Description
Title oflnvention
COMMUNICATION APPARATUS AND COMMUNICATION METHOD
Technical Field
[0001]
The present disclosure relates to communication apparatuses and
communication methods.
Background Art
[0002]
Wireless local area networks (LANs), typified by IEEE (Institute of
Electrical and Electronics Engineers) 802.11, have in recent years been widespread.
15 [0003]
802.11 is a random access type wireless communication standard, and in
802.11, when a plurality of communication apparatuses perform transmission
asynchronously, a mechanism such as carrier sense multiple access
(CSMA)/collision avoidance (CA) is employed to suppress a decrease in throughput
20 of communication due to collision of transmission packets. Specifically, a
communication apparatus conforming to 802.11 checks a state of a channel before
performing packet transmission and delays the packet transmission when other
packets are detected.
25
30
[0004]
Here, in 802.11, a known signal sequence called a physical layer
convergence protocol (PLCP) preamble is used to detect a packet transmitted from
another communication apparatus. Specifically, detection of a packet is performed
by correlating a signal sequence of a received packet with a known signal sequence.
[0005]
However, information amounts of content to be transmitted and the number
of products supporting a wireless LAN are continuously increasing, and thus it is
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desirable to further improve communication throughput.
[0006]
SP361950WOOO
Here, the PLCP preamble is used for processes for reception of packets, for
example, detection of a start timing of a packet, gain adjustment of a communication
5 apparatus at a reception side, channel estimation, correction of a frequency offset,
and the like. However, when packets can be received without performing the above
processes, an unnecessary PLCP preamble is transmitted, and the overhead of
communication increases.
10
15
[0007]
On the other hand, there is a technique of reducing the overhead of
commnnication by the PLCP preamble. For example, in Non-Patent Literature I, a
green field format is defined as a PLCP format, and a training signal for securing
backward compatibility is not included in the PLCP of the format. The overhead of
communication is reduced accordingly.
Citation List
Non-Patent Literature
[0008]
Non-Patent Literature I: 802.11 2012 IEEE Standard for
20 Information technology-Telecornrnnnications and information exchange between
systems Local and metropolitan area networks-Specific requirements Part 11:
25
Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications
Technical Problem
[0009]
Disclosure of Invention
However, even in the case of the green field format, since other training
signals are included, there are cases in which an unnecessary PLCP preamble is
30 transmitted.
[0010]
5
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In this regard, the present disclosure proposes a communication apparatus
and a communication method, which are novel and improved and capable of
reducing the overhead of communication while suppressing influence on a frame
reception process.
Solution to Problem
[0011]
According to the present disclosure, there is provided a communication
apparatus, including: a processing unit configured to select one of a frame of a first
10 format including a training signal and a frame of a second format not including a first
field which is at least a part of the training signal, and generate the frame of the
selected format; and a communication unit configured to transmit the frame of the
first format or the frame of the second format.
15
20
25
[0012]
According to the present disclosure, there is provided a communication
apparatus, including: a communication unit configured to receive a frame of a first
format including a training signal and a frame of a second format not including a first
field which is at least a part of the training signal.
[0013]
According to the present disclosure, there is provided a communication
method, including: selecting one of a frame of a first format including a training
signal and a frame of a second format not including a first field which is at least a
part of the training signal, and generating the frame of the selected format; and
transmitting the frame of the first format or the frame of the second format.
Advantageous Effects of Invention
[0014]
As described above, according to the present disclosure, a communication
apparatus and a communication method which are capable of reducing the overhead
30 of communication while suppressing influence on a frame reception process are
provided. Note that the effects described above are not necessarily limitative.
------------
5
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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. l] FIG. l is- a diagram illustrating an example configuration of a
communication system according to an embodiment of the present disclosure.
[FIG. 2A] FIG. 2A is a diagram illustrating a frame format of a mixed mode
10 supported by 802.11 n/ac.
[FIG. 28] FIG. 28 is a diagram illustrating a frame format supported by 802.11 a/g.
[FIG. 3] FIG. 3 is a diagram illustrating a frame exchange sequence according to a
related art.
[FIG. 4] FIG. 4 is a block diagram illustrating a schematic functional configuration of
15 a communication apparatus according to a first embodiment of the present disclosure.
[FIG. 5] FIG. 5 is a diagram illustrating an example configuration of a frame
including information indicating a T vsr candidate time length according to the
present embodiment.
[FIG. 6A] FIG. 6A is a diagram illustrating an example of a VSP frame in the present
20 embodiment.
[FIG. 68] FIG. 68 is a diagram illustrating an example of a VSP frame having a
shorter PLCP than the VSP frame illustrated in FIG. 6A according to the present
embodiment.
[FIG. 6C] FIG. 6C is a diagram illustrating an example of a VSP frame having a
25 shorter PLCP than the VSP frame illustrated in FIG. 68 according to the present
embodiment.
[FIG. 7] FIG. 7 is a flowchart conceptually illustrating a PLCP selection process of a
communication apparatus according to the present embodiment.
[FIG. 8] FIG. 8 is a flowchart conceptually illustrating a reception method selection
30 process of a communication apparatus according to the present embodiment.
[FIG. 9] FIG. 9 is a diagram illustrating a frame exchange sequence performed in a
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communication system according to the present embodiment.
[FIG. 10] FIG. 10 is a flowchart conceptually illustrating a PLCP selection process of
a cmmnunication apparatus according to a first modified example of the present
embodiment.
5 [FIG. 11] FIG. 11 is a diagram illustrating an example of a frame including a VSP
frame use request according to a second embodiment of the present disclosure.
[FIG. 12] FIG.12 is a flowchart conceptually illustrating a PLCP designation process
and a PLCP selection process of a communication apparatus according to the present
embodiment.
10 [FIG. 13] FIG. 13 is a flowchart conceptually illustrating a reception method
selection process of a communication apparatus according to the present embodiment.
[FIG. 14] FIG. 14 is a diagram illustrating a frame exchange sequence for describing
an example of a process of a communication system according to the present
embodiment.
15 [FIG. 15] FIG. 15 is a diagram illustrating an example of a frame exchange sequence
performed in one-to-many communication according to a related art.
[FIG. 16] FIG. 16 is a block diagram illustrating a schematic functional configuration
of a communication apparatus according to a third embodiment of the present
disclosure.
20 [FIG. 17] FIG. 17 is a flowchart conceptually illustrating a PLCP selection process of
a communication apparatus according to the present embodiment.
[FIG. 18] FIG. 18 is a diagram illustrating a frame exchange sequence for describing
an example of a process of a communication system according to the present
embodiment.
25 [FIG. 19] FIG. 19 is a diagram illustrating an example of a frame exchange sequence
performed in communication according to a related art when a PLCP is added
independently.
[FIG. 20] FIG. 20 is a diagram illustrating a frame exchange sequence for describing
an example of a process of a communication system according to a fourth
30 embodiment of the present disclosure.
[FIG. 21] FIG. 21 is a block diagram illustrating an example schematic configuration
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of a smartphone.
[FIG. 22] FIG. 22 is a block diagram illustrating an example schematic configuration
of a car navigation device.
[FIG. 23] FIG. 23 is a block diagram illustrating an example schematic configuration
5 of a wireless access point.
Mode(s) for Carrying Out the Inventio-n
[0016]
Hereinafter, (a) preferred embodiment(s) of the present disclosure will be
10 described in detail with reference to the appended drawings. 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.
[0017]
15 Further, description will proceed in the following order.
1. Overview of information system related to one embodiment of present disclosure
2. First embodiment (example in which PLCP is autonomously selected)
3. Second embodiment (example in which requested PLCP is selected)
4. Third embodiment (example in which PLCP is selected in space division
20 multiplexing communication)
5.fourth embodiment (example in which PLCP is selected in frequency division
multiplexing communication)
6. Application examples
7. Conclusion
25 [0018]
<1. Overview of information system according to embodiment of present disclosure>
Firstly, an overview of a communication system according to an
embodiment of the present disclosure will be described with reference to FIG. 1.
FIG. 1 is a diagram illustrating an example configuration of the communication
30 system of the embodiment of the present disclosure.
[0019]
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The communication system is configured with a plurality of communication
apparatuses 10. The communication apparatuses 10 have a wireless communication
function and operate as access points (APs) or terminals. Hereinafter, a
communication apparatus 1 0 operating as an AP will also be referred to as a master
5 unit, and communication apparatuses 10 operating as terminals will be referred to as
slave units. For this reason, in the communication system, communication is
possible between the master unit and the slave units. Here, communication from
the master unit to the slave units is referred to as downlink (DL) communication, and
communication from the slave units to the master unit is referred to as uplink (UL)
10 communication.
[0020]
For example, as shown in FIG. 1, the communication system may include a
plurality of communication apparatuses 10#0 to 10#4. The communication
apparatus 1 0#0 which is a master unit and the communication apparatuses 1 0# 1 to
15 10#4 which are slave units are connected through wireless communication and
directly transmit and receive frames to and from each other.
[0021]
Here, in the 802.11 standard, the PLCP preamble used for the frame
reception process is added to the frames to be transmitted/received. A configuration
20 of a frame according to a related art will be described with reference to FIGS. 2A and
2B. FIG. 2A is a diagram illustrating a format of a frame supported by 802.lla/g
(hereinafter, also referred to as a "legacy mode frame"), and FIG. 2B is a diagram
illustrating a frame format of a mixed mode supported by 802.lln/ac.
[0022]
25 First, as illustrated in FIG. 2A, the legacy mode frame is configured with a
legacy long training field (L-STF), a legacy short training field (L-LTF), a legacy
signal field (L-SI G), a Service, and a physical layer service data unit (PSDU).
[0023]
Further, as illustrated in FIG. 2B, the mixed mode frame is configured with
30 an L-STF, an L-LTF, an L-SIG, an Ext-SIG, an Ext-STF, an Ext-LTF, a Service, and a
PSDU. The Ext-STF or the like may be a high throughput (HT)-STF, a very high
i_i --
throughput (VHT)-STF, or the like.
[0024]
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SP3Gl950WOOOAs
described above, the mixed mode has the PLCP preamble such as the LSTF
in order to secure the backward compatibility with the legacy mode. A PLCP
5 used in frame exchange according to a related art will be described with reference to
FIG. 3. FIG. 3 is a diagram illustrating a frame exchange sequence according to a
related art.
[0025]
First, the master unit transmits a legacy mode transmission permissiOn
10 request frame. For example, as illustrated in FIG. 3, the master unit I 0#0 transmits
a request to send (RTS) frame to which the PLCP of the legacy mode is added to
slave units 1 0# 1 and 10#2.
[0026]
Then, the slave unit that has received the transmission permission request
15 frame transmits a legacy mode transmission permission frame to the master unit.
For example, as illustrated in FIG. 3, the slave unit 10#1 transmits a clear to send
(CTS) frame to which the PLCP of the legacy mode is added to the master unit 10#0.
[0027]
Then, the master unit that has received the transmission permission frame
20 transmits a mixed mode data frame to the slave unit. For example, as illustrated in
FIG. 3, the master unit 10#0 transmits a data frame to which the PLCP of the mixed
mode is added to the slave unit 1 0# 1. Thereafter, the PLCP of the mixed mode is
added to each frame to be transmitted.
25
30
[0028]
Since the PLCP preamble is added to the frame each time communication is
performed as described above, when a frame can be received without performing the
frame reception process using the PLCP preamble, an unnecessary PLCP preamble is
transmitted. For this reason, the overhead of communication is likely to increase.
