Description
Title of Invention
COMMUNICATION DEVICE AND COMMUNICATION METHOD
Technical Field
[00011
The present disclosure relates to a communication device and a
co~nmunicationm ethod.
10
Background Art
[00021
Recently, wireless communication technologies that transmit and receive
various data by close proximity wireless communication are being developed.
15 [0003]
For example, TransferJet (registered trademark) has been adopted in devices
such as digital cameras and personal computers (PCs) as a close proximity wireless
communication scheme, and constrncts an ecosystem for data comtnunicatio~~
between information processing devices. The TransferJet specifications are
20 standardized by the TransferJet Consortium indicated in Nan-Patent Literature 1
below, and PHYJCNL Specifications 1.0 is being used in current products.
[0004]
In addition, as an international standard, a standard closely similar to the
standard according to the TransferJet Consortium is being registered as ECMA-398
25 indicated in Nan-Patent Literature 2 below.
Citation List
Non-Patent Literature
[0005]
30 Non-Patent Literature 1: TransferJet
(l~ttp://\%?w%~.transferjct.org/)
Non-Patent Literature 2: ECMA-398 (http://~\~~.w.ecmainter11ational.
org/publications/files/ECh4A-STECMA-398.pd~
Sununa~yo f Invention
5 Technical Problem
[0006]
However, because of the increasing file sizes and storage capacities as well
as faster internal bus speeds connecting the central processing unit (CPU) and
storage in current digital devices, even greater speed increases are expected from
10 communication systems.
[0007]
Accordingly, the present disclosure provides a new and improved
communicatior~ device and co~nmunication method capable of realizing faster
communication.
15
Solution to Problem
[0008]
According to the present disclosure, there is provided a comn~unication
device including: a modulation unit configured to use, in each modulatior~ scheme,
20 syrnbol points for which an average power is the same across a predetermined
plurality of modulation schemes, and modulate transnlit data according to one of the
predetermined plurality of rnodulation schemes.
[0009]
According to the present disclosure, there is provided a communication
25 method including: using, in each ~nodulation scheme, symbol points for which an
average power is the same across a predetermined plurality of modulation schemes,
and rnodnlating transmit data according to one of the predetermined plurality of
modulation schemes.
30 Advantageous Effects of lnventio~l
[OOl 01
According to the present disclosure as described above, realizing faster
communication is possible. Note that the above advantageous effect is not strictly
limiting, and that any advantageous effect indicated in the present disclosure or
another advantageous effect that rnay be reasoned from the present disclosure may
5 also be exhibited in addition to, or instead of, the above advantageous effect.
Brief Description of Drawings
[OOll]
[FIG. 11 FIG. 1 is a block diagratn illustrating a configuration of a comtnunication
10 device according to an embodiment of the present disclosure.
[FIG. 21 FIG. 2 is a block diagram illustrating a configuration of a comtnunication
device according to a comparative example.
[FIG. 31 FIG. 3 is a diagratn illustrating the concept of pi/2-shifted BPSK in the
conventional scheme.
15 [FIG. 41 FIG. 4 is a diagram illustrating 16-QAM symbol point mapping according to
the present embodiment.
[FIG. 51 FIG. 5 is a diagram illustrating QPSK symbol point mapping according to
the present embodiment.
[FIG. 61 FIG. 6 is a diagram illustrating BPSK symbol point mapping according to
20 the present embodiment.
[FIG. 71 FIG. 7 is a diagram illustrating a baseband waveform used by a
commu~~icatiodnev ice according to the present embodiment.
[FIG. 81 FIG. 8 is a block diagram illustrating a configuration of a cotnmunication
device according to the present emnbodiment.
25 [FIG. 91 FIG. 9 is a diagratn illustrating a PSDU frame format of the conventional
scheme.
[FIG. 101 FIG. 10 is a diagram illustrating a PSDU frame format according to the
present embodimetlt.
[FIG. 111 FIG. 11 is a diagram illustrating an internal configuration or a pilot
30 sequence insertion unit according to the present embodiment.
[FIG. 121 FIG. 12 is a diagram illustrating an internal configuration of an LFSR
according to the present embodiment.
[FIG. 131 FIG. 13 is a diagram illustrating an internal configuration of a pilot
sequence insertion unit according to a reference configuration.
[FIG. 141 FIG. 14 is a conceptual diagram illustrating BER perfor~narice of the
5 conventional schenle and the proposed scherne.
[FIG. 151 FIG. 15 is a flowchart illustrating operation of a comnunication device
according to the present embodiment.
Description of Ernbodi~nents
10 [0012]
Hereinafter, (a) preferred embodiment(s) of the present disclosure will be
described in detail with reference to the appended drawings. In this specification
and the drawings, elements that have substantially the same function and structure
are denoted with the same reference signs, and repeated explanation is omitted.
15 [0013]
Hereinafter, the description will proceed in the following order.
1. Overview of communication device according to embodiment of present
disclosure
2. Embodiment
2-1. Configuration of comrnnnication module
2-2. Configuration of transmit data generation module
2-3. Operational process
3. Conclusion
[0014]
25 <1. Overview of cornrnunication device according to embodiment of present
disclosure
A co~rununicatioii device according to an embodiment of the present
disclosure conducts a comn~unicationp rocess that in~provesu pon the comn~unication
process prescribed by the Transfelllet Consortium (Non-Patent Literature 1) and in
30 ECMA-398 (Nan-Patent Literature 2). Hereinafter, the con~~llunicatiopnr ocess
prcscribcd by the TransferJet Consol-tium (Non-Patent Literature 1) and in ECMA398
@on-Patent Literature 2) will be predetermined the conventional scheme, while
the improved cotnmutiicatio~~p rocess in the present embodiment will be
predetermit~edth e proposed scheme.
[OO 151
5 In a colmnunication device according to the present embodiment, the
transmit signal is converted to a multi-level signal to realize high-speed transmission.
More specifically, the communication device accordit~gt o the present embodiment
adopts 16-quadrature amplitude modulation (16-QAM) and quadrature phase shift
keying (QPSK) in addition to the pi2-shifted binary phase shift keying (BPSK)
10 adopted in the conventional scheme. When the modulation scheme is 16-QAM, the
PHY rate, which had a maximum of 560 Mbps in the conventional scheme, reaches a
maximum of four times that rate, or 2240 Mbps.
[0016]
However, various problems may occur as a result of adopting 16-QAM and
15 QPSK. Accordit~gly, the communication device according to the present
embodiment resolves each problem with the following method.
