3-2. Configuration example of base station
3-3. Example of operation processing
4. Application example
5. Conclusion
10 [0016]
< 1. Overview >
First, the overview of a communication system 1 according to an
embodiment of the present disclosure will be described with reference to FIG. 1.
100 171
15 FIG. 1 is an explanatory diagram for explaining the outline of the
communication system 1 according to an embodiment of the present disclosure. As
shown in FIG. 1, the communication system 1 of the embodiment includes a plurality
of terminal devices 100 (that is, terminal devices 100A, 100B, and 100C), and a base
station 200. The communication system 1 is a system conforming to a wireless
20 LAN or a communication standard equivalent thereto, for example.
[0018]
The terminal devices 100 of the communication system I can belong to (be
connccted wirelessly to) different networks. For example, the terminal device 100A,
the terminal device 100B, and the base station 200 form a single wireless network.
25 This network has a star-type network structure in which each of the terminal devices
lOOA and lOOB is connected wirelessly to the base station 200. Meanwhile, the
terminal device lO0C is connected wirelessly to another base station not shown.
That is, the terminal device lO0C is a terminal forming a network different from the
network to which the terminal devices lOOA and l00B belong. In FIG. 1, thc base
30 station 200 and the temlinal devices 100 connectcd wirelessly are linked by arrows.
For the base station 200, wireless signals from the terminal devices lOOA and lOOB
are desired signals, and wireless signals from the terminal device 100C are
interference signals.
[0019]
Moreover, circular broken lines shown in FIG. 1 indicate signal detection
5 ranges 30 of the devices. FIG. 1 shows a signal detection range 30X of the base
station 200, a signal detection range 30A of the terminal device 100A, and a signal
detection range 30B of the terminal device 100B, for example. When another
terminal in the signal detection range 30 performs wireless transmission, each device
can detect the signals.
10 [0020]
I-Iere, with the positional relation shown in FIG. 1, transmission suppression
by carrier sense may be performed excessively.
[0021]
For example, the terminal device lO0C is positioned in the signal detection
15 range 30A, and thus when the terminal device lO0C performs wireless transmission,
the terminal device lOOA suppresses wireless transmission by carrier sense.
However, even if the terminal devices lOOA and 100C perform wireless transmission
at the same time, the base station 200 on the reception side can succeed in receiving
desired signals from the terminal device 100A. This is because the terminal device
20 lOOA is closer to the base station 200 than the terminal device 100C, whereby the
signal intensity of desired signals received by the base station 200 is higher than the
signal intensity of interference signals. Thus, the base station 200 can demodulate
desired signals from the terminal device lOOA without excessive reduction of the SN
ratio.
25 [0022]
In this manner, even when desired signals can be demodulated, transmission
opportunities may be lost excessively due to transmission suppression by carrier
sense. For example, in the example shown in FIG. 1, transmission opportunities of
the tcrminal device l00A may be lost excessively, reducing the throughput of the
30 whole system 1.
100231
In view or the above aspects, the communication system 1 according to an
embodiment of the present disclosure has been made. The communication system 1
of the embodiment can prevcnt exccssive transmission suppression by carrier sense
in the situation where transmission suppression is unnecessary. Particularly, the
5 embodiment provides a mechanism for preventing excessive transmission
suppression due to a terminal belonging to another network, such as an example
shown in FIG. I.
[0024]
<2. First embodiment>
10 [2-1. Configuration example of terminal device]
FIG. 2 is a block diagram showing an example of a logical configuration of
the terminal device 100 according to the embodiment. As shown in FIG. 2, the
terminal device 100 includes a wireless communication unit 110, a carrier sense unit
120, a storage unit 130, and a control unit 140.
15 [0025]
(1) Wireless communication unit 110
The wireless communication unit 110 transmits and receives wireless
signals. For example, the wireless communication unit 110 performs wireless
communication with the base station 200. To be more specific, the wireless
20 comnlunication unit 110 transmits uplink signals to the base station 200, and receives
downlink signals from the base station 200. The wireless communication unit 110
may have functions of an analog processing unit, an analog-to-digitalldigital-ioanalog
(ADIDA) conversion unit, and the like.
[0026]
25 For example, the wireless communication unit 110 of the embodiment
performs communication with the base station 200 forming a wireless network (first
wireless network). As described later in detail, the wireless communication unit
110 transmits a threshold change request output from the control unit 140 to the base
station 200, receives a threshold change response transmitted as a reply from the base
30 station 200, and outputs it to the control unit 140. Moreover, the wireless
co~nmunicationu nit 11 0 receives a threshold change notification, and outputs it to
the conl~.ol unit 140. The threshold change request is a mcssagc for requesting thc
order for changing a signal detection threshold. The threshold change response is a
message responding to a threshold change request for making the order for changing
or not changing a threshold. The threshold change notification is a message for
5 notifying that a signal detection threshold of any of the terminal devices 100 of the
base station 200 is changed.
[0027]
(2) Carrier sense unit 120
The carrier sense unit 120 has a function of performing carrier sense with
10 another device. For example, the carrier sense unit 120 performs measurement in a
time zone and a frequency band used by the wireless communication unit 100 for
wireless transmission. The carrier sense unit 120 may measure reception signal
intensity or measure an SN ratio. Then, the carrier sense unit 120 compares the
measurement result with a signal detection threshold to determine the state of a
15 network. For example, the carrier sense unit 120 determines that the network is in a
busy state when the measurement result exceeds the signal detection threshold, and
determines that the network is in an idle state when the measurement result does not
exceed the signal detection threshold. The busy state is a state in which another
terminal device 100 or the base station 200 in the signal detection range 30 is
20 performing wireless transmission. The idle state is a state in which another terminal
device 100 or the base station 200 in the signal detection range 30 is not performing
wireless transmission.
[0028]
In the embodiment, the control unit 140 described later sets a signal
25 detection threshold. As the signal detection threshold is increased, the signal
detection range 30 becomes small. As the signal detection threshold is reduced, the
signal detection range 30 becomes large. In the embodiment, based on the control
of the control unit 140, the signal detection threshold can be changed dynamically,
and the signal detection range 30 can be changed dynamically.
30 200291
The carrier sense unit 120 may perform carrier sense periodically with given
timc intervals, or pcrform carrier sense lbllowing the order by the coutrol unit 140.
The carrier sense unit 120 outputs information of the determination result indicating
whethcr the network is in a busy state or an idle state to the control unit 140.
[0030]
5 (3) Storage unit 130
The storage unit 130 is a part that records and reproduces data on a given
recording medium. The storage unit 130 is realized by a hard disc drive (HDD), for
example. The recording medium can be a solid memory such as a flash memory, a
memory card with an embedded solid memory, an optical disc, a magneto-optical
10 disc, a hologram memory, and the like. The storage unit 130 only needs to have a
configuration allowing recording and reproduction in accordance with an adopted
recording medium.
[003 11
For example, the storage unit 130 stores a default signal detection threshold.
15 In addition, the storage unit 130 may store information related to carrier sense by the
carrier sense unit 120.
[0032]
(4) Control unit 140
The control unit 140 functions as an operation processing device and a
20 control device, and controls the whole operation of the terminal device 100 in
accordance with various programs. The control unit 140 is realized by an electronic
circuit such as a central processing unit (CPU) and a microprocessor, for example.
Note that the control unit 140 may include a read only memory (ROM) that stores
programs and operation parameters used, and a random access memory (RAM) that
25 temporarily stores parameters viuying appropriately, and the like.
[0033]
For example, the control unit 140 has a function of permitting or
suppressing wireless transmission by the wireless communication unit 11 0 based on
a carrier sense result. To be more specific, the control unit 140 permits
30 transmission when the network is in an idle state, and suppresses transmission when
the network is in a busy state.
[0034]
When interference signals exceeding a signal detection threshold have been
received by carrier sense before data transmission, the control unit 140 suppresses
the data transmission. Here, the control unit 140 counts the number of times of
5 transmission suppression or records identification information of another terminal
device 100 that is a transmission origin of the interference signals. For example,
the control unlt 140 associates time information of transmission suppression with
identification information of another terminal device 100 that is a transmission origin
of the interference signal, and store the information in the storage unit 130. In the
10 following, the terminal device that is a transmission origin of interference signals is
also referred to as an interference terminal.
[0035]
Note that the wireless signals detected by carrier sense include interference
signals and, further, desired signals transmitted to the own terminal. When wireless
15 signals exceeding a signal detection threshold have been received by carrier sense,
the control unit 140 first controls the wireless communication unit 110 to demodulate
the wireless signals. When the destination is the own terminal, as a result of
demodulation, the control unit 140 determines that the received wireless signals are
desired signals. In this case, the control unit 140 obtains data included in the
20 desired signals, for example. On the other hand, when the destination is not the
own terminal, as a result of demodulation, the control unit 140 deteriuines that the
received wireless signals are interference signals.
