U.S. patent application number 16/908783 was filed with the patent office on 2020-10-08 for communication apparatus, communication method, and program.
This patent application is currently assigned to Sony Corporation. The applicant listed for this patent is Sony Corporation. Invention is credited to Shigeru SUGAYA.
Application Number | 20200322983 16/908783 |
Document ID | / |
Family ID | 1000004915273 |
Filed Date | 2020-10-08 |
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United States Patent
Application |
20200322983 |
Kind Code |
A1 |
SUGAYA; Shigeru |
October 8, 2020 |
COMMUNICATION APPARATUS, COMMUNICATION METHOD, AND PROGRAM
Abstract
A communication device, including: a processing unit configured
to generate a second frame used for releasing a stop of
transmission of a frame caused by a first frame, the second frame
including first destination information specifying a destination
stored in the first frame, the first frame being used for stopping
transmission of frames of communication devices other than the
destination and serving as a response to a communication request;
and a unit that transmits the second frame. A communication device,
that receives a second frame used for releasing a stop of
transmission of a frame caused by a first frame, the second frame
including first destination information specifying a destination
stored in the first frame, the first frame being used for stopping
transmission of frames of communication devices other than the
destination and serving as a response to a communication request. A
controller controls transmission of a frame.
Inventors: |
SUGAYA; Shigeru; (Kanagawa,
JP) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Sony Corporation |
Tokyo |
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JP |
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Assignee: |
Sony Corporation
Tokyo
JP
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Family ID: |
1000004915273 |
Appl. No.: |
16/908783 |
Filed: |
June 23, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16075461 |
Aug 3, 2018 |
10716138 |
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PCT/JP2017/006500 |
Feb 22, 2017 |
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16908783 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 72/0446 20130101;
H04L 5/0055 20130101; H04L 69/22 20130101; H04W 40/20 20130101;
H04W 84/12 20130101; H04W 74/04 20130101; H04W 76/30 20180201 |
International
Class: |
H04W 74/04 20060101
H04W074/04; H04W 84/12 20060101 H04W084/12; H04W 76/30 20060101
H04W076/30; H04L 5/00 20060101 H04L005/00; H04L 29/06 20060101
H04L029/06; H04W 40/20 20060101 H04W040/20; H04W 72/04 20060101
H04W072/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 13, 2016 |
JP |
2016-080027 |
Claims
1. (canceled)
2. A communication device, comprising: processing circuitry
configured to generate a second frame used for releasing a network
allocation vector (NAV) caused by one of a plurality of first
frames, the second frame including first destination information
specifying a destination specified from a piece of destination
information stored in the one of the plurality of first frames, the
plurality of first frames being used for setting respective NAVs
which stop transmission of frames of communication devices other
than destinations specified from the destination information stored
in the plurality of first frames; and wireless communication
circuitry configured to transmit the second frame.
3. The communication device according to claim 2, wherein the first
destination information is stored in a region different from a
region in which the transmission source information of the second
frame is stored.
4. The communication device according to claim 3, wherein the
different region from the region in which the transmission source
information of the second frame is stored includes a region in
which destination information of the second frame is stored.
5. The communication device according to claim 2, wherein the first
destination information is stored in a region different from both
of a region in which transmission source information of the second
frame is stored and a region in which destination information of
the second frame is stored.
6. The communication device according to claim 2, wherein the
second frame includes a frame doubling as an acknowledge, and the
first destination information related to the destination of the one
of the plurality of first frames which is a target of the
acknowledge using the second frame.
7. The communication device according to claim 2, wherein the
second frame includes a plurality of pieces of first destination
information.
8. The communication device according to claim 2, wherein the
second frame includes information specifying a type of the second
frame.
9. The communication device according to claim 8, wherein the
information specifying the type of the second frame is stored in a
region in which transmission period information of the second frame
is stored.
10. The communication device according to claim 2, wherein the
second frame includes information specifying a wireless
communication network to which a transmission source of the second
frame belongs, and the information specifying the wireless
communication network is stored in a region in which transmission
source information of the second frame is stored.
11. The communication device according to claim 2, wherein the
plurality of first frames include a clear to send (CTS) frame, a
CTS-to-self frame or a request to send (RTS) frame, and the second
frame includes a contention free (CF)-end frame.
12. A communication device, comprising: wireless communication
circuitry configured to receive a second frame used for releasing a
network allocation vector (NAV) caused by one of a plurality of
first frames, the second frame including first destination
information specifying a destination specified from a piece of
destination information stored in the one of the plurality of first
frames, the plurality of first frames being used for setting
respective NAVs which stop transmission of frames of communication
devices other than destinations specified from the destination
information stored in the plurality of first frames; and control
circuitry configured to control transmission of a frame on a basis
of the second frame received by the wireless communication
circuitry.
13. The communication device according to claim 12, wherein the
wireless communication circuitry is configured to receive the
plurality of first frames, and the control circuitry is configured
to control a NAV for each piece of the destination information on a
basis of the destination information included in the plurality of
received first frames and the first destination information
included in the received second frame.
14. The communication device according to claim 12, wherein the
second frame includes a frame doubling as an acknowledge, and the
control circuitry is configured to control retransmission of a
frame related to the acknowledge by the second frame on a basis of
the first destination information included in the second frame.
15. The communication device according to claim 12, wherein the
plurality of first frames include a clear to send (CTS) frame, a
CTS-to-self frame or a request to send (RTS) frame, and the second
frame includes a contention free (CF)-end frame.
16. A communication method, comprising: generating a second frame
used for releasing a network allocation vector (NAV) caused by one
of a plurality of first frames using a processor, the second frame
including first destination information specifying a destination
specified from a piece of destination information stored in the one
of the plurality of first frames, the plurality of first frames
being used for setting respective NAVs which stop transmission of
frames of communication devices other than destinations specified
from the destination information stored in the plurality of first
frames; and transmitting the second frame.
17. A communication method, comprising: receiving a second frame
used for releasing a network allocation vector (NAV) caused by one
of a plurality of first frames using a processor, the second frame
including first destination information specifying a destination
specified from a piece of destination information stored in the one
of the plurality of first frames, the plurality of first frames
being used for setting respective NAVs which stop transmission of
frames of communication devices other than destinations specified
from the destination information stored in the plurality of first
frames; and controlling transmission of a frame on a basis of the
received second frame.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
application Ser. No. 16/075,461, filed Aug. 3, 2018, which is based
on PCT filing PCT/JP2017/006500, filed Feb. 22, 2017, which claims
priority to JP 2016-080027, filed Apr. 13, 2016, the entire
contents of each are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a communication device, a
communication method and a program.
BACKGROUND ART
[0003] In recent years, wireless local area networks (LANs)
representative of Institute of Electrical and Electronics Engineers
(IEEE) 802.11 have been widely used. In addition, the number of
wireless LAN-compatible products (hereinafter, also referred to as
wireless communication devices) have also increased in accordance
with this. In contrast, wireless communication resources available
for communication are limited. Therefore, it is desirable to
increase the efficiency of communication between wireless
communication devices.
[0004] As an example of a technique for improving communication
efficiency, a technique called virtual carrier sensing is known.
Specifically, a technique for controlling a network allocation
vector (NAV) using a mechanism such as request to send (RTS)/clear
to send (CTS) is known. For example, a transmission device that
desires data transmission transmits an RTS frame to a reception
device which is a destination of data transmission, and the
reception device transmits a CTS frame to the transmission device
in a case in which data transmission is permitted. At this time,
communication devices other than destinations of the RTS frame and
the CTS frame set a NAV and stop data transmission during a NAV
period. Accordingly, it is considered that communication collision
is avoided, and communication can be performed efficiently as a
result.
[0005] Here, there is a mechanism of releasing the NAV before the
NAV period ends. For example, in a case in which communication
using the RTS and the CTS is performed between an access point (AP)
and a station (STA), the AP can release the set NAV by transmitting
a contention free (CF)-end frame. Further, in the CF-End frame, a
broadcast address is stored as destination information, and a basic
service set identifier (BSSID) is stored as transmission source
information.
[0006] However, in the mechanism where the NAV is released before
the NAV period ends, unfairness may arise in terms of opportunities
to access a transmission path. For example, the communication
device that has received the CF-End frame can release the NAV and
start communication, but the communication device which has not
received the CF-End frame is unable to perform communication until
the NAV period ends since the NAV remains set.
[0007] On the other hand, a method in which the STA transmits a
first disconnection process frame including a CF-End frame for
disconnecting a transmission opportunity (TXOP) set around the STA,
and the AP which has received the first disconnection process frame
transmits a second disconnection frame including a CF-End frame for
disconnecting the TXOP set around the AP is disclosed in Patent
Literature 1.
CITATION LIST
Patent Literature
[0008] Patent Literature 1: JP 5210887B
DISCLOSURE OF INVENTION
Technical Problem
[0009] However, in the technique disclosed in Patent Literature 1,
the unfairness regarding the opportunities to access the
transmission path is unlikely to be solved. For example, since the
transmission source information is not stored in the CTS frame, the
communication device which has received only the CTS frame does not
know the BSSID corresponding to the set NAV. For this reason, even
though the CF-End frame is received, the communication device is
unable to determine whether or not the BSSID stored in the CF-End
frame is the BSSID corresponding to the set
[0010] NAV. Therefore, in a case in which the BSSID stored in the
CF-End frame coincides with the BSSID corresponding to the set NAV,
when the NAV is not released, the opportunities for the
communication device to access the transmission path decrease. On
the other hand, in a case in which the BSSID stored in the CF-End
frame does not coincide with the BSSID corresponding to the set
NAV, when the NAV is released, communication collision is likely to
occur.
[0011] In this regard, the present disclosure proposes a mechanism
capable of preventing communication collision while suppressing a
reduction in the opportunities to access the transmission path.
Solution to Problem
[0012] According to the present disclosure, there is provided a
communication device, including: a processing unit configured to
generate a second frame used for releasing a stop of transmission
of a frame caused by a first frame, the second frame including
first destination information specifying a destination stored in
the first frame, the first frame being used for stopping
transmission of frames of communication devices other than the
destination and serving as a response to a communication request;
and a wireless communication unit configured to transmit the second
frame.
[0013] In addition, according to the present disclosure, there is
provided a communication device, including: a wireless
communication unit configured to receive a second frame used for
releasing a stop of transmission of a frame caused by a first
frame, the second frame including first destination information
specifying a destination stored in the first frame, the first frame
being used for stopping transmission of frames of communication
devices other than the destination and serving as a response to a
communication request; and a control unit configured to control
transmission of a frame on a basis of the second frame received by
the wireless communication unit.
[0014] In addition, according to the present disclosure, there is
provided a communication method, including: generating a second
frame used for releasing a stop of transmission of a frame caused
by a first frame using a processor, the second frame including
first destination information specifying a destination stored in
the first frame, the first frame being used for stopping
transmission of frames of communication devices other than the
destination and serving as a response to a communication request;
and transmitting the second frame.
[0015] In addition, according to the present disclosure, there is
provided a communication method, including: receiving a second
frame used for releasing a stop of transmission of a frame caused
by a first frame using a processor, the second frame including
first destination information specifying a destination stored in
the first frame, the first frame being used for stopping
transmission of frames of communication devices other than the
destination and serving as a response to a communication request;
and controlling transmission of a frame on a basis of the received
second frame.
[0016] In addition, according to the present disclosure, there is
provided a program causing a computer to implement: a processing
function of generating a second frame used for releasing a stop of
transmission of a frame caused by a first frame, the second frame
including first destination information specifying a destination
stored in the first frame, the first frame being used for stopping
transmission of frames of communication devices other than the
destination and serving as a response to a communication request;
and a wireless communication function of transmitting the second
frame.
[0017] In addition, according to the present disclosure, there is
provided a program causing a computer to implement: a wireless
communication function of receiving a second frame used for
releasing a stop of transmission of a frame caused by a first
frame, the second frame including first destination information
specifying a destination stored in the first frame, the first frame
being used for stopping transmission of frames of communication
devices other than the destination and serving as a response to a
communication request; and a control function of controlling
transmission of a frame on a basis of the second frame received by
the wireless communication function.
Advantageous Effects of Invention
[0018] As described above, according to the present disclosure, a
mechanism capable of preventing communication collision while
suppressing a reduction in the opportunities to access the
transmission path is provided. 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
described in this specification or other effects that may be
grasped from this specification.
BRIEF DESCRIPTION OF DRAWINGS
[0019] FIG. 1 is a diagram illustrating an example of control of a
NAV using an existing RTS and CTS.
[0020] FIG. 2 is a diagram illustrating a configuration of an
existing RTS frame.
[0021] FIG. 3 is a diagram illustrating a configuration of an
existing CTS frame.