[0017]
First, fluctuations occur in the power of the signal within a frame due to
multi-leveling. Howevel; since Transferjet is a low-power radio standard with a
20 prescribed instantaneous maxinlum power, power equalization of the signal within a
kame is necessary. Accordingly, the communication device according to the
present embodiment conducts power equalization by signal point (symbol point)
mapping. In this case, since it is not necessary to control the transmission aniplifiel;
power savings and smaller circuitry are realized.
25 [0018]
At this point, FIGS. 1 and 2 will be referenced to describe in detail the
power equalization by symbol point mapping in the communication device 1
accordittg to the present ernbodimeut. Specifically, the co~~~~lxunicadteiovinc e 1
according to the present embodimetlt, which coaducts power equalization by symbol
30 point mapping, will be compared to a communication device 100 accordirig to a
comparative example, \vhich collducts power equalization by aniplificatiotl level
control with a trans~nissiotla mplifier.
[0019]
FIG. 1 is a block diagram illustrating a configuration of tlie cotnmunication
device 1 according to an e~nboditnent of the present disclosure. FIG. 2 is a block
5 diagram illustrating a configuration of the cormnunication device 100 according to a
comparative example. Since the structural eletnents included in tlie cotnmunication
device 1 illustrated in FIG. 1 will be described in detail later, description will be
omitted at this point. The communication device 100 according to the comparative
example includes a modulator 210 that includes a mapping unit 220 which is
10 different fsotn the communication device 1 according to the present embodiment.
Note that both the mapping unit 22 and the niapping unit 220 are taken to conduct
mapping using multiple ~nodulations chemes according to 16-QAM, QPSK, and pi2-
shifted BPSK.
[0020]
15 With the communication device 100 according to the comparative example,
in the mapping unit 220, mapping is conducted so that the symbol point mapping
reaches a maximum. For this reason, as illustrated in FIG. 2, when making the
transmit power fixed, it has been necessaly to adjust the output according to each
modulation schetne by adjusting the power of a transnlission amplifier included in an
20 analog processing unit 225. In contrast, with the comn~ut~icationd evice 1
according to the present embodiment, mapping is conducted to adjust the symbol
mapping by the mapping unit 22 so that the average power becomes the same. For
this reason, with the communication device 1 according to the present embodiment,
as illustrated in FIG. 1, it is not necessary to adjust the output of the transnlission
25 amplifier includcd in an analog processing unit 25 according to each modulation
scheme. For this reason, with the communication device 1 according to the present
embodiment, in tlie transnlission amplifier included in the analog processing unit 25,
the transnlit signal may be anlplified by a fixed power.
[0021]
30 The above thus describes the power equalization by synibol point mapping
in the con~tnunicationd evice 1 according to the present embodiment.
roo221
Second, the signal-to-noise ratio (SNR) degrades due to multi-leveling.
For this reason, the co~nmunication device 1 according to the present embodiment
conducts coding with low-density parity-check (LDPC) codes.
5 [0023]
Third, the received error vector magnitude (EVM) degrades due to multileveling.
For this reason, tlie cotnnlunication device 1 according to the present
embodiment inserts a pilot sequence for equalization before and after the PHY
service data unit (PSDU) in a transmit frame.
10 [0024]
Furthermore, it1 order to iluprove the frame utilization eff~ciency, the
communication device 1 according to the present embodiment shortens the preamble
and mounts two or more CNL service data units (CSDUs).
[0025]
15 The communication device I according to the present embodiment may
improve the received SNR by adopting such a proposed scheme. By providing an
extra surplus of received SNR, the communication device 1 according to tlie present
embodiment enables more stable communication \vhile also securing a margin
against performance degradation due to individual inconsistencies during mass
20 production.
[0026]
The above thus describes an overview of the comniunication device
according to an embodiment of the present disclosure. Next, an embodiment of the
present disclosure will be described in detail.
25 [0027]
<2. Embodiment>
As illustrated in FIG. 1, the commnunication device according to an
embodiment of the present disclosure includes a cominunication mnodt~le 2 and a
transmit data generation module 3. Hereinaftet; first, FIGS. 1 to 7 will be
30 referenced to described a configuration of the communication module 2 according to
an embodinlent of the present disclosure.
[2-1. Configuration of communication module]
As illustrated in FIG. 1, the con~municationm odule 2 includes a modulator
21, a mapping unit 22, a baseband waveform generation unit 23, a frequency
conversion utlit 24, an analog processing utlit 25, and a transmission unit 26.
(Modulator 21 : Modulator)
The tnodtllator 21 includes a fi~nction of modulating binary transmit data
output from the transmit data generation tnodule 3 into an electrical signal.
Specifically, the modulator 21 functions as the mappitlg unit 22 and the baseband
10 waveform generation unit 23.
[0029]
(Mapping unit 22: 16-QAWQPSKIpi2-shifted BPSK Mapper)
The mapping unit 22 maps binary transmit data output from the transmit
data generation module 3 to syrnbol points on the complex plane. Table 1 below
15 summarizes the symbol point mapping by the mapping unit 22 described in detail
hereinafter.
[0030]
[Table 11
QPSK
BPSK
1 type
FIG. 4
2 types (A, B)
A: FIG. 5A
B: FIG. 5B
4 types (A, B, C, Dl
A: FIG. 6A
B: FIG. 6B
C: FIG. 6C
D: FIG. 6D
1. Continuously
transmit either A or
B
2. Alternately
transmit A and B
1. Conti~iuously
transmit either A or
B
2. Alternately
trausnlit A and B
3. Transmit either C
or D
4. Altenlateiy
transmit C and D
[003 11
Hereinaftel; symbol point mapping by the nlapping unit 22 will be described.
First, FIG. 3 will be referenced to describe sy~nbol point mapping in pi12-shifted
BPSK according to the conventional scheme.
6 100321
FIG. 3 is an explanatory diagram illustrating the concept of pi/2-shifted
BPSK in the conventional scheme. As illustrated in FIG. 3, pi12-shifted BPSK is
characterized by rotating the transmission axis by 90 degrees (pi12) for every one
syt~lbolto transmit. Such a rotation operation produces characteristics wherein the
10 signal envelope no longer passes through the origin of the complex plane during a
symbol transition, and the diff~culty of designing the transmission amplifier is
lessened.