[0036]
For example, the control unit 140 has a function of controlling, based on a
25 carrier sense result by the carrier sense unit 120, a signal detection threshold so that
another terminal device 100 belonging to another wireless network is outside a signal
detection range. To be more specific, the control unit 140 first monitors a carrier
sense result output from the carrier sense unit 120, and controls the wireless
communication unit 110 to transmit a threshold change request to the base station
30 200. Note that another wireless network indicates a wireless network (second
wireless network) formed by another base station 200, which is different from a
wireless network (first networli) lormed by the base station 200 with which the
terminal device 100 performs communication.
100371
For example, the control unit 140 controls the wireless communication unit
5 110 to transmit a threshold change request to the base station 200 with a trigger that
an index related to transmission suppression by carrier sense has exceeded a given
threshold. The index can be the number of times of transmission suppression by
carrier sense, for example. The present specification supposes that the control unit
140 counts the number of times of transmission suppression for each wireless frame,
10 and transmits a threshold change request when the number of times has exceeded a
given value. When the base station 200 permits the change of a threshold, and the
signal detection threshold is increased, another terminal transmitting interference
signals becomes outside the signal detection range 30. Thus, the carrier sense unit
120 determines an idle state, which allows transmission of a wireless frame subjected
15 to transmission suppression. As another example of the index, the control unit 140
may transmit a threshold change request with a trigger that the frequency or the ratio
of transmission suppression has exceeded a given valuc or that the transmission data
stored in a transfer buffer due to transmission suppression has exceeded a given
value, regarding a plurality of wireless frames, for example.
20 [0038]
The threshold change request may include a carrier sense result by the
carrier sense unit 120, for example. The threshold change request may include the
number of times of transmission suppression, identification information of an
interference terminal, or information indicating a measurement result of the reception
25 signal intensity of interference signals that is measured by the carrier sense unit 120.
In addition, the threshold change request may include information indicating the
importance of data subjected to transmission suppression by carrier sense. The
importance is supposed to be higher as permitted transmission delay is shorter. For
example, the importance of video streaming data may be high, while the importance
30 of web traffic such as a hypertcxt transfer protocol (HTTP) may be low.
[0039]
Moreover, the control unit 140 changes a signal dctcction threshold at the
carrier sense unit 120 bascd on a threshold change response transrnittcd from the
base station 200 as a response to a threshold change request, for example. The
threshold change response may include, for example, information indicating whether
5 the change of a threshold is permitted and information indicating a setting value of a
signal detection threshold to be set when the change is permitted. The setting value
may be, for example, information indicating an upper limit value or a lower limit
value of a variable signal detection threshold, and the control unit 140 may change,
in such a range, a signal detection threshold so that an interference terminal is outside
10 the signal detection range. A setting example of the signal detection tl~esholdb y
the control unit 140 will be described with reference to FIG. 3.
[0040]
FIG. 3 is an explanatory diagram for explaining an example of the change of
a signal detection threshold in the communication system 1 according to the first
15 embodiment. FIG. 3 shows an example of the case in which a threshold change
request from the terminal device lOOA is permitted. As shown in FIG. 3, the
terminal device IOOA increases a signal detection threshold to make the signal
detection range 30A smaller than that of FIG. 1. Thus, the terminal device lOOC
that is an interference terminal becomes outside the signal detection range 30A.
20 Consequently, even when the terminal device lOOC performs wireless transmission
using the same wireless resource, the terminal device 100A determines Lhe idle state,
thus avoiding suppression of wireless transmission. The setting example of a signal
detection threshold has been described above.
[0041]
25 The control unit 140 changes a signal detection threshold based on a
threshold change response, regarding data transmission as a trigger for the threshold
change request. As described above, the control unit 140 transmits a threshold
change request for a single wireless frame. When the threshold change request is
permitted, the control unit 140 changes a signal detection threshold for charrier sense
30 for this wireless frame. The control unit 140 may undo the change after ihe
wireless frame as a trigger is transmitted. This prevents excessive increase of
transmission opportunities 01 the terminal device 100. In addition, the control unit
140 may also transmit the subsequent wireless fiames while maintaining the changed
signal detection threshold. This reduces redundant proccssing of the terminal
device 100 for transmitting a threshold change request every time a wireless frame is
5 transmitted.
[0042]
The configuration example of the terminal device 100 according to the
embodiment has been described above. Next, a configuration example of the base
station 200 according to the embodiment will be described with reference to FIG. 4.
10 [0043]
[2-2. Configuration example of base station]
FIG. 4 is a block diagram showing an example of a logical configuration of
the base station 200 according to the embodiment. As shown in FIG. 4, the base
station 200 includes a wireless communication unit 210, a storage unit 220, and a
15 control unit 230.
[0044]
(1) Wireless communication unit 210
The wireless communication unit 210 transmits and receives wireless
signals. For example, the wireless communication unit 210 performs wireless
20 communication with the terminal device 100. To be more specific, the wireless
communication unit 210 transmits downlink signals to the terminal device 100, and
receives uplink signals from the terminal device 100. The wireless communication
unit 210 may have functions of an analog processing unit, an ADDA conversion unit,
and the lilce.
25 [0045]
The wireless communication unit 210 of the embodiment forms a wireless
network (first wireless network) and performs communication with the terminal
devices 100 belonging to the network. The wireless communication unit 210
receives a threshold change request from the terminal device 100, outputs it to the
30 control unit 230, and transmits as a reply a threshold change response output from
the control unit 230 to the terminal device 100 as a transmission origin of the
threshold changc request Moreover, the wireless communication unit 210
transmits a threshold change notification output from thc terminal device 100 to the
terminal deviccs 100 bclonging to the wireless network.
[0046]
5 (2) Storage unit 220
The storage unit 220 is a part that records and reproduces data on a given
recording medium. The storage unit 220 is realized by an HDD, for example. The
recording medium can be a solid memory such as a flash memory, a memory card
with an embedded solid memory, an optical disc, a magneto-optical disc, a hologram
10 memory, and the like. The storage unit 220 only needs to have a configuration
allowing recording and reproduction in accordance with an adopted recording
medium.
[0047]
For example, the storage unit 220 stores a range of a signal detection
15 threshold that can be set by the terminal device 100. Moreover, the control unit 230
may store the reception signal intensity at the wireless communication unit 210
regarding wireless signals received from terminals including an interference terminal
belonging to another wireless network.
[0048]
20 (3) Control unit 230
The control unit 230 functions as an operation processing device and a
control device, and controls the whole operation of the base station 200 in
accordance with various programs. The control unit 230 is realized by an electronic
circuit such as a CPU and a microprocessor, for example. Note that the control unit
25 230 may include a ROM that stories programs and operation parameters used, and a
RAM that temporarily stores parameters varying appropriately, and the like.
[0049]
Based on a threshold change request received from the first terminal device
100 belonging to the own wireless network (first network), the control unit 230 has a
30 function of controlling the second terminal device 100 belonging to a different
wireless network (second wireless network) to be outside the signal detection range
of the first terminal device 100. The control ulnt 230 determincs whether thc
change of a threshold is permitted based on various kinds of information regarding
the threshold change request received from the terminal device 100. Then, whcn
thc change of a threshold is permitted, the control unit 230 transmits as a reply a
5 threshold change response for changing the signal detection threshold of the terminal
device 100 to a transmission origin of the threshold change request. Thus, the
terminal device 100 that is a transmission origin of the threshold change request can
change the signal detection threshold.
[0050]
10 The control unit 230 permits the change of a threshold when at least one of
the following conditions is fulfilled, for example. Note that in the present
specification, the explanation will be given assuming that the control unit 230
permits the change of a threshold when all of the following conditions are fulfilled.
[0051]
15 For example, one of the conditions is that a terminal reported as an
interference terminal in the threshold change request is not a belonging terminal.
Note that belonging indicates belongingness to a wireless network (first wireless
network) formed by the own. The control unit 230 determines whether the
identification information reported as identification information of the interference
20 terminal is of the terminal device 100 connected to the base station 200 itself so as to
determine whether this condition is fulfilled. This condition allows the base station
200 to restrict terminals to be outside the signal detection range of the terminal
device 100 that is a transmission origin of a threshold change request, to the terminal
devices 100 belonging to other wireless networks. Moreover, the base station 200
25 can avoid the situation in which the belonging terminal devices 100 mutually control
themselves to be outside the signal detection range, thus preventing interference in
the own wireless network.