[0029]
On the other hand, a frame of a green field format defined by 802.11n
(hereinafter, also referred to as a "green field mode frame") does not include a signal
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such as the L-STF in order to secure the backward compatibility with the legacy
mode, unlike the mixed mode. However, even in the case of the green field mode
fi·ame, since the PLCP preamble such as the HT-STF is included, there is room for
improvement in communication efficiency.
5 [0030]
In this regard, the present disclosure proposes a communication apparatus
and a communication method which are capable of reducing the overhead of
communication while suppressing influence on the frame reception process. Details
thereof will be described below. Here, although an example of a communication
10 system in which the communication apparatus I 0#0 is a master unit is described in
FIG. I, another communication apparatus I 0 may be a master unit, or the
communication apparatus 1 0#0 may be a communication apparatus having a
plurality of direct links with other communication apparatuses 1 0# 1 to 1 0#4. In the
latter case, the aforementioned UL may be replaced with "simultaneous transmission
15 from one unit to a plurality of units," and the aforementioned UL may be replaced
with "simultaneous transmission from a plurality of units to one unit." Also, for
convenience of description, communication apparatuses 1 0 according to first to
fourth embodiments are distinguished by attaching numbers corresponding to the
embodiments to the ends thereof, such as a communication apparatus 10-1 and a
20 communication apparatus 10-2.
[0031]
<2. First embodiment (example in which PLCP is autonomously selected)>
The overview of the communication system according to one embodiment
of the present disclosure has been described above. Next, a communication
25 apparatus 10-1 according to a first embodiment of the present disclosure will be
described. The communication apparatus l 0-1 according to the present
embodiment autonomously selects the PLCP to be added to the frame to be
transmitted. The selected PLCP is also called a PLCP of a related art or a PLCP
which is shorter than the PLCP of the related art (hereinafter, also refened to as a
30 "very short PLCP (VSP)).
[0032]
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<2-1. Configuration of communication apparatus >
Firstly, a configuration of the communication apparatus I 0-1 according to
the first embodiment of the present disclosure will be described with reference to FIG.
4. FIG. 4 is a block diagram schematically illustrating a functional configuration of
5 the communication apparatus 10-1 of the first embodiment of the present disclosure.
[0033]
As illustrated in FIG. 4, the communication apparatus I 0-1 includes a data
processing unit 11, a communication unit 12, and a control unit 15. Firstly, basic
functions of the communication apparatus 10-1 will be described.
10 [0034]
((Basic functions))
The data processmg unit 11 performs a process for transmission and
reception of data. Specifically, the data processing unit 11 generates a frame on the
basis of data from a higher-levellayer of communication, and provides the generated
15 frame to a modulation/demodulation unit 13 described below. For example, the
data processing unit 11 generates a frame (or packets) from data, and performs
processes, such as addition of a MAC header for media access control (MAC),
addition of an error detection code, and the like, on the generated frame. The data
processing unit 11 also extracts data from a received frame, and provides the
20 extracted data to a higher-level layer of communication. For example, the data
processing unit 11 obtains data by performing, on a received frame, analysis of a
MAC header, detection and correction of code error, a reordering process, and the
like
25
[0035]
As illustrated in FIG. 4, the communication unit 12 includes a
modulation/demodulation unit 13 and radio interface units 14.
[0036]
The modulation/demodulation unit 13 performs a modulation process and
the like on a frame. Specifically, the modulation/demodulation unit 13 performs
30 encoding, interleaving, and modulation on a frame provided by the data processing
unit 11, in accordance with coding and modulation schemes and the like set by the
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control unit 15, to generate a symbol stream. Thereafter, the
modulation/demodulation unit 13 provides the generated symbol stream to the radio
interface unit 14. The modulation/demodulation unit 13 also performs
demodulation and decoding or the like on the symbol stream provided by radio
5 interface unit 14 to obtain a frame, and provides the obtained frame to the data
processing unit 11 or the control unit 15.
[0037]
Tbe radio interface unit 14, which includes an antenna, transmits and
receives a signal through the antenna. Specifically, the radio interface unit 14
10 converts a signal contained m a symbol stream provided from the
modulation/demodulation unit 13, into an analog signal, and performs amplification,
filtering, and frequency upconversion on the analog signal. Thereafter, the radio
interface unit 14 transmits the processed signal through the antenna. The radio
interface unit 14 also performs, on a signal from the antenna, reverse processes to
15 those which are performed for signal transmission, such as frequency
downconversion, digital signal conversion, and the like, and provides the signal
obtained by the processes to the modulation/demodulation unit 13.
[0038]
Further, two or more radio interface units 14 may be provided. Hereinafter,
20 the modulation/demodulation unit 13 and the radio interface unit 14 are collectively
referred to as a "communication unit 12."
[0039]
The control unit 15 controls an overall operation of the communication
apparatus 10-1. Specifically, the control unit 15 transfers information between each
25 function, sets conmmnication parameters, and schedules frames (or packets) in the
data processing unit 11, for example.
[0040]
(Parameter decision function)
The control unit 15 decides a parameter used in the PLCP selection process.
30 Specifically, the control unit 15 decides ·a time in which a communication
synchronization error with a communication link destination falls within a
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predetermined range. A communication synchronization target m the present
disclosure will be described later.
[0041]
More specifically, when a communication link is established, the control
5 unit 15 first determines whether the communication apparatus with which the
communication link is established is the communication apparatus 10-1
corresponding to the VSP. For example, at the time of association, the control unit
15 makes an attempt to acquire information indicating that it is a VSP -supporting
communication apparatus using an association request or response.
10 [0042]
When the communication apparatus with which the communication link is
established is determined not to be a communication apparatus supporting the VSP,
the control unit 15 turns off a VSP setting. For example, when it is unable to
acquire information indicating that the communication apparatus of the
15 communication link destination is the communication apparatus supporting the VSP,
the control unit turns off the VSP setting in communication with the communication
apparatus, for example, sets it to disable or the like. When the information is
acquired, the control unit 15 may turn on the VSP setting in commuuication with the
communication apparatus, for example, set it to enable or the like.
20 [0043]
Then, the control unit 15 calculates an estimated time length until the
communication synchronization error falls within a predetermined range (hereinafter,
also referred to as a "T vsr candidate time length"). Here, the communication
synchronization error indicates, for example, a timing synchronization error with the
25 communication apparatus 10-1 with which the communication link is established, a
frequency synchronization error with the comm1mication apparatus 10-1, and a
channel estimation error with the communication apparatus 10-1. Then, the control
unit 15 calculates a time length in which the timing synchronization error with the
communication apparatus 10-1 with which the communication link is established is
30 determined to fall within a predetermined range, a time length in which the
frequency synchronization error with the communication apparatus 10-1 is
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determined to fall within a predetermined range, and a time length in which the
channel estimation error with the communication apparatus 10-1 is determined to fall
within a predetermined range. The control unit 15 may calculate only a part of the
time length as the T vsr candidate time length.
5 [0044]
Then, the control unit 15 shares the calculated T vsr candidate time length
with the communication apparatus with which the comiflunication link is established.
For example, the control unit 15 generates a frame including information indicating
each of the calculated T vsr candidate time lengths (hereinafter, also referred to as a
10 "T vsr exchange frame") to the data processing unit 11, and causes the
communication unit 12 to transmit the T vsr exchange frame to the communication
apparatus. Further, the T vsr exchange frame used for sharing of the T vsr candidate
time length will be described with reference to FIG 5. FIG 5 is a diagram
illustrating an example configuration of the T vsr exchange frame including the
15 information indicating the T vsr candidate time length according to the present
embodiment.
[0045]
As illustrated in FIG 5, the T vsr exchange frame is configured with a PLCP,
a MAC header, a frame body, and a frame check sequence (FCS), and the
20 information indicating the T vsr candidate time length may be stored in the frame
body. For example, the infonnation indicating the T vsr candidate time length may
be configured with an Action Category, an Action ID (identification), and a My T vsr
Value. For example, a category of information, for example, "VSP," is stored in the
Action Category, a type of information within the category, for example, "VSP
25 Condition Notify," is stored in the Action ID, and a value of the information, that is,
the information indicating the T vsr candidate time length, is stored in the My T vsr
Value.
[0046]
Returning to the description of the configuration of the communication
30 apparatus I 0-1 according to the present embodiment with reference to FIG. 4, the
control unit 15 then decides a time in which the communication synchronization
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error falls within a predetermined range on the basis of the time lengths received
from the communication apparatus with which the communication link is established
and the calculated time lengths. For example, the control unit 15 selects the time
length shorter than other time lengths among the time lengths indicated by the
5 information included in the received frame and the calculated time lengths as a
predetermined timeT vsr used in the PLCP selection process.
[0047]
(PLCP selection function)
The control unit 15 selects the PLCP to be added to the frame to be
10 transmitted as a part of the processing unit. Specifically, the controlm1it 15 selects
the PLCP so that a frame including the training signal is generated as a frame of a
first format, or a frame not including at least a part of the training signal is generated
as a frame of a second format. For example, the control unit 15 selects either the
PLCP of the related art or the VSP.
15 [0048]
More specifically, the control unit 15 selects the VSP when a condition
related to a transmission time of a frame serving as a first condition is satisfied. For
example, the control unit 15 selects the VSP when a predetermined time does not
elapse after a frame to which the PLCP of the related art is added (hereinafter, also
20 refened to as an "original frame") is transmitted, and a transmission time of the
frame to be transmitted is known to the destination of the frame to be transmitted.
The transmission time may have a temporal width.
[0049]
The data processing unit 11 generates a frame on the basis of the PLCP
25 selected by the control unit 15. Specifically, the data processing unit 11 generates
the original frame or the frame to which the VSP is added (hereinafter, also referred
to as a "VSP frame"). Further, a VSP frame generation process of the data
processing unit 11 will be described with reference to FIGS. 6A and 6B. FIG. 6A is
a diagram illustrating an example of a VSP frame according to the present
30 embodiment, and FIG. 6B is a diagram illustrating an example of a VSP frame
having a shorter PLCP than the VSP frame illustrated in FIG. 6A. Further, FIG. 6C
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is a diagram illustrating an example of a VSP frame having a shorter PLCP than the
VSP frame illustrated in FIG. 6B.
[0050]
The data processing unit 11 generates a frame in which the training signal
5 for the backward compatibility is not included. For example, when the frame is
transmitted to the destination of the legacy mode frame after the legacy mode frame
is transmitted, the data processing unit 11 generates a VSP frame configured with a
PLCP including an L-SIG, an Ext-SIG, an Ext-STF, an Ext-LTF, and a Service
without including the L-STF and the like (hereinafter, also referred to as "VSP1")
10 and a PSDU (hereinafter, also referred to as a "VSPl frame") as illustrated in FIG.
6A.
[0051]
Further, the data processing unit 11 generates a frame configured with a
signal including information related to a data part of the frame and the data part.
15 For example, when the mixed mode frame or the VSPl frame is transmitted, and
then the frame is further transmitted to the transmission destination of the frame, the
data processing unit 11 generates a VSP frame configured with a PLCP including an
SIG and a Service without including the entire training signal such as the L-STF or
the Ext-STF (hereinafter, also referred to as "VSP2") and a PSDU (hereinafter, also
20 refetred to as a "VSP2 frame") as illustrated in FIG. 6B.
