愛総研・研究報告 創 刊 号 平 成11年
Applicaiion of Analyiic Receiving to the diffCD
1
¥
査
A i盟 tbe盟
i富
h
.
Capacity Land1
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査
obileC o臨 municationSystem and its Transl宣>>.issionCharacieristics over
民査ulti-Ray Rayleigb Fadi:n喜 Cbannel
解析受信の大容量陸上移動通信システム
diffCDMA
への適用と、そのマルチレイレイ
レーフェーデ、ィング伝播路特性
Masahichi Kishi tヲMichioShamoto tt
，
Masahiro Ohba tt，
Kuixi Yin ttt岸 政 七 ラ
社本道雄ラ
大 羽 勝 広 ラ
股 杢 喜
t Aichi Institute of Technologyう ToyotaラAichi
，
470
圃0356
JAPAN愛知工業大学総合技術研究所ヲ豊田市
t t DENSO CORPORATIONヲKariyaヲAichiラ
448
園8
6
6
1
JAPANデンソ一通信技術第
3
部，刈谷市
t t t Nanjing Normal University， NanjingヲChina 南京師範大学物理系電子情報ヲ南京中国 Abstrαct: The d.ぜrerentialcoding CDMA付師CDMA)isverified here to conquer thefiαtα1 transmission error when communicationsαre carried from high speed running vehicles through such urbαn environmentαsrapid multi-r可 R句leigh channels. With bαses of introducing d事erentialcoding into the primαη; modu-iαtion and employing anαlytic receiving for primαryd宥巴nntiα1demodulation， the proposing dijJCDMA improves trαnsmission characteristics of such similar CDMA systems as1S95αnd WcdmαOne JMT2000 when communicα'tionscαrried from more than 100 mile/h mobiles evenザthroughmulti-r句 environment.
計 四iously，dぜ，i[erentiα1coding primα叩 modulα'tionisnot considered tobe α~ble
to stand on CDMA owing to requiring strict sense synchronizαtion in demodulル
tion， whichissujferedfrom bit error under such rαlpid multi叫 )Rayleighfading
However， it becomes to beαble in high speedαnd high capacity trαnsmission afterthe αnα~lytic receiving beingαdopt into CDMA systems‘1n the demodulαtion procedure of the dijfCDMA， received wαves areαtftγst detectedαrfter multi-r句
propαgα'tion with certαininevitα!ble errors both in phaseωld frequency of the recovered carrier for the pseudo synchronizαtion primαry demodulαtion during theαnα!lytic receivin乞
62 愛知工業大学総合技術研究所研究報告，創刊号，平成11年ヲVol.l，Mar.1999
1
.
INTRODUCTION
As known weU， the analytic receiving has been developed for high capacity and high speed PSK digital transmission with such advantages as excluding selective f 同-quency fading， superior receiving sensitiv -ityう andetc. These superior characteristics are derived from the analytic signal proc -essmg. When arbitrary real function is given by f(t)ラ the co汀esponding analytic signal g(t)is spanned on the complex plane asラg
(
t
)
=
f
(
t
)
+
jf
(
t
)
H
e
r
e
.
、 、 ‘ 百 聞 ， ， 〆 切H A / ， . 、 、f
(
t
)
i
s
H
i
l
b
e
r
t
t
r
a
n
s._舟rmoff
(
t
)
(2) ji
s
c
o
m
p
l
e
x
u
n
i
t
， j=
よ
I ( 3 )
The instantaneous phaseB
(
t
)
and en幽 velopeA
(
t
)
are given as followsθ
(
t
)
=
t組 一lよ
位
/
f
(
t
)
、A
(
t
)
=
[
j
可
)
+
I
2
(
t
)
(
5
)
The analytic signalg(t)is described as the polar system by using these instantaneous varlOus.g
(
t
)
=
A
(
t
)
e
月(1)(
6
)
The real part of the analytic signal is coηe -sponding to the existing modulating signals. That is，R
e
{
g
(
t
)
}
=
A
(
t
)
cos{θ(t
)
}
(
7
)
Here
，
B
(
t
)
=
由/
+
B
o
(
t
)
ラω
c
おc
a
r
r
i
e
ra
n
g
u
l
a
r
f
r
e
q
u
e
n
c
，
y
。
10(
t
)
おphasei
n
f
o
r
m
a
t
i
m
a
t
t
i
m
e
t
.