[0022] FIG. 4 is a diagram illustrating a configuration of an
existing Ack frame.
[0023] FIG. 5 is a diagram illustrating an example of control of a
NAV using an existing CF-End.
[0024] FIG. 6 is a diagram illustrating a configuration of an
existing CF-End frame.
[0025] FIG. 7 is a diagram illustrating an example of control of a
NAV using only an existing CTS.
[0026] FIG. 8 is a diagram illustrating another example of control
of a NAV using only an existing CTS.
[0027] FIG. 9 is a diagram illustrating an example of control of a
NAV using a CF-End doubling as an existing Ack.
[0028] FIG. 10 is a diagram illustrating an example of release of a
NAV in existing carrier sensing.
[0029] FIG. 11 is a diagram illustrating another example of release
of a NAV in existing carrier sensing.
[0030] FIG. 12 is a diagram illustrating a configuration example of
a communication system according to one embodiment of the present
disclosure.
[0031] FIG. 13 is a block diagram illustrating an example of
schematic functional configurations of a transmission device and a
reception device according to one embodiment of the present
disclosure.
[0032] FIG. 14 is a block diagram illustrating an example of a
schematic functional configuration of a wireless communication
module according to the embodiment of the present disclosure.
[0033] FIG. 15 is a diagram illustrating an example of a
configuration of a second CF-End frame transmitted by a
transmission device according to one embodiment of the present
disclosure.
[0034] FIG. 16 is a diagram illustrating another example of a
configuration of a second CF-End frame transmitted by a
transmission device according to one embodiment of the present
disclosure.
[0035] FIG. 17 is a flowchart conceptually illustrating an example
of processing performed by a transmission device according to the
embodiment of the present disclosure.
[0036] FIG. 18 is a flowchart conceptually illustrating an example
of a NAV setting process in a reception device according to one
embodiment of the present disclosure.
[0037] FIG. 19 is a flowchart conceptually illustrating an example
of a NAV update process and a NAV release process in a reception
device according to one embodiment of the present disclosure.
[0038] FIG. 20 is a diagram for describing an example of
communication between a transmission device and a reception device
according to a related art.
[0039] FIG. 21 is a diagram for describing an example of
communication between a transmission device and a reception device
according to one embodiment of the present disclosure.
[0040] FIG. 22 is a diagram illustrating an example of a
configuration of a second CF-End+CF-Ack frame transmitted by a
transmission device according to a first modified example of one
embodiment of the present disclosure.
[0041] FIG. 23 is a diagram illustrating another example of a
configuration of a second CF-End+CF-Ack frame transmitted by a
transmission device according to the first modified example of one
embodiment of the present disclosure.
[0042] FIG. 24 is a diagram illustrating an example of a
configuration of a second CF-End+CF-Ack frame transmitted by a
transmission device according to a second modified example of one
embodiment of the present disclosure.
[0043] FIG. 25 is a diagram for describing an example of
communication between a transmission device and a reception device
according to a related art.
[0044] FIG. 26 is a diagram for describing an example of
communication between a transmission device and a reception device
according to the second modified example of one embodiment of the
present disclosure.
[0045] FIG. 27 is a block diagram illustrating an example of a
schematic configuration of a smartphone.
[0046] FIG. 28 is a block diagram illustrating an example of a
schematic configuration of a car navigation device.
[0047] FIG. 29 is a block diagram illustrating an example of a
schematic configuration of a wireless access point.
MODE(S) FOR CARRYING OUT THE INVENTION
[0048] Hereinafter, (a) preferred embodiment(s) of the present
disclosure will be described in detail with reference to the
appended drawings. Note that, in this specification and the
appended drawings, structural elements that have substantially the
same function and structure are denoted with the same reference
numerals, and repeated explanation of these structural elements is
omitted.
[0049] Further, in this specification and the drawings, there are
cases in which a plurality of elements having substantially the
same function are distinguished by adding different numbers to the
end of the same reference numeral. For example, a plurality of
elements having substantially the same function are distinguished
as necessary like a STA 200A and a STA 200B. However, in a case
where it is unnecessary to distinguish elements having
substantially the same function, only the same reference numeral is
added. For example, in a case where it is unnecessary to
particularly distinguish the STA 200A and the STA 200B, they are
simply referred to as "STAs 200."
[0050] Further, the description will proceed in the following
order. [0051] 1. Introduction [0052] 2. One embodiment of present
disclosure [0053] 2-1. Configuration of communication system [0054]
2-2. Basic function of communication device [0055] 2-3. Function
details of communication device [0056] 2-4. Process of
communication device [0057] 2-5. Operation examples [0058] 2-6.
Conclusion of one embodiment of present disclosure [0059] 3.
Modified examples [0060] 4. Application example [0061] 5.
Conclusion
1.INTRODUCTION
[0062] First, the technology related to a communication device
according to one embodiment of the present disclosure will be
described. As this technology, there is a mechanism called virtual
carrier sensing as described above. Specifically, in virtual
carrier sensing, a NAV is controlled using a mechanism such as
RTS/CTS. First, a basic form of virtual carrier sensing will be
described with reference to FIG. 1. FIG. 1 is a diagram
illustrating an example of control of a NAV using an existing RTS
and CTS.
[0063] As illustrated in FIG. 1, a transmission device 10 that
desires data transmission transmits an RTS frame to a reception
device 20 which is a destination of data transmission. The
reception device 20 which has received the RTS frame transmits a
CTS frame to the transmission device 10 in a case in which the data
transmission to the transmission device 10 is permitted.
[0064] Here, the RTS frame or the CTS frame may be received by
communication devices other than the transmission device 10 and the
reception device 20 which are the destinations of the RTS frame and
the CTS frame. The other communication device sets the NAV on the
basis of transmission period information stored in the received RTS
frame or the CTS frame as illustrated in FIG. 1.
[0065] The transmission device 10 and the reception device 20
communicate the data frame after communication of the CTS frame. If
the data frame is successfully communicated, an acknowledgment
(Ack) frame is communicated, and data transmission ends. Further,
the communication device releases the NAV because the NAV period
elapses as the communication related to the data transmission
between the transmission device 10 and the reception device 20
ends. Accordingly, the other communication devices can access the
transmission path. Configurations of the RTS frame, the CTS frame,
and the Ack frame will be further described with reference to FIGS.
2 to 4. FIG. 2 is a diagram illustrating a configuration of an
existing RTS frame. FIG. 3 is a diagram illustrating a
configuration of an existing CTS frame. FIG. 4 is a diagram
illustrating a configuration of an existing Ack frame.
[0066] As illustrated in FIG. 2, the RTS frame has fields such as
Frame Control, Duration, Receiver Address (RA), Transmitter Address
(TA), and Frame Check Sequence (FCS). The transmission period
information indicating a transmission period of a frame is stored
in the Duration field. Destination information of the RTS frame is
stored in the RA field, and transmission source information of the
RTS frame is stored in the TA field. Therefore, the other
communication device that has received the RTS frame sets the NAV
on the basis of the transmission period information stored in the
Duration field.
[0067] Further, as illustrated in FIG. 3, the CTS frame has fields
such as Frame Control, Duration, RA, and FCS. Similarly to the RTS
frame, transmission period information indicating a transmission
period of a frame is stored in the Duration field. Destination
information of the CTS frame is stored in the RA field. Therefore,
the other communication device that has received the CTS frame sets
the NAV on the basis of the transmission period information stored
in the Duration field. Further, the TA field is not prepared in the
CTS frame.
[0068] Further, as illustrated in FIG. 4, the Ack frame has fields
such as Frame Control, Duration, RA, and FCS. Similarly to the CTS
frame, transmission period information indicating a transmission
period of a frame is stored in the Duration field. Destination
information of the Ack frame is stored in the RA field. Further,
similarly to the CTS frame, the TA field is not prepared in the Ack
frame.
[0069] Next, virtual carrier sensing using a mechanism of releasing
the NAV before the NAV period ends will be described. Specifically,
a notification indicating the end of the transmission period, that
is, the end of the NAV period, is given to the other communication
devices using CF-End. Virtual carrier sensing using a mechanism of
releasing the NAV will be described with reference to FIG. 5. FIG.
5 is a diagram illustrating an example of control of the NAV using
the existing CF-End.
[0070] The transmission device 10 that desires data transmission
transmits the RTS frame to the reception device 20 which is the
destination of data transmission as illustrated in FIG. 5. The
reception device 20 which has received the RTS frame transmits the
CTS frame to the transmission device 10 in a case in which the data
transmission to the transmission device 10 is permitted. Further,
in a case in which the RTS frame or the CTS frame is received,
communication devices other than the transmission device 10 and the
reception device 20 which are the destinations of the RTS frame and
CTS frame set the NAV as illustrated in FIG. 5.
[0071] The transmission device 10 and the reception device 20
communicate the data frame after communication of the CTS frame.
Here, if the data transmission ends before a scheduled transmission
period ends, the transmission device 10 transmits a CF-End frame as
illustrated in FIG. 5. The reception device 20 which has received
the CF-End frame ends the communication with the transmission
device 10. Further, the reception device 20 which has received the
CF-End frame may separately transmit the CF-End frame as
illustrated in FIG. 5. Further, the other communication device
releases the NAV if the CF-End frame is received. Accordingly, the
other communication device can access the transmission path.
Further, a configuration of the CF-End frame will be described with
reference to FIG. 6. FIG. 6 is a diagram illustrating a
configuration of an existing CF-End frame.
[0072] As illustrated in FIG. 6, the CF-End frame has fields such
as Frame Control, Duration, RA, BSSID (TA), and FCS. Transmission
period information indicating a transmission period of a frame is
stored in the Duration field. A broadcast address is stored in the
RA field, and a BSSID of a BSS to which the communication device
transmitting the CF-End frame belongs is stored in the BSSID
field.
[0073] Further, an application form of virtual carrier sensing will
be described. Specifically, there is a mechanism for controlling
the NAV using only the CTS (CTS-to-self) out of the RTS and the
CTS. Virtual carrier sensing in which the NAV is controlled using
only the CTS will be described with reference to FIG. 7. FIG. 7 is
a diagram illustrating an example of control of the NAV using only
the CTS.
[0074] The transmission device 10 that desires data transmission
transmits the CTS-to-self frame as illustrated in FIG. 7. The
reception device 20 which has received the CTS-to-self frame sets
the NAV on the basis of the transmission period information stored
in the CTS-to-self frame. The transmission device 10 transmits the
data frame after transmitting the CTS-to-self frame. If the Ack
frame is received after the data frame is transmitted, and the data
transmission ends before the transmission period ends, the
transmission device 10 transmits the CF-End frame. The reception
device 20 which has received the CF-End frame releases the NAV.
Further, the configuration of the CTS-to-self frame is
substantially the same as that of the CTS frame, but the
configuration of the CTS-to-self frame differs from that of the CTS
frame in that information specifying the transmission source
information of the CTS-to-self frame, that is, the BSSID
(hereinafter also referred to as "BSSID information"), is stored in
the RA field.
[0075] Further, the CF-End frame may also be transmitted from the
reception device 20 as described above. An example in which the
CF-End frame is also transmitted from the communication device
which has received the CF-End frame under control of the NAV using
only the CTS will be described with reference to FIG. 8. FIG. 8 is
a diagram illustrating another example of the control of the NAV
using only the existing CTS.
[0076] As illustrated in FIG. 8, the reception device 20 which has
received the CTS-to-self frame transmitted from the transmission
device 10 sets the NAV At this time, other communication devices
located near the reception device 20 also receive the CTS-to-self
frame and set the NAV Then, if the data transmission ends before
the transmission period ends, the transmission device 10 transmits
the CF-End frame. The reception device 20 which has received the
CF-End frame transmits the CF-End frame separately as illustrated
in FIG. 8. The other communication devices which have received the
CF-End frame transmitted separately release the NAV.
[0077] Further, the CF-End may double as Ack. The control of the
NAV using the CF-End doubling as Ack will be described with
reference to FIG. 9. FIG. 9 is a diagram illustrating an example of
control of a NAV using the CF-End doubling as an existing Ack.
[0078] As illustrated in FIG. 9, the reception device 20 which has
received the CTS-to-self frame transmitted from the transmission
device 10 sets the NAV. Then, the transmission device 10 transmits
a data frame and a poll frame after transmitting the CTS-to-self
frame. The reception device 20 which has received the data frame
and the poll frame transmits an Ack frame for the data frame and a
data frame based on the poll frame. The transmission device 10
which has received the Ack frame and the data frame transmits a
CF-End+CF-Ack frame. If the CF-End+CF-Ack frame is received, the
reception device 20 releases the NAV. Further, the configuration of
the CF-End+CF-Ack frame is substantially the same as that of the
normal CF-End frame described above, but the configuration of the
CF-End+CF-Ack frame differs from that of the normal CF-End frame in
that information indicating the CF-End+CF-Ack frame is stored in a
Subtype field of the Frame Control field.