[0052]
Further, the data processing unit 11 generates a frame configured with only
the data part of the frame. For example, when the mixed mode frame or VSPl
frame is transmitted, and then the frame is further transmitted to the transmission
25 destination of the frame, the data processing unit 11 generates a VSP frame
confignred with a PLCP including only a Service without including the entire
training signal such as the L-STF or the Ext-STF and an SIG (hereinafter, also
referred to as "VSP3") and a PSDU (hereinafter, also referred to as a "VSP3 frame")
as illustrated in FIG. 6C.
30 [0053]
(Reception method selection function)
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The communication unit 12 receives the frame serving as the frame of the
first format including the training signal and the frame serving as the frame of the
second format not including at least a pmi of the training signal. Specifically, the
communication unit 12 performs the process of receiving the original frame and the
5 VSP frame. Further, when a predetennined time elapses after the original frame is
received, the communication unit 12 receives only the original fraJne.
[0054)
<2-2. Process of communication apparatus>
Next, a process of the communication appm·atus 10-1 according to the
10 present embodiment will be described with reference to FIGS. 7 to 9.
[0055)
(PLCP selection process)
First, the PLCP selection process will be described with reference to FIG 7.
FIG. 7 is a flowchart conceptually illustrating the PLCP selection process of the
15 communication apparatus 10-1 according to the present embodiment.
[0056)
First, the communication apparatus 10-1 determines whether a reception
time of the frame to be transmitted is known to the reception side (step S102).
Specifically, the control unit 15 determines whether or not an immediate response to
20 the fraJne to be transmitted is requested from another communication apparatus 1 0-1.
For example, the control unit 15 determines whether or not an immediate response
request is previously received from the destination of the frame to be transmitted or
whether or not an immediate response request is included in a fraJne serving as a
response to the original fraJne from the transmission destination.
25 [0057)
When the immediate response is requested, the control unit 15 causes the
communication unit 12 to transmit the fraJne when a predetermined time known to
the communication apparatus I 0-1 elapses after the frame is received from the
transmission destination. For exaJnple, the predetermined time is an inter frame
30 space (IFS) such as a short inter fraJne space (SIFS). Therefore, the communication
apparatus 10-1 which is the destination of the fraJnc to be transmitted can detect the
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reception time of the VSP frame more accurately and reduce a possibility of the
reception of the VSP frame failing.
[0058]
Further, in a process of this step, the control unit 15 may determine whether
5 or not transmission of the frame to be transmitted is permitted when a predetermined
time elapses after reception of a frame received later than other frames. In this case,
it can be estimated that the reception time of the frame to be transmitted is known to
the destination even if the transmission source of the frame received immediately
before its own apparatus transmits the frame differs from the destination of the frame
10 to be transmitted.
[0059]
When the reception time of the frame to be transmitted is determined to be
known to the reception side, the communication apparatns I 0-1 determines whether
or not a predetermined time T vsP elapses after the training signal is transmitted to the
15 destination of the frame to be transmitted (Step S104). Specifically, in the
parameter decision process, the control unit 15 detennines whether or not the time
T vsP decided as the time in which the communication synchronization error falls
within a predetermined range elapses.
20
[0060]
When the predetermined time T vsP is determined not to elapse after the
training signal is transmitted to the destination of the frame to be transmitted, the
communication apparatus 10-1 determines whether or not there is a non-transmitted
training signal (step S106). Specifically, the control unit 15 determines whether or
not the mixed mode frame or the VSP1 frame has been transmitted to the destination
25 of the frame to be transmitted in the previous frame transmission.
[0061]
When it is determined that there is no non-transmitted training signal, the
communication apparatns 10-1 adds the PLCP (VSP2) not including the training
signal or the PLCP (VSP:i) including only the Service to the frame to be transmitted
30 (step S108). Specifically, the control unit 15 selects VSP2 when it is determined
that the mixed mode frame or the VSP 1 frame has been transmitted to the destination
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of the frame to be transmitted in the previous frame transmission. Then, the data
processing unit 11 generates a frame to which the VSP2 is added.
[0062]
Further, when the condition for selecting the VSP2 is satisfied, and the
5 information related to the data part of the frame to be transmitted is uniquely decided,
the control unit 15 may select the VSP3. For example, when the infonnation
related to the data part of the fi·ame to be transmitted is shared between its own
apparatus and the destination of the frame to be transmitted in advance, the control
unit 15 selects the VSP3. In this case, the data processing unit 11 generates a frame
10 to which the VSP3 is added.
[0063]
When it is determined that there is a non-transmitted training signal, the
communication apparatus 10-1 adds the PLCP (VSP1) including the non-transmitted
training signal to the frame to be transmitted (step S110). More-specifically, the
15 control unit 15 selects VSP 1 when it is determined that the legacy mode frame has
been transmitted to the destination of the frame to be transmitted in the previous
frame transmission. Then, the data processing unit 11 generates a frame to which
the VSP1 is added.
20
[0064]
When it is determined in step S 1 02 that the reception time of the frame to be
transmitted is not known to the reception side or when it is determined in step S 104
that the predetermined time T vsP elapses after the training signal is transmitted to the
destination of the frame to be transmitted, the communication apparatus 10-1 adds
the PLCP of the related art to the frame to be transmitted (step S112). Specifically,
25 the control unit 15 selects the legacy mode or the mixed mode, and the data
processing unit 11 generates the mixed mode frame.
[0065]
(Reception method selection process)
Next, a reception method selection process will be described with reference
30 to FIG. 8. FIG. 8 is a flowchart conceptually illustrating the reception method
selection process of the communication apparatus 1 0-1 according to the present
!i
ri
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embodiment.
[0066]
First, the commnnication apparatus I 0-1 determines whether or not the
predetermined time T vsr elapses after the frame is received from the VSP-supporting
5 apparatus (step S202). Specifically, the control nnit 15 determines whether or not
T vsr elapses after the ii·ame is received from the communication apparatus 1 0-1
related to communication in which the VSP setting is not disabled.
[0067]
When the predetermined time T vsr is determined to elapse after the frame is
10 received from the VSP supporting apparatus, the communication apparatus 10-1 is on
standby only for the frame including the PLCP of the related art (step S204).
Specifically, when T vsr is determined to elapse after the frame is received from the
commnnication apparatus 10-1 related to the commnnication in which the VSP
setting is not disabled, the control unit 15 causes a state of the commnnication nnit
15 12 to transition to a state in which only the process of receiving the frame including
the PLCP of the related art is performed. Further, when the VSP frame is received
in the state in which only the process of receiving the frame including the PLCP of
the related art is performed, the commnnication nnit 12 does not perform the process
of receiving the VSP frame because the frame format is different.
20 [0068]
When the predetermined time T vsr is determined not to elapse after the
frame is received from the VSP supporting apparatus, the communication apparatus
1 0-1 is on standby for both the frame including the PLCP of the related art and the
frame including the VSP (step S206). Specifically, when T vsr is determined not to
25 elapse after the frame is received from the commnnication apparatus 10-1 related to
the commnnication in which the VSP setting is not disabled, the control unit 15
causes the state of the communication nnit 12 to transition to the state in which the
30
process of receiving the frame including the VSP is performed. In the process of
receiving the VSP frame, information obtained from the received training signal, for
example, a charmel estimation value (including a gain set value) is used.
[0069]
: lc_ _______ -~----···-·------~-~~~------"=
SP:361950WOOO
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(Specific example of communication)
Next, a specific example of communication performed according to the
process of FIGS. 7 and 8 will be described with reference to FIG. 9. FIG. 9 is a
diagram illustrating an example of a frame exchange sequence performed in the
5 communication system according to the present embodiment.
[0070]
First, a master unit 10-1 #0 transmits- the legacy mode transmission
permission request frame to slave units 10-1#1 and 10-1#2. Then, the slave unit 10-
1#1 that has received the frame transmits the legacy mode transmission permission
10 frame to the master unit 10-1#0. The mixed mode may be selected instead of the
legacy mode.
[0071]
Then, the master unit 10-1 #0 that has received the transmission permission
frame transmits the data frame which is the VSP1 frame to the slave unit 10-1#1.
15 Then, the slave unit 10-1 #1 that has received the frame transmits an ACK frame
which is the VSP1 frame to the master unit 10-1#0.
[0072]
Then, the master unit 10-1 #0 transmits the mixed mode frame to the slave
unit 10-1 #2. Then, the slave unit I 0-1 #2 that has received the frame transmits a
20 mixed mode ACK frame to the master unit 10-1#0. Instead of the mixed mode
frame, the legacy mode frame may be transmitted, but in this example, the mixed
mode frame is described as being transmitted.
[0073]
Then, the master unit I 0-1 #0 transmits the data frame which is the VSP2
25 frame to the slave unit I 0-1 # 1. Then, the slave unit 10-1 #I that has received the
frame transmits an ACK frame which is the VSP2 frame to the master unit 10-1 #0.
Here, the original frame and the VSP frame transmitted and received between the
master unit 10-1 #0 and the slave unit 10-1 # 1 are also received by other
communication apparatuses 10-1. Therefore, the slave unit 10-1 # 1 receives the
30 ACK frame transmitted from the slave unit 10-1 #2 to the master unit 10-1 #0 and can
detect the reception time of the data frame destined for the slave unit 1 0-1 # 1 which is
------------··
SP361950WOOO
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transmitted from the master unit 10-1 #0.
[0074]
Then, the master unit 10-1 #0 transmits the data frame which is the VSP2
frame to the slave unit 10-1 #2. Then, the slave unit 10-1 #2 that has received the
5 frame transmits anACK frame which is the VSP2 frame to the master unit 10-1#0.
[0075]
As described above, according to the first embodiment of the present
disclosure, the communication apparatus 10-1 selects any one of the fi·ame of the
first format including the training signal and the frame of the second format
10 including no first field which is at least a part of the training signal, generates the
frame of the selected format, and transmits the frame of the first format or the frame
of the second format. Further, the communication apparatus 10-1 receives the
frame of the first format including the training signal or the frame of the second
format including no first field which is at least a part of the training signal. For this
15 reason, it is possible to reduce the overhead of communication while suppressing
influence on the frame reception process since the already transmitted training signal
is not included in the PLCP.
[0076]
Further, at least a part of the training signals includes the training signal for
20 backward compatibility. For this reason, for example, when the mixed mode frame
including the training signal for backward compatibility is used and the legacy mode
frame is already transmitted, the PLCP is shortened, and the overhead of
comt11unication can be reduced.
25
[0077]
Further, the frame of the second format is configured with the signal
including information related to the data part of the frame and the data part and does
not include the training signal. Therefore, since the training signal is not included,
the PLCP can be further shortened, and the overhead of communication can be
further reduced.
30 [0078]
Further, the frame of the second format is configured with only the data part
5
SP361950WOOO
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of the frame and does not include the signal including the information related to the
data part and the training signal. Therefore, the PLCP is further shortened, and thus
it is possible to further reduce the overhead of communication.
[0079]
Further, the communication apparatus I 0-1 selects the frame of the second
format when the first condition related to the transmission time of the frame to be
transmitted is satisfied. Therefore, when the above condition is set so that the
reception success rate of the VSP frame is improved, it is possible to suppress the
reception failure of the VSP frame and improve the use efficiency of the wireless
10 communication resources.
[0080]
Further, the first condition includes that the transmission time of the frame
to be transmitted be before a predetermined time elapses after the frame of the first
format is transmitted to the destination of the frame to be transmitted. For this
15 reason, when the communication state changes over time and the use of the received
training signal is undesirable, the VSP frame is not transmitted, and thus the decrease
in the reception success rate of the VSP frame can be suppressed.