Phase differencel:1e
(
t
)
between real 加lction点。)
andf
k
(
t
)
is easily derived from a product of analyticg; (t)and coル jugate g * k(
t
)
analytic signals indepen・同 dent with each other as follows.g
;
(
t
)
g
'k(
t
)
=
{
A
;
(
t
)
e
J8;(I)}{
A
k
(
μ
'k(t)r
=
{
メ
(
t
)
+
jJ
;
(
t
)
}
{
ん
(
t
)-
jI
k
(
t
)
}
(8)=
{
メ
(
t
)
λ
(
t
)
+
丈
(
t
)I
k
(
t
)
}
+
j
{
よ
(
t
)
λ
(
t
)
一納入(t)}
Here
，
i
o
r
k
i
s
c
o
d
e
c
h
a
n
n
e
l
number
.
ラr
e
司p
e
c
t
i
w
l
y
.
Therefore， ph出e differenceI
:
1
B
(
t
)
between thesei and k code channels is glven asヲ 一l判
g
;
(
t
)
g*k
(
t
)
}
Aθ;k(
t
)
=R
市;
(t)g
¥
(
t
)
}
(9)t
a
n
-1J
;
;
(
t
)
fk
(
t
)
一
五
(
t
)fk
(
t
)
J
;
(
t
)
ん
(
t
)
+
J
;
(
t
)
fk
(
t
)
The加 alyticreceiving for differential coding PSK has already suggested in equa -tion 9冒 Thatis， substituting delayed func -tionメ
(
t-
T) into eq.9 instead off
k(
t
)
， phase difference gives demodulating in巨 forτnation phase values with most precision time resolution as discussed in the nextApplication ofAnalytic Receiving to th巴diffCDMAin High Capacity Land Mobile Comrnunication System 63 session. The in-or quadrature眉channelsig -nal is directly introduced from the real or imaginary part of the product， eq.8， respec酬 tively.
仰
=
R
e
{
g
i
(
t
)
g
¥
(
t
)
}
、B B ノ ハ υ 噌 E i / S 明 、q
i
k
(
t
)
=
叫
g
j
(
t
)g
¥
(
t
)
}
(
1
1
)
Substituting eq.1 into eqs.10 and 11 gives the other significant results of ana -lytic receiving for detecting in園 and quadrature channel signals as follows. i以
t
)
=
メ
(
t
)
f
k(
t
)
+
メ
(
t
)
f
k
(
t
)
(
1
2
)
q
i
k
(
t
)
= ;;(
t
)
五
(
t
)
一
;
;
(
t
)
f
k
(
t
)
(
1
3
)
2
.
ANAL
YTIC RECEIVING IN
PSKSYSTEMS
Fig.1 shows a comparison of BER vs. Eb / No response between analytic receiv・ ハ U 唱 寸 ハ U d u l H 同 凶 ∞ l 10.2 ¥剛
一
同
一 一 一 ⋮ ⋮
10.3 104 ・10 20 30 40 ElNo ，dB。
10 Fig. 1 Bit Error Rate p巴rformanceof QPSK System ing and existing synchronous detection for QPSK measured after propagation through such two-ray Rayleigh fading environment as 10 dB DUR with1.0 micro second delay spread. Transmission quality is remarkably damaged over Nyquist limit bandwidth radio channel in the multi-ray propagation environment even if BER being superior to the analytic receiving by 3dB in the static additive white Gaussian noise (A WGN) environment.On the other hand， the multi園 田y fading robustness is catastrophically improved by employing the analytic re同 ceiving over Nyquist limit bandwidth channel in the same environment from such high speed communications as from 100 milelh running vehic1e or 1，000 kmlh flying aircraft. The phase differenced.θ(t)gives the demodulating angular phase by substituting receiving and delayed signals Instead of two individual signals as fol1ows， -1l
i
1
n
t
g
(
t
)
g本(t-η
Aθ(
t
)
=
阻n
R~ g
(
t
)
g*(
t
-
η
η
一
η
j r S I -d f t i ︽f d
一
正
J ¥ Y 一 ハ リ / ， 目 i ¥ -r ' 同 ‘ 、 、f
J
一 手f
一
一
+
η
一 乃
山 口 V一
μ v〆
J 一f
J
A N
一 角
一n
a
(14) Here， T is symbol duration. As shown clearly in equations from 12 to 14ラ i(t)， q(t)andd.θ(t)are successfully defined in excluding carrier frequencyラ andsimultaneously described as full energy fonn with excluding 合equency spectrum e1imination. These equations will promise the advantages of tolerance both for frequency shift and multi.同ray64 愛知工業大学総合技術研究所研究報告，創刊号ヲ平成11年，Vol.l，Mar.1999
propagation. Circuitry configuration is di嗣
rectlyi1lustrated for the analytic receiving from eqs.(lO) and (11) as shown in均ム
where mark H， DラMUL，or1: means Hil・
bert transformerヲdelayby symbol duration T， multiplier， respectively.