[0033]
Herein, the communication device according to the present embodiment
15 adopts 16-QAM and QPSK in addition to the pi2-shifted BPSK adopted in the
convetltional scheme, and thereby attempts to increase the transmission speed.
However, fluctuations occur in the power of the signal within a frame due to tnultileveling.
Accordingly, the cornnlunication device according to the present
etnboditnent conducts power equalization of the signal withm a frame by using
20 symbol point mapping by the mapping unit 22.
[0034]
In other words, the mapping unit 22 according to the present embodiment
functions as a modulation unit that uses, in each modulation scheme, symbol points
for which the average power is the same across a predetermined plurality of
26 nlodulation schemes, and n~odulates transmit data according to one of the
predetermined plurality of modulation schemes. The mapping unit 22 conducts
modulation according to at least any of 16-QAM, QPSK, and BPSK as the
predetermined plurality of modulation schemes. The mapping unit 22 modulates
using syn~bol points in 16-QAM in all of the plurality of modulation schemes.
30 I-Iereinafter, FIG. 4 will be referenced to describe symbol points in 16-QAM.
[0035]
FIG. 4 is a diagram illustrating 16-QAM symbol point mapping according to
the present embodinlent. As illustrated in FIG. 4, in 16-QAM, symbol points are
mapped to (A+jA), (A+j3A), (3A+jA), ' ( 3 ~ + j 3 ~()A,- jA), (A-j3A), (3A-jA), (3Aj3A),
(-A+jA), (-A+j3A), (-3A+jA), (-3A+j3A), (-A-jA), (-A-j3A), (-3A-jA), and (-
5 3A-j3A). Herein, A is an arbitrary value indicating the normalized amplitude of the
transmit power. Table 2 below indicates the power of each symbol point in 16-
QAM illustrated in FIG. 4.
[0036]
[Table 21
10
[0037]
As illustrated in Table 2, for example, the power of the synlbol point (AtjA)
is 2A2, while the power of the symbol point (3A+j3A) is 1 8 ~ ~As. i llustrated in
Table 2, the average power of each synlbol point in 16-QAM is
15 4 x ( 2 ~ ~ + 1 0 ~ ~ + 1 0 ~ ~ + 1 8 ~ ~ ) 1 1 6 = 1 0 ~ ~ .
[0038]
Herein, as illustrated in Table 2, the power of the eight symbol points
(A+j3A), (-A-j3A), (-3A+jA), (3A-jA), (-A+j3A), (A-j3A), (3A+jA), and (-3A-jA) is
IOA~th,e same as the average power. In a modulation scheme other than 16-QAM,
20 the mapping unit 22 modulates using these symbol points, which have the same
power as the average power of 16-QAM. In QPSK and BPSK, since the mapping
unit 22 maps using only synlbol points have a power of ~ o Ath~e, a verage power
obviously is also 1 0 ~ ~Th.us , in 16-QAM, QPSK, and BPSK, thc average power of
the sytnbol points beconles the same. Hereinafter, first, FIG. 5 will be referenced to
25 describe symbol point mapping in QPSK.
[0039]
FIG 5 is a diagram illustrating QPSK symbol point nlapping accordi~lgto
the present embodiment. In QPSK, there are two possible symbol point mappings
that yield an average power of ~oA*a,s illustrated in FIGS. 5A aud 5B. The symbol
point mapping A (first symbol poiut set) illustrated in FIG. 5A includes the symbol
points (3A+jA), (-A+j3A), (-3A-jA), and (A-j3A). The symbol point mapping B
5 (second symbol point set) illustrated in FIG. 5B includes the symbol points (A+j3A),
(-3A+jA), (-A-j3A), and (3A-jA): When the modulation scheme is QPSK, the
mapping unit 22 n~odulatesu sing at least one of these two sy~nbopl oint mappings.
[0040]
In further detail, the mapping unit 22 modulates by alternating between the
10 symbol point mappiug A and the symbol point mappiug B every one symbol. In
other words, the mapping unit 22 conducts modulatiorl while rotating the
transmission axis for evesy one symbol to transmit. According to such a rotation
operation, the signal envelope no longer passes through the origin of the co~nplex
plane during a symbol transition, and the difficulty of designing the transmission
15 amplifier is lessened. Note that the mapping unit 22 may also continuously use
either the symbol point mapping A or the symbol point mapping B. Next, FIG. 6
will be referenced to describe symbol point mapping in QPSK.
[0041]
FIG. 6 is a diagram illustrating BPSK symbol point mapping according to
20 the present etnboditnent. 111 BPSK, there are four possible symbol point mappings
that yield an average power of ~oA', as illustrated in FIGS. 6A, 6B, 6C, and 6D.
The symbol point mapping A (third symbol point set) illustrated in FIG, 6A includes
the symbol points (A+j3A) and (-A-j3A). The symbol point mappiug B (fourth
symbol poiut set) illustrated in FIG. 6B includes the symbol points (-3A+jA) and
25 (3A-jA). The symbol point mapping C (fifth symbol point set) illustrated in FIG.
6C iucludes the symbol points (-A+j3A) and (A-j3A). The symbol point mapping
D (sixth symbol point set) illustrated in FIG. 6D iucludes the symbol points (3A+jA)
aud (-3A-jA). When the n~odulation scheme is BPSK, the mapping uuit 22
~llodulatesu sing at least one of these four symbol point mappings.
30 100421
Herein, the combination of the symbol point mappiugs A aud B as well as
the cotnbinatio~o~f the symbol point mappings C and D are each a combination
offset by 90 degrees. However, for other cotnbinations, such as the colnbi~lationo f
the symbol point mappings A and C or the combination of the symbol point
mappings A and D, the offset is 90 degrees or less, and are thus considered to have
5 little significance from the perspective of symbol point design.
[0043]
Thus, the mapping unit 22 modulates by alternating between the symbol
point mapping A and the symbol point mapping B every one syn~bol, or by
alternating between the syti~bolp oint mapping C and the symbol point mapping D
10 every one symbol. In other words, the mapping unit 22 conducts modulation while
rotating the transmission axis 90 degrees for every one symbol to transmit.
According to such a rotation operation, the signal envelope no longer passes through
the origin of the co~nplex plane during a symbol transition, and the difficulty of
designing the transtnission amplifier is lessened. Furthermore, as discussed earlier,
15 since modulation is conducted by BPSK while rotating the transmission axis 90
degrees similarly to the conventional scheme, the communication device 1 according
to the present embodiment is able to guarantee compatibility with the conventional
scheme. Note that the mapping unit 22 may also modulate by continuously using
one of the symbol point mappings A, B, C, and D.