[0079] Virtual carrier sensing has been described above. However,
in the communication using virtual carrier sensing described above,
communication collision is likely to occur, or transmission
opportunities are likely to decrease. Specifically, in a case in
which there is a BSS with an overlapping communication range
(hereinafter also referred to as an "overlapping BSS (OBSS)"), if
the CF-End frame from another OBSS 2 arrives at an OBSS 1 in which
the NAV is set, the NAV is released. However, since communication
is continued as the NAV is assumed to be continued in the OBSS 1,
if the communication device which has released NAV starts
communication, communication collision occurs. On the other hand,
in order to prevent such communication collision, the communication
device not releasing the NAV even when the CF-End frame is received
can be considered. However, in this case, the communication device
misses the transmission opportunity, and the communication
throughput decreases. A phenomenon occurring in the existing
virtual carrier sensing will be more specifically described with
reference to FIG. 10 and FIG. 11. FIG. 10 is a diagram illustrating
an example of release of a NAV in existing carrier sensing.
Further, FIG. 11 is a diagram illustrating another example of
release of a NAV in existing carrier sensing.
[0080] In FIG. 10, after the CTS frame is communicated, and the NAV
is set in the OBSS 1, the CTS frame is communicated, and the NAV is
set in the OBSS 2. Here, if the CTS frame from the OBSS 2 reaches
the OBSS 1, in a case in which the NAV based on the CTS frame of
the OBSS 2 is longer than the NAV in the OBSS 1, the NAV in the
OBSS 1 is updated on the basis of the CTS frame from the OBSS 2.
Further, only the destination information is stored in the CTS
frame, and the transmission source information is not stored.
Therefore, the BSS to which the transmission source of the CTS
frame belongs is unable to be determined from the CTS frame.
[0081] In this state, the CF-End frame is transmitted in the OBSS
1, and if the transmitted CF-End frame reaches the OBSS 2, the
communication device belonging to the OBSS 2 releases the set NAV
This is because the BSS for the NAV set on the basis of the
reception of the CTS frame is unable to be specified as described
above, and the NAV is uniformly released in response to the
reception of the CF-End frame. As a result, if the communication
device which has released the NAV starts communication in the OBSS
2, communication collision may occur in the OBSS 2.
[0082] Further, in FIG. 11, after the CTS frame is communicated,
and the NAV is set in the OBSS 1, the CTS frame is communicated,
and the NAV is set in the OBSS 2. Here, even when the CTS frame
from the OBSS 2 reaches the OBSS 1, in a case in which the NAV
based on the CTS frame of the OBSS 2 is smaller than the NAV in the
OBSS 1, the NAV in the OBSS 1 is not updated.
[0083] In this state, the CF-End frame is transmitted in the OBSS
2, and if the transmitted CF-End frame reaches the OBSS 1, the
communication device belonging to the OBSS 1 releases the set NAV
As a result, if the communication device which has released the NAV
starts communication in the OBSS 1, communication collision may
occur in the OBSS 1.
[0084] In this regard, in one embodiment of the present disclosure,
a communication system capable of preventing communication
collision while suppressing a reduction in opportunities to access
the transmission path and a communication device for implementing
the communication system are proposed. Hereinafter, a device that
transmits the CF-End frame is also referred to as a "transmission
device," and a device that sets the NAV by at least the CTS frame
and receives the CF-End frame is also referred to as a "reception
device."
2. ONE EMBODIMENT OF PRESENT DISCLOSURE
[0085] A communication system and a communication device according
to one embodiment of the present disclosure will be described.
<2-1. Configuration of Communication System>
[0086] First, a communication system according to one embodiment of
the present disclosure will be described with reference to FIG. 12.
FIG. 12 is a diagram illustrating a configuration example of a
communication system according to one embodiment of the present
disclosure.
[0087] A communication system according to one embodiment of the
present disclosure includes a plurality of communication devices.
The communication devices communicate frames with each other.
Further, the communication devices have a virtual carrier sensing
function.
[0088] Specifically, the communication system includes an AP 100
and an STA 200, and a wireless communication network such as a BSS
is formed by the AP 100 and the STA 200. Then, the AP 100 and the
STA 200 communicate using virtual carrier sensing. For example, an
AP 100A and each of STAs 200A and 200B illustrated in FIG. 12
establish a communication connection, so that a BSS 1 is formed.
Further, in a case in which data transmission is performed from the
STA 200A to the AP 100A, the RTS frame is transmitted from the STA
200A, and the CTS frame is received from the AP 100A which has
received the RTS frame. Upon receiving the RTS frame or the CTS
frame, the STA 200B sets the NAV and does not perform communication
until the data transmission from the STA 200A to the AP 100A ends.
In a case in which the data transmission ends before the NAV period
ends, the AP 100A or the STA 200A releases the NAV set in the STA
200B by transmitting the CF-End frame.
[0089] Further, there are cases in which there are a plurality of
BSSs, and the plurality of BSSs are adjacent to one another. For
example, a BSS 2 is formed by an AP 100B and STAs 200C and 200D
illustrated in FIG. 12, and a BSS 3 is formed by an AP 100C and
STAs 200E and 200F illustrated in FIG. 12. Hereinafter, the BSS 2
and the BSS 3 are also referred to as an OBSS 2 and an OBSS 3
because they are BSSs that overlap the BSS 1.
[0090] Further, virtual carrier sensing for the BSS to which it
belongs is executed with a high degree of certainty, but virtual
carrier sensing for the OBSS may be controlled depending on a
situation. For example, as illustrated in FIG. 12, the STA 200A is
located at a distance at which it can communicate with an AP 100B
and an STA 200C belonging to the OBSS 2. Therefore, there are cases
in which the STA 200A receives the CTS frame (including the
CTS-to-self) from the AP 100B and receives the RTS frame from the
STA 200C. In this regard, the STA 200A sets the NAV 2 for the OBSS
(hereinafter also referred to as an "ONAV") 2 with a high degree of
certainty.
[0091] On the other hand, as illustrated in FIG. 12, the STA 200A
is located at a distance at which it can communicate with the STA
200E belonging to the OBSS 3. Therefore, the STA 200A may receive
the RTS frame from the STA 200E. However, it is difficult to
receive the CTS frame (including the CTS-to-self) from the AP 100C.
In this regard, the STA 200A arbitrarily sets the ONAV 3.
[0092] In the above example, the AP 100 operates as the
transmission device, and the STA 200 operates as the reception
device, but the STA 200 may operate as the transmission device, and
the AP 100 may operate as the reception device.
<2-2. Basic Function of Communication Device>
[0093] Next, basic functions of a transmission device 100 and a
reception device 200 that are communication devices according to
one embodiment of the present disclosure will be described. First,
functional configurations of the transmission device 100 and the
reception device 200 according to one embodiment of the present
disclosure will be described with reference to FIG. 13. FIG. 13 is
a block diagram illustrating an example of schematic functional
configurations of a transmission device 100 and a reception device
200 according to one embodiment of the present disclosure. Further,
since the basic functions of the transmission device 100 and the
reception device 200 are substantially the same, only the
transmission device 100 will be described.
[0094] As illustrated in FIG. 13, a transmission device 100
includes a wireless communication module 101, a wired communication
module 102, a device control unit 103, an information input unit
104, and an information output unit 105.
[0095] The wireless communication module 101 performs wireless
communication with external devices. Specifically, the wireless
communication module 101 transmits data obtained from the device
control unit 103 and provides received data to the device control
unit 103. The details will be described later.
[0096] The wired communication module 102 communicates with an
external device via wired communication. Specifically, the wired
communication module 102 is connected to the Internet and
communicates with the external device via the Internet. For
example, the wired communication module 102 transmits data acquired
via communication by the wireless communication module 101 to the
external device via the Internet.
[0097] The device control unit 103 controls operation of the
transmission device 100 in general. Specifically, the device
control unit 103 controls communication of the wireless
communication module 101 and the wired communication module 102.
For example, the device control unit 103 causes the wireless
communication module 101 or the wired communication module 102 to
transmit data obtained from the information input unit 104.
Further, the device control unit 103 causes the information output
unit 105 to output data obtained by the communication of the
wireless communication module 101 or the wired communication module
102.
[0098] The information input unit 104 receives an input from the
outside of the transmission device 100. Specifically, the
information input unit 104 receives a user input or information
obtained from a sensor. For example, the information input unit 104
is an input device such as a keyboard or a touch panel or a
detection device such as a sensor.
[0099] The information output unit 105 outputs data. Specifically,
the information output unit 105 outputs data instructed from the
device control unit 103. For example, the information output unit
105 is a display that outputs images on the basis of image
information, a speaker that outputs sounds or music on the basis of
audio information, or the like.
[0100] Further, the wired communication module 102, the information
input unit 104 and the information output unit 105 among the above
components may not be included in the transmission device 100.
(Configuration of Wireless Communication Module)
[0101] Next, a functional configuration of the wireless
communication module 101 will be described with reference to FIG.
14. FIG. 14 is a block diagram illustrating an example of a
schematic functional configuration of the wireless communication
module 101 according to an embodiment of the present
disclosure.
[0102] As illustrated in FIG. 14, the wireless communication module
101 includes a data processing unit 110, a control unit 120, and a
wireless communication unit 130.
(1. Data Processing Unit)
[0103] The data processing unit 110 includes an interface unit 111,
a transmission buffer 112, a transmission frame constructing unit
113, a reception frame analyzing unit 114, and a reception buffer
115 as illustrated in FIG. 14 as the processing unit.
[0104] The interface unit 111 is an interface connected to other
functional components installed in the transmission device 100.
Specifically, the interface unit 111 performs reception of data
that is desired to be transmitted from another functional
component, for example, the device control unit 103, provision of
reception data to the device control unit 103, or the like.
[0105] The transmission buffer 112 stores data to be transmitted.
Specifically, the transmission buffer 112 stores data obtained by
the interface unit 111.
[0106] The transmission frame constructing unit 113 generates a
frame to be transmitted. Specifically, the transmission frame
constructing unit 113 generates a frame on the basis of data stored
in the transmission buffer 112 or control information set by the
control unit 120. For example, the transmission frame constructing
unit 113 generates a frame (packet) from data acquired from the
transmission buffer 112, and performs a process of adding a MAC
header for medium access control (MAC) and an error detection code
to the generated frame and the like.
[0107] The reception frame analyzing unit 114 analyzes a received
frame. Specifically, the reception frame analyzing unit 114
determines a destination of a frame received by the wireless
communication unit 130 and acquires data or control information
included in the frame. For example, the reception frame analyzing
unit 114 acquires data and the like included in the received frame
by performing analysis of the MAC header, detection and correction
of a code error, a reordering process, and the like on the received
frame.
[0108] The reception buffer 115 stores received data. Specifically,
the reception buffer 115 stores data acquired by the reception
frame analyzing unit 114. For example, the reception buffer 115
continues to hold data which is a part of a predetermined series of
data until a predetermined series of data is obtained. Then, if the
predetermined series of data is obtained, the predetermined series
of data is provided to a communication upper layer via the
interface unit 111.
(2. Control Unit)
[0109] The control unit 120 includes an operation control unit 121
and a signal control unit 122 as illustrated in FIG. 14 as parts of
the processing unit and the acquisition unit.
[0110] The operation control unit 121 controls an operation of the
data processing unit 110. Specifically, the operation control unit
121 controls the occurrence of communication. For example, if a
communication connection request occurs, the operation control unit
121 causes the data processing unit 110 to generate frames related
to a connection process or an authentication processing such as an
association process or an authentication process.
[0111] Further, the operation control unit 121 controls generation
of frames on the basis of a storage state of data in the
transmission buffer 112, an analysis result for a reception frame,
or the like. For example, in a case in which data is stored in the
transmission buffer 112, the operation control unit 121 instructs
the transmission frame constructing unit 113 to generate a data
frame in which the data is stored. Further, in a case in which
reception of a frame is confirmed by the reception frame analyzing
unit 114, the operation control unit 121 instructs the transmission
frame constructing unit 113 to generate an acknowledgment frame
which is a response to a received frame.
[0112] The signal control unit 122 controls an operation of the
wireless communication unit 130. Specifically, the signal control
unit 122 controls a transmission/reception process of the wireless
communication unit 130. For example, the signal control unit 122
causes the wireless communication unit 130 to set a parameter for
transmission and reception on the basis of an instruction from the
operation control unit 121.