f
(1) Fig.2 Circuitry configuration of the analytic recelvmg Even if the instantaneous phase θ(t) is shifted by certain phase eηorθo (t)in some successive symbol periods during poor ra司 dio channel propagation， the differential demodulating phaseLlθ(t)is preciselyA
θ
(
t
)
ニ{
θ
。(
t
)
+
8
0(
t
)
}
-{
θ。(
t-
T)+
θ
o(
t
-
T) }=θ
。
(
t
)-8
0(
t
-
T) (15) } 民 間 。o(t) isαpri耐v例iIlη抑1 VαJル
μεαttime t.θ
o (t)=
=
θ
o (t -T)，
becau -se of fading phenomena being sufficiently slow to be quasi static in comparison with the tl・ansmissionsymbol rate. Analytic receiving is also able to pre -cisely demodulate receiving signal even if the frequency of the receiving signal is off -set by ppm order from Doppler shift. That isラsincethe instantaneous phase being de -scribed出 θ(t)=θ。
(t)+ωc t +ωo(t)t in the PSK modulationラthedemodulating phase Aθ(t)is given asラA
θ
(t)=
{
θ
。(わ
OJct+ω
o(
t
)
t }-{
8
0(
t
-
T)+
OJc(
t
-
T)+
ω
o(
t
-
T)(
t
-
T)} ニθ。
(t)-8
0(
t
-
T)+ω
cT +mo(t)T (16) Here，臼cTis given by 2mlf， m is a natu -ral number ωo (t)==ωo (t -T)，
beca山E of fading phenomena being αlso s材i'ciently slow to be quasi static in comparison with the transmission symbol rate. And ωδ(t)T can be ignore，dbecause itかne -glected zero.。
- u o
u
l inter polation prevlOUS current Symbol Clo， Fig. 3 Various different competition schemes for introducing the ana -lytic receiving to CDMA SystemApplication ofAnalytic Receiving to the diffCDMA in High Capacity Land Mobile Communication System65
4
.
ANAL YTIC RECEIVING IN CDMA SYSTEMS Pilot CDMA System Differential detection shall be generally employed in vehic1e communication sys嗣 tem in order to avoid the fatal degradation of the synchronized detection in fading environment as shown in fig.1.百lIsad -vantageous is seemed to induce from em-ploying compensation between such adja -cent piv叫S部 adjacentsymbols. Innocently，
since CDMA is spanned over two quadrature axes， two different compensation schemes are facilitated over individual axis as shows in fig.3.The one is spanned on the simultaneousc10ck along to code axis， the other is spanned on the same code axis along to the time axis. The former will yield也e fundamental compensation function of extrapolating pi10t signal similar to the IS95 after substi -tutingれlVOindividual receiving CDMA sig四 nals into eq .12出 follows，
ら
(
t
)
=
い
の
古
川
側
ω
ト
め
か
z仰
}
l
巾ゆ以
ω
ト
ω
か
の
よ
付
Her
，
e
H{w
，
(
t
)
.
t
;
(
t
)
}
=
w
，
(
t
)
}
;
(
t
)
，
(18)w
，
(
t
)
i
s
t
h
e
v
a
l
u
e
0
1
DS
/
SS1
-
t
h
c
o
d
e
a
t
t
i
m
e
t
.