[0081]
Further, it is included that the predetermined time be a time in which the
20 communication synchronization error falls within a predetermined range. Therefore,
when the VSP frame is transmitted within the time in which the communication
success rate is maintained, it is possible to further suppress the decrease in the
reception success rate of the VSP frame.
25
[0082]
Further, it is included that the predetermined time be a time shorter than the
other time among times decided by the transmission destination of the frame of the
first format and its own apparatus. For this reason, when the transmission condition
of the VSP frame is set so that the communication synchronization error falls within
an allowable range in both of the communication apparatuses, it is possible to further
30 suppress the decrease in the reception success rate of the VSP frame.
[0083]
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Further, the first condition includes a condition that the transmission time of
the frame to be transmitted be known to the destination of the frame to be transmitted.
Therefore, the communication apparatus 10-1 that receives the VSP frame can be on
standby in the state in which the process of receiving the VSP frame is possihle, and
5 it is possible to suppress the occurrence of the reception failure of the VSP frame.
[0084]
Further, the firsT condition includes that the frame of the first format and the
frame of the second format also be received by other communication apparatuses
other than the transmission destination of the frame of the first format. For this
10 reason, the communication apparatus 10-1 in the non-communication state can detect
a timing at which the frame is transmitted to the communication apparatus I 0-1
without separately performing the communication of notifying of the transmission
timing, and it is possible to improve the efficiency of communication while
suppressing the occurrence of the reception failure of the VSP frame.
15 [0085]
Further, "being known" mentioned above includes that the transmission of
the frame to be transmitted be permitted when a predetermined time elapses after
reception of a frame received later than other frames. Therefore, the
communication apparatus 10-1 serving as the destination of the frame to be
20 transmitted can detect the reception time of the VSP frame more accurately and
reduce the possibility of the reception failure of the VSP frame.
[0086]
Further, "being known" mentioned above includes that the frame received
from another communication apparatus indicate the immediate response request.
25 Therefore, since the transmission time of the frame to be exchanged is more
accurately detected, it is possible to further suppress tbe occurrence of the reception
failure of the VSP frame.
[0087]
Further, when a predetermined time elapses after the frame is received, the
30 communication apparatus 10-1 receives only the frame of the first format.
Therefore, in the state in which it is not desirable to use the received training signal,
------------ -------------
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the process of receiving the VSP frame is not performed, and thus a load related to
the reception process is reduced, and the power consumption of the communication
apparatus 10-1 can be suppressed. The communication apparatus 10-1 may be
consistently on standby for both the original frame and the VSP frame. In this case,
5 since switching of the standby process is not performed, the process can be
simplified.
[0088]
<2-3. Modified examples>
The first embodiment of the present disclosure has been described above.
10 Note that this embodiment is not limited to the above examples. Modified
examples of the first and second embodiments will now be described.
[0089]
(First modified example)
As a first modified example of the present embodiment, the VSP frame may
15 be transmitted when the first condition related to the transmission time of the fi'ame
is satisfied and the communication apparatus 10-1 other than the destination of the
frame to be transmitted or its own apparatus is in the state in which the frame is not
transmitted. Further, the VSP frame may be transmitted when the first condition
related to the transmission time of the frame is satisfied and the transmission period
20 length of the frame to be transmitted is a threshold value or less. A process of the
communication apparatus 10-1 according to the present modified example will be
described with reference to FIG. 10. FIG. 10 is a flowchart conceptually illustrating
the PLCP selection process of the communication apparatus 10-1 according to the
first modified example of the present embodiment. Further, description of
25 processes that are substantially the same as the processes according to the first
embodiment is omitted.
[0090]
First, the communication apparatus 10-1 determines whether or not the
reception time of the frame to be transmitted is known to the reception side (step
30 S302).
[0091]
SP361950WOOO
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When the reception time of the frame to be transmitted is determined to be
known to the reception side, the communication apparatus 10-1 determines whether
or not the transmission period length of the frame to be transmitted is a threshold
value or less (step S304). Specifically, the control unit 15 determines whether or
5 not the transmission period length other than the PLCP part of the frame to be
transmitted, that is, the transmission period length other than the PLCP preamble and
the PLCP header, is a threshold value or less. Further, the control unit 15 may
perform the determination using a data length, for example, a byte length instead of
the transmission period length.
10 [0092]
When the transmission period length of the frame to be transmitted is
determined to be a threshold value or less, the communication apparatus 10-1
determines that it is a transmission suppression period indicated by a signal for
suppressing the frame transmission of the communication apparatus 1 0-1 other than
15 the destination of the frame to be transmitted and its own apparatus (step S306).
Specifically, the control unit 15 determines whether or not the transmission
permission request frame and the transmission permission frame to the transmission
permission request frame are exchanged before the transmission of the frame to be
transmitted. For example, the control unit 15 transmits the RTS frame, and
20 determines whether or not the CTS frame indicating that transmission to its own
apparatus is permitted is received as the response to the RTS frame. In this case,
since a network allocation vector (NAV) is set in communication apparatuses 10-1
that receive the CTS frame other than its own apparatus, the frame transmission of
other communication apparatuses 10-1 is suppressed in a period in which the NAV is
25 valid. Further, the NAV setting according to the embodiment of the present
disclosure may be performed by an exchange of a frame other than the RTS frame
and the CTS frame. For example, the NAV may be set by a DATA frame (including
a Quality of Service (QoS) DATA frame as well) and an ACK (including a block ack
frame as well) instead of the RTS frame or the CTS frame.
30 [0093]
When the frame transmission of the communication apparatus 10-1 other
:iL__ ______ _
SP:J61950WOOO
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than the destination of the frame to be transmitted and its own apparatus is
determined to be suppressed, the communication apparatus 1 0-1 determines whether
or not a predetermined time T vsr elapses after the training signal is transmitted to the
destination of the frame to be transmitted (step S308), and performs the process of
5 adding the PLCP in accordance with a determination result (steps S312 and S314).
[0094]
When it is detennined in step S304 that the transmission period length of the
frame to be transmitted is greater than the threshold value or when it is determined in
step S306 that the frame transmission of the communication apparatus I 0-1 other
10 than the destination of the frame to be transmitted and its own apparatus is not
suppressed, the communication apparatus 10-1 adds the PLCP of the related art to the
frame to be transmitted (step S316).
[0095]
As described above, according to the first modified example of the present
15 embodiment, the first condition includes that it be the transmission suppression
period indicated by the signal which is exchanged between the destination of the
frame to be transmitted and its own apparatus and used for suppressing the frame
transmission of communication apparatuses other than the destination of the frame to
be transmitted and its own apparatus. Here, when the frame transmission from
20 other communication apparatuses 10-1 is permitted, a mismatch occurs between the
type of frame transmitted from the master unit and the type of frame Jor which the
slave unit is on standby, and the possibility of the reception failure of the VSP fi·ame
mcreases. Therefore, when the frame transmission of other communication
apparatuses 1 0-1 is suppressed, it is possible to suppress the decrease in the reception
25 success rate ofthe VSP frame.
[0096]
Further, in the communication apparatus 10-1, the first condition includes
that the transmission period length of the frame to be transmitted be a threshold value
or less. Here, as the transmission period length of the frame to be transmitted
30 increases, that is, as the amount of data to be transmitted increases, the risk of frame
reception failure, for example, influence of the increase in consumption of wireless
'--------~·----~·-----------------
SP361950WOOO -
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communication resources and the increase in the transmission period which are
caused by the occurrence of retransmission, increases. Therefore, when the frame
transmission period length exceeds the threshold value, the frame transmission of the
VSP frame is not performed, and thus the risk can be prevented.
5 [0097]
(Second modified example)
As a second modified example of the present embodiment, the
communication apparatus 10-1 may check whether or not the transmission time of
the frame to be transmitted is known to communication apparatuses 1 0-1 other than
10 the communication apparatus 10-1 in the communication state. Specifically, the
control unit 15 causes the communication unit 12 to transmit the transmission
permission request to other communication apparatuses 10-1, and when the
transmission permission is received in response to the transmission permission
request from other communication apparatuses 10-1, the transmission time of the
15 frame to be transmitted is detennined to be known to the other communication
apparatus 10-1.
[0098]
For example, the control unit 15 causes the communication unit 12 to
transmit the RTS frame to other communication apparatuses 10-1 before the PLCP
20 selection process is performed. When the CTS frame is received as the response to
the RTS frame, the control unit 15 determines that the transmission time of the frame
to be transmitted is known to the transmission destination of the CTS frame.
[0099]
As described above, according to the second modified example of the
25 present embodiment, the communication apparatus 1 0-1 transmits the transmission
permission request to other communication apparatuses, and the first condition
includes that the transmission permission be received from other communication
apparatuses in response to the transmission permission request. Therefore, it is
possible to suppress the situation in which the VSP frame is transmitted to other
30 communication apparatuses 10-l, and the reception of the VSP frame fails in the
state in which other communication apparatuses 1 0-1 are unable to detect the
SP861950WOOO
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transmission timing of the VSP frame and are not on standby for the VSP frame.
[01 00]
<3. Second embodiment (example in which requested PLCP is selected)>
The communication apparatus I 0-1 according to the first embodiment of the
5 present disclosure has been described above. Next, a communication apparatus I 0-
2 according to the second embodiment of the present disclosure will be described.
The communication apparatus I 0-2 -according to the present embodiment selects the
PLCP to be added to the frame to be transmitted on the basis of a request from a
communication partner.
10 [0101]
<3-1. Configuration of communication apparatus>
The communication apparatus 10-2 has substantially the same functional
configuration as that of the first embodiment, except for a portion of the functions of
the data processing unit 11, the communication unit 12, and the control unit 15.
15 Note that substantially the same functions as those of the first embodiment will not
be described.
[0102]
(PLCP designation frmction)
The control unit 15 designates the PLCP to be added to the frame
20 transmitted from the communication destination to its own apparatus. Specifically,
the control unit 15 makes a decision regarding a VSP frame use request on the basis
of a certain condition related to the transmission time of the frame serving as a
second condition.
25
[0103]
For example, the control unit 15 makes a decision for requesting the
transmission of the VSP frame when the transmission time of the frame including
information related to the use request is before a predetermined time elapses after the
original frame is received, and the transmission time of the frame to be received as
the response to the frame including the information related to the use request is
30 known to its own apparatus. Further, the control unit 15 decides the type of VSP
frame, that is, VSPl, VSP2, or VSP3, when the decision related to the presence or
29/63
absence of the VSP frame use request is made.
[0104]
SP:3G1950WODO
The data processing unit 11 generates a frame including a VSP frame use
request. Specifically, the data processing unit 11 generates a frame including
5 information indicating the presence or absence of the VSP frame use request and the
type of VSP frame decided by the control unit 15. The frame including the VSP
frame use request will be described with reference to FIG. 11. FIG. 11 is a diagram
illustrating an example of the frame including the VSP frame use request according
to the present embodiment.
10 [0105]
The data processmg unit 11 generates a frame including information
indicating the presence or absence of the use request and the type. For example, the
information related to the use request includes a flag indicating the presence or
absence of the use request and the type (hereinafter, also referred to as a "use request
15 flag"), for example, VSP req illustrated in FIG. 11, and may be stored in a Service
field of the frame. A storage location of the use request flag is not limited thereto,
and the use request flag may be stored in any other field, for example, a SIGNAL
field, a Reserve field of a MAC header, or any other field dedicated thereto. Further,
the use request flag indicates that there is no use request when the value is 0, that the
20 VSPI frame is requested when the value is I, that the VSP2 frame is requested when
the valne is 2, and that the VSP3 frame is requested when the value is 3.