[0113] Further, the virtual carrier sensing function is controlled
by the control unit 120. For example, the control unit 120 causes
the data processing unit 110 to generate the RTS frame or the CTS
frame in accordance with the presence or absence of a transmission
request or a transmission permission. Further, if the RTS frame and
the CTS frame are received, the control unit 120 sets the NAV, and
releases the NAV after the NAV period ends.
(3. Wireless Communication Unit)
[0114] As illustrated in FIG. 14, the wireless communication unit
130, as a communication unit, includes a transmission processing
unit 131, a reception processing unit 132, and an antenna control
unit 133.
[0115] The transmission processing unit 131 performs a frame
transmission process. Specifically, the transmission processing
unit 131 generates a signal to be transmitted on the basis of a
frame provided from the transmission frame constructing unit 113.
More specifically, the transmission processing unit 131 generates a
signal related to a frame on the basis of a parameter set in
accordance with an instruction from the signal control unit 122.
For example, the transmission processing unit 131 generates a
symbol stream by performing encoding, interleaving, and modulation
on the frame provided from the data processing unit 110 in
accordance with a coding and modulation scheme instructed by the
control unit 120. Further, the transmission processing unit 131
converts the signal related to the symbol stream obtained by the
process at the previous stage into an analog signal, and performs
amplification, filtering, and frequency up-conversion on the
resulting signal.
[0116] The reception processing unit 132 performs a frame reception
process. Specifically, the reception processing unit 132 restores
the frame on the basis of the signal provided from the antenna
control unit 133. For example, the reception processing unit 132
acquires a symbol stream by performing a process opposite to the
signal transmission, for example, frequency down-conversion,
digital signal conversion, and the like on a signal obtained from
an antenna. Further, the reception processing unit 132 acquires a
frame by performing demodulation, decoding, and the like on the
symbol stream obtained by the process at the previous stage and
provides the acquired frame to the data processing unit 110 or the
control unit 120.
[0117] The antenna control unit 133 controls transmission and
reception of signals via at least one antenna. Specifically, the
antenna control unit 133 transmits the signal generated by the
transmission processing unit 131 via the antenna and provides the
signal received via the antenna to the reception processing unit
132.
<2-3. Function Details of Communication Device>
[0118] Next, functions of the transmission device 100 and the
reception device 200 according to one embodiment of the present
disclosure will be described.
(A. Transmission Device)
[0119] First, functions of the transmission device 100 will be
described.
(A-1. Setting of TXOP)
[0120] The transmission device 100 executes virtual carrier sensing
at the time of data transmission. Specifically, the transmission
device 100 sets a data transmission period by exchanging frames for
stopping transmission of frames of communication devices other than
the destination, that is, a frame related to a communication
request (third frame) and a frame related to a response to the
communication request (a first frame).
[0121] More specifically, the transmission device 100 sets the TXOP
for the data transmission by exchanging the RTS frame (third frame)
and the CTS frame (first frame). For example, if a data
transmission request occurs, the control unit 120 causes the data
processing unit 110 to generate an RTS frame whose destination is a
device serving as a destination of data transmission (hereinafter
also referred to as a "transmission destination device"). The
wireless communication unit 130 transmits the generated RTS frame.
Further, if the CTS frame is received by the wireless communication
unit 130, the data processing unit 110 acquires destination
information from the received CTS frame, and in a case in which the
destination indicated by the acquired destination information is
the transmission device 100 itself, the control unit 120 sets the
TXOP on the basis of the transmission period information stored in
the CTS frame. Thereafter, the transmission device 100 starts
transmitting the data frame related to the data transmission.
[0122] Further, the transmission device 100 may be the transmission
destination device. For example, if an RTS frame whose destination
is itself, that is, the transmission device 100, the control unit
120 determines whether or not the data transmission is permitted to
a device serving as a transmission source device of the RTS frame
(hereinafter also referred to as a "transmission source device").
If it is determined that the data transmission is permitted, the
control unit 120 causes the data processing unit 110 to generate a
CTS frame whose destination is the transmission source device. The
wireless communication unit 130 transmits the generated CTS frame.
Then, the control unit 120 sets the TXOP on the basis of the
transmission period information notified to the transmission source
device using the CTS frame. Thereafter, the transmission device 100
receives the data frame related to the data transmission.
(A-2. CF-End Notification)
[0123] In the data transmission period, the transmission device 100
transmits a frame (second frame) for releasing stop of transmission
of a frame caused by the frame (first frame) related to the
response to the communication request. Specifically, if the data
transmission ends before the set TXOP period ends, the control unit
120 causes the data processing unit 110 to generate a CF-End frame
(second frame) having the destination information (first
destination information) of the CTS frame (first frame)
(hereinafter also referred to as a "second CF-End frame"). Then,
the wireless communication unit 130 transmits the generated second
CF-End frame. For example, in a case in which the transmission
device 100 transmits the CTS frame, the control unit 120 causes the
data processing unit 110 to generate a second CF-End frame. On the
other hand, in a case in which the transmission device 100 does not
transmit the CTS frame, the control unit 120 causes the data
processing unit 110 to generate an existing CF-End frame. Further,
even in a case in which the transmission device 100 is not
transmitting the CTS frame, the control unit 120 may cause the data
processing unit 110 to generate the second CF-End frame when the
CTS frame is being received.
[0124] Further, a configuration of the second CF-End frame will be
described with reference to FIGS. 15 and 16. FIG. 15 is a diagram
illustrating an example of a configuration of the second CF-End
frame transmitted by the transmission device 100 according to one
embodiment of the present disclosure. FIG. 16 is a diagram
illustrating another example of a configuration of the second
CF-End frame transmitted by the transmission device 100 according
to one embodiment of the present disclosure.
[0125] The second CF-End frame has the destination information of
the CTS frame in a region different from a region in which the
transmission source information of the second CF-End frame is
stored. Specifically, the destination information of the CTS frame
is stored in the region in which the destination information of the
second CF-End frame is stored. For example, as illustrated in FIG.
15, the second CF-End frame has fields such as Frame Control,
CF-End Type, CTS RA, BSSID (TA), and FCS. Information in which a
type of CF-End frame is specified (hereinafter also referred to as
"CF-End type information") is stored in the CF-End Type field. In
detail, a value such as 0x01 is stored in the CF-End Type field.
Further, the destination information of the CTS frame is stored in
the CTS RA field. Further, BSSID information in which the BSSID is
specified is stored in the BSSID (TA) field. Further, the CF-End
Type field corresponds to the Duration field of the existing CF-End
frame. Further, the CTS RA field corresponds to the RA field of the
existing CF-End frame. For example, a value of 0 (that is, 0x00) is
stored in the Duration field of the existing CF-End frame, and a
broadcast address is stored in the RA field. Therefore, the second
CF-End frame is compatible with the existing CF-End frame.
[0126] Further, the second CF-End frame may have the destination
information of the CTS frame in another region. Specifically, the
destination information of the CTS frame is stored in a region
different from both of the region in which the transmission source
information of the second CF-End frame is stored and the region in
which the destination information of the second CF-End frame is
stored. For example, as illustrated in FIG. 16, the second CF-End
frame has fields such as Frame Control, CF-End Type, RA, BSSID
(TA), CTS RA, and FCS. A value such as 0x02 is stored in the CF-End
Type field of the second CF-End frame. As described above, it is
possible to cause various types of CF-End frames to coexist by
using information in which the type of second CF-End frame is
specified.
(B. Reception Device)
[0127] Then, functions of the reception device 200 will be
described.
(B-1. NAV Setting)
[0128] The reception device 200 stops transmission of a frame on
the basis of virtual carrier sensing. Specifically, the reception
device 200 sets the NAV on the basis of a fame for stopping
transmission of frames of communication devices other than the
destination, that is, a frame (third frame) related to the
communication request or a frame (first frame) related to the
response to the communication request. Further, the NAV period
corresponds to the data transmission period, that is, the TXOP
described above.
[0129] More specifically, the reception device 200 sets the NAV on
the basis of the received RTS frame (third frame) or the CTS frame
(first frame). For example, if the RTS frame or the CTS frame whose
destination is a communication device other than itself, that is,
the reception device 200 is received, the control unit 220 sets the
NAV on the basis of the transmission period information stored in
the received RTS frame or the CTS frame.
[0130] Here, the reception device 200 manages the NAV for each
piece of destination information of the received CTS frame.
Specifically, if the CTS frame is received by the wireless
communication unit 230, the data processing unit 210 acquires the
destination information from the CTS frame. Then, the control unit
220 associates the acquired destination information of the CTS
frame with the set NAV, and causes the acquired destination
information of the CTS frame to be stored in a storage unit (not
illustrated). Further, the reception device 200 manages the NAV for
each of the destination information and the transmission source
information of the received RTS frame. Specifically, if the RTS
frame is received by the wireless communication unit 230, the data
processing unit 210 acquires the destination information and the
transmission source information from the RTS frame. Then, the
control unit 220 associates the acquired destination information
and the transmission source information of the RTS frame with the
set NAV, and causes the acquired destination information and the
transmission source information of the RTS frame to be stored in
the storage unit.
(B-2. Control of NAV Based on CF-End)
[0131] The reception device 200 controls the transmission of the
frame on the basis of the frame (second frame) which is received
during the frame transmission stop period and releases the stop of
the transmission of the frame caused by the frame (first frame)
related to the response to the communication request. Specifically,
the control unit 220 controls the stop of the transmission of the
frame for each piece of destination information of the CTS frame on
the basis of the destination information included in the received
CTS frame and the destination information of the CTS frame included
in the received second CF-End frame. More specifically, in a case
in which the destination specified from the destination information
of the received CTS frame coincides with the destination specified
from the destination information of the CTS frame included in the
second CF-End frame, the control unit 220 releases the stop of the
transmission of the frame for the destination information of the
CTS frame related to the coinciding destination.
[0132] For example, if the second CF-End frame is received before
the set NAV period ends, the data processing unit 210 acquires the
destination information of the CTS frame from the second CF-End
frame. The control unit 220 determines whether or not the
destination indicated by the destination information of the
acquired CTS frame coincides with the destination indicated by the
destination information of the CTS frame stored in the storage
unit. If it is determined that the destinations of the two CTS
frames coincide with each other, the control unit 220 releases the
NAV associated with the destination information of the CTS
frame.
[0133] Further, the reception device 200 controls the stop of the
transmission of the frame for each piece of destination information
of the RTS frame on the basis of the destination information of the
RTS frame included in the received RTS frame and the transmission
source information of the second CF-End frame included in the
received second CF-End frame. Specifically, in a case in which the
destination specified from the destination information of the
received RTS frame coincides with the transmission source specified
from the transmission source information of the second CF-End frame
included in the second CF-End frame, the control unit 220 releases
the stop of the transmission of the frame for the destination
information of the RTS frame related to the transmission
source.
[0134] For example, if the second CF-End frame is received before
the set NAV period ends, the data processing unit 210 acquires the
transmission source information of the second CF-End frame, that
is, the BSSID information from the second CF-End frame. The control
unit 220 determines whether or not the BSSID indicated by the
acquired BSSID information coincides with the BSSID indicated by
the destination information of the RTS frame stored in the storage
unit, that is, the BSSID information. If it is determined that the
two BSSIDs coincide with each other, the control unit 220 releases
the NAV associated with the destination information of the RTS
frame.
[0135] Further, in a case in which the existing CF-End frame is
received instead of the second CF-End frame, the reception device
200 performs control only for the NAV associated with the
destination information of the RTS frame.
<2-4. Process of Communication Device>
[0136] Next, processes of the transmission device 100 and the
reception device 200 will be described.
(Process of Transmission Device)
[0137] First, a process of the transmission device 100 will be
described with reference to FIG. 17. FIG. 17 is a flowchart
conceptually illustrating an example of a process of the
transmission device 100 according to one embodiment of the present
disclosure.
[0138] The transmission device 100 determines whether or not an RTS
frame destined for the transmission device 100 is received (step
S301). Specifically, the data processing unit 110 acquires the
destination information from the RTS frame received by the wireless
communication unit 130, and determines whether or not the
communication device indicated by the destination information is
the transmission device 100.
[0139] If it is determined that the RTS frame destined for the
transmission device 100 is received, the transmission device 100
acquires transmission period information (step S302). Specifically,
if it is determined that the communication device indicated by the
destination information of the RTS frame is the transmission device
100, the data processing unit 110 acquires the transmission period
information from the Duration field of the RTS frame.
[0140] Then, the transmission device 100 acquires the destination
information of the CTS frame (step S303). Specifically, the data
processing unit 110 acquires the transmission source information
from the received RTS frame. In a case in which the CTS frame is
transmitted, the acquired transmission source information is the
destination information of the CTS frame.
[0141] Then, the transmission device 100 determines whether or not
the data transmission is permitted (step S304). Specifically, the
control unit 120 determines whether or not the data transmission is
permitted to the communication device indicated by the transmission
source information of the received RTS frame.
