U.S. patent application number 17/323307 was filed with the patent office on 2021-09-02 for communication device and communication control method.
This patent application is currently assigned to Sony Group Corporation. The applicant listed for this patent is Sony Group Corporation. Invention is credited to Shigeru SUGAYA.
Application Number | 20210273741 17/323307 |
Document ID | / |
Family ID | 1000005586803 |
Filed Date | 2021-09-02 |
United States Patent
Application |
20210273741 |
Kind Code |
A1 |
SUGAYA; Shigeru |
September 2, 2021 |
COMMUNICATION DEVICE AND COMMUNICATION CONTROL METHOD
Abstract
[Object] To enable a communication device which has received a
response frame to identify, a BSS to which a transmitting device of
the response frame belongs while ensuring backward compatibility.
[Solution] Provided is a communication device that transmits a
response frame, including: a generating unit configured to generate
the response frame in which information used for identification of
a BSS to which the communication device belongs or information used
for identification of an own device is included in or after a
padding bit specified in IEEE 802.11; and a transmitting unit
configured to transmit the response frame.
Inventors: |
SUGAYA; Shigeru; (Kanagawa,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sony Group Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
Sony Group Corporation
Tokyo
JP
|
Family ID: |
1000005586803 |
Appl. No.: |
17/323307 |
Filed: |
May 18, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16349996 |
May 15, 2019 |
11012180 |
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PCT/JP2017/036330 |
Oct 5, 2017 |
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17323307 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 84/12 20130101;
H04L 1/1607 20130101; H04L 41/022 20130101; H04L 1/0008 20130101;
H04W 74/002 20130101; H04W 28/06 20130101; H04W 72/0446
20130101 |
International
Class: |
H04L 1/00 20060101
H04L001/00; H04L 1/16 20060101 H04L001/16; H04L 12/24 20060101
H04L012/24; H04W 28/06 20060101 H04W028/06; H04W 72/04 20060101
H04W072/04; H04W 74/00 20060101 H04W074/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2016 |
JP |
2016-246538 |
Claims
1. A communication device that transmits a response frame,
comprising circuitry configured to: generate the response frame in
which first information used for identification of a BSS to which
the communication device belongs or second information used for
identification of the communication device is included in or after
padding bits specified in IEEE 802.11; and transmit the response
frame.
2. The communication device according to claim 1, wherein the
circuitry is further configured to include the first information
used for the identification of the BSS in the padding bits.
3. The communication device according to claim 1, wherein the
circuitry is further configured to set third information notifying
that the first information used for the identification of the BSS
is included in the response frame in or before the padding
bits.
4. The communication device according to claim 3, wherein the
circuitry is further configured to set third information notifying
that the first information used for the identification of the BSS
is included in the response frame in at least one of a reserved
field, a service field, or the padding bits specified in IEEE
802.11.
5. The communication device according to claim 1, wherein the
circuitry is further configured to include a tail bit after a bit
string, which is the first information used for the identification
of the BSS.
6. The communication device according to claim 1, wherein the first
information used for the identification of the BSS includes a BSS
color, wherein the response frame includes a CTS or an ACK, and
wherein the communication device includes an access point device or
a station device.
7. The communication device according to claim 1, wherein the
circuitry is further configured to add a footer that includes the
second information used for the identification of the communication
device after the padding bits.
8. The communication device according to claim 1, wherein the
second information used for the identification of the communication
device includes information related to an AID, wherein the response
frame includes a CTS or an ACK, and wherein the communication
device includes an access point device or a station device.
9. The communication device according to claim 1, wherein the
circuitry is configured to include a tail bit after a bit string,
which is the second information used for the identification of the
communication device.
10. A communication control method of transmitting a response frame
executed by a computer of a communication device, comprising:
generating the response frame in which first information used for
identification of a BSS to which the communication device belongs
or second information used for identification of the communication
device is included in or after a padding bits specified in IEEE
802.11; and transmitting the response frame.
11. A communication device that receives a response frame,
comprising circuitry configured to: receive the response frame in
which first information used for identification of a BSS to which a
transmitting device of the response frame belongs or second
information used for identification of the transmitting device is
included in or after padding bits specified in IEEE 802.11; and
identify the BSS on a basis of the first information used for the
identification of the BSS.
12. The communication device according to claim 11, wherein the
circuitry is further configured to: set a first transmission
suppression period in a case in which the BSS is identified as a
first BSS to which the communication device belongs; and set a
second transmission suppression period in a case in which the BSS
is identified as an OBSS that overlaps the first BSS.
13. The communication device according to claim 12, wherein the
circuitry is further configured to set the second transmission
suppression period for each OBSS.
14. The communication device according to claim 11, wherein the
circuitry is further configured to identify the BSS on a basis of
the first information used for the identification of the BSS in a
case in which information notifying that the first information used
for the identification of the BSS is included in the response frame
is included in or before the padding bits.
15. A communication control method of receiving a response frame
executed by a computer of a communication device, comprising:
receiving the response frame in which first information used for
identification of a BSS to which a transmitting device of the
response frame belongs or second information used for
identification of the transmitting device is included in or after
padding bits specified in IEEE 802.11; and identifying the BSS on a
basis of the first information used for the identification of the
BSS.
16. The communication control method according to claim 15, the
method further comprising: setting a first transmission suppression
period in a case in which the BSS is identified as a first BSS to
which the communication device belongs; and setting a second
transmission suppression period in a case in which the BSS is
identified as an OBSS that overlaps the first BSS.
17. The communication control method according to claim 16, the
method further comprising setting the second transmission
suppression period for each OBSS.
18. The communication control method according to claim 15, the
method further comprising identifying the BSS on a basis of the
first information used for the identification of the BSS in a case
in which information notifying that the first information used for
the identification of the BSS is included in the response frame is
included in or before the padding bits.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
application Ser. No. 16/349,996, filed May 15, 2019, which is based
on PCT filing PCT/JP2017/036330, filed Oct. 5, 2017, which claims
priority to JP 2016-246538, filed Dec. 20, 2016, the entire
contents of each are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a communication device and
a communication control method.
BACKGROUND ART
[0003] In recent years, standardization of new wireless LANs has
been reviewed by a working group of IEEE 802.11 or the like, and
among them, various reviews related to setting of a transmission
prohibition period (hereinafter referred to as a "network
allocation vector (NAV)" for the sake of convenience) have been
conducted.
[0004] For example, for a setting of an NAV based on a response
frame (CTS, ACK, or the like), a communication device which has
received a response frame addressed to another device determining a
basic service set (hereinafter referred to as a "basic service set
(BSS)" for the sake of convenience) from which a signal
corresponding to the response frame is transmitted and setting the
NAV in accordance with a determination result is under review.
Further, newly adding information used for this determination to
the response frame is also under review. A method of adding an
association identifier (AID) to a frame is disclosed in Patent
Literature 1.
CITATION LIST
Patent Literature
[0005] Patent Literature 1: JP 2015-122758A
DISCLOSURE OF INVENTION
Technical Problem
[0006] Here, a frame format of an existing response frame does not
include a transmitter address field (hereinafter referred to as a
"TA field" for the sake of convenience) in which address
information of a transmitting device is set. For this reason, for
example, in a case in which a station device (hereinafter referred
to as an "STA" for the sake of convenience) receives a response
frame which is transmitted from an access point device (hereinafter
referred to as an "AP" for the sake of convenience) to another STA,
the STA is unable to compare the address information of the AP
which is known in advance and the address information of the TA
field and determine whether or not the response frame is a signal
transmitted from an own BSS.
[0007] Further, when new methods of determining a BSS which is a
transmission source of the response frame are reviewed, it is more
desirable to consider backward compatibility as well. In other
words, if a communication device supporting an existing subordinate
standard is unable to appropriately receive the response frame
transmitted by a communication device supporting such a new method,
in a case in which the devices of both standards belong to the same
BSS, problems in which the NAV or the like is unable to be
appropriately set may occur.