[0106]
(PLCP selection function)
The control unit 15 selects the PLCP on the basis of the information related
25 to the use request included in the received frame. Specifically, the control unit 15
selects the VSP when the transmission time of the frame to be transmitted is known
to the destination of the frame to be transmitted, and the transmission of the VSP
frame is requested through the information related to the received use request.
VSPI, VSP2 or VSP3 is selected on the basis of the type of VSP indicated by the
30 information related to the use request.
[0107]
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(Reception method selection function)
The communication unit 12 selects the process of receiving the frame to be
transmitted on the basis of the use request to respond to the use request decided by
the control 1mit 15. Specifically, the communication unit 12 is on standby for a
5 fi·ame of a type indicated by the information related to the use request included in the
transmitted frame. For example, the communication unit 12 is on standby for the
original frame when the value of the usc request flag is 0, on standby for the VSPl
frame when the value is I, on standby for the VSP2 frame when the value is 2, and
on standby for the VSP3 frame when the value is 3.
10 [0108]
<3-2. Process of communication apparatus>
Next, a process of the communication apparatus 10-2 according to the
present embodiment will be described with reference to FIGS. 12 to 14.
[0109]
15 First, a PLCP designation process and a PLCP selection process will be
described with reference to FIG 12. FIG 12 is a flowchart conceptually illustrating
the PLCP designation process and the PLCP selection process of the communication
apparatus 10-2 according to the present embodiment. Further, description of
processes that are substantially the same as the processes of the first embodiment will
20 be omitted.
[0110]
(PLCP designation process)
First, the communication apparatus I 0-2 determines whether or not the
reception time of the response frame to the frame to be transmitted is known (step
25 S402). Specifically, the control unit 15 determines whether or not the immediate
response request is transmitted to the transmission destination of the frame to be
transmitted. When the immediate response is a fixed setting common to the
communication apparatuses 10-2, the process of this step may be omitted.
30
[0111]
When the reception time of the response frame to the frame to be
transmitted is determined to be known, the communication apparatus 10-2
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determines whether or not the transmission of apparatuses other than the destination
of the frame to be transmitted and its own apparatus is suppressed (step 8404).
[0112]
When the transmission of apparatuses other than the destination of the frame
5 to be transmitted and its own apparatus is determined to be suppressed, the
communication apparatus 10-2 detennines whether or not a predetermined time T vsr
elapses after the training signal is received from the destination of the frame to be
transmitted (Step S406).
10
[0113]
When a predetermined time T vsr is determined not to elapse after the
training signal is received from the destination of the frame to be transmitted, the
communication apparatus 10-2 designates the VSPas the PLCP used for the response
frame (step S408). Specifically, the control unit 15 detetmines the presence or
absence oCa non-transmitted training signal, selects VSP 1 when there is a non-
15 transmitted training signal, and designates "1" as the value of the use request flag.
If there is no non-transmitted training signal, the control unit 15 selects VSP2 and
designates "2" as the value of the use request flag.
[0114]
When the condition for selecting VSP2 is satisfied and the information
20 related to the data part of the frame to be transmitted is uniquely decided, the control
unit 15 may select VSP3 and set "3" as the value of the use request flag.
[0115]
When a predetermined time T vsP is determined to elapse after the training
signal is received. from the destination of the frame to be transmitted, the
25 communication apparatus 10-2 designates the PLCP of the related art as the PLCP
used for the response frame (step S410). Specifically, the control unit 15 selects the
PLCP of the related art and designates "0" as the value of the use request flag.
[0116]
(PLCP selection process)
30 Then, the communication apparatus 10-2 determines whether or not the
reception time of the frame to be transmitted is known to the reception side (step
8412).
[0117]
32/63
SP3Gl950WOOO
When the reception time of the frame to be transmitted is determined to be
known to the reception side, the communication apparatus 1 0-2 dete1mines whether
5 or not the VSP is designated in the frame most recently received from the destination
of the frame to be transmitted (step S414). Specifically, the control unit 15 acquires
the use request flag of the frame which is received later-than any of other received
frames before the process of this step, and determines whether or not the value of the
use request flag is 0.
10 [0118]
When the VSP is determined to be designated in the frame most recently
received from the destination of the frame to be transmitted, the communication
apparatus 10-2 adds the VSP designated in the received frame to the frame (step
S416). Specifically, when the value of the use request flag is determined not to be 0,
15 the control unit 15 selects the VSP corresponding to the value designated by the use
request flag. For example, the control unit 15 selects VSP1 when the value of the
use request flag is 1, selects VSP2 when the value is 2, and selects VSP3 when the
value is 3. Then, the data processing unit 11 adds the VSP selected by the control
unit 15 to the frame to be transmitted.
20 [0119]
When the VSP is determined not to be designated in the frame most recently
received from the destination of the frame to be transmitted, the communication
apparatus 10-2 adds the PLCP of the related art to the frame to be transmitted (step
S418). Specifically, when the value of the use request flag is determined to be 0,
25 the control unit 15 selects the PLCP of the related art. For example, when the value
of the use request flag is 0, the control unit 15 selects the PLCP of the legacy mode
or the mixed mode. Then, the data processing unit 11 adds the PLCP selected by
the control unit 15 to the frame to be transmitted.
[0120]
30 (Reception method selection process)
il
!I,________~
Next, the reception method selection process will be described with
----------------
SP;3Gl950WOOO
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reference to FIG. 13. FIG. 13 is a flowchart conceptually illustrating the reception
method selection process of the communication apparatus 10-2 according to the
present embodiment.
[0121]
5 First, the communication apparatus 10-2 determines whether or not the
frame in which the VSP is designated as the PLCP used for the response frame is
transmitted (step S502). Specifically, the control unit 15 determines whether or not
the value of the use request flag included in the transmitted frame is designated to be
0.
10 [0122]
When the frame in which the VSP is designated as the PLCP used for the
response frame is determined not to be transmitted, the communication apparatus 10-
2 is on standby for only the frame including the PLCP of the related art (step S504).
Specifically, when it is determined that the value of the use request flag is designated
15 to be 0, the control unit 15 causes the state of the communication unit 12 to transition
to the state in which the process of receiving the frame including the PLCP of the
related art is performed.
[0123]
When the frame in which the VSP is designated as the PLCP used for the
20 response frame is determined to be transmitted, the communication apparatus 10-2 is
on standby for only the frame including the VSP designated in the transmission
frame (step S506). Specifically, when it is determined that the value of the use
request flag is set to 1, the control unit 15 causes the state of the communication unit
12 to transition to the state in which the process of receiving the frame including the
25 VSP1 is performed. Further, when it is determined that the value of the use request
flag is set to 2, the control unit 15 causes the state of the communication unit 12 to
transition to the state in which the process of receiving the frame including the VSP2
is performed. Further, when it is determined that the value of the use request flag is
set to 3, the control unit 15 causes the state of the communication unit 12 to
30 transition to the state in which the process of receiving the frame including the V SP3
is performed. In the process of receiving the VSP frame, the information obtained
-------- --------
SP:361950WOOO
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from the received training signal, for example, the channel estimation value
(including the gain set value) or the like, is used.
[0124]
(Specific example of communication)
5 Next, a specific example of communication performed according to the
process of FIG. 12 and FIG. 13 will be described with reference to FIG. 14. FIG. 14
is a diagram iilustrating an example of a frame exchange sequence performed in the
communication system according to the present embodiment. Further, description
of processes that are substantially the same as the processes of the first embodiment
10 will be omitted.
[0125]
First, a master unit 1 0-2#0 transmits the legacy mode transmission
permission request frame including the use request flag having the value of 0 to slave
units 10-2#1 and 10-2#2. Then, the slave unit 10-2#1 that has received the frame
15 transmits the legacy mode transmission permission frame including the use request
flag having the value of 1 to the master unit 10-2#0.
[0126]
Then, the master unit 1 0-2#0 that has received the transmission permission
frame including the use request flag having the value of 1 transmits the data frame
20 which is the VSPl frame including the use request flag having the value of 1 to the
slave unit 10-2#1. Then, the slave unit 10-2#1 that has received the frame transmits
the ACK frame which is the VSPl frame including the use request flag having the
value of 2 to the master unit 1 0-2#0.
25
30
[0127]
Then, the master unit 10-2#0 transmits the mixed mode frame including the
use request flag having the value of 0 to the slave unit 1 0-2#2. Then, the slave unit
10-2#2 that has received the frame transmits the mixed mode ACK frame including
the use request flag having the value of 2 to the master unit 1 0-2#0.
[0128]
Then, the master unit 10-2#0 transmits the data frame which is the VSP2
frame including the use request flag having the value of 2 to the slave unit 10-2#1.
5
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Then, the slave unit 10-2#1 that has received the frame transmits the ACK frame
which is the VSP2 frame including the use request flag having the value of 2 to the
master unit I 0-2#0.
[0129]
Then, the master unit 1 0-2#0 transmits the data fi·ame which is the VSP2
frame including the use request flag having the value of 2 to the slave unit 1 0-2#2.
Then, the slave unit 1 0-2#2 that has received the frame transmits the ACK frame
which is the VSP2 frame including the use request flag having the value of 2 to the
master unit 1 0-2#0.
10 [0130]
Thus, according to the second embodiment of the present disclosure, the
communication apparatus 10-2 transmits the VSP frame when the frame including
the VSP frame use request is received. Therefore, since the PLCP is selected on the
basis of the use request of which the reception side notifies, more appropriate PLCP
15 is selected than when the PLCP is selected according to the determination of the
transmitting side, and it is possible to suppress the occurrence of the frame reception
failure caused by erroneous selection of the PLCP.
[0131]
Further, the communication apparatus 10-2 receives the frame including the
20 use request for the frame of the second format which is transmitted when a second
condition related to the transmission time of the frame is satisfied. Therefore, since
the condition for the transmission of the use request is set so that the reception
success rate of the VSP frame is improved, it is possible to suppress the reception
failure of the VSP frame and improve the use efficiency of the wireless
25 communication resources.
[0132]
The second condition includes that the transmission time of the frame
including the use request be before a predetermined time elapses after the frame of
the first format is received from the destination of the frame including the use request,
30 and that the transmission time of the frame received as the response to the frame
including the use request be known to the transmission source of the frame including
5
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the use request. Therefore, since the use request is transmitted in the situation in
which the reception success rate of the VSP frame is higher than in other conditions,
it is possible to suppress the occurrence of reception failure of the VSP frame.
[0133)
Further, one of the frame of the first format and the frame of the second
format is selected as a frame to be received, on the basis of the use request included
in the transmitted frame, and the frame of the selected format is received.
Therefore, since only the frame of the PLCP format requested by its own apparatus is
awaited, it is possible to reduce the possibility of the frame reception failure and
10 improve the communication efficiency.
[0134]
In the above example, the presence or absence of the VSP frame use request
is indicated by the flag, but the presence or absence of the use request may be
indicated depending on whether or not the information related to the use request is
15 included in the frame.
[0135]
<4. Third embodiment (example m which PLCP is selected m space division
multiplexing communication)>
The communication apparatus 10-2 related to the second embodiment of the
20 present disclosure has been described above. Next, a communication apparatus 10-
3 according to the third embodiment of the present disclosure will be described. In
the first and second embodiments, one-to-one communication between
communication apparatuses is an application target, but in the present embodiment,
one-to-many communication is an application target. First, one-to-many
25 communication according to a related art will be described with reference to FIG. 15.