[0142] If it is determined that the data transmission is permitted,
the transmission device 100 transmits the CTS frame (step S305).
Specifically, if it is determined that the data transmission is
permitted to the communication device, the control unit 120 causes
the data processing unit 110 to generate the CTS frame having the
transmission source information acquired in step S303 as the
destination information. Then, the wireless communication unit 130
transmits the generated CTS frame. Further, the transmission period
information stored in the CTS frame indicates the TXOP for the
permitted data transmission.
[0143] Thereafter, the transmission device 100 receives the data
frame (step S306). Specifically, the wireless communication unit
130 and the data processing unit 110 perform a reception process on
the data frame transmitted from the transmission source of the RTS
frame.
[0144] Then, the transmission device 100 determines whether or not
the data transmission ends (step S307). Specifically, the control
unit 120 determines whether or not the communication of the data
frame ends.
[0145] If it is determined that the data transmission ends, the
transmission device 100 determines whether or not the transmission
period ends (step S308). Specifically, the control unit 120
determines whether or not the set TXOP period ends.
[0146] If it is determined that the transmission period does not
end, the transmission device 100 determines whether or not the
transmission device 100 transmits the CTS frame (step S309).
Specifically, if it is determined that the data transmission ends
but the TXOP period does not end, the control unit 120 determines
whether or not the transmission device 100 transmits the CTS frame
for the data transmission.
[0147] If it is determined that the transmission device 100
transmits the CTS frame, the transmission device 100 generates the
second CF-End frame having the destination information of the CTS
frame (step S310). Specifically, if it is determined that the
control unit 120 transmits the CTS frame, the control unit 120
causes the data processing unit 110 to generate the second CF-End
frame having the destination information of the transmitted CTS
frame and the CF-End type information having a value of 0x01 or
0x02.
[0148] Further, if it is determined that the transmission device
100 does not transmits the CTS frame, the transmission device 100
generates the second CF-End frame having the broadcast address
(step S311). Specifically, if it is determined that the
transmission device 100 does not transmits the CTS frame, the
control unit 120 causes the data processing unit 110 to generate
the second CF-End frame having the broadcast address and the CF-End
type information having a value of 0x00 as the destination
information. Further, the second CF-End frame generated in this
step is substantially the same as the existing CF-End frame.
[0149] Then, the transmission device 100 transmits the generated
second CF-End frame (step S312). Specifically, the wireless
communication unit 130 transmits the generated second CF-End
frame.
[0150] Further, if it is determined that the RTS frame destined for
the transmission device 100 is not received in step S301, the
transmission device 100 determines whether or not the CTS-to-self
frame is received (step S313). Specifically, the data processing
unit 110 determines whether or not the CTS-to-self frame is
received by the wireless communication unit 130.
[0151] If it is determined that the CTS-to-self frame is received,
the transmission device 100 acquires the transmission period
information (step S314). Specifically, if it is determined that the
CTS-to-self frame is received, the data processing unit 110
acquires the transmission period information from the Duration
field of the CTS-to-self frame.
[0152] Then, the transmission device 100 determines whether or not
the received CTS-to-self frame is a frame related to the BSS to
which the transmission device 100 belongs (step S315).
Specifically, the control unit 120 determines whether or not the
BSS indicated by the BSSID information acquired from the RA field
of the CTS-to-self frame is the BSS to which the transmission
device 100 belongs.
[0153] If it is determined that the received CTS-to-self frame is
the frame related to the BSS to which the transmission device 100
belongs, the transmission device 100 receives the data frame (step
S316), and determines whether or not the data transmission ends
each time the data frame is received (step S317).
[0154] If it is determined that the data transmission ends, the
transmission device 100 determines whether or not the second CF-End
frame is received (step S318). Specifically, the control unit 120
determines whether or not the second CF-End frame is received by
the wireless communication unit 130.
[0155] If it is determined that the second CF-End frame is
received, the transmission device 100 generates the second CF-End
frame having the broadcast address (step S311), and transmits the
generated second CF-End frame (step S312). Further, here, the
existing CF-End frame may be transmitted instead of the second
CF-End frame.
[0156] Further, if it is determined in step S313 that the
CTS-to-self frame is not received, the transmission device 100
determines whether or not an RTS frame destined for another
communication device is received (step S319). Specifically, if the
RTS frame is received by the wireless communication unit 130, the
data processing unit 110 determines whether or not the
communication device indicated by the destination information of
the RTS frame is another communication device other than the
transmission device 100.
[0157] If it is determined that the RTS frame destined for another
communication device is received, the transmission device 100
acquires the transmission period information (step S320) and sets
the NAV (step S321). Specifically, if it is determined that the RTS
frame destined for another communication device is received, the
data processing unit 110 acquires the transmission period
information from the Duration field of the RTS frame, and sets the
NAV on the basis of the acquired transmission period
information.
(Process of Reception Device)
[0158] Next, a process of the reception device 200 will be
described with reference to FIGS. 18 and 19. FIG. 18 is a flowchart
conceptually illustrating an example of a NAV setting process in
the reception device 200 according to one embodiment of the present
disclosure.
[0159] The reception device 200 determines whether or not the RTS
frame destined for another communication device is received (step
S401). Specifically, if the RTS frame is received by the wireless
communication unit 230, the data processing unit 210 acquires the
destination information from the RTS frame, and determines whether
or not the communication device indicated by the destination
information is another communication device other than the
reception device 200.
[0160] If it is determined that the RTS frame destined for another
communication device is received, the reception device 200 acquires
the destination information and the transmission source information
of the RTS frame (step S402). Specifically, if it is determined
that the destination of the received RTS frame is another
communication device, the data processing unit 210 acquires the
destination information and the transmission source information
from the RTS frame. Then, the data processing unit 210 causes the
acquired destination information and the transmission source
information to be stored in the storage unit.
[0161] Further, if it is determined in step S401 that the RTS frame
destined for another communication device is not received, the
reception device 200 determines whether or not a CTS frame destined
for another communication device is received (step S403).
Specifically, if the CTS frame is received by the wireless
communication unit 230, the data processing unit 210 acquires the
destination information from the CTS frame, and determines whether
or not the communication device indicated by the destination
information is another communication device other than the
reception device 200.
[0162] If it is determined that the CTS frame destined for another
communication device is received, the reception device 200 acquires
the destination information of the CTS frame (step S404).
Specifically, if it is determined that the destination of the
received CTS frame is another communication device, the data
processing unit 210 acquires the destination information from the
CTS frame. Then, the data processing unit 210 causes the acquired
destination information to be stored in the storage unit.
[0163] Then, the reception device 200 determines whether or not the
RTS frame is received before the CTS frame is received (step S405).
Specifically, the data processing unit 210 determines whether or
not the RTS frame is received during a period from a time point at
which the CTS frame is received to a time point which goes back by
a predetermined time back.
[0164] If it is determined that the RTS frame is received before
the CTS frame is received, the reception device 200 estimates the
transmission source of the CTS frame (step S406). Specifically, if
it is determined that the RTS frame is received during a period
from a time point at which the CTS frame is received to a time
point which goes back by a predetermined time back, the data
processing unit 210 estimates that the destination of the RTS frame
is the transmission source of the CTS frame. Then, the data
processing unit 210 causes the destination information of the RTS
frame to be stored in the storage unit as the transmission source
information of the CTS frame.
[0165] Then, the reception device 200 acquires the transmission
period information from the received frame (step S407).
Specifically, the data processing unit 210 acquires the
transmission period information from the Duration field of the
received RTS frame or the CTS frame.
[0166] Then, the reception device 200 determines whether or not the
NAV is set (step S408). Specifically, the control unit 220
determines whether or not the NAV is already set for the
destination information or a pair of destination information and
transmission source information acquired from the received RTS
frame or the CTS frame.
[0167] If it is determined that the NAV is not set, the reception
device 200 newly sets the NAV (step S409). Specifically, the
control unit 220 newly provides a NAV counter for the acquired
destination information or a pair of destination information and
transmission source information, and sets a value of the NAV
counter on the basis of the acquired transmission period
information.
[0168] On the other hand, if it is determined that the NAV is
already set, the reception device 200 updates the NAV (step S410).
Specifically, the control unit 220 updates the value of the NAV
counter for the acquired destination information or the pair of
destination information and transmission source information on the
basis of the acquired transmission period information.
[0169] Further, FIG. 19 is a flowchart conceptually illustrating an
example of a NAV update process and a NAV release process in the
reception device 200 according to one embodiment of the present
disclosure.
[0170] The reception device 200 determines whether or not the
second CF-End frame is received (step S420). Specifically, the data
processing unit 210 determines whether or not the second CF-End
frame is received by the wireless communication unit 230.
[0171] If it is determined that the second CF-End frame is
received, the reception device 200 determines whether or not the
broadcast address is stored (step S421). Specifically, if it is
determined that the second CF-End frame is received, the data
processing unit 210 determines whether or not the broadcast address
is stored in the second CF-End frame. Further, the data processing
unit 210 may determine whether or not the value of the CF-End type
information stored in the CF-End Type field of the second CF-End
frame is 0x00.
[0172] If it is determined that the broadcast address is stored,
the reception device 200 determines whether or not the NAV for the
transmission source information of the second CF-End frame is being
set (step S422). Specifically, if it is determined that the
broadcast address is stored, the data processing unit 210 acquires
the BSSID information which is the transmission source information
stored in the BSSID (TA) field of the received second CF-End frame.
Then, the control unit 220 determines whether or not the NAV
counter for the acquired BSSID information is set.
[0173] If it is determined that the NAV for the transmission source
information of the second CF-End frame is being set, the reception
device 200 releases the NAV for the transmission source information
(step S423). Specifically, if it is determined that the NAV counter
for the acquired BSSID information is set, the control unit 220
sets the value of the NAV counter to 0.
[0174] Further, if it is determined in step S421 that the broadcast
address is not stored, the reception device 200 determines whether
or not the NAV for the destination information of the CTS frame
stored in the second CF-End frame is being set (step S424). More
specifically, the data processing unit 210 acquires the destination
information of the CTS frame from the received second CF-End frame.
Then, the control unit 220 determines whether or not the NAV
counter is set for the destination information of the acquired CTS
frame.
[0175] If it is determined that the NAV for the destination
information of the CTS frame is being set, the reception device 200
releases the NAV for the destination information of the CTS frame
(step S425). Specifically, the control unit 220 sets the value of
the NAV counter for the destination information of the acquired CTS
frame to 0.
[0176] Then, the reception device 200 determines whether or not
there is data which is scheduled to be transmitted (step S426).
Specifically, the control unit 220 determines whether or not there
is data stored in the transmission buffer 212.
[0177] If it is determined that there is data which is scheduled to
be transmitted, the reception device 200 determines whether or not
there is a NAV being set (step S427). Specifically, if it is
determined that there is data stored in the transmission buffer
212, the control unit 220 determines whether or not there is a NAV
counter whose value is not 0.
[0178] If it is determined that there is a NAV being set, the
reception device 200 updates the NAV each time a predetermined time
passes (step S428). Specifically, if it is determined that there is
a NAV counter whose value is not 0, the control unit 220 subtracts
the value of the NAV counter.
[0179] On the other hand, if it is determined that there is no NAV
being set, the reception device 200 determines whether or not an
access control period elapses (step S429). Specifically, if it is
determined that there is no NAV counter whose value is not 0, the
control unit 220 stands by until a predetermined period such as a
distributed coordination function (DCF) inter frame space (DIFS)
elapses.
[0180] If it is determined that the access control period elapses,
the reception device 200 transmits the data frame (step S430).
Specifically, if a predetermined period such as the DISF elapses,
the control unit 220 causes the data processing unit 210 to
generate the data frame. Then, the wireless communication unit 230
transmits the generated data frame.
<2-5. Operation Examples>
[0181] The processes of the transmission device 100 and the
reception device 200 according to one embodiment of the present
disclosure have been described above. Next, operation examples of
the transmission device 100 and the reception device 200 will be
described by comparison with operation examples of the transmission
device 10 and the reception device 20 according to the related
art.
(Operation Example of Communication Device of Related Art)
[0182] First, operation examples of the transmission device 10 and
the reception device 20 according to the related art will be
described with reference to FIG. 20. FIG. 20 is a diagram for
describing an example of communication between the transmission
device 10 and the reception device 20 according to the related art.
Here, transmission devices 10A and 10B and a reception device 20
belonging to an OBSS 1 and transmission devices 10C and 10D
belonging to an OBSS 2 will be described.