[0008] In this regard, the present disclosure was made in light of
the foregoing, and the present disclosure provides a communication
device and communication control method which are novel and
improved and capable of identifying a BSS to which a transmitting
device of a response frame belongs while ensuring backward
compatibility.
Solution to Problem
[0009] According to the present disclosure, there is provided a
communication device that transmits a response frame, including: a
generating unit configured to generate the response frame in which
information used for identification of a BSS to which the
communication device belongs or information used for identification
of an own device is included in or after a padding bit specified in
IEEE 802.11; and a transmitting unit configured to transmit the
response frame.
[0010] Moreover, according to the present disclosure, there is
provided a communication control method of transmitting a response
frame executed by a computer, including: generating the response
frame in which information used for identification of a BSS to
which an own device belongs or information used for identification
of the own device is included in or after a padding bit specified
in IEEE 802.11; and transmitting the response frame.
[0011] Moreover, according to the present disclosure, there is
provided a communication device that receives a response frame,
including: a receiving unit configured to receive the response
frame in which information used for identification of a BSS to
which a transmitting device of the response frame belongs or
information used for identification of the transmitting device is
included in or after a padding bit specified in IEEE 802.11; and an
identifying unit configured to identify the BSS on the basis of the
information used for the identification of the BSS.
[0012] Moreover, according to the present disclosure, there is
provided a communication control method of receiving a response
frame executed by a computer, including: receiving the response
frame in which information used for identification of a BSS to
which a transmitting device of the response frame belongs or
information used for identification of the transmitting device is
included in or after a padding bit specified in IEEE 802.11; and
identifying the BSS on the basis of the information used for the
identification of the BSS.
Advantageous Effects of Invention
[0013] As described above, according to the present disclosure, it
is possible for a communication device which has received a
response frame to identify a BSS to which a transmitting device of
the response frame belongs while ensuring backward
compatibility.
[0014] 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
[0015] FIG. 1 illustrates a configuration of a wireless LAN system
according to an embodiment of the present disclosure.
[0016] FIG. 2 is a diagram illustrating a frame configuration of a
response frame specified in IEEE 802.11.
[0017] FIG. 3 is a diagram for describing the background of the
present disclosure.
[0018] FIG. 4 is a diagram for describing the background of the
present disclosure.
[0019] FIG. 5 is a diagram illustrating an example of a frame
configuration of a CTS according to the present embodiment.
[0020] FIG. 6 is a diagram illustrating a chronological relation
between a CTS to which a footer is added and a data frame in the
present embodiment.
[0021] FIG. 7 is a diagram illustrating a setting of a NAV
according to the present embodiment.
[0022] FIG. 8 is a diagram illustrating a setting of a NAV
according to the present embodiment.
[0023] FIG. 9 is a diagram illustrating a functional configuration
of each of an STA and an AP according to the present
embodiment.
[0024] FIG. 10 is a flowchart illustrating a CTS transmission
operation and a data frame reception operation by a communication
device according to the present embodiment.
[0025] FIG. 11 is a flowchart illustrating an operation of
receiving a CTS addressed to another device and setting a NAV by a
communication device according to the present embodiment.
[0026] FIG. 12 is a flowchart illustrating a data frame
transmission operation by a communication device according to the
present embodiment.
[0027] FIG. 13 is a diagram illustrating an example of a frame
configuration of a CTS according to a first modification of the
present disclosure.
[0028] FIG. 14 is a diagram illustrating an example of a frame
configuration of a CTS according to the first modification of the
present disclosure.
[0029] FIG. 15 is a diagram illustrating an example of a frame
configuration of a CTS according to a second modification of the
present disclosure.
[0030] FIG. 16 is a diagram illustrating an example of a frame
configuration of a CTS according to the second modification of the
present disclosure.
[0031] FIG. 17 is a diagram illustrating an example of a frame
configuration of a CTS according to the second modification of the
present disclosure.
[0032] FIG. 18 is a block diagram illustrating an example of a
schematic configuration of a smartphone.
[0033] FIG. 19 is a block diagram illustrating an example of a
schematic configuration of a car navigation device.
[0034] FIG. 20 is a block diagram illustrating an example of a
schematic configuration of a wireless access point.
MODE(S) FOR CARRYING OUT THE INVENTION
[0035] Hereinafter, a preferred embodiment 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.
[0036] Note that description will be given in the following
order.
1. Overview of wireless LAN system 2. Functional configuration of
device 3. Operation of device
4. Modifications
[0037] 5. Application examples
6. Others
7. Conclusion
1. OVERVIEW OF WIRELESS LAN SYSTEM
[0038] An embodiment of the present disclosure relates to a
wireless LAN system. First, an overview of a wireless LAN system
according to an embodiment of the present disclosure is
described.
(1-1. Configuration of Wireless LAN System)
[0039] First, a configuration of a wireless LAN system according to
an embodiment of the present disclosure will be described with
reference to FIG. 1. FIG. 1 is a diagram illustrating a
configuration of a wireless LAN system according to an embodiment
of the present disclosure. The wireless LAN system according to an
embodiment of the present disclosure includes an AP 200 and an STA
100 as illustrated in FIG. 1. A BSS 10 is constituted by one AP 200
and one or more STAs 100.
[0040] A type and a scheme of a wireless LAN system according to an
embodiment of the present disclosure are arbitrary. For example, a
modulation scheme, a code rate, or the like of the wireless LAN
system according to the present embodiment can be arbitrarily set.
Further, the wireless LAN system according to the present
embodiment can be installed in an arbitrary place. For example, the
wireless LAN system according to the present embodiment may be
installed in office buildings, housing, commercial facilities,
public facilities, or the like.
[0041] In addition, an area of the BSS 10 according to the present
embodiment may overlap with an area of another BSS 10 using an
overlapping frequency channel (hereinafter, referred to as "overlap
basic service set (OBSS)" for convenience), in that case, a signal
transmitted from the STA 100 located in the overlap area may
interfere with a signal transmitted from the OBSS.
[0042] Referring to the example of FIG. 1, areas of a BSS 10a, a
BSS 10b, and a BSS 10c partially overlap each other, and an STA
100b belonging to the BSS 10a is located in the overlapping region.
In this case, the BSS 10b and the BSS 10c are OBSSs for the BSS
10a, the BSS 10a and the BSS 10c are OBSSs for the BSS 10b, and the
BSS 10a and the BSS 10b are OBSSs for the BSS 10c. Further, there
are cases in which a signal transmitted from the STA 100b located
in the overlapping region of the BSS 10a, the BSS 10b, and the BSS
10c interferes with signals transmitted from the BSS 10b and BSS
10c which are the OBSSs of the BSS 10a.
[0043] The AP 200 according to the present embodiment is a
communication device to be connected to an external network, and to
provide communication with the external network for the STA 100.
For example, the AP 200 is connected to the Internet, and provides
communication between the STA 100 and a device on the Internet or a
device connected via the Internet.
[0044] The STA 100 according to the present embodiment is a
communication device that communicates with the AP 200. The STA 100
may be any communication device. For example, the STA 100 may be a
display with a display function, a memory with a storage function,
a keyboard and a mouse with an input function, a speaker with a
sound output function, or a smartphone with a function of executing
advanced calculation processing.
[0045] In a case in which each communication device of the AP 200
and the STA 100 receives an RTS addressed to another device or a
CTS addressed to another device, each communication device of the
AP 200 and the STA 100 sets "own BSS NAV (a first transmission
suppression period)" in a case in which these signals are
identified as signals transmitted from the own BSS, and sets an
"OBSS NAV (a second transmission suppression period)" in a case in
which these signals are identified as signals transmitted from the
OBSS. Each communication device prevents the occurrence of
interference by not performing frame transmission during the period
in which the NAV is set.
(1-2. Background)
[0046] The overview of the wireless LAN system according to the
present embodiment has been described above. Next, the background
of the present disclosure will be described with reference to FIGS.
2 to 4.
[0047] First, a frame configuration of a response frame specified
in IEEE 802.11 will be described with reference to FIG. 2. FIG. 2
is a diagram illustrating a frame configuration of a response frame
specified in IEEE 802.11. Further, the following description will
proceed under the assumption that the response frame is a CTS or an
ACK, but the present disclosure is not limited thereto.