[0052]
For example, one of the conditions set be the control unit 230 is that all of
30 the terminal devices 100 belonging to the own wireless network have higher
reception signal intensity at the wireless communication unit 210 than an interference
terminal. Thc control unit 230 measures the reception signal intensity of wireless
signals transmitted from each terminal, which are received at the wireless
communication unit 210, so as to determine whether this condition is fulfilled based
on the reception signal intensity. For example, the control unit 230 determines that
5 this condition is fulfilled when the belonging terminal device 100 having lower
reception signal intensity than the interference terminal does not exist. Meanwhile,
the control unit 230 determines that this condition is not fulfilled when the belonging
terminal device 100 having lower reception signal intensity than the interference
terminal exists. For example, in the positional relation shown in FIG. 1, the
10 terminal device lOOC has the farthest distance to the base station 200. Thus, the
reception signal intensity of interference signals from the terminal device 1OOC is
lower than the reception signal intensity from the terminal devices lOOA and 100B.
In this case, the control unit 230 determines that the conditions are fulfilled. Note
that the control unit 230 may storelupdate measurement results of the reception
15 signal intensity from the terminals including interference terminals in the storage unit
220. The control unit 230 may determine the condition based on past measurement
results referring to the storage unit 220.
Here, this condition will be described in detail with reference to FIG. 5.
[0053]
20 FIG. 5 is an explanatory diagram for explaining an example of the change of
a signal detection threshold in the communication system 1 according to the
embodiment. FIG 5 shows an example of the case in which a threshold change
request from the terminal device lOOA is permitted although the condition is not
fulfilled. It is supposed that the terminal devices 100A and l00B belong to the base
25 station 200, and the terminal device lOOC is an interference terminal belonging to
another wireless network. As shown in FIG. 5, the interference terminal lO0C has a
smaller distance to the base station 200 than the terminal device 100B. Thus, the
belonging terminal device l00B has smaller signal intensity at the wireless
communication unit 210 than the interference terminal 100C, which does not fulfill
30 the condition. When the terminal device l00A increases the signal detection
threshold so that the interference terminal lOOC is outside the signal detection range
30A while the condition is not fulfilled, it becomes difficult that the terminal device
l00A detects even wireless transmission from the terminal dcvice l0OB by carrier
sensc, thus increasing the possibility of interhence. Here, the terminal device
l00A has a smaller distance to the base station 200 than the terminal device 100B.
5 Thus, the terminal device lOOA has higher reception signal intensity at the base
station 200 than the terminal device 100B. Therefore, when the signal detection
threshold is changed without fulfilling the condition, the possibility of interference
increases and, further, it becomes difficult that the base station 200 obtains wireless
signals from the terminal device l00B having lower reception signal intensity.
10 With this condition, the base station 200 can reject the change of a signal detection
threshold in such a situation.
[0054]
For example, one of the conditions set by the control unit 230 is that the
importance of data subjected to transmission suppression is higher than that of data
15 transmitted from any of the terminal devices 100 belonging to the own wireless
network. The control unit 230 determines that the condition is fulfilled when the
importance of data subjected to transmission suppression is higher than that of data
transmitted from any of the belonging terminals 100. Meanwhile, the control unit
230 determines that the condition is not fnlfilled when data higher in importance than
20 data subjected to transmission suppression is transmitted from the belonging terminal
device 100. The control unit 230 may determine the condition based on data being
transmitted to and received from the belonging terminal device 100 or data
transmitted to and received from the terminal device 100 most recently, or determine
the condition receiving, as needed, a report of the importance of data from the
25 belonging terminal device 100. With this condition, the base station 200 can set the
priority to transmission of data of higher importance by allowing the terminal device
100 that is a transmission origin of a threshold change request to obtain the
transmission opportunity regarding important data.
[0055]
30 The control unit 230 permits the change of a signal detection threshold
when all of these conditions are fulfilled. The control unit 230 generates a
threshold change response Tor changing a signal detection thi-cshold. The threshold
change responsc includes information indicating un upper limit value of the signal
detection threshold. Note that the upper limit valuc of the signal detection threshold
may be calculated by the control unit 230 or may be a preliminarily set value.
5 Meanwhile, when these conditions are not fulfilled, the control unit 230 generates a
threshold change response for rejecting the change of a signal detection threshold.
[0056]
Here, only with the change of the signal detection threshold of the terminal
device 100, it is still possible that the hase station 200 fails in receiving desired
10 signals. This point will he described in detail with reference to FIG. 6.
[0057]
FIG. 6 is an explanatoly diagram for explaining an example of the change of
a signal detection threshold in the communication system 1 according to the first
embodiment. FIG. 6 shows an example of the case in which a threshold change
15 request from the terminal device IOOA is permitted. In FIG. 6, the terminal device
lO0C is positioned in the signal detection range 30 of the hase station 200. Thus,
the hase station 200 can detect wireless signals from the terminal device l00A and
the terminal device 100C. When the base station 200 detects signals, it performs
reception processing (including demodulation processing, error correction processing,
20 and the like) of the signals from one of them, based on their reception signal intensity.
Thus, the base station 200 may perform reception processing of wireless signals from
the terminal device 100C. In such a case, it becomes difficult to perform reception
processing of wireless signals from the terminal device 100A. That is, only with
the change of the signal detection threshold of the terminal device 100A, it is still
25 possible to fail in receiving wireless signals from the terminal device l00A fails.
[0058]
Thus, when the control unit 230 changes a signal detection threshold of the
terminal device 100 belonging to the own wireless network, it may change a signal
detection threshold of the wireless communication unit 210. This function will be
1
30 described in detail with reference to FIG. 7.
[0059]
FIG. 7 is an explanatory diagram for explaining an example of the changc of
a signal detection threshold in the communication system 1 according to the first
embodiment. FIG. 7 shows an example of the case in which a threshold change
request from the terminal device 100A is permifled. As shown in FIG. 7, the base
5 station 200 increases a signal detection threshold so that the signal detection range
30X is smaller than FIG. 6. Thus, the terminal device lOOC that is an interference
terminal is outside the signal detection range 30X, which allows the base station 200
to perform reccption processing of wireless signals from the terminal device IOOA
without performing reception processing of wireless signals from the terminal device
10 10oc.
[0060]
Moreover, the control unit 230 controls the wireless communication unit
210 to transmit a threshold change notification indicating that the terminal device
100 changes the signal detection threshold to the terminal devices 100 belonging to
15 the own wireless network. For example, when the change of the threshold has been
permitted, the control unit 230 transmits a threshold change notification to all of the
belonging terminal devices 100. Thus, the terminal device 100 can recognize that
another terminal device 100 belonging to the own wireless network changes the
signal detection threshold. The threshold change notification may include
20 identification information of the terminal device 100 for which the signal detection
threshold is changed. Thus, the terminal device 100 can specify another terminal
device 100 changing the signal detection threshold. Moreover, the terminal device
100 can determine whether another terminal device 100 having changed the signal
detection threshold belongs to the own wireless network. In this case, only when an
25 interference terminal has changed the signal detection threshold and it belongs to the
wireless network to which the terminal device 100 belongs, the terminal device 100
transmits a threshold change cancellation request described later so as to avoid
transmission and reception of unnecessary messages.
[0061]
30 When the terminal device 100 having an increased signal detection
threshold exists, it has more transmission opportunities than other terminal devices
100, which may, convcrsely, reducc transmission opportunities of other teiminal
devices 100 and cause interference. Then, the comniunication system 1 cancels the
change of a threshold and undoes the signal detection threshold changed once. The
terminal device 100 can recognize, by a threshold change notification, that another
5 terminal device 100 changes the signal detection threshold, and thus the terminal
device 100 can also request the cancellation of the change of a threshold. The
concrete contents of cancellation of the change of a threshold will be described in
detail in the following second embodiment, and thus the explanation is omitted here.
Note that the threshold change notification may be included in a beacon frame
10 transmitted by the base station 200 or may be included in broadcast signals.
[0062]
The configuration example of the base station 200 according to the
embodiment has been described above. Next, the operation processing example of
the communication system 1 according to the embodiment will he described with
15 reference to FIG. 8 to FIG. 10.
[0063]
[2-3. Example of operation processing]
FIG. 8 is a sequence diagram showing an example of a flow of signal
detection threshold change processing performed in the communication system 1
20 according to the embodiment. The sequence shown in FIG. 8 is related to the
terminal devices IOOA, 100B, and lOOC and the base station 200. Note that the
positional relation of these devices is as shown in FIG. 1.
[0064]
As shown in FIG. 8, at Step S102, the terminal device l00A first performs
25 carrier sense before transmitting data. Here, it is supposed that the terminal device
l00A has received interference signals from the terminal device 100C. The
processing by the terminal device 1OOA in this case will be described in detail with
reference to FIG. 9.