20 [0044]
The foregoing thus describes symbol point mapping by the mapping unit 22.
The mapping unit 22 outputs the complex sequence obtained by mapping binary
transmit data output from the transmit data generation module 3 onto the con~plex
plane to the baseband waveform generation unit 23.
25 [0045]
- Supple~nentarle marks
In the present embodiment, since there were symbol points having the same
power as the average power of 16-QAM, the average power could also be made the
same in QPSK and BPSK. The modulator 21 may adopt another tnodulation
30 schei~~suec h as 64-QAM or 256-QAM, but in anotller modulation scheme, cases in
which there are no symbol points having the same power as the average power are
also conceivable. In such cases, the modulator 21 may make the average power the
satlie in each modulation sclienie by using approximate sy~nbolso r an ordinary highresolution
digital-to-analog converter (DAC).
[0046]
5 (Baseband waveforni generation unit 23: Baseband Waveforn~ Generator)
The baseband waveform generation unit 23 iiicludes a function of
generating a baseband waveform on the basis of a sequence output from the mapping
unit 22. The baseband waveform generation unit 23 according to the present
embodiment generates a baseband waveforni using the waveform illustrated in FIG. 7,
10 which bas been used in the conventional scheme. FIG. 7 is a diagram illustrating a
baseband waveform used by the communication device 1 according to the present
embodiment. As illustrated in FIG. 7, the period of the waveform is expressed by
eight normalized samples indicated along the liorizontal axis, and is the inverse llRs
of the symbol rate Rs. Note that Table 3 below illustrates the amplitude values of
15 the transmit waveforni illustrated in FIG. 7.
[0047]
[Table 31
[0048]
20 The baseband wa\refor~ig ene~ationu nit 23 outputs the generated baseband
wavefonn to the frequency conversion unit 24.
[0049]
(Frequency conversion unit 24: Upconverter)
The frequency conversion unit 24 includes a fi~~ictioonf converting the
fsequency of the signal to be transmitted that was output from the modulator 21.
For exatllple, the fsequency cotlr~ersion unit 24 conducts frequency conversion
treating the center frequency as 4.48 GHz, in accordance with the TransferJet
standard. The frequency conversion unit 24 outputs the fsequency-converted signal
5 to be transmitted to the analog processing unit 25.
[OOSO]
(Analog processing unit 25: BPF, AIII~&, SW)
The analog processing unit 25 iticludes a fi~nctioro~f conducting various
signal processing on a signal to be transmitted that was output from the frequency
10 conversion unit 24. For example, the analog processing unit 25 includes a
transmission anlplifier (TxAmp), and amplifies the signal to be transmitted that was
output from the frequency conversion unit 24. At this point, as discussed earlier,
since mapping is performed in the mapping unit 22 so that the average power is the
same in any of 16-QAM, QPSK, and BPSK, the transmission amplifier does not need
15 to adjust the amplification level according to the modulation scheme. In other
words, the transmission amplifier amplifies by a fixed power, regardless of the
modulation scheme. Othenvise, the analog processing unit 25 may also include a
band-pass filter (BPF) and an antenna switch (SW). The analog processing unit 25
outputs the signal obtained by conducting this various signal processing to the
20 transmission unit 26.
[OOSl]
(Transmission unit 26: Coupler)
The transnlission unit 26 includes a function of transmitting the transmit
signal (transmit data) output from the analog processing unit 25 by close proximity
25 wireless comnlunication. For example, the transnlission unit 26 is made up of an
inductive coupler, and conducts close proximity wireless conununication with
external equipnlent in accordance with the TransferJet standard. In further detail,
the transn~ission unit 26 conducts close proxitnity wireless conlnlunication with
anothcr comn~unication device (a colnmunication device equipped with close
30 proximity wireless comtnunication functions) present within a predetermined
communication range from the transmission unit 26. At this point, close proximity
wireless co~ntnunication between the transmission unit 26 and the other
communication device becomes possible only when the transmission unit 26 and the
otlier comnlunication device are in a state of close proximity to each other, Herein,
a state of close proximity means a state of being in close proximity or in contact in
5 which the distance between tlte transmission unit 26 and the other communication
device is w i t h a predeter~iiinedr ange (3 c111, for example).
[0052]
The above thus describes a configuration of the communication module 2
according to the present embodiment. Next, FIGS. 8 to 14 will be referenced to
10 describe a coniiguration of the transmit data generation module 3.
[0053]
[2-2. Configuration of transmit data generation module 31
FIG. 8 is a block diagram illustrating a configuration of the communication
device 1 according to the present embodiment. As illustrated in FIG. 8, the transmit
15 data generation module 3 includes a PSDU generation unit 31, a CSDU insertion unit
32, a coding unit 33, a pilot sequence insertion unit 34, a comniunicatiot~ scheme
configuration unit 35, and a preamble insertion unit 36. The transmit data
generation module 3 generates a PSDU as transmit data, and outputs to the
communication module 2.
20 [0054]
(PSDU generation unit 3 1)
The PSDU generation unit 31 includes a function of generating transmit
data (PSDU) to output to the communication module 2. In further detail, the PSDU
generation unit 31 generates the portion of the PSDU which is unchanged from the
26 conventional scheme, and combines this portio~l with the portion related to the
proposed scheme output or the like from the CSDU insertion unit 32 and the like
discussed later to generate the PSDU. Note that the PSDU generation unit 3 1 may
also generate a PSDU of the coliveritio~lals cllenle, and the CSDU insertion unit 32
and the like may modify a portion tlicreof to thereby generate a PSDU according to
30 the proposcd scl~eme. Hereinafter, FIGS. 9 and 10 will be referenced to describe
the PSDU frame format in the convelltional scheme and the present emboditnent.
[OOSS]
FIG. 9 is a diagram illustrating a PSDU frame format of the conr~e~itional
scheme. As illustrated in FIG. 9, the PSDU of the conventional scheme is made up
of a Preamble, Sync, and PHY header, followed by the PHY payload. The PI3Y
5 payload iticludes a common CNL header, and two sets of a Sub CNL header, a
CSDU from 0 KB to 4 KB, and a frame check sequence (FCS). Also, as illustrated
in FIG. 9, the PI-IY header i~lcludes a 4-bit field (Version) stating the version
infor~nation of tlie communication scheme, a 4-bit field (Rate) stating the
com~unicationra te, an 8-bit reserved field (Reserved), a 16-bit field (Length) stating
10 infor~nationa bout the length of the PSDU, and a 16-bit field (HCS) stating a header
check sequence for the PHY header.