[0048] As illustrated in FIG. 2, a response frame specified in IEEE
802.11 includes a SIGNAL field, a Service field, a PLCP Service
Data Unit (PSDU) field, a Tail bit and a Padding bit. Further, the
SIGNAL field includes a Rate field, a Reserved field, a Length
field, a Parity bit, and a Tail bit, and the PSDU field includes a
Frame Control field, a Duration field, a Receiver Address field
(indicated by "RA" in FIG. 2), and a Frame Check Sequence (FCS)
field.
[0049] Here, as described above, the TA field is not included in
the frame format of the response frame. Therefore, for example, in
a case in which a certain STA receives a response frame which is
transmitted from an AP of the own BSS to another STA, the STA is
unable to compare the address information of the AP which is
already known and the address information of the TA field and
determine whether or not the response frame is a signal transmitted
from the own BSS. In other words, the STA is unable to determine
whether or not the response frame is a signal transmitted from the
own BSS unless the STA already knows the address information of
another STA belonging to the own BSS by a certain method.
[0050] Further, in a case in which a certain STA receives a
response frame transmitted from an OBSS, the STA is unable to
determine the OBSS from which the response frame is transmitted
unless the STA already knows the address information of each of the
AP and the STA belonging to the OBSS.
[0051] Next, the influence of the STA being unable to determine the
BSS from which the response frame is transmitted will be described
with reference to FIG. 3.
[0052] A case in which regions of a BSS 1 and a BSS 2 partially
overlap each other and an STA 1b belonging to the BSS 1 is located
in the overlapping region as illustrated in FIG. 3 is considered.
In other words, the STA 1b may receive not only a signal
transmitted from the BSS 1 which is the own BSS, but also a signal
transmitted from the BSS 2 which is the OBSS.
[0053] First, in step S1000 of FIG. 3, the STA 1b is assumed to
receive a CTS addressed to the AP 1 from the STA 1a belonging to
the own BSS. The STA 1b can determine that the CTS is a signal
transmitted from the own BSS by comparing the address information
of the AP which is already known and the address information of the
AP set in the RA field of the CTS. Therefore, the STA 1b sets the
own BSS NAV on the basis of a Duration included in the CTS.
[0054] Then, in a case in which the STA 1b receives a CTS addressed
to the AP 2 from the STA 2 belonging to the OBSS in step S1004, the
STA 1b is unable to identify the BSS from which the CTS is
transmitted as described above. Therefore, the STA 1b is unable to
perform access control different from that in a case in which the
CTS is transmitted from the own BSS. For example, the STA 1b is
unable to perform, for example, access control of enabling
transmission of a signal with a predetermined condition in a case
in which it is determined on the basis of a received field strength
or the like of the CTS that the influence of the interference is
not large. In the example of FIG. 3, the STA 1b sets and updates
the own BSS NAV as a process in a case in which the BSS from which
the CTS is transmitted is unable to be identified. Then, the STA 1b
is unable to transmit a signal until the own BSS NAV is released by
receiving an ACK in step S1008.
[0055] Further, in the existing technology, a communication device
is unable to set the OBSS NAV for each OBSS. In other words, even
in a case in which there is a plurality of OBSSs, the communication
device sets a single OBSS NAV. Therefore, even in a case in which
the CTS is received from a plurality of OBSSs under the assumption
that the communication device is able to identify the BSS which is
the transmission source of the CTS by a certain method, the OBSS
NAV is unable to be set for each OBSS. Next, the influence of the
OBSS NAV not being set for each OBSS will be described with
reference to FIG. 4.
[0056] A case in which regions of a BSS 1, a BSS 2, and a BSS 3
partially overlap each other, and an STA 1 belongs to the BSS 1 is
located in the overlapping region as illustrated in FIG. 4 is
considered. In other words, there are cases in which the STA 1
receives not only a signal transmitted from the BSS 1 which is the
own BSS, but also signals transmitted from the BSS 2 and the BSS 3
which are OBSSs.
[0057] First, in step S1100 of FIG. 4, the STA 1 receives a CTS
addressed to an AP 2 from an STA 2 belonging to the BSS 2 which is
the OBSS. Here, the STA 1 is assumed to be able to determine, by a
certain method, that the CTS is a signal transmitted from the OBSS
and set the OBSS NAV. Then, in step S1104, the STA 1 receives a CTS
addressed to the AP 3 from an STA 3 belonging to the BSS 3 which is
the OBSS. Even if the STA can determine that the CTS is a signal
transmitted from the OBSS by a method similar to that described
above but is unable to set the OBSS NAV for each OBSS as described
above, the STA 1 updates the OBSS NAV without newly setting a
separate OBSS NAV.
[0058] Accordingly, when the STA 1 receives a Contention Free-END
(CF-END) (indicated by "CFE" in FIG. 4) from the STA3 in step
S1108, the STA 1 releases the OBSS NAV, even though data
transmission and reception are not completed in the BSS 2 which is
the OBSS. Accordingly, in step S1112, interference occurs due to
the signal transmitted by the STA 1 and the signal transmitted from
BSS 2. The occurrence of such interference lowers the utilization
efficiency of the transmission path.
[0059] In this regard, the inventor of the present disclosure was
finally able to create the present disclosure focusing on the above
circumstances. Information used for identification of the BSS is
set in the response frame related to the present disclosure.
Accordingly, the communication device which has received the
response frame can determine the BSS from which the response frame
is transmitted on the basis of the information and appropriately
select the own BSS NAV or the OBSS NAV depending on a determination
result. Further, the communication device according to the present
embodiment can set a different OBSS NAV for each OBSS. Accordingly,
the communication device according to the present embodiment can
appropriately set and release the OBSS NAV. Further, the present
disclosure can ensure the backward compatibility. In other words,
the communication device according to the present embodiment can
also appropriately communicate with existing communication devices
(hereinafter referred to as "legacy devices" for the sake of
convenience) to which the present disclosure is not applied.
Further, although the CTS is mainly described as the response frame
in this specification, the present disclosure is not limited to
this example, and the present disclosure may be applied to other
response frames such as the ACK. An example in which the present
disclosure is applied to the ACK will be described in detail in "6.
Others."
(1-3. Overview of Functions of Wireless LAN System)
[0060] The background of the present disclosure has been described
above. Next, an overview of the functions of the wireless LAN
system according to the present embodiment will be described.
[0061] The communication device in the wireless LAN system
according to the present embodiment adds a footer (Footer) having
information used for identification of the BSS to which the
transmitting device of the CTS belongs to the CTS. More
specifically, the communication device according to the present
embodiment generates a footer having a "BSS color" as the
information used for the identification of the BSS to which the
transmitting device of the CTS belongs, and adds the footer after
the padding bit of the CTS specified in IEEE 802.11.
[0062] Here, the BSS color is a bit string used for uniquely
identifying the BSS, and the communication device can determine the
BSS from which a signal corresponding to the CTS is transmitted on
the basis of the BSS color included in the footer added to the CTS.
More specifically, the communication device stores the BSS color of
the own BSS in advance, and can determine whether or not the
received CTS is a signal transmitted from the own BSS by comparing
the BSS color of the own BSS stored in the own device with the BSS
color included in the received CTS. Further, since the
communication device according to the present embodiment stores the
BSS color of each OBSS in advance, the communication device
according to the present embodiment can determine the OBSS from
which the received CTS is transmitted by comparing the BSS color of
each BSS stored in the own device with the BSS color included in
the received CTS.
[0063] Accordingly, the communication device according to the
present embodiment sets the own BSS NAV in a case in which it is
determined that the CTS is a signal transmitted from the own BSS,
and sets the OBSS NAV for each OBSS in a case in which it is
determined that the CTS is a signal transmitted from the OBSS.
Since the communication device according to the present embodiment
sets the OBSS NAV for each OBSS, it is possible to prevent the
occurrence of an event in which the OBSS NAV is released on the
basis of the CF-END from another OBSS even though communication of
a certain OBSS is not completed as illustrated in the example
illustrated in FIG. 4.