[0065]
30 FIG. 9 is a flowchart showing an example of a flow of carrier sense
processing performed in the terminal devicc 100 according to the embodiment. As
shown in FIG 9, at Step S202, the carrier sense unit 120 first lncasures reception
signals. Then, at Step S204, the carrier sense unit 120 determines whether a
measurement value of the reception signals exceeds a signal detection threshold.
When it is determined that the measurement value does not exceed the signal
5 detection threshold (No at S204), the network is in an idle state, and thus the control
unit 140 sets, at Step S212, a flag of data transmission and finishes carrier sense.
Meanwhile, when it is determined that the measurement value exceeds the signal
detection threshold (Yes at S204), the network is in a busy state, and thus the control
unit 140 suppresses wireless transmission and counts the number of times of
10 suppression at Step S206. Here, the control unit 140 associates the mcasurernent
value and the identification information of the interference terminal, and stores them
in the storage unit 130. Next, at Step S208, the control unit 140 determines whether
the number of times of suppression has exceeded a given value. When the number
of times of suppression has not exceeded a given value (No at S208), the processing
15 returns to Step S202 again. Meanwhile, when the number of times of suppression
has exceeded a given value (Yes at S208), the control unit 140 sets, at Step S210, a
flag of transmission of a threshold change request, and finishes carrier sense.
[0066]
The processing at Step S102 of FIG. 8 has been described above. In the
20 following, the description returns to FIG. 8. When the flag of transmission of a
threshold change request is set, the processing shifts to Step S104. When the flag of
data transmission is set, the processing shifts to Step 5118. The following will
describe the case in which the flag of transmission of a threshold change request is
set.
25 [0067]
Subsequently, at Step S104, the terminal device lOOA transmits a threshold
c11ange request to the base station 200. The terminal device lOOA performs carrier
sense various times at Step S102, and transmits, when the flag of transmission of a
threshold change request is set, the thresllold change request before transmitting data.
30 For example, the threshold change request may include the identification information
of an interference terminal, the measurement result of interference signals (reception
signal intensity or SN ratio), and the information indicating the irnportancc of data
subjected to transmission suppression.
[0068l
Next, at Step 8106, the base station 200 performs change request
5 determination processing. The processing by the base station 200 here will be
described in detail with reference to FIG. 10.
[0069]
FIG. 10 is a flowchart showing an example of a flow of change request
determination processing performed in the base station 200 according to the
10 embodiment. As shown in FIG. 10, at Step S302, the control unit 230 first
determines whether the interference terminal is a belonging terminal. When the
interference terminal is a belonging terminal (Yes at S302), the control unit 230
rejects the threshold change request at Step S312. Meanwhile, when the
interference terminal is not a belonging terminal (No at S302), the control unit 230
15 measures, at Step S304, reception signal intensity from each terminal at the wireless
communication unit 210. Next, at Step S306, the control unit 230 determines
whether the belonging terminal device 100 having lower reception signal intensity
than the interference terminal exists. When it is determined that the belonging
terminal device 100 having lower reception signal intensity than the interference
20 terminal exists (Yes at S306), the control unit 230 rejects the threshold change
request at Step S312. Meanwhile, when it is determined that the belonging terminal
device 100 does not exist (No at S306), the control unit 230 determines, at Step S308,
whether the importance of data subjected to transmission suppression is higher than
that of transmission data of other belonging terminal devices 100. When it is
25 determined that the importance of data subjected to transmission suppression is
higher (Yes at S308), the control unit 230 permits the threshold change request at
Step S310. Meanwhile, when it is determined that the importance of the data is
lower (No at S308), the control unit 230 rejects the threshold change request at Step
S312.
30 [0070]
The processing at Step 5106 of FIG. 8 has been described above. In the
Ibllowing, the description returns to FIG. 8. Note that the following describes an
example of the case in which the change of a threshold has been permitted at Step
S106.
[0071]
5 Subsequently, at Step S108, the base station 200 transmits a threshold
change response as a reply to the terminal device IOOA. The threshold change
response includes information indicating that the threshold change request is
permitted and information indicating un upper limit value of the signal detection
threshold. Note that when the change of a threshold is not permitted, the base
10 station 200 transmits a threshold change response indicating that the threshold
change request is rejected to the terminal device 100A, for example.
[0072]
Next, at Step S110, the base station 200 transmits as a reply a threshold
change notification to the belonging terminal devices 100. Both the terminal
15 devices lOOA and lOOB having received the threshold change notification store a
threshold changed state as a current state.
100731
Then, at Step S112, the terminal device lOOA changes the signal detection
threshold based on the threshold change response. To be more specific, the control
20 unit 140 increases the signal detection threshold, in a range of an upper limit value of
the signal detection threshold included in the threshold change response, so that the
interference terminal is outside the signal detection range.
[0074]
Moreover, at Step S114, the base station 200 changes the own signal
25 detection threshold. To be more specific, the control unit 230 increases the signal
detection threshold so that the interference terminal is outside the signal detection
I range.
I 1 [0075]
i
! Then, at Step S116, the terminal device lOOA performs camer sense again.
I
I 30 The processillg here is as described above with reference to FIG. 9. When the
terminal device 100A has increased the signal detection threshold so that the terminal
device IOOC is outside the signal detection range at Stcp S112, it fails in detecting
interference signals from the terminal device 1 OOC. Thus, the terminal device lOOA
sets a flag of data transmission and finishes carrier sense.
[0076]
5 In this manner, the terminal device lOOA performs data transmission at Step
s11x.
[0077]
<3. Second embodiment>
The present embodiment is a form in which the change of a threshold is
10 cancelled to undo the signal detection threshold changed once.
[007X]
[3-1. Configuration example of terminal device]
A configuration example of the terminal device 100 according to the
embodiment is same as the fist embodiment. Here, the characteristic configuration
15 of the terminal device 100 of the embodiment will be described.
[0079]
(Wireless communication unit 110)
The wireless communication unit 110 of the embodiment transmits a
threshold change cancellation request .to the base station 200. The wireless
20 communication unit 110 receives a threshold change cancellation notification from
the base station 200. The threshold change cancellation request is a message for
cancelling the change of a signal detection threshold. The threshold change
cancellation request includes identification information of the terminal device 100
for which the change of a threshold is cancelled. The threshold change cancellation
25 notification is a message for notifying of cancellation of the change of a signal
detection threshold.
[OOXO]
(Control unit 140)
The control unit 140 has a function of cancelling the change of the own
30 signal detection threshold. For example, the control unit 140 cancels the change of
the own signal detection threshold based on the order from the base station 200.
For example, when the wircless communication unit 110 has received a threshold
change cancellation notification in the state where the signal detection threshold of
the control unit 140 is changed, the control unit 140 cancels the change of the signal
detection threshold and restores an original default value. Moreover, the control
5 unit 140 may determine spontaneously whether the change of the signal detection
threshold should be cancelled. For example, when the control unit 140 has changed
the own signal detection threshold and data transrnissior~ as a trigger for a threshold
change request has been completed, the control unit 140 controls the wireless
communication unit 110 to transmit a threshold change cancellation request to the
10 base station 200. Then, when the base station 200 transmits as a reply a threshold
change cancellation notification, the control unit 140 cancels the change of the signal
detection threshold and restores an original default value. In this manner, it is
possible to prevent the case in which the signal detection threshold remains high and
transmission opportunities of other terminal devices 100 are suppressed excessively.
15 Moreover, when a threshold change cancellation request is transmitted to the base
station 200 under the above-described condition in the state where the signal
detection threshold of the control unit 140 is changed, the control unit 140 may
restore an original default value of the own threshold before receiving a threshold
change cancellation notification. That is, the control unit 140 may cancel the
20 change of the signal detection threshold when the data transmission as a trigger for a
threshold change request has been completed. Note that the threshold change
cancellation request includes, as identification information of the terminal device 100
for which the change of a threshold is cancelled, the own identification information.
[0081]
25 Moreover, the control unit 140 according to the embodiment has a function
of cancelling the change of a signal detection threshold of another terminal device
100 belonging to the own wireless network. For example, the control unit 140
determines whether to request the cancellation of a threshold change and controls,
when requesting it, the wireless communication unit 110 to transmit a threshold
30 change cancellation request to the base station 200. As described later, the base
station 200 having received the threshold change cancellation request determines
whether to permit the cancellation of a threshold change and transmits, w11e11
permitting it, a threshold change cancellation notification to the belonging terminal
device 100. When the terminal device 100 with a changcd signal detection
threshold has received the threshold change cancellation notification, it cancels the
5 change of the signal detection threshold and restores an original default value. In
this manner, the terminal device 100 can prevent excessive increase of transmission
opportunities of another terminal device 100 with an increased signal detection
threshold, and secure the own transmission opportunities.