[0056]
FIG. 10 is a diagram illustrating a PSDU frame format according to the
present embodiment. In FIG. 10, the poi-tions of the PSDU frame format according
15 to the present embodiment which are different from the conventional scheme are
shaded with hatching. As illustrated in FIG. 10, in the proposed scheme,
modifications are made to the Preamble, the Version field, the Rate field, and the
Reserved field. Additionally, a Pilot Sequence and a Postamble are added.
Furthermore, the number of sets of the Sub CNL Header, CSDU, and FCS is
20 increased. A detailed description of these portions which are different from the
conventio~lal scheme will be given together with tlie description of the CSDU
insertion unit 32, tlie coding unit 33, the pilot sequence insertion unit 34, the
commu~~icatiosnch eme configuration unit 35, or the preamble insertion unit 36.
[0057]
25 (CSDU insertion unit 32)
The CSDU insertion unit 32 includes a function of inserting two or Inore
co~uiectionla yer service data units (CSDUs) into the physical layer service data unit
(PSDU). The CSDU insertion unit 32, by i~isertingt wo or more CSDUs into the
PSDU, is able to reduce tlie alilount of overhead needed to transmit a ccl-tain number
30 of CSDUs, and increase throughput.
[OOSS]
In the Common CNL Header illustrated in FIGS. 9 and 10, the transmit UID,
the receive UID, the Revision, infor~nationi ndicating the number of CSDUs, and the
like are stored. The transmit data is managed in sets of the Sub CNL Header,
CSDU (maxinlum 4 KB), and FCS every 4 KB, and in the conventional regulation,
5 the nlaxirnum fi~~mbeorf CSDUs is 2. In the present embodiment, the CSDU
insertion unit 32 is capable of setting the number of CSDUs in the Conlmon CNL
Header to 2 or more.
[0059]
At this point, the upper limit on the length of the PSDU in the convet~tional
10 scheme was the length that could be expressed with the 16 bits of the Length field in
the PHY Header. In the present embodiment, since the number of CSDUs may
become 2 or more, the 8 bits of the Resewed field are newly used as the Length.
Consequently, the upper limit on the length of the PSDU is extended, enabling
support for up to a maximum length of 24 bits.
15 [0060]
(Coding unit 33)
The coding unit 33 includes a fimction of coding the transmit data with
LDPC codes. The coding unit 33 conducts coding using the parity check matsix of
LDPC codes illustrated in Table 4 below. As illustrated in Table 4, the coding unit
20 33 uses code rates expressed as 14/15, 13/15, and 11/15. By conducting coding
with LDPC codes, the coding unit 33 is able to compensate the SNR required by
multi-leveling. Note that the coding unit 33 may also code the transmit data with
Reed-Solomon codes or Viterbi codes, which have been used in the conventional
scheme.
25 [0061]
[Table 41
I pa& length (bits) 1 96 1 192 I 384
code rate
information-block
lend, k (bits)
luahix elemenfs whose
values are '1' in chc
fUst 15 columns of
parity check matrix H
(Pilot sequence insertion unit 34)
1411 5
1344
The pilot sequence insertion unit 34 includes a function of inserting a pilot
5 sequence into the transmit data. In further detail, as illustrated in FIG. 10, the pilot
sequence insertion unit 34 performs the insertion of the Pilot Sequence and the
Postamble so as to bracket the portion from the Conlmon CNL Header to the end of
the packet. By having the pilot sequence insertion unit 34 insert a pilot sequence
13/15
1248
into the transmit frame, the receiving side becomes able to easily realize signal
10 processing with an equalizer or the like, and thus the received SNR required by
multi-leveling such as 16-QAM may be itnproved. Note that the Pilot Sequence
11/15
1056
and the Postatnble are modulated according to the n~odulation scheme stated in the
Rate field or the PHY Header. Hereinafter, FIG. 11 will be referenced to describe
an internal configuration of the pilot sequence illsertioll unit 34.
15 [0063]
FIG. 11 is a diagram illustrating an internal configuration of the pilot
sequence insertion unit 34 according to the present embodiment. As illustrated it1
FIG. 11, the pilot sequence insertion unit 34 includes a linear feedback shift register
(LFSR) 341 and a bit selector 342.
5 200641
- LFSR 34 1
The LFSR 341 functions as a scrambling sequence generator that generates
a scrambling sequence for spread spectrum. The scrambling sequence generated by
the LFSR 341 is used for spread spectrum of the transmit signal in both the
10 conventional scheme and the present embodiment. In the present embodiment, the
scrambling sequence generated by the LFSR 341 is reused for the generation of the
pilot sequence by the pilot sequence insertion unit 34. Hereinafter, FIG. 12 will he
referenced to describe the LFSR 341 in detail.
[0065]
15 FIG. 12 is a diagram illustrating an internal configuration of the LFSR 341
according to the present embodiment. As illustrated in FIG. 12, the LFSR 341
generates a random binary sequence called an M-sequence, on the basis of a
generator polynomial expressed by Expression 1 below.
[0066]
20 [Math. 11
G ( X ) = X ~ ~ + X ~ ~ + X ~(E+xXpre~ss+ion~ 1 )
[0067]
Note that in the conventional scheme, the inverted XOR of the scrambling
sequence obtained by the LFSR and the transinit signal is computed across the entire
25 packet including preamble, lieader, and payload, and the result is treated as the final
transmit signal. Likewise, in the present embodiment, the contmunication device 1
computes the inverted XOR of the scrarnblitlg sequence and the transmit signal
across the entire packet, and treats the result as the final transrnit signal.
[0068]
- Bit selector 342
The bit selector 342 iucludes a function of selecting, from the scra~ttbling
sequence generated by the LFSR 341, a number of bits equal to the number of bits
per one symbol in the modulation scheme used by the modulator 21, and treating the
selected bits as a pilot sequence. The number of bits per one symbol is 4 in the case
of 16-QAM, 2 in the case of QPSK, and 1 in the case of BPSK. Accordingly,
6 supposing that the scrambling sequence generator 341 always generates a 4-bit
sequence as illustrated in FIG. 11, the bit selector 342 selects all 4 bits when the
modulation scheme is 16-QAM, 2 bits in the case of QPSK, and 1 bit in the case of
BPSK. Although FIG. I1 illustrates an example in which the bit selector 342 selects
the 2 bits of the first half in the case of QPSK and the leading bit in the case of BPSK,
10 bits may also be selected from another arbitrary position. The scrambling sequence
selected by the bit selector 342 becomes the Pilot Sequence or the Postatnble.