[0064] Further, the communication device according to the present
embodiment also sets information related to an AID of the own
device (that is, the transmitting device of the CTS) in the footer
in addition to the BSS color when constructing the CTS.
Accordingly, the communication device which has received the CTS
can identify the transmitting device of the CTS. Further, the
communication device which has received the CTS can detect the BSS
to which the transmitting device of the CTS belongs on the basis of
the BSS color.
[0065] Here, for example, a case in which the communication device
receives the CF-END which is a signal used for releasing the NAV is
considered. Even in a case in which the CF-END does not include the
BSS color, the communication device can determine the BSS to which
the communication device transmitting the CF-END belongs on the
basis of the address information of the transmitting device
included in the CF-END and the BSS color and the information
related to the AID of the CTS which are received before the CF-END.
Accordingly, even in a case in which a plurality of OBSS NAVs is
set, the communication device can appropriately determine the OBSS
NAV which has to be released.
[0066] Here, a frame configuration of the CTS according to the
present embodiment will be described with reference to FIG. 5. FIG.
5 is a diagram illustrating an example of a frame configuration of
the CTS according to the present embodiment.
[0067] As illustrated in FIG. 5, a footer including a BSS color
(indicated by "BSS Color" in FIG. 5), information related to an AID
(indicated by "AID" in FIG. 5), a Parity bit, and a Tail bit is
added to the CTS according to the present embodiment. Further, FIG.
5 illustrates an example in a case in which OFDM in which a
modulation scheme of a sub carrier is BPSK, and a code rate is 1/2
is used, and the footer includes the number of bits (24 bits)
corresponding to one OFDM symbol.
[0068] Then, arbitrary information (hereinafter referred to as
"footer notification information" for the sake of convenience)
indicating that the footer is added is set in the Reserved field (a
bit "1" is set in FIG. 5). The communication device which has
received the CTS can recognize that the footer is added since the
footer notification information is set in the Reserved field, and
can appropriately perform the reception processing for the
footer.
[0069] Further, since the BSS color is included in the footer, the
legacy device can perform the reception processing without error
even in a case in which the CTS according to the present embodiment
is received. More specifically, in a case in which the legacy
device receives the CTS according to the present embodiment, since
the legacy device does not recognize that the footer is added, the
legacy device can perform the normal reception processing to the
padding bit specified by the frame length information in the Length
field without performing the reception processing for the footer.
As described above, in the present embodiment, since the BSS color
is set after the field through which the legacy device performs the
reception processing on the basis of the frame length information,
the backward compatibility can be ensured.
[0070] Further, since the Parity bit is included in the footer, the
communication device can appropriately perform error detection for
the footer portion at the time of decoding. Further, the frame
configuration illustrated in FIG. 5 is merely an example, and an
arrangement order, the number of bits, the modulation scheme, the
code rate, or the like of each piece of information included in the
footer can be appropriately changed.
[0071] Next, a chronological relation between the CTS and the data
frame according to the present embodiment will be described with
reference to FIG. 6. FIG. 6 is a diagram illustrating a
chronological relation between the CTS to which the footer is added
and the data frame in the present embodiment. FIG. 6A illustrates a
chronological relation between the CTS of the related art to which
no footer is added and the data frame, and FIG. 6B illustrates a
chronological relation between the CTS according to the present
embodiment to which the footer is added and the data frame.
[0072] In the CTSs of both of FIGS. 6A and 6B, first, a short
training symbol (indicated by "L-STF" in FIGS. 6A and 6B) and a
long training symbol (indicated by "L-LTF" in FIGS. 6A and 6B) are
set as a PLCP preamble. Thereafter. SIGNAL (indicated by "L-SIG" in
FIGS. 6A and 6B) and data including a PSDU or the like (hereinafter
referred to as "CTS Data" for the sake of convenience) are set. As
illustrated in FIG. 6, the data length to the CTS data in the CTS
of FIG. 6A is equal to that in the CTS of FIG. 6B.
[0073] Here, in FIG. 6A (that is, the CTS of the related art to
which no footer is added), information (indicated by "Sig Ext" in
FIG. 6A) which is appropriately expanded if necessary is added, and
the data frame is transmitted after the transmission of the CTS
Data ends and a short inter frame space (SIFS) elapses. On the
other hand, in FIG. 6B (that is, the CTS according to the present
embodiment), the footer including the BSS color or the like is
added after the CTS Data. Here, similarly to FIG. 6A, a timing at
which the data frame is transmitted is after the transmission of
the CTS Data ends and the SIFS elapses. Here, since the footer is
adjusted to a bit length that can be communicated within the SIFS,
the data frame can be communicated without influence later (FIG. 6B
illustrates an example in which a footer corresponding to one OFDM
symbol (4 .mu.s) in which the modulation scheme of the sub carrier
is BPSK, and the code rate is 1/2 is added). In other words, the
backward compatibility can be ensured by adjusting the footer to
the bit length that can be communicated within the SIFS.
[0074] Next, the setting of the NAV according to the present
embodiment will be described with reference to FIG. 7. In FIG. 7
corresponding to FIG. 3 described above, a BSS 10a and a BSS 10b
partially overlap each other, and an STA 100b belonging to the BSS
10a is located in the overlapping region. Further, there are cases
in which the STA 100b receives not only a signal transmitted from
the BSS 10a which is the own BSS but also a signal transmitted from
the BSS 10b which is the OBSS.
[0075] First, in step S1200 of FIG. 7, the STA 100b receives a CTS
addressed to an AP 200a from an STA 100a belonging to the own BSS.
Here, since the footer including the BSS color is added to the CTS,
the STA 100b can recognize that the CTS is a signal transmitted
from the own BSS on the basis of the BSS color (the STA 100b may
recognize that the CTS is a signal transmitted from the own BSS on
the basis of the address information of the AP 200a which is set in
the RA field of the CTS, similarly to the example of FIG. 3). Then,
the STA 100b sets the own BSS NAV on the basis of the Duration
included in the CTS. Then, in step S1204, the STA 100b which has
received the CTS addressed to the AP 200b from the STA 100c
belonging to the OBSS can recognize that the CTS is a signal
transmitted from the OBSS on the basis of the BSS color included in
the footer of the CTS.
[0076] Then, in a case in which it is recognized that the received
CTS is a signal transmitted from the OBSS, the STA 100b performs
access control in accordance with the received field strength of
the CTS. More specifically, in a case in which the received field
strength of the CTS is lower than a predetermined threshold value,
the STA 100b sets the OBSS NAV, and then, in a case in which a
predetermined condition is satisfied during the OBSS NAV, the STA
100b sets a state in which signal transmission is possible
(hereinafter referred to as a "conditional transmittable state" for
the sake of convenience). Here, the "predetermined condition" may
be an arbitrary condition. For example, the "predetermined
condition" may be a condition that the communication device which
has received the CTS calculates an upper limit value of
transmission power that can prevent a communication failure due to
interference on the basis of the received field strength of the
CTS, and signal transmission becomes possible if the transmission
power becomes equal to or less than the upper limit value. On the
other hand, in a case in which the received field strength of the
CTS is equal to or larger than the predetermined threshold value,
the STA 100b sets the OBSS NAV without setting the conditional
transmittable state.
[0077] Step S1204 of FIG. 7 indicates an example in which, when the
received field strength of the CTS is lower than the predetermined
threshold value, the STA 100b sets the OBSS NAV and then sets the
conditional transmittable state. Accordingly, if the predetermined
condition is satisfied, the STA 100b can transmit data as in step
S1208. Thereafter, in a case in which an ACK addressed to the AP
200b is received from the STA 100c belonging to the OBSS in step
S1212, the STA 100b releases the OBSS NAV and the conditional
transmittable state.