[0082]
10 When the control unit 140 recognizes that the signal detection threshold of
another terminal device 100 belonging to the own wireless network has been
changed, based on the threshold change notification received from the base station
200, it requests cancellation of the change of a threshold with various factors as a
trigger. For example, the control unit 140 controls the wireless communication unit
15 110 to transmit a threshold change cancellation request to the base station 200 with a
trigger that the number of times of suppression of data transmission by carrier sense
has exceeded a given value. Alternatively, the control unit 140 controls the wireless
communication unit 110 to transmit a threshold change cancellation request to the
base station 200 with a trigger that a failure rate of data transmission has exceeded a
20 given value. In these cases, the threshold change cancellatioll request includes, as
identification information of the terminal device 100 for which the change of a
threshold is cancelled, identification information of an interference terminal detected
by carrier sense. With these triggers, the terminal device 100 can restore the own
transmission opportunities afler yielding transmission opportunities to another
25 terminal device 100 having changed the signal detection threshold.
[OOS3]
The characteristic configuration example of the terminal device 100
according to the embodiment has been described above. The following will
describe the characteristic configuration example of the base station 200 according to
30 the embodiment.
[OOS4]
[3-2. Configuration example of base station]
A configuration example of the base station 200 according to the
embodiment is same as the first embodiment. I-Iere, the characteristic configuration
of the base station 200 of the embodiment will be described.
5 [0085]
(Wireless communication unit 210)
The wireless communication unit 210 of the embodiment receives a
threshold change cancellation request from the terminal device 100. Moreover, the
wireless communication unit 210 transmits a threshold change cancellation
10 notification to the belonging terminal device 100.
[0086]
(Control unit 230)
The control unit 230 of the embodiment determines whether the cancellation
of the change of a threshold is necessary, based on the threshold change cancellation
15 request received from the terminal device 100, and transmits a threshold change
cancellation notification. For example, the control unit 230 permits the cancellation
of the change of a threshold when the identification information of an interference
terminal included in the threshold change cancellation request indicates a belonging
terminal and is of a terminal for which the change of a threshold has been permitted,
20 while it rejects the cancellation of the change of a threshold in other cases. Note
that the threshold change notification and the threshold change cancellation
notification may have the same frame configuration with an only difference in on or
off of a flag indicating whether the threshold value is changed.
[0087]
25 Moreover, the control unit 230 of the embodiment may determine
spontaneously whether the cancellation of the change of a threshold change is
necessary without waiting a threshold change cancellation request from the terminal
device 100. For example, the control unit 230 may determine whether the
cancellatioll of the change of a threshold is necessary based on a reception success
30 rate, at the wireless communication unit 210, of wireless signals transmitted from the
belonging terminal device 100. For example, the control unit 230 determines that
the change of the threshold is to be cancelled when the rcccption success ratc, the
reception success rate per unit time, or the like is lower than a given value, wh~leit
determines that the change of the threshold is not to be cancelled when it exceeds a
given value. Then, when it is determined that the change of the Lhreshold is to be
5 cancelled, the control unit 230 controls the wireless communication unit 210 to
transmit a threshold change cancellation notification to the belonging terminal device
100. In this manner, the communication system 1 can cancel the change of the
threshold based on not only thc determination of the terminal device 100 but also the
determination of the base station 200.
10 [0088]
Note that the control unit 230 may include, in a threshold change
cancellation notification, identification information of the terminal device 100 for
which the threshold change is to be cancelled. Then, the terminal device 100 may
cancel the change of the own signal detection threshold only when the own
15 identification information is included in the threshold change cancellation
notification. In this case, the base station 200 can specify some belonging terminal
devices 100 with a changed signal detection threshold to cancel the change of the
signal detection threshold. Moreover, the control unit 230 may include, in a
threshold change cancellation notification, information for ordering the cancellation
20 of the change regarding all of the belonging terminal devices 100. In this case, the
base station 200 call control all of the belonging terminal devices 100 wiih a changed
signal detection threshold to cancel the change of the signal detection threshold.
[0089]
The characteristic configuration example of the base station 200 according
25 to the embodiment has been described above. Next, an operation processing
example of the conlmunication system 1 according to the embodiment will be
described with reference to FIG. 11.
[0090]
13-3. Example of operation processing]
30 FIG. 11 is a sequence diagram showing an example of a flow of threshold
change cancellation processing performed in the communication system 1 according
to the embodiment The sequence shown in FIG. 11 IS related to the tel~ninal
devices 100A and 100B, and the base station 200. Note that thc positional relation
of these devices is as shown in FIG. 1. It is supposed that the signal detection
threshold of the terminal device lOOA is incleased by the signal detection threshold
5 change processing described above with reference to FIG. 8.
[0091]
At Step S402, the terminal device l00B first performs carrier sense before
transmitting data. Here, wireless signals transmitted to the base station 200 by the
terminal device lOOA are detected by the terminal device 100B.
10 [0092]
Next, at Step S404, the terminal device lOOB performs cancellation request
transmission determination processing. For example, it is assumed that the signal
detection threshold of another terminal device 100 belonging to the own wireless
network has been changed. In this case, the control unit 140 determines that a
15 cancellation request is to be transmitted when the number of times of suppression of
data transmission by carrier sense has exceeded a given value, or when a failure rate
of data transmission has exceeded a given value, while the control unit 140
determines that a cancellation request is not to be transmitted when they have not
exceeded a given value. For example, it is assumed that the signal detection
20 threshold of the terminal device 100 itself has been changed. In this case, the
control unit 140 determines that a cancellation request it to be transmilled when the
data transmission as a trigger for a threshold change request has been completed,
while it determines that a cancellation request is not to be transmitted when the data
transmission has not been completed. The following will describe an example in
25 which the control unit 140 of the terminal device lOOB has determined that a
cancellation request is to be transmitted regarding the terminal device 100A that is a
transmission origin of interference signals.
[0093]
Subsequently, at Step S406, the teilninal device lO0B transmits a threshold
30 change cancellation request to the base station 200. For example, the threshold
change cancellation request includes identification information of the teiminal device
lOOA that is a transmission origin of interl'erencc signals, as an object of cancellation
of the change of the threshold.
[00941
Next, at Step S408, the base station 200 performs cancellation request
5 determination processing. To be more specific, the control unit 230 determines
whether the identification information of the interlerence terminal included in the
threshold change cancellation request indicates a belonging terminal and is of a
terminal for which the change of the threshold has been permitted. The control unit
230 permits the cancellation of the change of the threshold when these are fulfilled,
10 while it rejects the cancellation when at least one of them is not fulfilled.
[0095]
Next, at Step S410, the base station 200 transmits a threshold change
cancellation notification to the belonging terminal devices 100. Both the terminal
devices IOOA and lOOB having received the threshold change cancellation
15 notification store the update of a current state from a threshold changed state to a
normal state.
[0096]
Then, at Step S412, the terminal device 100 having received the threshold
change cancellation notification changes the signal detection threshold based on the
20 threshold change cancellation notification. In this example, the signal detection
threshold of the terminal device lOOA is changed. Thus, only the terminal device
IOOA restores an original default value of the signal detection threshold.
Meanwhile, the signal detection threshold of the terminal device 100B is not changed
and is still default. Thus, it is kept as it is without any change. Note that the base
25 station 200 restores an original default value when the signal detection threshold is
I
i changed.
[0097]
<4. Application examples>
I
I The technology according to the present disclosure can be applied to various
1 i
I
30 products. For example, the terminal device 100 may be realized as mobile
terminals such as smastphones, tablet personal computers (PCs), notebook PCs,
portable game terminals, or digital camcras, fixed-type terminals such as television
receivers, printers, digital scanners, or nctwork storages, or car-mounted terminals
such as car navigation apparatuses. Further, the terminal device 100 may be
realized as terminals (also referred to as machine type communication (MTC)
5 terminals) which perform machine to machine (M2M) communication, such as smart
meters, vending machine, remote monitoring apparatuses and point of sale (POS)
terminals. Furthermore, the terminal device 100 may be wireless communication
modules mounted in such terminals (for example, integrated circuit modules
configured in one die).
10 [0098]
For example, the base station 200 may be realized as a wireless LAN access
point (which is also referred to as a wireless base station) that has no router function
or has a router function. The base station 200 may be realized as a mobile wireless
LAN router. Furthermore, the base station 200 may be wireless communication
15 modules mounted in such devices (for example, integrated circuit modules
configured in one die).
[0099]
[4-1. First application example]
FIG. 12 is a block diagram showing an example of a schematic
20 configuration of a smartphone 900 to which the technology of the present disclosure
can be applied. The smartphone 900 includes a processor 901, a memory 902, a
storage 903, an externally connected interface 904, a camera 906, a sensor 907, a
microphone 908, a input device 909, a display device 910, a speaker 911, a wireless
communication interface 913, an antenna switch 914, an antenna.915, a bus 917, a
25 battery 918, and an auxiliary controller 919.