[0183] In the OBSS 1, the transmission device 10A transmits the RTS
frame to the transmission device 10B, and the transmission device
10B which has received the RTS frame transmits the CTS frame to the
transmission device 10A. Here, since the reception device 20
receives only the CTS frame, the reception device 20 sets the NAV
on the basis of the CTS frame.
[0184] Further, in the OBSS 2, the transmission device 10C
transmits the RTS frame to the transmission device 10D, and the
transmission device 10D which has received the RTS frame transmits
the CTS frame to the transmission device 10C. Here, the reception
device 20 receives the CTS frame transmitted from the transmission
device 10C. Since the NAV for the OBSS is managed with one setting,
the reception device 20 updates the NAV on the basis of the CTS
frame.
[0185] Thereafter, in the OBSS 2, the data frame and the existing
CF-End frame are transmitted from the transmission device 10C, and
the transmission device 10D which has received the frames transmits
the existing CF-End frame. Here, since the reception device 20
receives the existing CF-End frame transmitted from the
transmission device 10D, the reception device 20 releases the NAV
on the basis of the existing CF-End frame. Then, the reception
device 20 transmits the data frame.
[0186] However, in the OBSS 1, since the transmission device 10A is
transmitting the data frame, a frame collision occurs due to the
transmission of the data frame by the reception device 20. As a
result, the data transmission between the transmission device 10A
and the transmission device 10B is likely to fail.
(Operation Example of Communication Device According to One
Embodiment of Present Disclosure)
[0187] Then, an example of communication between the transmission
device 100 and the reception device 200 according to one embodiment
of the present disclosure will be described with reference to FIG.
21. FIG. 21 is a diagram for describing an example of communication
between the transmission device 100 and the reception device 200
according to one embodiment of the present disclosure. Here,
transmission devices 100A and 100B and a reception device 200
belonging to an OBSS 1 and transmission devices 100C and 100D
belonging to an OBSS 2 will be described.
[0188] In the OBSS 1, the transmission device 100A transmits the
RTS frame to the transmission device 100B, and the transmission
device 100B which has received the RTS frame transmits the CTS
frame to the transmission device 100A. Here, in order to receive
only the CTS frame transmitted from the transmission device 100B,
the reception device 200 sets the destination information of the
CTS frame, that is, a NAV1 for the transmission device 100A.
[0189] Further, in the OBSS 2, the transmission device 100C
transmits the RTS frame to the transmission device 100D, and the
transmission device 100D which received the RTS frame transmits the
CTS frame to the transmission device 100C. Here, the reception
device 200 receives the CTS frame transmitted from the transmission
device 100C. In the reception device 200, since the NAV is managed
for each piece of destination information of the CTS frame, the
reception device 20 sets the destination information of the CTS
frame, that is, a NAV 2 for the transmission device 100C.
[0190] Thereafter, in the OBSS 2, the data frame and the second
CF-End frame are transmitted from the transmission device 100C, and
the transmission device 100D which has received the frames
transmits the second CF-End frame. In the second CF-End frame, the
destination information of the CTS frame transmitted by the
transmission device 100D is stored. Here, in order to receive the
second CF-End frame transmitted from the transmission device 100D,
the reception device 200 releases only the destination information
coinciding with the destination information stored in the second
CF-End frame, that is, the NAV 2 for the transmission device 100C.
On the other hand, since the NAV 1 for the transmission device 100A
is not released, the reception device 200 transmits the data frame
after the period for the NAV 1 ends.
[0191] For this reason, the transmission of the data frame of the
transmission device 100A in the OBSS 1 is not disturbed. In other
words, it is possible to prevent the occurrence of communication
collision. As a result, it is possible to suppress a reduction in
communication efficiency between the transmission device 100A and
the transmission device 100B.
<2-6. Conclusion of One Embodiment of Present Disclosure>
[0192] Thus, according to one embodiment of the present disclosure,
the transmission device 100 generates a second frame which has
first destination information specifying a destination stored in a
first frame which is used for stopping transmission of a frame of a
communication device other than the destination and serves as a
response to a communication request and is used for releasing the
stop of the transmission of the frame caused by the first frame.
Then, the transmission device 100 transmits the second frame.
Further, the reception device 200 receives the second frame having
the first destination information and controls the transmission of
the frame on the basis of the received second frame.
[0193] In the related art, since the BSSID information is not
stored in the CTS frame, even though the CF-End frame is received
by the communication device that received only the CTS frame, the
NAV for the BSSID information stored in the CF-End frame is unable
to be determined. Therefore, in a case in which the NAV is
released, communication collision is likely to occur, and in a case
in which the NAV is not released, the communication opportunities
are likely to decrease.
[0194] On the other hand, according to one embodiment of the
present disclosure, the reception device 200 can appropriately
release the NAV since the transmission device 100 notifies of the
destination information of the CTS frame together with the CF-End.
Therefore, it is possible to prevent communication collision while
suppressing the reduction in opportunities to access the
transmission path.
[0195] Further, the first destination information is stored in a
region different from the region in which the transmission source
information of the second frame is stored. Therefore, it is
possible to notify of the destination information of the CTS frame
with the second CF-End frame while leaving the transmission source
information of the second CF-End frame. Therefore, it is possible
to maintain the existing process using the transmission source
information, and it is possible to minimize the change amount of
the communication process.
[0196] Further, the region different from the region in which the
transmission source information of the second frame is stored
includes a region in which the destination information of the
second frame is stored. Here, the broadcast address is stored in
the region in which the destination information of the existing
CF-End frame is stored. However, if it is known that the CF-End
frame is a broadcasted frame, the broadcast address can be omitted.
Therefore, it can be said that the region in which the destination
information is stored is a redundant region. In this regard, when
the destination information of the CTS frame is stored in the
region in which the destination information is stored, it is
possible to notify of the destination information of the CTS frame
in accordance with the existing frame format. Therefore, it is
possible to suppress the change amount of the communication
process. Further, in a case in which the frame size is maintained,
it is possible to suppress an increase in communication volume as
well.
[0197] Further, the first destination information is stored in a
region different from both the region in which the transmission
source information of the second frame is stored and the region in
which the destination information of the second frame is stored.
For this reason, for example, when the destination information of
the CTS frame is stored in a region added to the existing frame
format, the communication process of the existing CF-End frame can
be used without change. Therefore, it is possible to further
suppress the change amount of the communication process.
[0198] Further, the second frame includes information specifying a
type of second frame. Therefore, it is possible to communicate a
plurality of CF-End frames depending on a situation. For example,
it is possible to select the second CF-End frame in which the
CF-End type is 0x01 or the second CF-End frame in which the CF-End
type is 0x02 depending on a communication situation.
[0199] Further, the information specifying the type of second frame
is stored in the region in which the transmission period
information of the second frame is stored. Therefore, it is
possible to use the frame format of the existing CF-End frame, and
it is possible to secure the frame compatibility. For example, in a
case in which the CF-End type information is stored in the Duration
field as described above, since 0x00 is stored in the corresponding
field in the existing CF-End frame, the CF-End type of the existing
CF-End frame is specified to be 0x00, and thus it is possible to
secure the compatibility with the existing CF-End frame. Therefore,
even in a case in which there is a communication device not
compatible with the second CF-End frame, the transmission device
100 can transmit the second CF-End frame compatible with the
existing CF-End frame by executing the process of the second CF-End
frame.
[0200] Further, the second frame includes the information
specifying the wireless communication network to which the
transmission source of the second frame belongs, and the
information specifying the wireless communication network is stored
in the region in which the transmission source information of the
second frame is stored. Therefore, the reception device 200 can
acquire the BSSID information as well as the destination
information of the CTS frame related to the release of the NAV.
Therefore, the reception device 200 can detect the BSS from which
the NAV is released without performing a separate process.
[0201] Further, the first frame includes the CTS frame, and the
second frame includes the CF-End frame. Therefore, it is possible
to suppress both the occurrence of communication collision and the
decrease in the communication opportunities caused by the release
of the NAV by the CF-End frame in the existing RTS/CTS
mechanism.
[0202] Further, the reception device 200 receives the first frame,
and controls the stop of the transmission of the frame for each
piece of first destination information on the basis of the first
destination information included in the received first frame and
the first destination information included in the received second
frame. Therefore, since the NAV is managed for each piece of
destination information of the CTS frame, even in a case in which a
plurality of CTS frames having different destinations are received,
the NAV can be appropriately released. Therefore, it is possible to
prevent the NAV from being erroneously released or the NAV to be
released from being left uncontrolled.
[0203] Further, the reception device 200 receives the third frame
related to the communication request, and controls the stop of the
transmission of the frame for each piece of transmission source
information in which the transmission source of the third frame
included the received third frame is specified or each piece of
destination information in which the destination of the third frame
is specified. Therefore, the NAV is managed even for RTS frame for
each piece of address information as in the CTS frame, and thus the
NAV can be released appropriately. Therefore, it is possible to
cause the reception device 200 which has received only the RTS
frame to prevent communication collision while suppressing the
reduction in the communication opportunities.
3. MODIFIED EXAMPLES
[0204] One embodiment of the present disclosure has been described
above. Further, one embodiment of the present disclosure is not
limited to the above example. First and second modified examples of
one embodiment of the present disclosure will be described
below.
(First Modified Example)
[0205] As a first modified example of one embodiment of the present
disclosure, the second CF-End frame may double as the acknowledge.
Specifically, the transmission device 100 transmits a second
CF-End+CF-Ack frame having destination information related to the
destination of the CTS frame which is an acknowledge target using a
second CF-End frame doubling as the acknowledge (hereinafter also
referred to as a "second CF-End+CF-Ack frame"). Further, the
reception device 200 receives the second CF-End+CF-Ack frame, and
controls retransmission of the frame related to the acknowledge by
the receive second CF-End+CF-Ack frame on the basis of the
destination information of the CTS frame included in the received
second CF-End+CF-Ack frame.
[0206] Next, a configuration of the second CF-End+CF-Ack frame will
be described with reference to FIGS. 22 and 23. FIG. 22 is a
diagram illustrating an example of a configuration of the second
CF-End+CF-Ack frame transmitted by the transmission device 100
according to the first modified example of the present disclosure.
FIG. 23 is a diagram illustrating another example of a
configuration of the second CF-End+CF-Ack frame transmitted by the
transmission device 100 according to the first modified example of
one embodiment of the present disclosure.
[0207] The second CF-End+CF-Ack frame includes information
specifying the communication device which is the destination
information of the CTS frame and is the acknowledge target for the
data frame (hereinafter also referred to as "acknowledge target
information"). For example, as illustrated in FIG. 22, the second
CF-End+CF-Ack frame has fields such as Frame Control, CF-End Type,
ACK RA, BSSID (TA), and FCS. A value such as 0x03 is stored in the
CF-End Type field. Further, the acknowledge target information is
stored in the ACK RA field.
[0208] Further, the second CF-End+CF-Ack frame may include the
acknowledge target information stored in another region. For
example, as illustrated in FIG. 23, the second CF-End+CF-Ack frame
has fields such as Frame Control, CF-End Type, RA, BSSID (TA), ACK
RA, and FCS. A value such as 0x04 is stored in the CF-End Type
field of the second CF-End+CF-Ack frame.
[0209] For example, if the data frame is received from the
reception device 200, and the data transmission ends, the control
unit 120 causes the data processing unit 110 to generate the second
CF-End+CF-Ack frame. Then, the wireless communication unit 130
transmits the generated second CF-End+CF-Ack frame.
[0210] On the other hand, if the second CF-End+CF-Ack frame is
received by the wireless communication unit 230, the data
processing unit 210 acquires the acknowledge target information
from the second CF-End+CF-Ack frame. Then, the control unit 220
releases the TXOP for the acknowledge target information. Further,
the control unit 220 determines that the data frame transmitted
before the second CF-End+CF-Ack frame is received is successfully
received and stops the retransmission process for the data
frame.
[0211] As described above, according to the first modified example
of one embodiment of the present disclosure, the transmission
device 100 transmits the second CF-End+CF-Ack frame having the
destination information related to the destination of the CTS frame
serving as the target of the acknowledge using the second
CF-End+CF-Ack frame. Further, the reception device 200 receives the
second CF-End+CF-Ack frame, and controls the retransmission of the
frame related to the acknowledge by the received second
CF-End+CF-Ack frame on the basis of the destination information of
the CTS frame included in the received second CF-End+CF-Ack frame.
Here, in a case in which the data frame is transmitted from the
reception device 200, when the second CF-End frame is transmitted,
although it is possible to appropriately release the TXOP, the
acknowledge is not notified of. Therefore, the data frame may be
retransmitted from the reception device 200 depending on the
transmission timing of the Ack frame despite the successful
reception of the data frame transmitted from the reception device
200. On the other hand, in accordance with the present modified
example, the second CF-End frame doubling as the acknowledge, that
is, the second CF-End+CF-Ack frame is transmitted, and thus it is
possible to notify both the acknowledge and the release of TXOP at
once. Therefore, it is possible to suppress a decrease in
communication efficiency by suppressing the possibility of
unnecessary retransmission of the data frame.