[0078] Next, the setting of the NAV according to the present
embodiment will be described with reference to FIG. 8. In FIG. 8
corresponding to FIG. 4 described above, a BSS 10a, a BSS 10b, and
a BSS 10c partially overlap each other, and an STA 100b belonging
to the BSS 10a is located in the overlapping region. In other
words, there are cases in which the STA 100b receives not only a
signal transmitted from the BSS 10a which is the own BSS but also
signals transmitted from the BSS 10b and the BSS 10c which are the
OBSSs.
[0079] First, in step S1300 of FIG. 8, the STA 100b receives the
CTS addressed to an AP 200b from an STA 100c belonging to the BSS
10b which is the OBSS. Here, since the footer including the BSS
color is added to the CTS, the STA 100b can recognize that the CTS
is a signal transmitted from the BSS 10b which is the OBSS on the
basis of the BSS color. Then, the STA 100b sets the OBSS NAV for
the BSS 10b (indicated by "OBSS1 NAV" in FIG. 8) on the basis of
the Duration included in the CTS. In step S1304, the STA 100b
receives the CTS addressed to the AP 200c from the STA 100d
belonging to the BSS 10c which is the OBSS, and sets the OBSS NAV
for the BSS 10c (indicated by "OBSS2 NAV" in FIG. 8) by a similar
method.
[0080] Thereafter, in a case in which the CF-END addressed to the
AP 200c is received from the STA 100d belonging to the BSS 10c in
step S1308, the OBSS2 NAV which is the NAV for the BSS 10c is
released, and the OBSS1 NAV which is the NAV for the BSS 10b is not
released. Accordingly, since the STA 100b does not perform the
transmission process, interference does not occur even in a case in
which the data frame is transmitted from the BSS 10b in step
S1312.
2. FUNCTIONAL CONFIGURATION OF DEVICE
[0081] The overview of the functions of the wireless LAN system
according to the present embodiment has been described above. Next,
a functional configuration of each of the STA 100 and the AP 200
according to the present embodiment will be described with
reference to FIG. 9. FIG. 9 is a diagram illustrating a functional
configuration of each of the STA 100 and the AP 200 according to
the present embodiment. Further, the function of adding the footer
including the BSS color to the CTS described above, the function of
determining the BSS from which a signal corresponding to the CTS is
transmitted on the basis of the BSS color, the function of setting
various types of NAVs on the basis of a determination result, and
the like can be realized by any one of the STA 100 or the AP 200.
In other words, since the STA 100 and the AP 200 can have the same
functional configuration, the functional configuration of the STA
100 will be described below, and the description of the functional
configuration of the AP 200 will be omitted.
[0082] As illustrated in FIG. 9, the present embodiment STA 100
includes a wireless communication unit 110, a data processing unit
120, and a control unit 130. Here, the wireless communication unit
110 functions as a transmitting unit and a receiving unit, the data
processing unit 120 functions as a generating unit and an
identifying unit, and the control unit 130 functions as a
transmission suppression period setting unit.
[0083] The wireless communication unit 110 includes an antenna
control unit 111, a reception processing unit 112, and a
transmission processing unit 113. The data processing unit 120
includes a reception frame analyzing unit 121, a receiving buffer
122, an interface unit 123, a transmission buffer 124, and a
transmission frame constructing unit 125. The control unit 130
includes an operation control unit 131 and a signal control unit
132.
(Antenna Control Unit 111)
[0084] The antenna control unit 111 controls transmission and
reception of signals via at least one antenna. More specifically,
the antenna control unit 111 provides the signal received via the
antenna to the reception processing unit 112, and transmits the
signal generated by the transmission processing unit 113 via the
antenna.
(Reception Processing Unit 112)
[0085] The reception processing unit 112 performs frame reception
processing on the basis of the signal provided from the antenna
control unit 111. For example, the reception processing unit 112
outputs a baseband reception signal by performing analog processing
and down-conversion on a signal obtained from an antenna. Then, the
reception processing unit 112 calculates correlation between a
predetermined signal pattern and the reception signal, while
shifting the reception signal that is a target of computation on a
time axis, and detects a preamble on the basis of appearance of a
peak of correlation. Accordingly, the reception processing unit 112
can detect the RTS, the CTS, the data frame, the ACK, the CF-END,
or the like. Further, the reception processing unit 112 acquires a
frame by performing demodulation, decoding, and the like on a
baseband reception signal and provides the acquired frame to the
reception frame analyzing unit 121. Further, the reception
processing unit 112 also decodes the footer in a case in which a
notification indicating that the footer is added to the CTS is
given from the reception frame analyzing unit 121 to be described
later.
(Transmission Processing Unit 113)
[0086] The transmission processing unit 113 performs transmission
processing of a transmission frame provided from a transmission
frame constructing unit 125. More specifically, the transmission
processing unit 113 generates a transmission signal on the basis of
a frame provided from the transmission frame constructing unit 125
and parameter set by an instruction from a signal control unit 132.
For example, the transmission processing unit 113 generates a
baseband transmission signal by performing encoding, interleaving,
and modulation on the frame provided from the transmission frame
constructing unit 125 in accordance with coding and modulation
schemes, and the like, instructed by the signal control unit 132.
In addition, the transmission processing unit 113 performs
up-conversion on the baseband transmission signal obtained by the
preceding processing.
(Reception Frame Analyzing Unit 121)
[0087] The reception frame analyzing unit 121 analyzes the received
frame and acquires various types of information. For example, the
reception frame analyzing unit 121 analyzes the Reserved field of
the received CTS, and determines the presence/absence of the footer
on the basis of whether or not the footer notification information
is set. Further, in a case in which it is determined that the
footer is added to the CTS, the reception frame analyzing unit 121
gives a notification indicating the presence of the footer to the
reception processing unit 112 and causes the reception processing
unit 112 to decode the footer. After the footer is decoded, the
reception frame analyzing unit 121 analyzes the footer and acquires
the BSS color, the information related to the AID, and the like
included in the footer. The reception frame analyzing unit 121
determines the BSS from which the signal corresponding to the CTS
is transmitted on the basis of the acquired BSS color. The
reception frame analyzing unit 121 provides various types of
information (various types of information such as the result of
determining the BSS from which the signal corresponding to the CTS
is transmitted, the Duration included in the CTS, the received
field strength of the CTS, and the like) obtained by the processing
to the operation control unit 131 to be described later.
(Receiving Buffer 122)
[0088] The receiving buffer 122 stores data included in the
received frame. The stored data is arbitrary. For example, the
receiving buffer may store data included in the data frame or the
BSS color, the information related to the AID, and the like
included in the CTS.
(Interface Unit 123)
[0089] The interface unit 123 is an interface connected to another
component included in the STA 100. More specifically, the interface
unit 123 performs reception of data that is desired to be
transmitted from the other component, for example, an application
or a user interface, provision of reception data to the application
or the user interface, or the like.
(Transmission Buffer 124)
[0090] The transmission buffer 124 stores transmission data
provided from the interface unit 123.
(Transmission Frame Constructing Unit 125)
[0091] The transmission frame constructing unit 125 constructs a
transmission frame. More specifically, the transmission frame
constructing unit 125 constructs the CTS to which the footer
including the BSS color, the information related to AID, and the
like is added under the control of the operation control unit 131
to be described later. Further, in addition to the CTS, the
transmission frame constructing unit 125 constructs various
transmission frames such as the RTS, the data frame, the ACK, and
the CF-END.
(Operation Control Unit 131)
[0092] The operation control unit 131 controls the NAV setting
processing as a collision prevention procedure. More specifically,
the operation control unit 131 acquires the information related to
the CTS (various types of information such as the result of
determining the BSS from which the signal corresponding to the CTS
is transmitted, the Duration included in the CTS, the received
field strength of the CTS, and the like) from the reception frame
analyzing unit 121. Further, in a case in which the CTS is a signal
transmitted from the own BSS, the operation control unit 131 sets
the own BSS NAV on the basis of the Duration. In a case in which
the CTS is a signal transmitted from the OBSS, the operation
control unit 131 sets the OBSS NAV on the basis of the Duration. In
a case in which the CTS is a signal transmitted from the OBSS, the
operation control unit 131 further compares the received field
strength of the CTS with a predetermined threshold value, and sets
the conditional transmittable state during the OBSS NAV period in a
case in which the received field strength of the CTS is lower than
a predetermined threshold value. In a case in which the received
field strength of the CTS is equal to or larger than the
predetermined threshold value, the conditional transmittable state
is not set. Further, the operation control unit 131 also controls
the NAV setting processing by the RTS, the NAV release processing,
the frame construction processing, the frame transmission
processing, and the like in addition to the above operations.