[O 1001
The processor 901 may be, for example, a central processing unit (CPU) or
a system on chip (SoC), and controls functions of an application layer and other
layers of the smartphone 900. The memory 902 includes a random access memoiy
30 ( U M ) and a read only memory (ROM), and stores programs executed by the
processor 901 and data. The storage 903 can include a storage medium such as a
semiconductor memory or a hard disk. The externally connected intedace 904 is an
interface for connecting an externally attached device such as a memory card or a
universal serial bus (USB) device to the smartphone 900.
[OlOl]
5 The camera 906 has an image sensor, for example, a charge coupled device
(CCD) or a complementary metal oxide semiconductor (CMOS) to generate captured
images. The sensor 907 can include a sensor group including, for example, a
positioning sensor, a gyro sensor, a geomagnetic sensor, an acceleration sensor, and
the like. The microphone 908 converts sounds input to the smartphone 900 into
10 audio signals. The input device 909 includes, for example, a touch sensor that
detects touches on a screen of the display device 910, a key pad, a keyboard, buttons,
switches, and the like to receive manipulations or information inputs from a user.
The display device 910 has a screen such as a liquid crystal display (LCD), or an
organic light emitting diode (OLED) display to display output images of the
15 smartphone 900. The speaker 911 converts audio signals output from the
smartphone 900 into sounds.
[O 1021
The wireless communication interface 913 supports one or more wireless
LAN standards of IEEE 802.11a, llb,. llg, 1 ln, llac, and llad to execute the
20 wireless LAN communication. The wireless communication interface 913 can
communicate with another apparatus via a wireless LAN access point in an
infrastructure mode. In addition, the wireless communication interface 913 can
directly communicate with another apparatus in a direct communication mode such
as an ad hoc mode, Wi-Fi Direct, or the like. Wi-Fi Direct (registered trademark) is
25 different from the ad hoc mode, and thus one of two terminals operates as an access
point. However, communication is performed directly between the terminals. The
wireless communication interface 913 can typically include a baseband processor, a
radio frequency (FW) circuit, a power amplifier, and the lilte. The wireless
communicatioil interface 913 may be a single-chip module on which a memory that
30 stores a communication control program, a processor that executes the program, and
a relevant circuit are integrated. The wireless communication interface 913 may
support another kind of wireless comn~unication scheme such as a cellular
communication scheme, a short-range wireless communicatiou scheme, or a
proximity wireless communication scheme in addition to the wireless 1,AN scheme.
The antenna switch 914 switches a connection destination of the antenna 915 for a
5 plurality of circuits (for example, circuits for different wireless communication
schemes) included in the wireless communication interface 913. The antenna 915
has a single or a plurality of antenna elements (for example, a plurality of antenna
elements constituting a MIMO antenna), and is used for transmission and reception
of wireless signals from the wireless communication interface 913.
10 [0103]
Note that the smartphone 900 may include a plurality of antennas (for
example, antennas for a wireless LAN or antennas for a proximity wireless
communication scheme, or the like), without being limited to the example of FIG. 12.
In this case, the antenna switch 914 may be omitted from the configuration of the
15 smartphone 900.
[0 1 041
The bus 917 connects the processor 901, the memory 902, the storage 903,
the externally connected interface 904, the camera 906, the sensor 907, the
microphone 908, the input device 909, the display device 910, the speaker 911, the
20 wireless communication interface 913, and the auxiliary contl-oller 919 to one
another. The battery 918 supplies electric power to each of the bloclts of the
smartphone 900 shown in FIG. 12 via power supply lines partially indicated by
dashed lines in the drawing. The auxiliary controller 919 causes, for example,
required minimum functions of the smartphone 900 to be operated in a sleep mode.
25 [OlOS]
In the smartphone 900 shown in FTG 12, the wireless communication unit
110, the carrier sensing unit 120, the storage unit 130, and the control unit 140 shown
in FIG. 2 may be mounted on the wireless communication interface 913. At least
some of the functions may be mounted on the processor 901 or the auxiliary
30 controller 919.
[O 1061
The smartphone 900 may operate as a wireless access point (software AP)
when the processor 901 performs an access point function at an application level.
The wireless communication interface 913 may have the wireless access point
function.
5 [0107]
[4-2. Second application example]
FIG. 13 is a block diagram showing an example of a schematic
configuration of a car navigation apparatus 920 to which the technology of the
present disclosure can be applied. The car navigation apparatus 920 includes a
10 processor 921, a memory 922, a global positioning system (GPS) module 924, a
sensor 925, a data interface 926, a content player 927, a storage medium interface
928, an input device 929, a display device 930, a speaker 931, a wireless
communication interface 933, an antenna switch 934, an antenna 935, and a battery
938.
15 [0108]
The processor 921 may be, for example, a CPU or an SoC controlling a
navigation function and other functions of the car navigation apparatus 920. The
memory 922 includes a RAM and a ROM storing programs executed by the
processor 921 and data.
20 [0109]
The GPS module 924 measures a position of the car navigation apparatus
920 (for example, latitude, longitude, and altitude) using GPS signals received from a
GPS satellite. The sensor 925 can include a sensor group including, for example, a
gyro sensor, a geomagnetic sensor, a barometric sensor, and the like. The data
25 interface 926 is connected to an in-vehicle network 941 via, for example, a terminal
that is not illustrated to acquire data generated on the vehicle side such as car speed
data.
[01 101
The content player 927 reproduces content stored in a storage medium (for
30 example, a CD or a DVD) inserted into the storage medium interface 928. The
input device 929 includes, for example, a touch sensor that detects touches on a
screen of the display device 930, buttons, switches, and the like to receivc
nlanipulations or information inputs from a user. The display device 930 has a
screen such as an LCD or an OLED display to display images 01 the navigation
function or reproduced content. The speaker 93 1 outputs sounds of the navigation
5 function or reproduced content.
[Olll]
The wireless communication interface 933 supports one or more wireless
LAN standards of IEEE 802.1 la, 11 b, 11 g, 1 ln, 1 lac, and 1 lad to execute wireless
LAN communication. The wireless communication interlace 933 can communicate
10 with another apparatus via a wireless LAN access point in the infrastructure mode.
In addition, the wireless communication interface 933 can directly communicate with
another apparatus in a direct communication mode, such as an ad hoe mode, Wi-Fi
Direct, or the like. The wireless communication interface 933 can typically have a
baseband processor, an RF circuit, a power amplifier, and the like. The wireless
15 communication interface 933 may be a single-chip module on which a memory that
stores a communication control program, a processor that executes the program, and
a relevant circuit are integrated. The wireless communication interface 933 may
support another kind of wireless communication scheme such as a short-range
wireless communication scheme, a proximity wireless communication scheme, or the
20 cellular communication scheme in addition to the wireless LAN scheme. The
antenna switch 934 switches a connection destination of the antenna 935 for a
plurality of circuits included in the wireless communication interface 933. The
antenna 935 has a single or a plurality of antenna elements and is used for
transmission and reception of wireless signals from the wireless communication
25 interface 93 3.
[0112]
Note that the car navigation apparatus 920 may include a plurality of
antennas, without being limited to the example of FIG. 13. In this case, the antenna
switch 934 may be omitted from the configuration of the car navigation apparatus
30 920.
[0113]
The battery 938 supplies electric power to each or the bloclts oC the car
navigation apparatus 920 shown in FIG. 14 via powcr supply lines partially indicated
by dashed lines in the drawing. In addition, the battery 938 accumulates electric
power supplied from the vehicle.
5 [0114]
In the car navigation apparatus 920 shown in FIG. 13, the wireless
communication unit 110, the carrier sensing unit 120, the storage unit 130, and the
control unit 140 shown in FIG. 2 may be mounted on the wireless communication
interface 933. At least some of the functions may be mounted on the processor 901.
10 [0115]
Moreover, the wireless communication interface 933 may operate as the
above-described base station 200 and provide wireless connection to a terminal of a
user on a vehicle.
[0116]
15 The technology of the present disclosure may be realized as an in-vehicle
system (or a vehicle) 940 including one or more blocks of the above-described car
navigation apparatus 920, the in-vehicle network 941, and a vehicle-side module 942.
The vehicle-side module 942 generates vehicle-side data such as a vehicle speed, the
number of engine rotations, or failure information and outputs the generated data to
20 the in-vehicle network 941.
[0117]
[4-3. Third application example]
FIG. 14 is a block diagram showing an example of a schematic
configuration of a wireless access point 950 to which the technology of the present
25 disclosure can be applied. The wireless access point 950 includes a controller 951,
a memory 952, an input device 954, a display device 955, a network interface 957, a
wireless communication interface 963, an antenna switch 964, and an antenna 965.