[0069]
- Supplemental remarks
As discussed earlier, the modulator 21 may also adopt 64-QAM, 256-QAM,
15 or the like as the modulation scheme. At this point, an internal configuration of the
pilot sequence insertion unit in the case of the modulator 21 adopting 64-QAM will
be described as a reference configuration with reference to FIG. 13.
[0070]
FIG. 13 is a diagram illustrating an internal configuration of a pilot sequence
20 insertion unit 340 according to a reference configuration. Since the number of bits
per one symbol is 6 bits in 64-QAM, the bit selector 342 needs to select 6 bits.
Accordingly, as illustrated in FIG. 13, the pilot sequence insertion unit 34 generates a
6-bit random-number syn~bol by using two LFSRs 341 that each output a 4-bit
sequence. Specifically, the bit selector 342 generates a 6-bit random-number
25 symbol by selecting the 4 bits output from the LFSR 341-1 and 2 bits from among
the 4 bits output from the LFSR 341-2. At this point, when selecting 2 bits, the bit
selector 342 is taken to select the 2 bits of the first half, similarly to the case of
QPSK. Also, the initial values used in the LFSRs 341-1 and 341-2 are assumed to
be different.
30 [0071]
(Comtnunication scheme configuration uuit 35)
The con~munication scheme configuration unit 35 includes a function of
configuring, in the PSDU, information for reporting the co~l~muuicatioslcl heme to
the receiving side. Specifically, the commu~~icatiosnc heme configuration unit 35
configures information indicating the cotntnunication scheme in tlie Rate field and
5 the Version field of the PHY Header.
[0072]
- Regarding the Rate field
In the Rate field, the communication scheme configuration unit 35
configures information indicating the modulation scheme and the transn~issionr ate
10 (any value from 0x1 to OxA). Table 5 illustrates combinations of a modulation
scheme at~da transmission rate adopted by the communication device 1 according to
the present embodiment.
[0073]
[Table 51
Rate410
Rate522
Ilat e2(il
Itatel30
RS + Y i t c r b i
280 RS . I \'i twbi
280 35 Yitcrbi
I
560 j 2240 1611 I.UPC(II/I5)
i
560 112.0 1043 LUPC(14/15)
560 1120 820 I.UI'C(1 1[15)
I BI'SK
Rntt.66 0x2 i s h i f t 560
, IIFSK
KaLe32 0x1 2 s h i f t 560
280
280
280
280
I I
Ox6 I Pi/? sliift 1 HI'SK
0x5 1 l'ii2 slii Tt
1 BPSK
0x4 I ' shift.
/ UIJSK
0 x T z s h i f t
560 560
560
-~
560
560
- -
,110
.. . --.
LUI'C(14:15)
560 522
560
280
261
130
KS + \'i t e r b i
RS - Viteybi
[0074]
Rate32 to Rate522 in Table 5 are cornbinations of a modulation scheme and
a transmission rate in the conventional scheme. In addition to these, the
con~municationd evice 1 according to the present embodiment newly adopts the five
5 rates of Rate2088, Rate1641, Rate1044, Rate820, and Rate410 as the proposed
schelne using LDPC codes and QPSK or 16-QAM. Along with the above, the
communication scheme configuration unit 35 assigns the numbers from 0x6 to OxA,
which were not used in the conventional scheme, to the five new rates.
[0075]
10 Next, FIG. 14 will be referenced to describe the performance of the
conventional scheme and the proposed scheme illustrated in Table 5.
[0076]
FIG. 14 is a conceptual diagram illustrating bit error rate (BER)
performance of the conventional scheme and the proposed scheme. Since the
15 present embodiment guarantees backward compatibility, the receiving side is also
capable of demodulating signals modulated according to the conventional scheme.
In the conventional scheme and the present embodiment, the transmitting side is
always capable of transmitting at a free transmission rate. Generally, the
transmitting side decides the transmission rate by using an algorithm that raises the
20 transmission rate when the SNR on the receiving side is high, and lowers the
trans~nissior~alt e \vhen the SNR on the receiving side is low. The communication
device 1 according to the present embodiment likewise adopts such an algorithm,
starting with Rate32, next switching to Rate65, and so on, raising the transmission
rate in order from the bottom to the top of Table 5 accorditlg to the com~l~uilication
25 conditions. At this point, as illustrated in FIG. 14, Rate522 of the conventional
scheme requires more energy to achieve a similar BER as Rate820 according to the
proposed scheme, thus demonstrating that Rate522 has lower performance conlpared
to Rate820. Accordingl): when conlmunicating with a terminal capable of
coln11lunieation according to the proposed scheme, the cor~xnnnication device 1
30 according to the present embodiment skips Rate522 and uses Rate410 after Rate261.
Consequently, the communication device 1 according to the present embodinlent is
able to adjust the translnission rate efficiently.
[0077]
- Regarding the Version field
The cotnmunication scheme configuration unit 35 configures the value
6 "0x2" in the Version field (4 bits) in the PHY Header. Since the value "0x1" is used
in the conventional scheme, the receiving side is able to distinguish between
comlnunication according to the conventional scheme and communication according
to the proposed scheme. Note that the communication device 1 is also able to apply
the conventional scheme to the communication module 2 and apply the present
10 embodiment to the transmit data generation module 3. Specifically, the
comtnunication device 1 configures "0x2" in the Version from Rate32 to Rate522,
inserts two or more CSDUs and a pilot sequence, and also transmits a PSDU frame
having a shortened Preamble. Note that even if the packet has a Version of "0x2",
or in other words, even if the modulation scheme by the modulator 21 is 16-QAM or
15 QPSK, the Preamble, Sync, and PHY Header illustrated in FIG. 10 are taken to be
modulated by pi/2-shifted BPSK. On the other hand, the data from the Pilot
Sequence to the Postamble is modulated according to the modulation scheme stated
in the Rate field.
[0078]
20 (Preamble insertion unit 36)
The preamble insertion unit 36 includes a fiinction of inserting a preamble
of a length from 7.28 us to 0 us into the PSDU. The preamble insertion unit 36
shortens the length of the 7.28 us preamble from the conventional scheme. The
preamble insertion unit 36 is able to freely configure the length from 7.28 us to 0 us.