(Signal Control Unit 132)
[0093] The signal control unit 132 controls processing of the
wireless communication unit 110 as an access control processing
procedure. More specifically, the signal control unit 132 controls
transmission/reception processing of the wireless communication
unit 110. For example, the signal control unit 132 causes the
wireless communication unit 110 to set control information for
transmission and reception on the basis of an instruction from the
operation control unit 131. In addition, the signal control unit
132 controls vacant channel detection processing as in CSMA/CA. For
example, the signal control unit 132 decides transmission start or
transmission standby of a signal on the basis of a carrier sense
result and back off time.
3. OPERATION OF DEVICE
[0094] The functional configuration of the device according to the
present embodiment has been described above. Next, an operation of
the device according to the present embodiment will be
described.
(3-1: CTS Transmission Operation and Subsequent Data Frame
Reception Operation)
[0095] First, a CTS transmission operation and a subsequent data
frame reception operation will be described with reference to FIG.
10. FIG. 10 is a flowchart illustrating a CTS transmission
operation and a data frame reception operation by the communication
device according to the present embodiment. Further, the following
description will proceed with an example in which an operating
entity is the AP 200, but the operating entity may be the STA
100.
[0096] First, in a case in which the wireless communication unit
210 of the AP 200 receives the RTS addressed to the own device in
step S1400 (Yes in step S1400), in step S1404, the control unit 230
determines whether or not data can be received on the basis of the
Duration or the like included in the RTS frame. In a case in which
the control unit 230 determines that data can be received (Yes in
step S1404), and the own device can correspond to the present
disclosure (Yes in step S1408), in step S1412, the transmission
frame constructing unit 225 constructs the footer. In step S1416,
the transmission frame constructing unit 225 constructs the SIGNAL
field, the service field, the PSDU field, and the like, and
construct the CTS by adding the footer after the padding bit. In a
case in which the own device is unable to correspond to the present
disclosure in step S1408 (No in step S1408), the footer
construction processing in step S1412 is omitted, and the
transmission frame constructing unit 225 constructs a CTS including
no footer. In step S1420, the wireless communication unit 210
transmits the CTS.
[0097] In a case in which the wireless communication unit 210
receives a data frame addressed to the own device after the SIFS
elapses since the wireless communication unit 210 transmits the CTS
(Yes in step S1424), in step S1428, the wireless communication unit
210 performs processing such as data decoding. In a case in which
the processing such as the data decoding is completed without error
(Yes in step S1432), in step S1436, the data processing unit 220
stores information indicating that reception of data is completed.
In a case in which an error occurs in the processing such as the
data decoding (No in step S1432), in step S1440, the data
processing unit 220 stores content of the error. Further, in a case
in which the wireless communication unit 210 does not receive data
addressed to the own device in step S1424 (No in step S1424), the
process of steps S1428 to S1440 is skipped.
[0098] In a case in which the wireless communication unit 210
receives a Block ACK Request in step S1444 (Yes in step S1444), in
step S1448, the control unit 230 acquires the reception result of
the data frame. In step S1452, the transmission frame constructing
unit 225 generates a Block ACK on the basis of the reception result
of the data frame, and the wireless communication unit 210
transmits the Block ACK, and then ends the process. Further, the
process ends in a case in which the wireless communication unit 210
does not receive the RTS addressed to the own device in step S1400
(No in step S1400), in a case in which the control unit 230
determines that data is unable to be received in step S1404 (No in
Step S1404), or in a case in which the wireless communication unit
210 does not receive the Block ACK Request in step S1444 (No in
step S1444).
(3-2. Reception Operation of CTS Addressed to Another Device)
[0099] Next, the reception operation of the CTS addressed to
another device will be described with reference to FIG. 11. FIG. 11
is a flowchart illustrating an operation of receiving the CTS
addressed to another device and setting the NAV by the
communication device according to the present embodiment. Further,
the following description will proceed with an example in which the
operating entity is the STA 100, but the operating entity may be
the AP 200.
[0100] First, in a case in which the wireless communication unit
110 of the STA 100 receives the CTS addressed to another device in
step S1500 (Yes in step S1500), in step S1504, the wireless
communication unit 110 decodes the CTS. In step S1508, the
reception frame analyzing unit 121 analyzes the decoded CTS and
acquires the Duration. In step S1512, the reception frame analyzing
unit 121 determines the presence or absence of footer on the basis
of whether or not the footer notification information is set in the
Reserved field. In a case in which the reception frame analyzing
unit 121 determines that the footer is added (Yes in step S1512),
in step S1516, the wireless communication unit 110 decodes the
footer, and in step S1520, the reception frame analyzing unit 121
acquires the BSS color included in the footer.
[0101] In step S1524, the reception frame analyzing unit 121
determines the BSS from which a signal corresponding to the CTS is
transmitted on the basis of the acquired BSS color. In a case in
which it is determined that the CTS is a signal transmitted from
the OBSS (Yes in step S1524), in step S1528, the operation control
unit 131 sets the OBSS NAV on the basis of the Duration included in
the CTS.
[0102] Thereafter, the operation control unit 131 acquires the
received field strength of the CTS in step S1532, and compares the
received field strength of the CTS with a predetermined threshold
value in step S1536. In a case in which the received field strength
of the CTS is lower than the predetermined threshold value (Yes in
step S1536), the operation control unit 131 sets the conditional
transmittable state during the OBSS NAV in step S1540, and then
ends the process. In a case in which the received field strength of
the CTS is equal to or greater than the predetermined threshold
value (No in step S1536), the operation control unit 131 ends the
process without setting the conditional transmission enabled
state.
[0103] In a case in which it is determined in step S1524 that the
CTS is a signal transmitted from the own BSS (No in step S1524), in
step S1548, the operation control unit 131 sets the own BSS NAV on
the basis of the Duration included in the CTS, and then ends the
process.
[0104] In a case in which it is determined in step S1512 that the
footer is not added to the CTS (No in step S1512), and the CTS is
determined to be a signal transmitted from the own BSS on the basis
of the address information of the AP 200 of the own BSS set in the
RA field of the CTS (Yes in step S1544), in step S1548, the
operation control unit 131 sets the own BSS NAV on the basis of the
Duration included in the CTS and then ends the process.
[0105] In a case in which it is determined in step S1544 that the
CTS is not a signal transmitted from the own BSS (No in step
S1544), in step S1552, the operation control unit 131 sets the OBSS
NAV on the basis of the Duration included in the CTS. Thereafter,
the operation control unit 131 acquires the received field strength
of the CTS in step S1556, and compares the received field strength
of the CTS with a predetermined threshold value in step S1560. In a
case in which the received field strength of the CTS is lower than
the predetermined threshold value (No in step S1560), in step
S1540, the operation control unit 131 sets the conditional
transmittable state during the OBSS NAV and then ends the process.
In a case in which the received field strength of the CTS is equal
to or larger than the predetermined threshold value (Yes in step
S1560), the process ends without the conditional transmittable
state being set by the operation control unit 131. Further, in a
case in which the wireless communication unit 110 does not receive
the CTS addressed to another device in step S1500 (No in step
S1500), the process ends.
(3-3. Transmission Operation of Data Frame)
[0106] Next, a data frame transmission operation will be described
with reference to FIG. 12. FIG. 12 is a flowchart illustrating an
operation of transmitting the data frame by the communication
device according to the present embodiment. Further, the following
description will proceed with an example in which the operating
entity is the STA 100, but the operating entity may be the AP
200.