[0118]
The controller 951 may be, for example, a CPU or a digital signal processor
30 (DSP), and operates various functions (for example, access restriction, routing,
encryption, firewalls, and log management, and the like) of an internet protocol (IP)
layer and higher layers of the wireless access point 950. The memory 952 includcs
a RAM and a ROM, and stores programs executcd by the controller 951 and various
kinds of data (for example, a terminal list, a routing table, a cryptographic ltcy,
security setting, a log, and the like).
5 [0119]
The input device 954 includes, for example, buttons, switches, and the like
to receive operation from a user. The display device 955 includes an LED lamp or
the like to display an operation status of the wireless access point 950.
[0120]
10 The network interface 957 is a wired communication interface for
connecting the wireless access point 950 to a wireless communication network 958.
The network interface 957 may include a plurality of connection terminals. The
wircd communication network 958 may be a LAN such as Ethemet (registered
trademark) or a wide area network (WAN).
15 [0121]
The wireless communication interface 963 supports one or more wireless
LAN standards of IEEE 802.1 la, llb, llg, 1 ln, 1 lac, and llad to provide wireless
communication as an access point to adjacent terminals. The wireless
communication interface 963 can typically include a baseband processor, an RF
20 circuit, a power amplifier, and the like. The wireless communication interface 963
may be a single-chip module on which a memory that stores a communication
control program, a processor that executes the program, and a relevant circuit are
integrated. The antenna switch 964 switches a connection destination of the
antenna 965 for a plurality of circuits included in the wireless communication
25 interface 913. The antenna 965 has a single or a plurality of antenna elements, and
is used for transmission and reception of wireless signals from the wireless
communication interface 963.
[O 1221
In the wireless access point 950 shown in FIG. 14, the wireless
30 communication unit 210, the storage unit 220, and the control unit 230 shown in FIG.
@
4 may be mounted on the wireless communication interface 963. At least some of
the functions may be mountcd on the controller 95 1.
[0123]
< 5. Conclusion >
In the above, one embodiment of the present disclosure has been described
in detail with reference to FIG. 1 to FIG. 14. In the embodiment described above,
the terminal device 100 that performs communication with the base station 200
forming a wireless network, performs carrier sense with another device and controls,
based on a carrier sense result, a signal detection threshold so that another terminal
device belonging to another wireless network is outside a signal detection range. In
this manner, the terminal device 100 can prevent excessive transmission suppression
by carrier sense in the situation where transmission suppression is unnecessary. To
be more specific, the terminal device 100 can prevent excessive transmission
suppression due to a terminal device belonging to another network. In this manner,
it is possible to improve the throughput of the whole communication system 1.
[0 1241
The terminal device 100 transmits a threshold change request to the base
station 200 and changes a signal detection threshold based on a threshold change
response transmitted as a replay from the base station 200. In this manner, the base
station 200 can control the change/cancellation/retention of a signal detection
threshold of the belonging terminal devices 100 in a unified manner.
[0125]
The terminal device 100 transmits a threshold change cancellation request
for cancelling the change of a signal detection threshold to the base station 200.
The terminal device 100 can avoid excessive concentration of transmission
opportunities on some terminal devices 100 by canceling the change regarding an
interference terminal or canceling the change regarding the terminal device 100 itself.
[0126]
In the embodiment, the base station 200 forming a wireless network and
performing comnlunication with the terminal device 100 transmits as a reply a
threshold change response so that a te~~nindaelv ice belonging to a different wireless
network is outside a signal detection range of the belonging terminal device 100,
based on a threshold change request received from the belonging terminal device 100.
Thus, the base station 200 can prevent the belonging terminal devicc 100 from
perlbrming excessive transmission suppression by carrier sense in spite of the
situation where transmission suppression is unnecessary. To be more specific, the
5 base station 200 can prevent the belonging terminal device 100 from performing
excessive transmission suppression due to a terminal device belonging to another
network.
(01271
Moreover, the base station 200 changes the own signal detection threshold
10 when the signal detection threshold of the belonging terminal device 100 is changed.
In this manner, the base station 200 can make an interference terminal outside the
signal detection range, preventing unnecessary reception processing.
[0128]
The preferred embodiment(s) of the present disclosure hashave been
15 described above with reference to the accompanying drawings, whilst the present
disclosure is not limited to the above examples. A person skilled in the art may find
various alterations and modifications within the scope of the appended claims, and it
should be understood that they will naturally come under the technical scope of the
present disclosure.
20 [0129]
For example, the above has described the example in which the
communication system is a system conforming to a wireless LAN or a
communication standard equivalent thereto. However, the present technology is not
limited to such an example. For example, the communication system may be a
25 system conforming to other communication standards.
[0130]
Moreover, thc above has described that the terminal device 100 changes a
signal detection threshold for carrier sense regarding a wireless frame as a trigger for
a threshold change request, and cancels the change after transmission is completed.
30 Howeve]; the present technology is not limitcd to such an cxample. For example,
the terminal device 100 may change a signal detection threshold for carrier sense
regarding a series oS data (video, files, and the lilte) including a wireless frame as a
trigger for a threshold change request, and cancel the change after the tran~missionis
completed.
[0131]
5 Furthermore, the above has described that the base station 200 determines
whether the change of a threshold is permitted or detcrmines whether the
cancellation of the change of a threshold is permitted. However, the present
technology is not limited to such an example. For example, the terminal device 100
may perform a part of such determination processing. For example, the terminal
10 device 100 may determine whether an interference terminal belongs lo the own
wireless network, and then transmit a threshold change request or a threshold change
cancellation request to the base station 200. In this case, the processing load of the
base station 200 is reduced.
[0132]
15 The series of processes carried out by each apparatus described in the
present specification may be realized by software, hardware, or a combination of
software and hardware. Programs that compose such software may be stored in
advance for example on a storage medium (non-transitory medium) provided inside
or outside each apparatus. As one example, during execution by a computer, such
20 programs are written into a random access memory (RAM) and executed by a
processor such as a CPU.
[0133]
Note that it is not necessary for the processes described in this specification
with reference to the flowchart to be executed in the order shown in the flowchart.
25 Some processing steps may be pcrformed in parallel. Further, some of additional
steps can be adopted, or some processing steps can be omitted.
[O 1 341
Further, the effects described in this specification are merely illustrative or
exemplified effects, and are not limitative. That is, with 01 in the place of the above
30 effects, the technology according to the present disclosure may achieve other effects
that are clear to those skilled in the art based on the description of this specification.
[0135]
Additionally, the present technology may also be configured as below
(1)
A terminal devicc, including:
5 a wireless communication unit that performs communication with a base
station that forms a first wireless network;
a carrier sense unit that performs carrier sense with another device; and
a control unit ihat controls a signal detection threshold so that another
terminal device belonging to a second wireless network different from the first
10 wireless network is outside a signal detection range, based on a carrier sense result
by the carrier sense unit.
(2)
The terminal device according to (I),
wherein the control unit controls the wireless communication unit to
15 transmit a threshold change request to the base station with a trigger that an index
related to transmission suppression by the carrier sense has exceeded a given
threshold.
(3)
The terminal device according to (2),
20 wherein the threshold change request ineludes identification information of
another terminal device that is a transmission origin of wireless signals detected by
the carrier sense unit.
(4)
The terminal device according to (2) or (3),
25 wherein the threshold change request includes information indicating a
measurement result of reception signal intensity measured by the carrier sense unit.
(5)
The terminal device according to any one of (2) to (4),
wherein the threshold change request includes information indicating an
30 iillportance of data subjected to transmission suppression by the carrier sense.
(6)
The terminal device according to any one of (2) to (5),
wherein the control unit changes the signal dctection threshold based on a
threshold change response, regarding data transmission as a trigger for the threshold
change request.
5 (7)
The terminal device according to any one of (I) to (6),
wherein the control unit controls, when having recoynized that a signal
detection threshold of another terminal device belonging to the first wireless network
has been changed based on a threshold change notification received from the base
10 station, the wireless communication unit to transmit a threshold change cancellation
request to the base station with a trigger that the nmber of limes of suppression of
data transmission by the carrier sense has exceeded a given value or that a failure rate
of data transmission has exceeded a given value.
(8)
15 The terminal device according to (2) or any one of (3) to (7) citing (2),
wherein the control unit controls the wireless communication unit to
transmit a threshold change cancellation request to the base station when data
transmission as a trigger for the threshold change request has been completed.
(9)
20 The terminal device according to (2) or any one of (3) to (8) citing (2),
wherein the control unit cancels a change of the signal detection threshold
when data transnlission as a trigger for the threshold change request has been
completed, or cancels a change of the signal detection threshold based on a threshold
change cancellation notification received from the base station.