FIG. 15 is a diagram illustrating an example of a frame exchange sequence
performed in one-to-many communication according to a related art.
[0136]
First, the master unit transmits the legacy mode transmission permission
30 request frame. For example, as illustrated in FIG. 15, the master unit 10#0 transmits
the RTS fran1e to which the PLCP of the legacy mode is added to the slave unit 1 0# 1.
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[0137]
Then, the slave unit that has received the transmission permission request
frame transmits the legacy mode transmission permission frame to the master unit.
For example, as illustrated in FIG. 15, the slave unit 1 0#1 transmits the CTS frame to
5 which the PLCP of the legacy mode is added to the master unit 1 0#0.
[0138]
Then, the master unit that has received the transmission permission frame
generates a plurality of data frames, and transmits the data frames to which the PLCP
of the mixed mode common to the generated data frames is added to the slave unit
10 using multiplexing communication. For example, as illustrated in FIG. 15, the
master unit 10#0 transmits a plurality of data frames DATA #01 to DATA #04 to
which the PLCP of the mixed mode is added to the slave units 1 0# 1 to 1 0#4 using
space division multiplexing communication. Then, the PLCP of the mixed mode is
added to the frame to be exchanged later.
15 (0139]
As described above, even in the case of one-to-many communication, the
PLCP preamble is added to the frame each time communication is performed, and
there are cases in which an unnecessary PLCP preamble is transmitted.
Furthermore, since a plurality of communication apparatuses transmit the frames, the
20 reduction in efficiency of wireless communication resources may be greater than in
the case of one-to-one communication. Therefore, the communication apparatus
10-3 according to the present embodiment is based on the communication apparatus
according to the first embodiment, and uses a common VSP as the PLCP of the
frames to be multiplexed.
25 [0140]
<4-1. Configuration of communication apparatus>
First, a configuration of the communication apparatus 10-3 according to the
third embodiment of the present disclosure will be described with reference to FIG.
16. FIG. 16 is a block diagram illustrating a schematic functional configuration of
30 the commw1ication apparatus 10-3 according to the third embodiment of the present
disclosure. Further, description of components and functions which are
38/63
substantially the same as in the first embodiment will be omitted.
[0 141]
SP361950WOOO
As illustrated in FIG. 16, the communication unit 12 includes a signal
processing unit 16 in addition to the modulation/demodulation unit 13 and the radio
5 interface unit 14.
[0142]
The signal processing unit 16 performs a process involved in space-division
multiplex communication. Specifically, the signal processing unit 16 performs a
signal process involved in space separation, on a symbol stream provided by the
10 modulation/demodulation unit 13, and provides symbol streams obtained by the
processto the respective radio interface units 14. The signal processing unit 16 also
performs a spatial process, such as a symbol stream separation process or the like, on
symbol streams obtained from the radio interface units 14, and provides a symbol
streamobtained by the process to the modulation/demodulation unit 13.
15 [0143]
The data processing unit 11 generates a plurality of frames and adds a PLCP
common to the plurality of frames. Specifically, the data processing unit 11
generates frames destined for a plurality of communication apparatuses 10-3, and
adds the PLCP selected by the control unit 15 to the generated frames in common.
20 [0144]
<4-2. Process of communication apparatus>
Next, a process of the communication apparatus 10-3 according to the
present embodiment will be described. The process is substantially the same as the
process according to the first embodiment except for the PLCP selection process, and
25 thus only the PLCP selection process will be described with reference to FIG. 17.
FIG. 17 is a flowchart conceptually illustrating the PLCP selection process of the
communication apparatus 1 0-3 according to the present embodiment. Further,
description of processes that are substantially the same as the processes of the first
embodiment will be omitted.
30 [0145]
(PLCP selection process)
5
10
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First, the communication apparatus 10-3 determines whether or not the
reception time of the frame to be transmitted is known to the reception side (step
S602).
[0146]
When the reception time of the frame to be transmitted is determined to be
!mown to the reception side, the communication apparatus 10-3 determines whether
or not the transmission of apparatuses other than the destination of the frame to be
transmitted and its own apparatus is suppressed (step S604).
[0147]
When the transmission of apparatuses other than the destination of the frame
to be transmitted and its own apparatus is determined to be suppressed, the
communication apparatus 10-3 determines whether or not a predetermined time T vsr
elapses after the training signal is transmitted to any one of the destinations of the
frame to be transmitted (step S606). Specifically, for each of the communication
15 apparatuses 10-3 that is the destination of the frame to be transmitted, the control unit
15 determines whether or not T vsr elapses after the training signal is transmitted to
each of the communication apparatuses 10-3, that is, after the original frame is
transmitted. T vsr is decided and managed for each communication link with the
communication apparatus 10-3.
20 [0148]
When a predetermined time T vsr is determined not to elapse after the
training signal is transmitted to all the destinations of the frame to be transmitted, it
is determined whether or not there is a non-transmitted training signal (step S608).
The control unit 15 does not select VSP unless a predetermined time T vsr is
25 determined not to elapse after the training signal is transmitted to all the destinations
of the frames to be transmitted.
[0149]
If it is determined that there is no non-transmitted training signal, the
communication apparatus 10-3 adds the PLCP not including the training signal to the
30 frame to be transmitted (step S610). Specifically, the control unit 15 selects VSP2
when the mixed mode frame or the VSP1 frame is determined to be transmitted to
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the destination of the frame to be transmitted in the previous frame transmission.
Then, the data processing unit 11 adds VSP2 to each of the generated frames destined
for a plurality of communication apparatuses 10-3.
[0 150]
5 If it is determined that there is a non-transmitted training signal, the
communication apparatus 10-3 adds the PLCP including the non-transmitted training
to the frame to be transmitted (step 8612). Specifically, the control unit 15 selects
VSP 1 when the legacy mode frame is determined to be transmitted to the destination
of the frame to be transmitted in the previous frame transmission. Then, the data
10 processing unit 11 adds VSPI to each of the generated frames destined for a plurality
of communication apparatuses I 0-3.
[0151]
When the determination results of step 8602 and step 8604 are false and the
determination result of step 8606 is true, the communication apparatus 10-3 adds the
15 PLCP of the related art to the frame to be transmitted (step S614). Specifically, the
control unit 15 selects the legacy mode or the mixed mode, and the data processing
unit 11 adds the PLCP of the mixed mode to each of the generated frames destined
for a plurality of communication apparatuses 10-3.
[0152]
20 (Specific exan1ple of communication)
Next, a specific example of communication performed according to the
process of FIG. 17 and the like will be described with reference to FIG. 18. FIG. 18
is a diagram illustrating an example of frame exchange sequence performed in the
communication system according to the present embodiment. Further, description
25 of processes that are substantially the same as the processing of the first embodiment
will be omitted.
[0 153]
First, a master unit 10-3#0 transmits the legacy mode transmission
permission request frame to a slave unit I 0-3# 1. Then, the slave unit 1 0-3# 1 that
30 has received the frame transmits the legacy mode transmission permission frame to
the master unit 1 0-3#0.
SP361950WOOO
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[0154]
Then, the master unit 10-3#0 that has received the transmission permission
frame generates the data frame destined for the slave units 10-3#1 to 10-3#4, and
transmits the frames to which the PLCP of the mixed mode common to the data
5 frames is added to the slave units 10-3#1 to 10-3#4 using space division multiplexing
communication. Each of the slave units 10-3#1 to 10-3#4 that have received the
frame transmits the ACK frame that is the VSPI frame to the master unit 1 0-3#0.
Since the ACK frames are consequently multiplexed, the master unit 1 0-3#0 receives
the ACK frame by performing a process of separating the multiplexed ACK frame.
10 [0155]
Then, the master unit 1 0-3#0 generates the data frames destined for the
slave units 10-3#1 to 10-3#4, and transmits the frames to which the VSP2 common
to the data frames is added to the slave units 10-3#1 to 10-3#4 using space division
multiplexing communication. Eacli of the slave units 10-3# 1 to 10-3#4 that have
15 received the frame transmits the ACK frame to which VSP2 is added to the master
unit 10-3#0.
[0156]
As described above, according to the third embodiment of the present
disclosure, the communication apparatus 10-3 generates a plurality of VSP frames
20 and transmits the plurality of VSP frames using space division multiplexing
communication. Therefore, since the PLCP preamble is reduced to be smaller than
in one-to-many communication, it is possible to reduce the overhead of
communication and improve the use efficiency of the wireless communication
resources.
25 [0157]
<5. Fourth embodiment (example in which PLCP is selected in frequency division
multiplexing communication)>
The communication appm-atus 10-3 according to the third embodiment of
the present disclosure has been described above. Next, a communication appm-atus
30 10-4 according to the fourth embodiment of the present disclosure will be described.
In the fourth embodiment, the PLCP is added to the frames to be multiplexed in
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common, but in the present embodiment, the PLCP is independently added to each of
the frames to be multiplexed. First, communication according to a related art when
the PLCP is added independently will be described with reference to FIG. 19. FIG.
19 is a diagram illustrating an example of a frame exchange sequence performed by
5 communication according to a related art when PLCP is added independently.
[0158]
First, the master-unit transmits the legacy mode transmission permission
request frame. For example, as illustrated in FIG. 15, the master unit 10#0 transmits
the RTS frame to which the PLCP of the legacy mode is added to the slave unit 1 0# 1.
10 [0159]
Then, the slave unit that has received the transmission permission request
frame transmits the legacy mode transmission permission frame to the master unit.
For example, as illustrated in FIG. 15, the slave unit 10#1 transmits the CTS frame to
which the PLCP of legacy mode is added to the master unit 1 0#0.
15 [0160]
Then, the master unit that has received the transmission permission frame
generates a plurality of data frames and adds the PLCP of the mixed mode to each of
the generated data frames independently. Then, the master unit transmits each of
the data frames to which the PLCP is added to the slave unit using multiplexing
20 communication. For example, as illustrated in FIG. 15, the master unit 10#0
transmits a plurality of data frames DATA #01 to DATA #04 to which the PLCP of
the mixed mode is added to the slave units 1 0# 1 to # 10#4 using frequency division
multiplexing communication. Then, the PLCP of the mixed mode is added to each
of frames to be exchanged later.
25
30
[0161]
As described above, since the PLCP preamble is added to the frame each
time communication is performed, there are cases in which an unnecessary PLCP
preamble is transmitted. In this regard, the communication apparatus 10-4
according to the present embodiment is based on the communication apparatus
according to the first embodiment, and uses an individual VSP as the PLCP of each
of the frames to be multiplexed.
SP361950WOOO
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[0162]
<5-l. Configuration of communication apparatus>
The communication apparatus I 0-4 have substantially the same functional
configuration as that of the first embodiment, except for a portion of the functions of
5 the data processing unit 11 and the communication unit 12. Note that substantially
the same functions as those of the first to third embodiments will not be described.
[0163]
The modulation/demodulation unit 13 and the signal processing unit 16 in
the communication unit 12 perform a process involved in frequency-division
10 multiplexing. Specifically, the modulation/demodulation unit 13 divides a frame
provided from the data processing unit II into portions, the number of which is equal
to the number of subcarriers, and modulates each portion of the frame obtained by
the division. Thereafter, the modulation/demodulation unit 13 combines signals
obtained by the modulation, and provides the signal obtained by the combination to
15 the signal processing unit 16. The signal processing 1mit 16 performs a process,
snch as addition of a guard interval, or the like, on the signal provided from the
modulation/demodulation unit 13, and provides a signal obtained by the process, i.e.,
a symbol stream, to the radio interface unit 14.