[0107] First, in step S1600, the data processing unit 120 acquires
transmission data from a predetermined application, a user
interface, or the like via the interface unit 123. In step S1604,
the transmission buffer 124 stores the transmission data. In step
S1608, the operation control unit 131 acquires parameters such as
address information of a transmission destination device. In step
S1612, the operation control unit 131 acquires information related
to the NAV set in the own device. In a case in which the own BSS
NAV is set (Yes in step S1616), in step S1620, the operation
control unit 131 sets the transmission waiting state until the own
BSS NAV ends.
[0108] Further, in a case in which the own BSS NAV is not set in
step S1616 (No in step S1616), and the OBSS NAV is set (Yes in step
S1624), in step S1628, the operation control unit 131 acquires
information related to the transmission condition of the
conditional transmittable state. In step S1632, the operation
control unit 131 sets various types of parameters related to the
transmission processing so that the acquired transmission condition
is satisfied. For example, the operation control unit 131 sets the
transmission power to a low value. Thereafter, in step S1636, the
wireless communication unit 110 transmits data, and then the
process ends. In a case in which the OBSS NAV is not set in step
S1624 (No in step S1624), in step S1636, the wireless communication
unit 110 transmits data, and then the process ends.
4. MODIFICATIONS
[0109] The operation of the device according to the present
embodiment has been described above. Next, modifications of the
present disclosure will be described.
(4-1. First Modification)
[0110] First, a first modification of the present disclosure will
be described with reference to FIGS. 13 and 14. FIGS. 13 and 14 are
diagrams illustrating an example of a frame configuration of the
CTS according to a first modification of the present
disclosure.
[0111] In the above embodiment, the footer notification information
is set in the Reserved field. However, this is merely an example,
and a position at which the footer notification information is set
is arbitrary. The first modification of the present disclosure is
an embodiment in which the footer notification information is set
at a position other than the Reserved field.
[0112] For example, as illustrated in FIG. 13, the footer
notification information may be set in the Service field. In the
example of FIG. 13, a bit string in which all bits are "1" is set
in the Service field as the footer notification information.
[0113] Further, as illustrated in FIG. 14, the footer notification
information may be set in the padding bit specified in IEEE 802.11.
In the example of FIG. 14, a bit string in which all bits are "1"
is set in the padding bit as the footer notification
information.
[0114] Further, the case in which the bit string in which all bits
are "1" is set in the Service field or the padding bit as the
footer notification information is merely an example, and any
information may be set.
[0115] As described above, since the position at which the footer
notification information is set can be flexibly changed, the
present disclosure can be applied to various wireless LAN
systems.
[0116] Further, the footer notification information may be set in a
state in which it is distributed to a plurality of fields.
Accordingly, since more information can be notified of, information
other than the information indicating that the footer is added can
be notified of. For example, the information related to the
position at which the BSS color is set, information related to the
data length of the footer, or the like may be notified of.
(4-2. Second Modification)
[0117] The first modification of the present disclosure has been
described above. Next, a second modification of the present
disclosure will be described with reference to FIGS. 15 to 17.
FIGS. 15 to 17 are diagrams illustrating an example of a frame
configuration of the CTS according to a second modification of the
present disclosure.
[0118] In the above embodiment, the BSS color is set in the footer.
However, the position at which the BSS color is set is not limited
to the footer. The second modification of the present disclosure is
an embodiment in which the BSS color is set in the padding bit
specified in IEEE 802.11 other than the footer. In the second
modification, since there are cases in which the footer is not
added as will be described below, the description will proceed
using "BSS color notification information" as the information
indicating that the BSS color is set rather than the "footer
notification information." The communication device which has
received the CTS according to the present embodiment can recognize
that the BSS color is set in the padding bit on the basis of the
BSS color notification information and determine the BSS from which
a signal corresponding to the CTS is transmitted on the basis of
the BSS color.
[0119] For example, as illustrated in FIG. 15, the BSS color may be
set in the tail of the padding bit, and the AID, the Reserved
field, the Parity bit, and the Tail bit may be set in the footer.
Further, in FIG. 15, the BSS color notification information is set
in the head of the padding bit, but similarly to the footer
notification information, the position at which the BSS color
notification information is set is arbitrary.
[0120] Further, as illustrated in FIG. 16, the tail bit may be set
between the BSS color set in the padding bit and the AID set in the
footer. Here, in the example illustrated in FIG. 15, since the tail
bit is set in the tail of the footer, but the tail bit is not set
between the BSS color and the AID, the communication device which
has received the CTS is unable to acquire the BSS color in a case
in which the decoding processing terminated in the tail bit in the
tail of the footer fails. On the other hand, as illustrated in FIG.
16, even though the decoding processing terminated in the tail bit
in the tail of the footer fails since the tail bit is set between
the BSS color set in the padding bit and the AID set in the footer,
in a case in which the decoding processing terminated in the tail
bit between the BSS color and the AID is successful, the
communication device which has received the CTS can acquire the BSS
color.
[0121] Further, as illustrated in FIG. 17, the BSS color and tail
bit are set in the padding bit, and the footer may not be added.
Accordingly, the communication device can omit the processing of
generating the footer.
[0122] Further, in the second modification of the present
disclosure, the backward compatibility can be ensured. More
specifically, in a case in which the legacy device receives the CTS
according to the present embodiment, since it is not recognized
that the BSS color is set in the padding bit, the decoding
processing terminated in the Tail bit set just before the padding
bit is performed, and thus the reception processing can be
performed without error.
5. APPLICATION EXAMPLES
[0123] The technology according to the present disclosure can be
applied to various products. For example, the STA 100 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 STA 100
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 STA 100 may be wireless communication modules
mounted in such terminals (for example, integrated circuit modules
including one die).
[0124] On the other hand, for example, the AP 200 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. Further, the AP 200 may be realized as a mobile wireless
LAN router. Further, the AP 200 may also be a wireless
communication module (for example, an integrated circuit module
configured with one die) mounted on such devices.
5-1. First Application Example
[0125] FIG. 18 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.
[0126] 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.
[0127] 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.
[0128] The wireless communication interface 913 supports one or
more wireless LAN standards of IEEE 802.11a, 11b, 11g, 11n, 11ac,
11ad, and 11ax and the like, 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.
[0129] 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. 18. In this case, the antenna
switch 914 may be omitted from the configuration of the smartphone
900.
[0130] 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. 18 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.
[0131] 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.
5-2. Second Application Example
[0132] FIG. 19 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.
[0133] 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.
[0134] 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.
[0135] 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.
[0136] The wireless communication interface 933 supports one or
more wireless LAN standards of IEEE 802.11a, 11b, 11g, 11n, 11ac,
11ad, and 11ax 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.
[0137] Note that the car navigation device 920 may include a
plurality of antennas, without being limited to the example of FIG.
19. In this case, the antenna switch 934 may be omitted from the
configuration of the car navigation device 920.
[0138] The battery 938 supplies electric power to each of the
blocks of the car navigation device 920 illustrated in FIG. 19 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.
[0139] In addition, the wireless communication interface 933 may
operate as the AP 200 described above, and provide wireless
communication for a terminal of a user on the vehicle.
[0140] 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.
5-3. Third Application Example
[0141] FIG. 20 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.
[0142] 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).
[0143] The input device 954 includes, for example, a button, a
switch, or the like, and receives operation performed by a user.
The display device 955 includes an LED or the like and displays an
operation status of the wireless access point 950.
[0144] 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).
[0145] The wireless communication interface 963 supports one or
more wireless LAN standards of IEEE 802.11a, 11b, 11g, 11n, 11ac,
11ad, 11ax, 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, a
power amplifier, and the like. 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.
6. OTHERS
[0146] The above description has proceeded mainly with the example
in which the present disclosure is applied to the CTS which is a
sort of response frame. Here, the present disclosure can be applied
to the ACK which is a sort of response frame in addition to the
CTS.
[0147] More specifically, each communication device can construct
the ACK to which the footer including the BSS color is added as in
the above embodiment and set the BSS color in the padding bit
specified in IEEE 802.11. Further, the information indicating that
the footer is added or the information indicating that the BSS
color is set in the padding bit is set in the frame together,
similarly to the above embodiment, and thus description thereof is
omitted.