(Second Modified Example)
[0212] As a second modified example of one embodiment of the
present disclosure, the number of first destination information
stored in the second CF-End frame may be two or more. Specifically,
the transmission device 100 transmits the second CF-End+CF-Ack
frame having a plurality of pieces of acknowledge target
information. A configuration of the CF-End+CF-Ack frame in the
present modified example will be described with reference to FIG.
24. FIG. 24 is a diagram illustrating an example of a configuration
of the second CF-End+CF-Ack frame transmitted by the transmission
device 100 according to the second modified example of one
embodiment of the present disclosure.
[0213] The second CF-End+CF-Ack frame includes a plurality of
pieces of acknowledge target information. For example, as
illustrated in FIG. 24, the second CF-End+CF-Ack frame has fields
such as Frame Control, CF-End Type, n ACK RAs, BSSID (TA), and FCS.
A value such as 0x05 is stored in the CF-End Type field. Further, n
pieces of acknowledge target information are stored in n ACK RA
fields.
[0214] For example, if the data frames are received from a
plurality of reception devices 200, and the data transmission ends,
the control unit 120 generates the acknowledge target information
for the reception device 200 which has transmitted the data frame
in which the data frame has been successfully received among a
plurality of reception devices 200. Then, the control unit 120
causes the data processing unit 110 to generate the second
CF-End+CF-Ack frame including a plurality of pieces of generated
acknowledge target information. Then, the wireless communication
unit 130 transmits the generated second CF-End+CF-Ack frame.
[0215] On the other hand, if the second CF-End+CF-Ack frame is
received by the wireless communication unit 230, the data
processing unit 210 acquires a plurality of pieces of acknowledge
target information from the second CF-End+CF-Ack frame. Then, in a
case in which the communication device indicated by one of a
plurality of pieces of acknowledge target information is the
reception device 200, the control unit 220 releases the TXOP.
Further, the control unit 220 determines that the data frame
transmitted before the second CF-End+CF-Ack frame is received is
successfully received and stops the retransmission process for the
data frame.
[0216] Further, an operation example of the transmission device 100
and the reception device 200 according to the present modified
example will be described with reference to FIGS. 25 and 26 by
comparison with an operation example of the transmission device 10
and reception device 20 according to the related art. FIG. 25 is a
diagram for describing an example of communication between the
transmission device 10 and the reception device 20 according to the
related art. FIG. 26 is a diagram for describing an example of
communication between the transmission device 100 and the reception
device 200 according to the second modified example of one
embodiment of the present disclosure.
(Operation Example of Communication Device of Related Art)
[0217] First, an operation example of the transmission device 10
and the reception device 20 according to the related art will be
described with reference to FIG. 25. Here, a case in which one
transmission device 10 communicates with the reception device 20A
and the reception device 20B will be described.
[0218] The transmission device 10 transmits a trigger frame for
multiple communication. The reception devices 20A and 20B which
have received the trigger frame transmit the RTS frame using
communication resources designated by the trigger frame. Therefore,
the RTS frames are multiplexed. The transmission device 10 which
has received the multiplexed RTS frame transmits the CTS frame
whose destination is the reception devices 20A and 20B. Each of the
reception devices 20A and 20B which have received the CTS frame
sets the TXOP. Further, communication devices other than the
reception devices 20A and 20B set the NAV.
[0219] Thereafter, the data frame is transmitted from each of the
reception devices 20A and 20B. The data frames may be multiplexed.
Here, it is assumed that the data frame transmitted from the
reception device 20B out of the two data frames is not received by
the transmission device 10. In this case, the transmission device
10 which has received only the data frame transmitted from the
reception device 20A transmits the existing CF-End+CF-Ack frame if
the data transmission ends within the TXOP period.
[0220] However, since the existing CF-End+CF-Ack frame has the same
configuration as the existing CF-End frame, the broadcast address
is stored as the destination information. Therefore, it is unable
to be determined which of the reception devices 20A and 20B the
destinations of the existing CF-End+CF-Ack frames received by the
reception devices 20A and 20B are. Therefore, in a case in which
the frame retransmission process is stopped uniformly on the basis
of the reception of the existing CF-End+CF-Ack frame, the data
frame of the reception device 20B which has not been successfully
received is not transmitted to the transmission device 10 without
being retransmitted.
(Operation Example of Communication Device According to One
Embodiment of Present Disclosure)
[0221] Next, an example of communication between the transmission
device 100 and the reception device 200 according to one embodiment
of the present disclosure will be described with reference to FIG.
26. Here, a case in which one transmission device 100 communicates
with the reception device 200A and the reception device 200B will
be described.
[0222] Similarly to the example of FIG. 25, the transmission device
100 transmits the trigger frame for multiple communication. The
reception devices 200A and 200B which have received the trigger
frame transmit the RTS frame using communication resources
designated by the trigger frame. The transmission device 100 which
has received the multiplexed RTS frame transmits the CTS frame
whose destinations are the reception devices 200A and 200B. Each of
the reception devices 200A and 200B which have received the CTS
frame sets the TXOP. Further, communication devices other than the
reception devices 200A and 200B set the NAV.
[0223] Thereafter, the data frame is transmitted from each of the
reception devices 200A and 200B. Here, it is assumed that the data
frame transmitted from the reception device 200B out of the two
data frames is not received by the transmission device 100. In this
case, if the data transmission ends within the TXOP period, the
transmission device 100 which has received only the data frame
transmitted from the reception device 200A transmits the second
CF-End+CF-Ack frame having the acknowledge target information for
the reception device 200A.
[0224] Therefore, if the second CF-End+CF-Ack frame is received,
the reception device 20A does not execute the retransmission
process for the transmitted data frame. On the other hand, since
the reception device 20B is not an acknowledge target related to
the second CF-End+CF-Ack frame, the reception device 20B executes
the retransmission process for the transmitted data frame. As a
result, the data frame is retransmitted and received by the
transmission device 10.
[0225] Further, in the example of FIGS. 25 and 26, the example in
which the RTS frame and the data frame are multiplexed to be
transmitted at the same timing has been described, but the
transmission timings of the RTS frame and the data frame may be
different between the reception devices 200.
[0226] As described above, according to the second modified example
of one embodiment of the present disclosure, the second CF-End
frame includes the destination information of a plurality of CTS
frames. Therefore, a plurality of reception devices 200 can be set
as the target of the second CF-End frame. Accordingly, it is
possible to control a plurality of NAVs or TXOPs by one frame, and
it is possible to perform communication more efficiently as
compared with the case in which the second CF-End frame is
transmitted for each of a plurality of NAVs or TXOPs. In
particular, according to the second CF-End+CF-Ack frame including a
plurality of pieces of acknowledge target information, the
acknowledge target can be designated from among a plurality of
reception devices 200. Accordingly, it is possible to appropriately
retransmit the frame to the reception device 200.
[0227] Further, in the above example, the example in which the
second CF-End frame is the second CF-End+Ack frame has been
described, but the destination information of a plurality of CTS
frames may be included in the normal second CF-End frame which does
not double as the acknowledge.
4. APPLICATION EXAMPLE
[0228] The technology according to the present disclosure can be
applied to various products. For example, the reception device 200
may be realized as mobile terminals such as smartphones, tablet
personal computers (PCs), notebook PCs, portable game terminals, or
digital cameras, fixed-type terminals such as television receivers,
printers, digital scanners, or network storages, or car-mounted
terminals such as car navigation devices. In addition, the
reception device 200 may be realized as terminals that perform
machine to machine (M2M) communication (also referred to as machine
type communication (MTC) terminals) such as smart meters, vending
machines, remotely controlled monitoring devices, or point of sale
(POS) terminals. Furthermore, the reception device 200 may be
wireless communication modules mounted in such terminals (for
example, integrated circuit modules configured by one die).
[0229] On the other hand, for example, the transmission device 100
may be realized as a wireless LAN access point (also referred to as
a wireless base station) which has a router function or does not
have a router function. The transmission device 100 may be realized
as a mobile wireless LAN router. The transmission device 100 may
also be a wireless communication module (for example, an integrated
circuit module configured with one die) mounted on such
devices.
[4-1. First Application Example]
[0230] FIG. 27 is a block diagram illustrating an example of a
schematic 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 external
connection interface 904, a camera 906, a sensor 907, a microphone
908, an 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 battery 918, and an auxiliary controller
919.
[0231] 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 random access memory (RAM) and read only memory
(ROM), and stores data and programs executed by the processor 901.
The storage 903 can include a storage medium such as a
semiconductor memory or a hard disk. The external connection
interface 904 is an interface for connecting an externally
attachable device such as a memory card or a universal serial bus
(USB) device to the smartphone 900.
[0232] 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
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
operation or information input 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
smartphone 900. The speaker 911 converts audio signals output from
the smartphone 900 into sounds.
[0233] The wireless communication interface 913 supports one or
more wireless LAN standards of IEEE 802.11a, 11b, 11g, 11n, 11ac,
and 11ad, to establish wireless communication. The wireless
communication interface 913 can communicate with another device via
a wireless LAN access point in an infrastructure mode. In addition,
the wireless communication interface 913 can directly communicate
with another device in a direct communication mode such as an ad
hoc mode or Wi-Fi Direct (registered trademark). Note that, Wi-Fi
Direct is different from the ad hoc mode. One of two terminals
operates as an access point, and communication is performed
directly between the terminals. The wireless communication
interface 913 can typically include a baseband processor, a radio
frequency (RF) circuit, a power amplifier, and the like. The
wireless communication interface 913 may be a one-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 913 may support
another kind of wireless communication scheme such as a cellular
communication scheme, a near-field communication scheme, or a
proximity wireless communication scheme in addition to the wireless
LAN scheme. The antenna switch 914 switches a connection
destination of the antenna 915 among a 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 through the
wireless communication interface 913.
[0234] 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. 27. In this case, the antenna
switch 914 may be omitted from the configuration of the smartphone
900.
[0235] The bus 917 connects the processor 901, the memory 902, the
storage 903, the external connection interface 904, the camera 906,
the sensor 907, the microphone 908, the input device 909, the
display device 910, the speaker 911, the wireless communication
interface 913, and the auxiliary controller 919 with each other.
The battery 918 supplies electric power to each of the blocks of
the smartphone 900 illustrated in FIG. 27 via power supply lines
partially indicated by dashed lines in the drawing. The auxiliary
controller 919 causes, for example, necessary minimum functions of
the smartphone 900 to be operated in a sleep mode.
[0236] In the smartphone 900 illustrated in FIG. 27, the data
processing unit 210, the control unit 220, and the wireless
communication unit 230 described above with reference to FIG. 13
may be implemented in the wireless communication interface 913.
Further, at least some of the functions may be implemented in the
processor 901 or the auxiliary controller 919. For example, the
data processing unit 210 acquires the destination information of
the CTS frame from the second CF-End frame received by the wireless
communication unit 230. The control unit 220 manages the NAV for
each piece of destination information of the CTS frame and releases
the NAV for the destination information of the acquired CTS frame.
Thus, it is possible to suppress a possibility of a NAV being
erroneously released and release an appropriate NAV. Therefore, in
communication performed by the smartphone 900, it is possible to
prevent communication collision while suppressing the decrease in
the communication opportunities.
[0237] Note that the smartphone 900 may operate as a wireless
access point (software AP) as the processor 901 executes the
function of an access point at an application level. In addition,
the wireless communication interface 913 may have the function of a
wireless access point.
[4-2. Second Application Example]
[0238] FIG. 28 is a block diagram illustrating an example of a
schematic configuration of a car navigation device 920 to which the
technology of the present disclosure can be applied. The car
navigation device 920 includes a 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.
[0239] The processor 921 may be, for example, a CPU or an SoC
controlling a navigation function and other functions of the car
navigation device 920. The memory 922 includes RAM and ROM storing
data and programs executed by the processor 921.
[0240] The GPS module 924 measures a position of the car navigation
device 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
interface 926 is connected with an in-vehicle network 941 via, for
example, a terminal (not illustrated) to acquire data generated on
the vehicle side such as car speed data.
[0241] The content player 927 reproduces content stored in a
storage medium (for 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 receive
operation or information input from a user. The display device 930
has a screen such as an LCD or an OLED display to display images of
the navigation function or reproduced content. The speaker 931
outputs sounds of the navigation function or reproduced
content.