[0164]
20 The signal processing unit 16 performs a process, such as removal of a
guard interval, or the like, on the symbol stream related to received waves provided
from the radio interface unit 14, and provides a signal obtained by the process to the
modulation/demodulation unit 13. The modulation/demodulation unit 13 extracts a
subcarrier signal from the signal provided from the signal processing unit 16, and
25 demodulates each subcarrier. Thereafter, the modulation/demodulation unit 13
combines frames obtained by the demodulation, and provides the combined frame to
the data processing unit II.
[0165]
The data processing unit II generates a plurality of frames and adds the
30 PLCP to each of the plurality of frames. Specifically, the data processing unit ll
generates frames destined for a plurality of communication apparatuses 10-3, and
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adds the PLCPs selected by the control unit 15 to the generated frames.
[0 166]
<5-2. Process of communication apparatus>
Next, a specific example of communication performed m the
5 communication system according to the present embodiment will be described with
reference to FIG. 20. FIG. 20 is a diagram illustrating an example of a frame
exchange sequence performed in the communication system according to the present
embodiment. Since the flow of a process of the communication apparatus 10-4 is
substantially the same as the flow of the process according to the first embodiment,
10 description thereof is omitted. Further, descriptions of processes that are
substantially the same as the processes of the first and third embodiments will be
omitted.
[0167]
(Specific example of communication)
15 First, a master unit 1 0-4#0 transmits the legacy mode transmission
permission request frame to a slave unit 10-4#1. Then, the slave unit 10-4#1 that
has received the frame transmits the legacy mode transmission permission frame to
the master unit 1 0-4#0.
[0168]
20 Then, the master unit 1 0-4#0 that has received the transmission permission
frame generates the data frames destined for the slave units 1 0-4#1 to 1 0-4#4, and
adds the PLCP of the mixed mode to each of the data frames. Then, the master unit
1 0-4#0 transmits the frames to the slave units 1 0-4# 1 to 1 0-4#4 using frequency
division multiplexing communication. Then, each of the slave units 1 0-4# 1 to 10-
25 4#4 that have received the frame transmits the ACK frame which is the VSP1 frame
to the master unit 10-4#0.
[0169]
Then, the master unit 1 0-4#0 generates the data frames destined for the
slave units 10-4#1 to 10-4#4, and transmits the frames to which VSP2 common to
30 the data frames is divided to the slave units 10-4#1 to 10-4#4 using frequency
division multiplexing communication. Then, each of the slave units 10-4#1 to 10-
::1'---------
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4#4 that have received the frame transmits the ACK frame to which VSP2 is added to
the master unit I 0-4#0.
[0170]
As described above, according to the fourth embodiment of the present
5 disclosure, the communication apparatus 10-3 generates a plurality of VSP frames
and transmits the plurality of VSP frames using frequency division multiplexing
-communication. Therefore, since the PLCP preamble is reduced, it is possible to
reduce the overhead of communication and impmve the use efficiency of wireless
communication resources.
10 [0171]
Further, the communication apparatus I 0-4 adds the PLCP to each of the
frames to be multiplexed. Thus, since different PLCPs can be added to the frames
destined for the communication apparatuses 10-3 that differ in the result of the PLCP
selection process, when some frames do not satisfY a VSP addition condition, the
15 case in which the PLCP of the related art is added to all the frames is reduced.
20
Further, it is possible to further pmmote the reduction in the overhead of
communication.
[0172]
<6. Application example>
The technology according to the embodiments of the disclosure can be
applied to various products. For example, a slave unit among the communication
apparatus I 0 may be realized as mobile terminals such as smartphones, tablet PCs
(Personal Computers), notebook PCs, portable game terminals, or digital cameras,
fixed-type terminals such as television receivers, printers, digital scanners, or
25 network storages, or car-mounted terminals such as car navigation devices. In
addition, the slave unit may be realized as terminals that perform M2M (Machine to
Machine) communication (also referred to as MTC (Machine Type Communication)
terminals) such as smart meters, vending machines, remotely controlled surveillance
devices, or POS (Point Of Sale) terminals. Furthermore, the slave unit may be
30 wireless communication modules mow1ted in such terminals (for example, integrated
circuit modules configured by one die).
SP361950WOOO
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[0 173]
On the other hand, for example, a master unit among the communication
apparatus 10 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.
5 The master unit may be realized as a mobile wireless LAN router. The master unit
may also be a wireless communication module (for example, an integrated circuit
module configured with one die) mounted on the device.
10
[0174]
<6-1. First application example>
FIG. 21 is a block diagram showing 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 externally connected interface 904, a camera 906, a sensor 907, a
microphone 908, a input device 909, a display device 910, a speaker 911, a wireless
15 communication interface 913, an antenna switch 914, an antenna 915, a bus 917, a
battery 918, and an auxiliary controller 919.
[0175]
The processor 901 may be, for example, a CPU (Central Processing Unit) or
an SoC (System on Chip), and controls functions of an application layer and other
20 layers of the smartphone 900. The memory 902 includes a RAM (Random Access
Memory) and a ROM (Read Only Memory), and stores programs executed by the
processor 901 and data. The storage 903 can include a storage medium such as a
semiconductor memory or a hard disk. The externally connected interface 904 is an
interface for connecting an externally attached device such as a memory card or a
25 USB (Universal Serial Bus) device to the smartphone 900.
[0176]
The camera 906 has an image sensor, for example, a CCD (Charge Coupled
Device) or a CMOS (Complementary Metal Oxide Semiconductor), to generate
captured images. The sensor 907 can include a sensor group including, for example,
30 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
il
~I
I
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audio signals. The input device 909 includes, for example, a touch sensor that
detects touches on a screen of the display device 910, a key pad, a keyboard, buttons,
switches, and the like, to receive manipulations or information inputs from a user.
The display device 910 has a screen such as a liquid crystal display (LCD), or an
5 organic light emitting diode (OLED) display to display output images of the
smartphone 900. The speaker 911 converts audio signals output from the
smmiphone 900 into sounds.
[0177]
The wireless communication interface 913 supports one or more wireless
10 LAN standards of IEEE 802.lla, llb, llg, lln, llac, and llad, to execute the
wireless LAN 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
15 an ad hoc mode or Wi-Fi Direct (registered trademark). Wi-Fi Direct is different
from the ad hoc mode, and thus one of two terminals operates as an access point.
However, communication is performed directly between the terminals. The
wireless communication interface 913 can typically include a baseband processor, an
RF (Radio Frequency) circuit, a power amplifier, and the like. The wireless
20 communication interface 913 may be a single-chip module on which a memory that
stores a communication control program, a processor that executes the program, and
a relevant circuit are integrated. The wireless communication interface 913 may
support another kind of wireless communication scheme such as a cellular
communication scheme, a short-range wireless communication scheme, or a
25 proximity wireless communication scheme in addition to the wireless LAN scheme.
The antenna switch 914 switches a connection destination of the antenna 915 for 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
30 elements constituting a MIMO antenna), and is used for transmission and reception
of wireless signals from the wireless communication interface 913.
l\c_ ____ _
---·--~~-----------------------
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[0 178]
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. 21.
5 In this case, the antenna switch 914 may be omitted from the configuration of the
smartphone 900.
[0179]
The bus 91 7 connects the processor 90 I, the memory 902, the storage 903,
the externally connected interface 904, the camera 906, the sensor 907, the
10 microphone 908, the input device 909, the display device 910, the speaker 911, the
wireless communication interface 913, and the auxiliary controller 919 to one
another. The battery 918 supplies electric power to each of the blocks of the
smartphone 900 shown in FIG. 21 via power supply lines partially indicated by
dashed lines in the drawing: The auxiliary controller 919 causes, for example,
15 necessary minimum functions of the smartphone 900 to be operated in a sleep mode.
[0180]
In the smartphone 900 shown in FIG. 21, the data processing unit 11, the
communication unit 12, and the control unit 15 described with reference to FIG. 4
may be mounted in the wireless communication interface 913. At least some of the
20 functions may be mounted on the processor 901 or the auxiliary controller 919. For
example, the control unit 15 causes the frame not including the transmitted training
signal to be transmitted to the communication unit 12, and thus it is possible to
reduce the overhead of communication.
[0 181]
25 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.
[0182]
30 <6-2. Second application example>
FIG. 22 is a block diagran1 showing an example of a schematic
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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 GPS (Global Positioning System) module 924, a sensor 925, a data
interface 926, a content player 927, a storage medium interface 928, an input device
5 929, a display device 930, a speaker 931, a wireless communication interface 933, an
antenna switch 934, an antenna 935, and a battery 938.
[0183]
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
10 memory 922 includes a RAM and a ROM storing programs executed by the
processor 921 and data.
[0184]
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
15 GPS satellite. The sensor 925 can include a sensor group including, for example, a
gyro sensor, a geomagnetic sensor, a pneumatic sensor, and the like. The data
interface 926 is connected to an in-vehicle network 941 via, for example, a terminal
that is not illustrated to acquire data generated on the vehicle side such as car speed
data.
20 [0185]
The content player 927 reproduces content stored in a storage medium (for
example, a CD or a DVD) inserted into the storage mediU111 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
25 manipulations or information inputs 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.
[0186]
30 The wireless communication interface 933 supports one or more wireless
LAN standards ofiEEE 802.lla, lib, llg, lin, llac, and llad, to execute wireless
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LAN communication. The wireless communication interface 933 can communicate
with another device via a wireless LAN access point in the infrastTucture mode. In
addition, the wireless communication interface 933 can directly communicate with
another device in a direct commtmication mode such as an ad hoc mode or Wi-Fi
5 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 single-chip module on which a memory that
stores a communication control program, a processor that executes the program, and
a relevant circuit are integrated. The wireless communication interface 93 3 may
10 support another kind of wireless communication scheme such as a short-range
wireless 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 for a
plurality ofcircuits included in the wireless communication interface 933. The
15 antenna 935 has a single or a plurality of antenna elements and is used for
transmission and reception of wireless signals from the wireless communication
interface 933.
[0187]
Note that the car navigation device 920 may include a plurality of antennas,
20 without being limited to the example of FIG. 22. In this case, the antenna switch
934 may be omitted from the configuration of the car navigation device 920.
[0 188]
The battery 938 supplies electric power to each of the blocks of the car
navigation device 920 shown in FIG. 22 via power supply lines partially indicated by
25 dashed lines in the drawing. In addition, the battery 938 accumulates electric power
supplied from the vehicle.
[0189]
In the. car navigation device 920 shown in FIG. 22, the data processing unit
11, the communication unit 12, and the control unit 15 described with reference to
30 FIG. 4 may be mounted in the wireless communication interface 933. At least some
of the functions may be mounted on the processor 921. For example, the control
5
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unit 15 causes the frame not including the transmitted training signal to be
transmitted to the communication unit 12, and thus it is possible to reduce the
overhead of communication.
[0190]
Further, the wireless communication interface 933 may operate as the
master unit described above and may provide a wireless connection to a terminal of a
user riding in a vehicle. At that time, for example, the overhead of commtmication
in the wireless connection is reduced, and the communication time is reduced, and
thus it is possible to suppress the power consumption of the terminal of the user.
10 [0191]
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, an 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
15 number of engine rotations, or failure information and outputs the generated data to
the in-vehicle network 941.