26 Consequently, the length of the overall PSDU is shortened, and thus the transmission
speed tnay be increased. Furthermore, by shortening the length ofthe preamble, the
frame utilization efliciency improves, and tl~oughptrt improves. Note that the
preamble is used for gain adjustment on the receiving side as a preparatory signal
prior to receiving. Since the transmit power is small for close proximity wireless
30 comtnunication such as TransferJet, the lead-in time for gain adjustment may be
shortened, and as a result, the preamble nlap be shortened.
The above thus describes a co~lfiguration of the transmit data generation
module 3 according to the present embodiment. Next, FIG. 15 will be referenced to
describe an operational process of tlie communication device 1.
5 [0080]
[2-3. Operational process]
FIG. 15 is a flowvcha~ti llustrating operation of the communication device 1
according to the present embodiment. As illustrated in FIG. 15, first, in step S102,
the comn~unicationd evice 1 inse~tsth e CSDU fsame. In fu-ther detail, the CSDU
10 insertion unit 32 inserts the CSDU into the PSDU generated by the PSDU generation
unit 3 1. At this point, the CSDU insertion unit 32 may insert two or more CSDUs.
[0081]
Next, in step S104, the comtnunication device 1 conducts LDPC coding.
In further detail, tlie coding unit 33 conducts LDPC coding on the transmit data using
15 any of the parity check matrix illustrated in Table 4 above.
[0082]
Next, in step S106, the communication device 1 inserts a pilot sequence.
In further detail, the pilot sequence insertion unit 34 performs the insettion of the
Pilot Sequence and the Postamble so as to bracket the portion fsom the Common
20 CNL Header to the end of the packet.
[0083]
Next, in step S108, the comtnunication device 1 configures the
connnt~nications cheme. In further detail, the communication scheme configuration
unit 35 configures information indicating the conimunication scheme in the Rate
25 field and the Version field of the PHY Header.
[0084]
Next, in step S110, the comtnunication device 1 inserts a preatnble. 111
further detail, the preamble insertion unit 36 inserts a preamble of a length from 7.28
us to 0 us into the PSDU.
30 [0085]
Next, in step S 112, the cotntnunication device 1 modulates the transmit data
so that the average polver in each nlodulation scheme becotnes the same. In further
detail, first, the mapping unit 22 nlaps bina~ytr ansmit data output from the transmit
data generation module 3 to syn~bopl oints on the complex plane. At this point, the
mapping unit 22 maps synlbol points in each modulation scheme so that the average
5 power becomes the sanlc among 16-QAM, QPSK, or BPSK. More specifically, the
mapping unit 22 uses the syrnbol point mappings illustrated in FIG. 4 in the case of
16-QAM, FIG. 5 in the case of QPSK, and FIG. 6 in the case of BPSK, respectively.
Next, the baseband waveform generation unit 23 generates a baseband waveform
using the waveform illustrated in FIG. 7, on the basis of a sequence output from the
10 mapping unit 22.
[0086]
Next, in step S114, the communication device 1 performs various signal
processing on the transmit signal. In further detail, the frequency conversion unit
24 performs frequency conversion on the transmit signal, while the analog
15 processing unit 25 amplifies the frequency-converted transmit signal, applies a bandpass
filter, and the like. In the above step S112, since mapping is performed so that
the average power is the same in any of 16-QAM, QPSK, and BPSK, the
transmission amplifier included in the analog processing unit 25 amplifies the
transmit signal by a fixed power.
20 [0087]
Subsequently, in step S118, the conlnlunication device 1 transmits the
transn~it signal. In further detail, the transmission unit 26 transmits the transmit
signal output eon1 the analog processing unit 25 by close proximity wireless
cornnlunication.
25 [0088]
The above thus describes an operational process of the comtnunication
device 1 according to the present e~llbodirnent.
[0089]
<3. Conclusion>
30 As described above, the conlnlunication device 1 according to the present
e~nbodinlenti s able to realize faster transn~issionb y converting the transmit signal to
a multi-level signal. 111 addition, by conducting power equalization with symbol
point mappings against the inconsistencies in signal power within a frame produced
by multi-leveling, the comnnu~icatioti device 1 is able to realize anlplification by a
fixed power in the transmission amplifier, and eliminate the need for control of the
5 amplification level. Furthermore, by adopting various communication schemes that
itnprove the received SNR and the received EVM, the communication device 1
according to the present e~nboditnente nables more stable cornnlunication while also
securing a margin against performance degradation due to individual inconsistencies
during mass production.
10 [0090]
The preferred embodiment(s) of the present disclosure hasthave been
described above with reference to the accompanying drawings, whilst the present
disclosure is not limited to the above examples. A person skilled in the art may find
various alterations and modifications within the scope of the appended claims, and it
15 should be understood that they will naturally come under the technical scope of the
present disclosure.
[0091]
For example, in the foregoing embodiment, the communication device 1 is
described as conducting close proximity wireless communication conforming to the
20 TransferJet standard, but the present technology is not limited to such an example.
For example, the communication device 1 may also communicate with external
equipment by Bluetooth (registered trademark), ZigBee (registered trademark),
Ultra-wideband (UWB), or the like.
[0092]
25 Additionally, it is possible to create a computer program for causing
hardware such as a CPU, ROM, and RAM built into an infornlation processing
device to exhibit functions similar to each structural element of the above
co~iimunicatiod~e~v ice 1. Also, a recording medium having such a computer
program recorded thereon is also provided.
30 [0093]
In addition, the effects described in the present specification are merely
illustrative and demonstrative, and not limitative. In other words, the technology
according to the present disclosure can exhibit other effects that are evident to those
skilled it1 the art along with or instead of the effects based on the present
5 specification.
[0094]
Additionally, the present technology may also be configured as below.
(1)
A communication device including:
a modulation unit configured to use, in each lnodulation scheme, symbol
points for which an average power is the same across a predetermined plurality of
modulation schemes, and modulate transmit data according to one of the
predetermined plurality of modulation scl~enies.
(2)
15 The communication device according to (I), wherein
the modulation unit modulates using symbol points in 16-QAM in any of
the predetermined plurality of modulation schemes, and in a modulation scheme
other than 16-QAM, modulates using symbol points having the same power as the
average power of 16-QAM.
20 (3)
The comtnunication device according to (1) or (2), wherein
the predetermined plurality of modulation schemes includes at least one of
16-QAM, QPSK, and BPSK.