Being accumulated within Walsh code length， eq.17 is modified出， 、 ‘ ， ノ n y 〆 ' E、
、 ‘ E ノ 4 ' ι ， ， . ‘ ‘ 、て ん
、 ‘ ， ノ ， e ' b r ' E ‘ 、 ︽ F T 山+
、 . ， ノ 手 ， v / ， ‘ ‘ 、 pん
、 ‘ ， ノ 4 ' b / ， ‘ 、 、f
山一 一
、 ‘ . ， ノ 4 t 〆 ' E、
J L YH
e
r
e
，
メ
(
t
)
，
fk
(
t
)
，
1
;
(
t
)
，
o
r
fk
(
t
)
i
s
a
p
p
r
o
x
i
m
a
t
e
l
y
g
i
v
e
n
t
h
e
a
v
e
r
a
g
e
d
w
i
t
h
i
n
t
h
e
W
a
l
s
h
d
e
-
.
司p
r
e
a
d
i
n
gc
o
d
e
d
u
r
a
t
i
o
n
0
1
メ
(
t
)
，
f
k
(
t
)
ラメ
(
t
)
，
o
r
fk
(
t
)
，r
e
-司p
e
c
t
i
v
e
l
y
.
Quadrature channel compone凶 qik(t) is similarly given as follows.記
k(
t
)
=
五
(
t
)
f
k
(
t
)
一
五
(
t
)
λ
(
t
)
(20) B叫hiik(1)and;
バ
]
(
t)of eqs.19 and 20 are clearly shown to be .same to the analytic receiving for the PSK defined by eqs.13 and 14 only with exception of averaged value. Differential CDMA System The later will yields the most efficient frequency usage compensation function as the absolute solution for di百eI百ltialcoding CDMA after de-spreading by substituting receiving CDMA and its delayed signals into eqs.13 and 14. The de-spreading in -channel signali; (t)of code-i is given by i ;一叫附
(οの 中 )ωt(
い
い
い
叫
州
附
ゆ
66 愛知工業大学総合技術研究所研究報告，創刊号，平成11年，Vo1.1，M訂.1999
+
{
い
叫
州
附
附
(οtの
ψ )
唱
か
8叫川
wlパ点(刈οの
以
)
ω焔
MA
tο(
w叫
州
附
い
iパ点(οtト
)8ト
叫
州
(
山
λμ(οt斗
仰 Therefore，
averaged(
i
i
t
)
is given byi
i
(
t
)
=
λ
(
t
)
J
;
(
t
-
T
)
(22) 、 、 . ， ノT
4 ' a v 〆 ' E ‘ 、 A f l 山 、 ‘ ， ノ 4 ' ' 〆 ' E ‘ 、 T r h+
Quad凶 町e channel componentq
i
(
t
)
is also given as follows.包
(
t
)
=
点
(
t
)
λ
(
t
)
一
五
(
t
)
J
;
(
t
-
T
)
(23) These eqs.22 and 23 also酔aranteeto introduce the novel diffCDMA with bases ofthe anal戸icreceiving by employing twoQ
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n u Bit timingFig. 4 ECC bit map comparison among typical grouping schemes on the plane spanned by time and code Table 1 Radio Link Parameters. 20Hz π/4副 島d以:;>PS: 明匂lsh32
B
α
責臼，51) time different signals on the same code. All of the pi10t signals are perfectly exc1uded in this diffCDMA to yield the most efficient frequency usage. The diff<ごD1v仏 is also significantly shown in the above to guarantee their accu -racy by exc1uding vagueness both of phase and企equencyinduced during propagation over poor multi-ray channel owing to the genius of analytic receiving. In eqs.19 and 20， or eqs.22 and 23， the pair ofi;k(t) andq
;
k
(t)， or pair ofI;(t) and忌
(t)holds the Hilbert transform relation with each other， respectively.4
.