[0148] The embodiment in which the present disclosure is applied to
the ACK is particularly effective in a case in which the NAV is set
by the ACK. For example, in a case in which the STA 100 cannot
receive the RTS and the CTS due to a certain reason and receives
the ACK transmitted thereafter, the STA 100 can determine the BSS
from which a signal corresponding to the ACK is transmitted on the
basis of the BSS color included in the footer of the ACK. Then, in
a case in which it is determined that the ACK is a signal
transmitted from the own BSS, the STA 100 sets the own BSS NAV on
the basis of the Duration included in the ACK, and in a case in
which it is determined that the ACK is a signal transmitted from
the OBSS, the STA 100 sets the OBSS NAV on the basis of the
Duration included in the ACK. Further, in this embodiment, a value
other than 0 is set as the Duration included in the ACK.
Accordingly, the STA 100 can reduce the possibility of the
occurrence of interference even in an unstable communication
environment in which the RTS and the CTS are unable to be received,
but the ACK can be received.
[0149] Further, the embodiment in which the present disclosure is
applied to the ACK is effective not only in a case in which
preparation for data transmission/reception is performed by the RTS
and the CTS but also in a case in which preparation for data
transmission/reception is performed by small capacity data and the
ACK. For example, in a case in which the STA 100 transmits data,
the STA 100 transmits not the RTS but small capacity data to the AP
200 before the data is transmitted. The AP 200 which has received
the small-capacity data transmits the ACK to the STA 100, and the
STA 100 which has received the ACK determines that data
transmission is permitted, and transmits data to the AP 200.
[0150] At this time, in a case in which the STA 100 other than the
STA 100 that transmits the data receives the ACK, the STA 100 can
determine the BSS from which a signal corresponding to the ACK is
transmitted on the basis of the BSS color included in the footer of
the ACK. Then, in a case in which it is determined that the ACK is
a signal transmitted from the own BSS, the STA 100 sets the own BSS
NAV on the basis of the Duration included in the ACK, and in a case
in which it is determined that the ACK is a signal transmitted from
the OBSS, the STA 100 sets the OBSS NAV on the basis of the
Duration included in the ACK. Further, also in this case, a value
other than 0 is set as the Duration included in the ACK.
Accordingly, it is possible to reduce the possibility of the
occurrence of interference even in a case in which preparation for
data transmission/reception is performed with the small capacity
data and the ACK.
7. CONCLUSION
[0151] As described above, the response frame in accordance with
the present disclosure includes the BSS color in the footer or the
padding bit. Accordingly, the communication device which has
received the response frame can determine the BSS from which a
signal corresponding to the response frame is transmitted on the
basis of the BSS color and appropriately select the own BSS NAV or
the OBSS NAV in accordance with the determination result. Further,
the communication device according to the present embodiment can
set a different OBSS NAV for each OBSS. Accordingly, the
communication device according to the present embodiment can
appropriately set and release the OBSS NAV. Further, the present
disclosure can ensure the backward compatibility. In other words,
the communication device according to the present embodiment can
appropriately communicate with the legacy device to which the
present disclosure is not applied.
[0152] The preferred embodiment of the present disclosure has 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.
[0153] For example, respective steps illustrated in FIGS. 10 to 12
need not necessarily be processed in a chronological order in
accordance with a sequence described as the flowchart. In other
words, respective steps may be processed in an order different from
the order described as the flowchart or may be processed in
parallel.
[0154] Further, some of the components of the STA 100 can be
installed outside the STA 100 as appropriate. Similarly, some of
the components of the AP 200 may be installed outside the AP 200 as
appropriate. In addition, some functions of the STA 100 may be
implemented by the control unit 130. For example, the control unit
130 may implement some functions of the wireless communication unit
110 or the data processing unit 120. Similarly, some functions of
the AP 200 may be implemented by the control unit 230. For example,
the control unit 230 may implement some functions of the wireless
communication unit 210 or the data processing unit 220.
[0155] 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.
[0156] Additionally, the present technology may also be configured
as below.
(1)
[0157] A communication device that transmits a response frame,
including:
[0158] a generating unit configured to generate the response frame
in which information used for identification of a BSS to which the
communication device belongs or information used for identification
of an own device is included in or after a padding bit specified in
IEEE 802.11; and
[0159] a transmitting unit configured to transmit the response
frame.
(2)
[0160] The communication device according to (1), in which the
generating unit adds a footer including the information used for
the identification of the BSS after the padding bit.
(3)
[0161] The communication device according to (2), in which the
footer is added after a bit specified by frame length information
included in the response frame.
(4)
[0162] The communication device according to any one of (1) to (3),
in which the generating unit sets information notifying that the
information used for the identification of the BSS is included in
the response frame in or before the padding bit.
(5)
[0163] The communication device according to (4), in which the
generating unit sets information notifying that the information
used for the identification of the BSS is included in the response
frame in at least one of a reserved field, a service field, or the
padding bit specified in IEEE 802.11.
(6)
[0164] The communication device according to (1) to (5), in which
the generating unit includes a tail bit after a bit string which is
the information used for the identification of the BSS.
(7)
[0165] The communication device according to any one of (1) to (6),
in which the information used for the identification of the BSS
includes a BSS color,
[0166] the response frame includes a CTS or an ACK, and
[0167] the communication device includes an access point device or
a station device.
(8)
[0168] The communication device according to any one of (1) to (6),
in which the information used for the identification of the own
device includes information related to an AID,
[0169] the response frame includes a CTS or an ACK, and
[0170] the communication device includes an access point device or
a station device.
(9)
[0171] The communication device according to any one of (1) to (8),
in which the generating unit includes a tail bit after a bit string
which is the information used for the identification of the own
device.
(10)
[0172] A communication control method of transmitting a response
frame executed by a computer, including:
[0173] generating the response frame in which information used for
identification of a BSS to which an own device belongs or
information used for identification of the own device is included
in or after a padding bit specified in IEEE 802.11; and
[0174] transmitting the response frame.
(11)
[0175] A communication device that receives a response frame,
including:
[0176] a receiving unit configured to receive the response frame in
which information used for identification of a BSS to which a
transmitting device of the response frame belongs or information
used for identification of the transmitting device is included in
or after a padding bit specified in IEEE 802.11; and
[0177] an identifying unit configured to identify the BSS on the
basis of the information used for the identification of the
BSS.
(12)
[0178] The communication device according to (11), further
including, a transmission suppression period setting unit
configured to set a first transmission suppression period in a case
in which the BSS is identified as an own BSS, and set a second
transmission suppression period in a case in which the BSS is
identified as an OBSS that overlaps the own BSS.
(13)
[0179] The communication device according to (12), in which the
transmission suppression period setting unit sets the second
transmission suppression period for each OBSS.
(14)
[0180] The communication device according to any one of (11) to
(13), in which the identifying unit identifies the BSS on the basis
of the information used for the identification of the BSS in a case
in which information notifying that the information used for the
identification of the BSS is included in the response frame is
included in or before the padding bit.
(15)
[0181] A communication control method of receiving a response frame
executed by a computer, including:
[0182] receiving the response frame in which information used for
identification of a BSS to which a transmitting device of the
response frame belongs or information used for identification of
the transmitting device is included in or after a padding bit
specified in IEEE 802.11; and
[0183] identifying the BSS on the basis of the information used for
the identification of the BSS.
REFERENCE SIGNS LIST
[0184] 100 STA [0185] 200 AP [0186] 110, 210 wireless communication
unit [0187] 111, 211 antenna control unit [0188] 112, 212 reception
processing unit [0189] 113, 213 transmission processing unit [0190]
120, 220 data processing unit [0191] 121, 221 reception frame
analyzing unit [0192] 122, 222 receiving buffer [0193] 123, 223
interface unit [0194] 124, 224 transmission buffer [0195] 125, 225
transmission frame constructing unit [0196] 130, 230 control unit
[0197] 131, 231 operation control unit [0198] 132, 232 signal
control unit
* * * * *