(4)
26 The communication device according to (3), wherein
in a case in which the nlodulation schenle is QPSK, the modulation unit
nlodulates using at least one of a first synibol point set including the syn~bopl oints
(3A+jA), (-A+j3A), (-3A-jA), and (A-j3A), and a second sy~nbopl oint set including
the sytnbol points (A+j3A), (-3A+jA), (-A-j3A), and (3A-jA).
30 (5)
The communication device according to (3) or (4), wherein
in a case in which the n~odulation scheme is BPSK, the n~odulation uuit
rnodulates usitlg at least one of a third symbol point set including the symbol points
(A+j3A) and (-A-j3A), a fourth symbol point set including the synlbol points (-
3A+jA) and (3A-jA), a fifth symbol point set including the synlbol points (-A+j3A)
6 and (A-j3A), and a sixth symbol point set including the synlbol points (3A+jA) and
(-3A-jA).
(6)
The communication device according to (4), wherein
the lnodulation unit modulates by alternately using the first synlbol point set
10 and the second synlbol point set.
(7)
The comnlunication device according to (5), wherein
the modulation unit tnodulates by alternately using the third symbol point
set and the fourth symbol point set, or by alternately using the fifth symbol point set
15 and the sixth symbol point set.
(8)
The communication device according to any one of (1) to (7), further
including:
a translnission unit configured to transmit the transmit data by close
20 proximity wireless communication.
(9)
The communication device according to any one of (1) to (8), further
including:
a coding unit configured to code the transmit data with an LDPC code.
26 (10)
The cotntnunication device according to any one of (1) to (9), further
including:
a scrambling sequence generator configured to generate a scrambling
sequence for spread spectrum; and
30 a pilot sequence insertion unit configured to insert a pilot sequence into the
transmit data, wherein
the pilot sequence insertion unit selects, fiom the scrambling sequence
generated by the scramblitlg sequence generatol; a number of bits equal to a lumber
of bits per one sy~nbolin the modulation scheme used by the modnlation unit, and
treats the selected bits as the pilot sequence.
5 (11)
The co~nmunication device according to any one of (1) to (lo), further
incuding:
a CSDU insertion unit configured to insert two or more connection layer
service data units (CSDUs) into a physical layer service data unit (PSDU).
10 (12)
The comtnunication device according to any one of (1) to (ll), further
including:
a preamble insertion unit configured to insert a preamble of a length from
7.28 us to 0 us into the transmit data.
15 (13)
A comniunicatiotl tnethod including:
using, in each modulation scheme, symbol points for which an average
power is the same across a predetermined plurality of modulation schemes, and
modulating transmit data according to one of the predetermined plurality of
20 modulation schemes.
Reference Signs List
[0095]
1 communication device
25 2 co~ll~llunicatimoto~d ule
21 modulator
22 mapping unit
23 baseband wavefort11 generation unit
24 fkequency conversion unit
30 25 analog processing unit
26 transmission unit
transmit data generation module
PSDU generation unit
CSDU insertion unit
coding unit
pilot sequence insertion unit
LFSR
bit selector
communication scheme configuration unit
preamble insertion unit
CLAIMS
Claim 1
A comtnunication device comprising:
a modulation unit configured to use, in each modulation scheme, symbol
5 points for which an average power is the same across a predetermined plurality of
n~odulation schemes, and modulate transmit data according to one of the
predetern~inedp lurality of modulation schemes.
Claim 2
10 The communication device according to claim 1, wherein
the modulation unit modulates using syn~bol points in 16-QAM in any of
the predetermined plurality of modulation schemes, and in a modulation scheme
other than 16-QAM, modulates using symbol points having the same power as the
average power of 16-QAM.
15
Claim 3
The communication device according to claim 1, wherein
the predetermined plurality of modulation schemes includes at least one of
16-QAM, QPSK, and BPSK.
20
Claim 4
The communication device according to claim 3, wherein
in a case in which the modulation scheme is QPSK, the n~odulationu nit
n~odulatesu sing at least one of a first symbol point set including the symbol points
25 (3A-i ;A), (-Aij3A), (-3.4-;A), and (A-j3A), and a second symbol point set including
the synlbol points (A+j3A), (-3A+jA), (-A-j3A), and (3A-;A).
Claim 5
The co~nlnunicationd evice according to claim 3, wherein
30 in a case in which the modulation schenle is BPSK, the mod~~latiounn it
modulates using at least one of a third symbol point set including the symbol points
(A+j3A) and (-A-j3A), a fourth sytnbol point set including the sytnbol points (-
3A+jA) and (3A-jA), a fifth symbol point set including the symbol points (-A+j3A)
and (A-j3A), and a sixth symbol point set including the symbol points (3A+jA) and
(-3A-j A).
6
Claim 6
The communication device according to claim 4, wherein
the modulation unit niodulates by alternately using the first symbol point set
and the second symbol point set.
10
Claitn 7
The comtnut~icationd evice according to claim 5, wherein
the modulation unit modulates by alternately using the third symbol point
set and the fourth symbol point set, or by alternately using the fifth symbol point set
15 and the sixth symbol point set.
Claim 8
The comtnunication device according to claim 1, further comprising:
a transmission unit configured to transmit the transmit data by close
20 proxitnity wireless communication.
Claitn 9
The communication device according to claim 1, further comprising:
a coding unit configured to code the transmit data with an LDPC code.
26
Claim 10
The connnunication device according to claim 1, further comprising:
a scrambling sequence generator configured to generate a scrambling
sequence for spread spectrum; and
30 a pilot sequence insc~tionu nit configured to insert a pilot sequence into the
tl.ansmit data, wherein
the pilot sequence insertion unit selects, from the scrambling sequence
generated by the scrambling sequence generator, a number of bits equal to a number
of bits per one sy~nbol in the modulation scheme used by the modulation unit, and
treats the selected bits as the pilot sequence.
5
Claim 11
The communication device according to claim 1, further comprising:
a CSDU insertion unit configured to insert two or more connection layer
service data units (CSDUs) into a physical layer service data unit (PSDU).
10
Claim 12
The communication device according to claim 1, further comprising:
a preamble insertion unit configured to insert a preamble of a length from
7.28 us to 0 us into the transmit data.
15
Claim 13
A cornmunication method comprising:
using, in each modulation scheme, symbol points for which an average
power is the same across a predetermined plurality of modulation schemes, and
20 modulati~lg transmit data according to one of the predetermined plurality of
modulation schenles.