SIMULATION RESULTS
The analytic receiving is verified in such two CDMA systems as shown in fig.3 through computer simulation. Simulations are performed under conditions listed in table 1. All 1.66 Mbps signals訂ecarried by 4.096Mcps on 4.096恥任l
Z
企equency bandwidth at the 20Hz domain from 100mi1elh vehic1es running through such three environments as two-ray Rayleigh fading of DUR= 10dB with1.0 micro sec -ond delay spread，自atfading， and static A WON. The all codes of 32 length Walsh sequence are employed to span 32 code space. The BCH (63，51) ECC is employed to coηect double eηors within 63bit blockApplication ofAnalytic Receiving to the di狂CDMAin High Capacity Land Mobile Communication System67 along individual bit string of 32k sym -bol/second. Fig.4 shows 3 kind bit mapping schemes where ECC being employed. Grouping S means the case of 12 redundant bits of BCH ECC being inte中olatedafter every 51 information bits. Individua1 れIVO BCH (63，51) block codes are simultaneously adopted into every spec仕um spreading code along time bases. Grouping B is rather simple to adopt BCH with somewhat 10ss in transmission efficientう where12 redun -dant bits are interpolated af王erevery 50 inforτnation bits. Every shortened BCH (62，50) is employed for every DS/SS code along to time axis. The resulting grouping P is performed along to DS/SS code axis. That isヲshortenedBCH (62ラ50)is also con -venient to introduce into diffCD恥1A， be -cause one of 32 code channels being devot -ハ リ Y Y 1 u l h z ' ︼ 出 叫 白 羽 一 目 白 曲alu説話。 - Q曲 出al(2-my紬惑 ー聞は(組。 -Hkt(2-my抽g) J L ハ U 1 1 今 1 d 園 口 U 1 i A U
-4 胃 ハU 咽 - - A
。
203
0
4
0
E〆
V
oラdB 10 Fig. 5 Bit Error Rate performance of CDMA Syst巴m ed to so-called controlling signa.1Therefore，ん
Tand Doppler shi託 制 制 ぬbe0.008 and 0.16 ppm in the all simulations， re -spectively. Such compensations as RAf包 receiving and power control are e出ilyfa -cilitated in the diffCDMA， which are ex -cluded from simulations to make the ana -lytic receiving effect clear. E b / N 0 is measured on the maximum transmission capacity of1.66Mbps when all the 32 code being employed in the differential CDMA system as the both cases for up and down link. The pilot CDMA system is measured on the down link as the maximum仕ans -mission capacity of 1.60Mbps when one code being devoted for common pilot and the left 31 codes being employed for 31 individual information channe.1SimuJation results are shown in fig.5 to be theoretically expected in r巴ceiving reliability through static environment， where the differential CDMA is degraded by 3 dB in comparison with the pilot CDMA owing to doubled noise power interfered over adjacent symbols. Simultaneouslyヲ BERvs. Eb / No responses are splendid as shown in the same figure measured from 100mile!h running vehicles passing through flat fading or two凶rayfading environment. Computer simulations are successfully verified to be almost e汀or free at Eb / No =1 OdB for1.66 Mbps high capacity and 4.096 Mcps of the diffCD恥1A through such poor propagation channel as two-ray Rayleigh fading ofDUR=10dB and 1.0 micro-sec delay spread from 10068 愛知工業大学総合技術研究所研究報告，創刊号，平成11年，Vol.1，Mar.1999 milelh running mob1ie with employing BCH(63ラ51)double eηor correction. The frequenpy usage efficiency is observed to be 0.40 bitlHz， and BER is zero at Eb / No =1 OdB compensated for spreading gain where 64 bits being devoted to e汀or free transmission.
CONCLUSION
The diffCDMA has been successful1y proposed with emphasis on maximization both the transmission reliability and capac -ity. Such high reliabi1ity as eηor free is examined from 100miJelh running vehicles 由roughpoor radio propag剖ionchannel of transmitting 1.6 Mbps CDMA to high speed running vehicles. It is clearly shown in the computer simulations that the pro邑 posing diffCDMA is able to put meg-bit/second order high capacity and 100 milelh high-speed mobile CDMA systems on the developing stages. The transmission capacity has extended by twice with owing to implicit interpolating signal based on differential coding instead of employing pilot signals of extrapolation. The frequen園 cy usage efficiency will be improved with employing such techniques as continuous phase primary modulationラcontinuouschip shaping secondary modulation， virtual segment interleaving， power control， and RAKE receiving. The circuitry complexity will be effectively reduced in diffCDMAヲ which is implemented in the isomorphic topology between up and down links owing to the novel analytic receiving.REFERENCES
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