[0242] The wireless communication interface 933 supports one or
more wireless LAN standards of IEEE 802.11a, 11b, 11g, 11n, 11ac,
11ad, and the like to execute wireless communication. The wireless
communication interface 933 can communicate with another device via
a wireless LAN access point in the infrastructure mode. In
addition, the wireless communication interface 933 can directly
communicate with another device in a direct communication mode such
as an ad hoc mode or Wi-Fi Direct. The wireless communication
interface 933 can typically have a baseband processor, an RF
circuit, a power amplifier, and the like. The wireless
communication interface 933 may be a one-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 near-field communication
scheme, a proximity wireless communication scheme, or the cellular
communication scheme in addition to the wireless LAN scheme. The
antenna switch 934 switches a connection destination of the antenna
935 among 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 and to the wireless
communication interface 933.
[0243] Note that the car navigation device 920 may include a
plurality of antennas, without being limited to the example of FIG.
28. In this case, the antenna switch 934 may be omitted from the
configuration of the car navigation device 920.
[0244] The battery 938 supplies electric power to each of the
blocks of the car navigation device 920 illustrated in FIG. 28 via
power supply lines partially indicated by dashed lines in the
drawing. In addition, the battery 938 accumulates electric power
supplied from the vehicle side.
[0245] In the car navigation device 920 illustrated in FIG. 28, the
data processing unit 210, the control unit 220, and the wireless
communication unit 230 described above with reference to FIG. 13
may be implemented in the wireless communication interface 913.
Further, at least some of the functions may be implemented in the
processor 921. For example, the data processing unit 210 acquires
the destination information of the CTS frame from the second CF-End
frame received by the wireless communication unit 230. The control
unit 220 manages the NAV for each piece of destination information
of the CTS frame and releases the NAV for the destination
information of the acquired CTS frame. Thus, it is possible to
suppress a possibility of a NAV being erroneously released and
release an appropriate NAV. Therefore, in communication performed
by the car navigation device 920, it is possible to prevent
communication collision while suppressing the decrease in the
communication opportunities.
[0246] Further, the wireless communication interface 933 may
operate as the above-described transmission device 100 and may
provide a wireless connection to a terminal carried by the user
riding in the vehicle. At this time, for example, in a case in
which the data transmission ends before the TXOP period ends, the
control unit 120 causes the data processing unit 110 to generate
the second CF-End frame having the destination information of the
CTS frame. Then, the wireless communication unit 130 transmits the
generated second CF-End frame. Thus, the NAV or the TXOP to be
released can be designated. Accordingly, it is possible to cause
the terminal communicating with the car navigation device 920 to
appropriately release the NAV, and it is possible to prevent
communication collision while suppressing the decrease in the
communication opportunities.
[0247] Further, 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 device 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 the in-vehicle
network 941.
[4-3. Third Application Example]
[0248] FIG. 29 is a block diagram illustrating an example of a
schematic configuration of a wireless access point 950 to which the
technology of the present 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.
[0249] The controller 951 may be, for example, a CPU or a digital
signal processor (DSP) and operates various functions (for example,
access limitation, routing, encryption, a fire wall, and log
management) of the Internet Protocol (IP) layer and higher layers
of the wireless access point 950. The memory 952 includes RAM and
ROM and stores a program executed by the controller 951 and various
kinds of control data (for example, a terminal list, a routing
table, an encryption key, security settings, and a log).
[0250] The input device 954 includes, for example, a button or a
switch, and receives operation performed by a user. The display
device 955 includes an LED lamp and displays an operation status of
the wireless access point 950.
[0251] The network interface 957 is a wired communication interface
that connects the wireless access point 950 with a wired
communication network 958. The network interface 957 may include a
plurality of connection terminals. The wired communication network
958 may be a LAN such as Ethernet (registered trademark) or may be
a wide area network (WAN).
[0252] The wireless communication interface 963 supports one or
more wireless LAN standards of IEEE 802.11a, 11b, 11g, 11n, 11ac,
11ad, and the like to supply wireless connection to a nearby
terminal as an access point. The wireless communication interface
963 can typically include a baseband processor, an RF circuit, and
a power amplifier. The wireless communication interface 963 may be
a one-chip module in which memory storing a communication control
program, a processor executing the program, and relevant circuits
are integrated. The antenna switch 964 switches a connection
destination of the antenna 965 among a plurality of circuits
included in the wireless communication interface 963. The antenna
965 includes one antenna element or a plurality of antenna elements
and is used to transmit and receive a wireless signal through the
wireless communication interface 963.
[0253] In the wireless access point 950 illustrated in FIG. 29, the
data processing unit 110, the control unit 120, and the wireless
communication unit 130 described above with reference to FIG. 13
may be realized by the wireless communication interface 963. In
addition, at least a part of these functions may be implemented by
the controller 951. For example, in a case in which the data
transmission ends before the TXOP period ends, the control unit 120
causes the data processing unit 110 to generate the second CF-End
frame having the destination information of the CTS frame. Then,
the wireless communication unit 130 transmits the generated second
CF-End frame. Thus, the NAV or the TXOP to be released can be
designated. Accordingly, it is possible to cause the terminal
communicating with the wireless access point 950 to appropriately
release the NAV, and it is possible to prevent communication
collision while suppressing the decrease in the communication
opportunities.
5. CONCLUSION
[0254] As described above, according to one embodiment of the
present disclosure, the transmission device 100 notifies of the
destination information of the CTS frame together with the CF-End,
and thus the reception device 200 can appropriately release the
NAV. Therefore, it is possible to prevent communication collision
while suppressing the reduction in opportunities to access the
transmission path.
[0255] The preferred embodiment(s) of the present disclosure
has/have been 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.
[0256] For example, in the above embodiment, the transmission
device 100 transfers the CF-End frame in response to the reception
of the CF-End frame, but the present technology is not limited to
this example. For example, the reception device 200 may transfer
the CF-End frame in response to reception of the CF-End frame. As a
result, it is possible to cause the communication device which is
unable to directly receive the CF-End frame from the transmission
device 100 to receive the CF-End frame.
[0257] Further, in the above embodiment, the example in which the
BSSID information, that is, the destination information of the RTS
frame is used in the control of the NAV related to the RTS frame
has been described, but the control of the NAV related to the RTS
frame may be performed by using the transmission source information
of the RTS frame. Specifically, the reception device 200 controls
the stop of the transmission of the frame for each piece of
transmission source information of the RTS frame on the basis of
the transmission source information in which the transmission
source of the RTS frame included in the received RTS frame is
specified and the destination information of the CTS frame included
in the received second CF-End frame. For example, if the second
CF-End frame is received before the set NAV period ends, the data
processing unit 210 acquires the destination information of the CTS
frame from the second CF-End frame. The control unit 220 determines
whether or not the destination indicated by the destination
information of the acquired CTS frame coincides with the
transmission source indicated by the transmission source
information of the RTS frame stored in the storage unit. If it is
determined that the destination of the CTS frame coincides with the
transmission source of the RTS frame, the control unit 220 releases
the NAV associated with the transmission source information of the
RTS frame.
[0258] Further, the effects described in this specification are
merely illustrative or exemplified effects, and are not limitative.
That is, with or in the place of the above effects, the technology
according to the present disclosure may achieve other effects that
are clear to those skilled in the art from the description of this
specification.
[0259] Further, steps illustrated in the flowcharts of the above
embodiment include not only processes which are chronologically
performed in accordance with the described order but also processes
which are not necessarily chronologically performed but performed
in parallel or individually as well. Further, it is needless to say
that even in steps which are processed chronologically, the order
can be appropriately changed depending on circumstances.
[0260] In addition, it is also possible to produce a computer
program for causing hardware incorporated in communication devices
100 and 200 to exhibit functions equivalent to those of the
respective logic configurations of the aforementioned the
communication devices 100 and 200. In addition, a storage medium
that stores the computer program therein is also provided.
[0261] Additionally, the present technology may also be configured
as below. [0262] (1)
[0263] A communication device, including:
[0264] a processing unit configured to generate a second frame used
for releasing a stop of transmission of a frame caused by a first
frame, the second frame including first destination information
specifying a destination stored in the first frame, the first frame
being used for stopping transmission of frames of communication
devices other than the destination and serving as a response to a
communication request; and
[0265] a wireless communication unit configured to transmit the
second frame. [0266] (2)
[0267] The communication device according to (1), in which the
first destination information is stored in a region different from
a region in which transmission source information of the second
frame is stored. [0268] (3)
[0269] The communication device according to (2), in which the
region different from the region in which the transmission source
information of the second frame is stored includes a region in
which destination information of the second frame is stored. [0270]
(4)
[0271] The communication device according to (1), in which the
first destination information is stored in a region different from
both of a region in which transmission source information of the
second frame is stored and a region in which destination
information of the second frame is stored. [0272] (5)
[0273] The communication device according to any one of (1) to (4),
in which the second frame includes a frame doubling as an
acknowledge, and
[0274] the first destination information included in the second
frame includes the first destination information related to a
destination of the first frame which is a target of an acknowledge
using the second frame. [0275] (6)
[0276] The communication device according to any one of (1) to (5),
in which the second frame includes a plurality of pieces of first
destination information. [0277] (7)
[0278] The communication device according to any one of (1) to (6),
in which the second frame includes information specifying a type of
the second frame. [0279] (8)
[0280] The communication device according to (7), in which the
information specifying the type of the second frame is stored in a
region in which transmission period information of the second frame
is stored. [0281] (9)
[0282] The communication device according to any one of (1) to (8),
in which the second frame includes information specifying a
wireless communication network to which a transmission source of
the second frame belongs, and
[0283] the information specifying the wireless communication
network is stored in a region in which transmission source
information of the second frame is stored. [0284] (10)
[0285] The communication device according to any one of (1) to (9),
in which the first frame includes a clear to send (CTS) frame,
and
[0286] the second frame includes a contention free (CF)-end frame.
[0287] (11)
[0288] A communication device, including:
[0289] a wireless communication unit configured to receive a second
frame used for releasing a stop of transmission of a frame caused
by a first frame, the second frame including first destination
information specifying a destination stored in the first frame, the
first frame being used for stopping transmission of frames of
communication devices other than the destination and serving as a
response to a communication request; and
[0290] a control unit configured to control transmission of a frame
on a basis of the second frame received by the wireless
communication unit. [0291] (12)
[0292] The communication device according to (11), in which the
wireless communication unit receives the first frame, and
[0293] the control unit controls the stop of the transmission of
the frame for each piece of first destination information on a
basis of the first destination information included in the received
first frame and the first destination information included in the
received second frame. [0294] (13)
[0295] The communication device according to (11) or (12), in which
the second frame includes a frame doubling as an acknowledge,
and
[0296] the control unit controls retransmission of a frame related
to the acknowledge by the second frame on a basis of the first
destination information included in the second frame. [0297]
(14)
[0298] The communication device according to any one of (11) to
(13), in which the wireless communication unit receives a third
frame related to the communication request, and
[0299] the control unit controls the stop of the transmission of
the frame for each piece of transmission source information in
which a transmission source of the third frame included in the
received third frame is specified or destination information in
which a destination of the third frame is specified. [0300]
(15)
[0301] A communication method, including:
[0302] generating a second frame used for releasing a stop of
transmission of a frame caused by a first frame using a processor,
the second frame including first destination information specifying
a destination stored in the first frame, the first frame being used
for stopping transmission of frames of communication devices other
than the destination and serving as a response to a communication
request; and
[0303] transmitting the second frame. [0304] (16)
[0305] A communication method, including:
[0306] receiving a second frame used for releasing a stop of
transmission of a frame caused by a first frame using a processor,
the second frame including first destination information specifying
a destination stored in the first frame, the first frame being used
for stopping transmission of frames of communication devices other
than the destination and serving as a response to a communication
request; and
[0307] controlling transmission of a frame on a basis of the
received second frame. [0308] (17)
[0309] A program causing a computer to implement:
[0310] a processing function of generating a second frame used for
releasing a stop of transmission of a frame caused by a first
frame, the second frame including first destination information
specifying a destination stored in the first frame, the first frame
being used for stopping transmission of frames of communication
devices other than the destination and serving as a response to a
communication request; and
[0311] a wireless communication function of transmitting the second
frame. [0312] (18)
[0313] A program causing a computer to implement:
[0314] a wireless communication function of receiving a second
frame used for releasing a stop of transmission of a frame caused
by a first frame, the second frame including first destination
information specifying a destination stored in the first frame, the
first frame being used for stopping transmission of frames of
communication devices other than the destination and serving as a
response to a communication request; and
[0315] a control function of controlling transmission of a frame on
a basis of the second frame received by the wireless communication
function.
REFERENCE SIGNS LIST
[0316] 100 transmission device, AP [0317] 110, 210 data processing
unit [0318] 120, 220 control unit [0319] 130, 230 wireless
communication unit [0320] 200 reception device, STA
* * * * *