[0192]
<6-3. Third application example>
FIG. 23 is a block diagram showing an example of a schematic
20 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.
[0193]
25 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 a RAM
and a ROM and stores a program executed by the controller 951 and various kinds of
30 control data (for example, a terminal list, a routing table, an encryption key, security
settings, and a log).
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[0194]
The input device 954 includes, for example, a button or a switch, and
receives a manipulation from a user. The display device 955 includes an LED lamp
and displays an operation status of the wireless access point 950.
5 [0195]
The network interface 957 is a wired communication interface that connects
the wireless access point 950 to 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)
10 or may be a Wide Area Network (WAN).
[0196]
The wireless communication interface 963 supports one or more wireless
LAN standards ofiEEE 802.11a, llb, llg, lin, !lac, and llad, to supply wireless
connection to a nearby terminal as an access point. The wireless communication
15 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 a 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
20 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.
[0197]
In the wireless access point 950 shown in FIG. 23, the data processing unit
25 11, the communication unit 12, and the control unit 15 described with reference to
FIG. 4 may be mounted on the wireless communication interface 963. At least
some of the functions may be mounted on the controller 951. For example, the
control unit 15 causes the frame not including the transmitted training signal to be
transmitted to the communication unit 12, and thus it is possible to reduce the
30 overhead of communication.
[0198]
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<7. Conclusion>
According to the first embodiment of the present disclosure, the already
transmitted training signal is not included in the PLCP, and thus it is possible to
reduce the overhead of communication while suppressing influence on the frame
5 reception process.
[0199]
According to the second embodiment of the present disclosure, the PLCP is
selected on the basis of the use request of which the reception side notifies, and thus
more appropriate PLCP is selected than when the PLCP is selected through the
10 determination of the transmission side, and it is possible to suppress the occurrence
of the frame reception failure which is caused by the erroneous selection of the PLCP.
[0200]
Further, according to the third embodiment of the present disclosure, the
PLCP preamble is reduced even in one-io-many communication, and thus it is
15 possible to reduce the overhead of communication and improve the use efficiency of
the wireless communication resources.
[0201]
Further, according to the fourth embodiment of the present disclosure, the
PLCP preamble is reduced, and thus it is possible to reduce the overhead of
20 communication and improve the use efficiency of wireless communication resources.
[0202]
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
25 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.
[0203]
For example, in the first and second embodiments, the example in which the
30 frame is transmitted from the master unit to the slave unit has been described, but the
present technology is not limited to this example. For example, using the Reverse
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Direction function, a frame may be transmitted to the master unit continuously from
the slave unit that has received the frame from the master unit.
[0204]
In the above embodiments, VSPl, VSP2, and VSP3 have been described as
5 the examples of the PLCP (VSP) in which a part or all of the training signal is
omitted, but the VSP is not limited thereto, and various PLCPs in which the training
signal is omitted so that the frame reception process can be performed may be ·
employed as the VSP.
10
[0205]
Further, not only a process in which steps shown in the flowcharts of the
above embodiments are performed in a time-series manner in accordance with a
described sequence but also a process in which the steps are not necessarily
processed in a time-series manner but are executed in parallel or individually is
included. Also, it is self-evident that even steps processed in a time-series manner
15 can be appropriately changed in sequence depending on circumstances.
[0206]
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
20 that are clear to those skilled in the art from the description of this specification.
[0207]
Additionally, the present technology may also be configured as below.
(1)
A communication apparatus, including:
25 a processing unit configured to select one of a frame of a first format
including a training signal and a frame of a second format not including a first field
which is at least a part of the training signal, and generate the frame of the selected
format; and
a communication unit configured to transmit the frame of the first format or
30 the frame of the second format.
(2)
i1
5
10
15
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The communication apparatus according to ( 1 ),
wherein the first field includes a training signal for backward compatibility.
(3)
The communication apparatus according to (1 ),
wherein the frame of the second format is configured with a signal including
information related to a data part of a frame and the data part, and does not include
the training signal.
(4)
The communication apparatus according to (1 ),
wherein the frame of the second format is configured with only a data part
of a frame, and does not include a signal including information related to the data
part and the training signal.
(5)
The communication apparatus according to any one of (1) to (3),
wherein the processing unit selects the frame of the second format when a
first condition related to a transmission time of a frame to be transmitted is satisfied.
(6)
The communication apparatus according to ( 5),
wherein the first condition includes that the transmission time of the frame
20 to be transmitted be before a predetermined time elapses after the frame of the first
format is transmitted to a destination of the frame to be transmitted.
(7)
The communication apparatus according to (6),
wherein the predetermined time is a time in which a communication
25 synchronization error falls within a predetermined range.
(8)
The communication apparatus according to ( 6),
wherein the predetermined time is a time shorter than the other time among
times decided by the transmission destination of the frame of the first format and the
30 communication apparatus.
(9)
5
10
15
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. The communication apparatus according to any one of (5) to (8),
wherein the first condition includes that the transmission time of the frame
to be transmitted be known to the destination of the frame to be transmitted.
(l 0)
The communication apparatus according to (9),
wherein being known includes that transmission of the frame to be
transmitted be permitted when a predetermined time elapses after reception of a
frame received later than other frames.
(11)
The communication apparatus according to (9),
wherein being known includes that a frame received from another
communication apparatus indicates an immediate response request.
(12)
The communication apparatus according to any one of ( 5) to (H),
wherein the first condition includes that it be a transmission suppression
period indicated by a signal which is exchanged between the destination of the frame
to be transmitted and the communication apparatus and used for suppressing
transmission of communication apparatuses other than the destination of the frame to
be transmitted and the communication apparatus.
20 (13)
25
30
The communication apparatus according to any one of (5) to (12),
wherein the first condition includes that a transmission period length of the
frame to be transmitted be a threshold value or less.
(14)
The communication apparatus according to any one of ( 5) to ( 13 ),
wherein, when frames to be transmitted to a plurality of destinations are
multiplexed, the processing unit selects the frame of the second format when the first
condition is satisfied for all the plurality of destinations.
(15)
The communication apparatus according to any one of (1) to (4),
wherein the processing unit selects the frame of the second fonnat when a
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frame including a use request for the frame of the second format is received.
(16)
The communication apparatus according to (15),
wherein the communication unit receives the frame including the use
5 request for the frame of the second format which is transmitted when a second
condition related to a transmission time of a frame is satisfied.
(17)
The communication apparatus according to (16),
wherein the second condition includes that a transmission time of the fi·ame
10 including the use request be before a predetermined time elapses after the frame of
the first format is received from a destination of the frame including the use request,
and that a transmission time of a frame received as a response to the frame including
the use request be known to a transmission source of the frame including the use
request.
15 (18)
A communication apparatus, including:
a communication unit configured to receive a frame of a first format
including a training signal and a frame of a second format not including a first field
which is at least a part of the training signal.
20 (19)
25
The communication apparatus according to (18), further including:
a processing unit configured to select one of the frame of the first format
and the frame of the second format as a frame to be received, on the basis of a use
request included in a transmitted frame,
wherein the communication unit receives the frame of the selected format.
(20)
A communication method, including:
selecting one of a frame of a first format including a training signal and a
frame of a second format not including a first field which is at least a part of the
30 training signal, and generating the frame of the selected format; and
transmitting the frame of the first format or the frame of the second format.
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Reference Signs List
[0208]
10 communication apparatus
5 11 data processing unit
12 communication unit
13 modulation/demodulation unit
14 radio interface unit
15 control unit
10 16 signal processing unit

CLAIMS
Claim I
Acommunication apparatus, comprising:
a processing unit configured to select one of a frame of a first format
5 including a training signal and a frame of a second format not including a first field
which is at least a part of the training signal, and generate the frame of the selected
format; and
10
a communication unit configured to transmit the frame of the first format or
the frame of the second format.
Claim 2
The communication apparatus according to claim 1,
wherein the first field includes a training signal for backward compatibility.
15 Claim 3
20
The communication apparatus according to claim 1,
wherein the frame of the second format is configured with a signal including
information related to a data part of a frame and the data part, and does not include
the training signal.
Claim4
The communication apparatus according to claim 1,
wherein the frame of the second format is configured with only a data part
of a frame, and does not include a signal including information related to the data
25 part and the training signal.
Claim 5
The communication apparatus according to claim 1,
wherein the processing unit selects the frame of the second format when a
30 first condition related to a transmission time of a frame to be transmitted is satisfied.
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Claim 6
The communication apparatus according to claim 5,
wherein the tlrst condition includes that the transmission time of the frame
to be transmitted be before a predetermined time elapses after the frame of the first
5 format is transmitted to a destination of the frame to be transmitted.
Claim 7
The communication apparatus according to claim 6,
wherein the predetermined time is a time in which a communication
10 synchronization error falls within a predetermined range.
Claim 8
The communication apparatns according to claim 6,
wherein the predetermined time is a time shorter than the other time among
15 times decided by the transmission destination of the frame of the first format and the
communication apparatns.
20
25
30
Claim 9
The communication apparatus according to claim 5,
wherein the first condition includes that the transmission time of the frame
to be transmitted be known to the destination of the frame to be transmitted.
Claim 10
The communication apparatns according to claim 9,
wherein being known includes that transmission of the frame to be
transmitted be permitted when a predetermined time elapses after reception of a
frame received later than other frames.
Claim 11
The communication apparatns according to claim 9,
wherein being known includes that a frame received from another
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communication apparatus indicates an immediate response request.
Claim 12
The communication apparatus according to claim 5,
5 wherein the first condition includes that it be a transmission suppression
10
15
period indicated by a signal which is exchanged between the destination of the frame
to be transmitted and the- communication apparatus and used for suppressing
transmission of communication apparatuses other than the destination of the frame to
be transmitted and the communication apparatus.
Claim 13
The communication apparatus according to claim 5,
wherein the first condition includes that a transmission period length of the
frame to be transmitted be a-threshold value or less.
Claim 14
The communication apparatus according to claim 5,
wherein, when frames to be transmitted to a plurality of destinations are
multiplexed, the processing unit selects the frame of the second format when the first
20 condition is satisfied for all the plurality of destinations.
Claim 15
The communication apparatus according to claim I,
wherein the processing unit selects the frame of the second format when a
25 frame including a use request for the frame of the second format is received.
Claim 16
The communication apparatus according to claim 15,
wherein the communication unit receives the frame including the use
30 request for the frame of the second format which is transmitted when a second
condition related to a transmission time of a frame is satisfied.
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Claim 17
The communication apparatus according to claim 16,
wherein the second condition includes that a transmission time of the fi-ame
5 including the use request be before a predetermined time elapses after the fi·ame of
the first fonnat is received from a destination of the frame including the use request,
and that a transmission time of a frame received as a response to the frame including
the use request be known to a transmission source of the frame including the use
request.
10
Claim 18
A communication apparatus, comprising:
a communication unit configured to receive a frame of a first fmmat
including a trainingsignal and a frame of a second fmmat not including· a first field
15 which is at least a part of the training signal.
Claim 19
The communication apparatus according to claim 18, further 'comprising:
a processing unit configured to select one of the frame of the first format
20 and the frame of the second format as a frame to be received, on the basis of a use
request included in a transmitted frame,
25
30
wherein the communication unit receives the frame of the selected format.
Claim 20
A communication method, comprising:
selecting one of a frame of a first fmmat including a training signal and a
frame of a second fmmat not including a first field which is at least a part of the .
training signal, and generating the frame of the selected fonnat; and
transmitting the fi·ame of the first format or the frame of the second fmmat.