25 (10)
The terminal device according to any one of (1) to (9),
wherein the wireless communication unit transmits a threshold change
request or a threshold change cancellation request to the base station
(11)
The terminal device according to any one of (I) to (lo),
wherein the wireless communication unit receives a threshold change
response, a threshold change notilication, or a threshold change cancellation
notification from the base station.
(12)
A base station, including:
5 a wireless communication unit that forms a first wireless network and
performs communication with a terminal device; and
a control unit that transmits as a reply, through the wireless communication
unit, a threshold change response for changing a signal detection threshold so that a
second terminal device belonging to a second wireless network different from the
10 first wireless network is outside a signal detection range of a first terminal device,
based on a threshold change request received from the first terminal device
belonging to the first wireless network.
(13)
The base station according to (12),
15 wherein the control unit generates the threshold change response when all of
the terminal devices belonging to the first wireless network have higher reception
signal intensity at the wireless communication unit than the second terminal device.
(14)
The base station according to (12) or (13),
20 wherein the control unit generates the threshold change response when an
importance of data subjected to transmission suppression is higher than an
importance of data transmitted from any of the terminal devices belonging to the first
wireless network.
(15)
25 The base station according to any one of (12) to (14),
wherein the control unit changes a signal detection threshold of the wireless
cominunication unit when a signal detection threshold of the first terminal device is
changed.
(16)
The base station according to any one of (12) to (1 5),
wherein the control unit controls the wireless communication unit to
transmit a threshold change notification indicating that the first terminal device
changes the signal detection threshold to the telminal device belonging to the first
wireless network.
(1 7)
5 The base station according to (16),
wherein the threshold change notification includes identification
information of the first terminal device for which the signal detection threshold is
changed.
(18)
10 The base station according to any one of (12) to (17),
wherein the control unit controls the wireless communication unit to
transmit a threshold change cancellation notification to the terminal device belonging
to the first wireless network, based on a reception success rate, at the wireless
communication unit, of wireless signals transmitted from the terminal device
15 belonging to the first wireless network.
(1 9)
A program that causes a computer to function as:
a wireless communication unit that performs communication with a base
station that forms a first wireless network;
20 a carrier sense unit that performs carrier sense with another device; and
a control unit that controls a signal detection threshold so that another
terminal device belonging to a second wireless network different from the first
wireless network is outside a signal detection range, based on a carrier sense result
by the carrier sense unit.
25 (20)
A program that causes a computer to function as:
a wireless communication unit that forms a first wireless network and
performs communication with a terminal device; and
a control unit that transmits as a reply, through the wireless communication
30 unit, a threshold change response for changing a signal detection threshold so that a
second terminal device belonging to a second wireless network different from the
first wireless network is outside a signal detection range or a first terminal device,
based on a threshold change request received from thc first terminal device
belonging to the first wireless network.
(21)
5 A method, including:
in a terminal device that performs communication with a base station that
forms a first wireless network,
performing canier sense with another device; and
controlling a signal detection threshold so that another terminal device
10 belonging to a second wireless network different from the first wireless network is
outside a signal detection range, based on a carrier sense result.
(22)
A method, including:
in a base station that forms a first wireless network and performs
15 communication with a terminal device,
transmitting as a reply a threshold change response for changing a signal
detection threshold so that a second terminal device belonging to a second wireless
network different from the first wireless network is outside a signal detection range
of a first terminal device, based on a threshold change request received from the first
20 terminal device belonging to the first wireless network.
Reference Signs List
101361
1 communication system 1
25 100 terminal device 100
110 wireless communication unit 11 0
120 carrier sense unit 120
130 storage unit 130
140 control unit I40
30 200 base station 200
210 wireless communication unit 210
220 storage unit 220
230 control unit 230
30 signal detection range 30
CLAIMS
Claim 1
A terminal device, comprising:
a wirelcss communication unit that performs communication with a base
5 station that forms a first wireless network;
a carrier sense unit that performs canier sense with another device; and
a control unit that controls a signal detection threshold so that another
terminal device belonging to a second wireless network different from the first
wireless network is outside a signal detection range, based on a carrier sense result
10 by the carrier sense unit.
Claim 2
The terminal device according to claim 1,
wherein the control unit controls the wireless communication unit to
15 transmit a threshold change request to the base station with a trigger that an index
related to transmission suppression by the carrier sense has exceeded a given
threshold.
Claim 3
20 The terminal device according to claim 2,
wherein thc threshold change request includes identification information of
another terminal device that is a transmission origin of wireless signals detected by
the carrier sense unit.
25 Claim 4
The terminal device according to claim 2,
wherein the threshold change request includes information indicating a
measurement result of reception signal intensity measured by the carrier sense unit.
30 Claim 5
The terminal device according to claim 2,
wherein the threshold change request includes information indicating an
importance of data subjected to transmission suppression by the carrier sense.
Claim 6
5 The terminal device according to claim 2,
wherein the control unit changes the signal detection threshold based on a
threshold change response, regarding data transmission as a trigger for the threshold
change request.
10 Claim 7
The terminal device according to claim 1,
wherein the control unit controls, when having recognized that a signal
detection threshold of another terminal device belonging to the first wireless network
has been changed based on a threshold change notification received from the base
15 station, the wireless communication unit to transmit a threshold change cancellation
request to the base station with a trigger that the number of times of suppression of
data transmission by the carrier sense has exceeded a given value or that a failure rate
of data transmission has exceeded a given value.
20 Claim 8
The terminal device according to claim 2,
wherein the control unit controls the wireless communication unit to
transmit a threshold change cancellation request to the base station when data
transmission as a trigger for the threshold change request has been completed.
25
Claim 9
The terminal device according to claim 2,
wherein the control unit cancels a change of the signal detection threshold
when data transmission as a trigger for the threshold change request has been
30 conlpleted, or cancels a change of the signal detection threshold based on a threshold
change cancellation notification rcceived from the base station.
Claim 10
The terminal device according to claim 1,
wherein the wireless communication unit transmits a threshold change
6 request or a threshold change cancellation request to the base station.
Claim 11
The terminal device according to claim 1,
wherein the wireless communication unit receives a threshold change
10 response, a threshold change notification, or a threshold change cancellation
notification from the base station.
Claim 12
A base station, comprising:
15 a wireless communication unit that forms a first wireless network and
performs communication with a terminal device; and
a control unit that transmits as a reply, through the wireless communication
unit, a threshold change response for changing a signal detection threshold so that a
second terminal device belonging to a second wireless network different from the
20 first wireless network is outside a signal detection range of a first terminal device,
based on a threshold change request received from the first terminal device
belonging to the first wireless network.
Claim 13
25 The base station according to claim 12,
wherein the control unit generates the threshold change response when all of
the terminal devices belonging to the first wireless network have higher reception
I signal intensity at the wireless communication unit than the second terminal device.
30 Claim 14
The base station according to claim 12,
wherein the control unit generates the threshold change rcsponse when an
importance of data subjected to transmission suppression is higher than an
importance of data transmitted from any of the terminal devices belonging to the ilrst
wireless network.
5
Claim 15
The base station according to claim 12,
wherein the control unit changes a signal detection threshold of the wireless
communication unit when a signal detection threshold of the first terminal device is
10 changed.
Claim 16
The base station according to claim 12,
wherein the control unit controls the wireless communication ulit to
15 transmit a threshold change notification indicating that the first terminal device
changes the signal detection threshold to the terminal device belonging to the first
wireless network.
Claim 17
20 The base station according to claim 16,
wherein the threshold change notification includes identification
information of the first terminal device for which the signal detection threshold is
changed.
25 Claim 18
Thc base station according to claim 12,
wherein the control unit controls the wireless communication unit to
transmit a threshold change cancellation notification to the terminal device belonging
to the first wireless network, based on a reception success rate, at the wireless
30 communication unit, of wireless signals transmitted from the terminal device
belonging to the first wireless network.
Claim 19
A program that causes a computer to function as:
a wireless communication unit that performs communication with a base
5 station that forms a first wireless network;
a carrier sense unit that performs carrier sense with another device; and
a control unit that controls a signal detection threshold so that another
terminal device belonging to a second wireless network different from the first
wireless network is outside a signal detection range, based on a carrier sense result
10 by the carrier sense unit.
Claim 20
A program that causes a computer to function as:
a wireless communication unit that forms a first wireless network and
15 performs communication with a terminal device; and
a control unit that transmits as a reply, through the wireless communication
unit, a threshold change response for changing a signal detection threshold so that a
second terminal device belonging to a second wireless network different from the
first wireless network is outside a signal detection range of a first terminal device,
20 based on a threshold change request received from the first terminal device
belonging to the first wireless network.