Tutorial on TDD Systems

Tutorial on TDD Systems

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Description

Tutorial on TD
D Systems
FCC O
f
fic
e
o
f
Engineer
in
g and Techn
o
logy
Monday
,
De
cember
3, 2
0
01
Part 1: Overview
of Duplex Schemes
Rém
i
Cha
y
er
Chairman
TDD Coali
t
io
n
http:/
/w
w
w
.tddcoalition.
org
E-
ma
il:
rc
h
a
y
e
r@
h
a
rr
is
.co
m The TD
D Coalition
It is th
e po
sition of
the TDD Coalition th
at
wi
th p
r
o
p
e
r
planning a
n
d

reg
u
lato
ry co
nside
r
ation
s
,
TDD and
oth
e
r
duple
x
ing
t
ech
nologies can
coe
x
ist in
the
sam
e
ge
og
ra
phic a
nd
spe
c
t
r
al spa
c
e
Aper
to Ne
t
w
orks
LinkAir
Malibu Netw
orks
Arra
y
c
omm
BeamRe
ach
Netw
or
ks
Na
v
i
ni Ne
tw
orks
Caly
Netw
orks
Pointred Te
c
hnologies
Radian
t Ne
t
w
ork
s
Clear
w
i
re Te
chnologies
Harri
s Corpo
r
a
t
ion
Raze
Techn
o
logies
InterDigi
t
al
Wa
v
i
on Ltd
IP Wireless
December 3,
2
0
0
1
2 Overview of the Duplex Schemes
!
Definitions
"
FDD
"
TDD
"
Adaptive TD
D
!
Comparison of TDD
vs FDD
"
Spect
r
u
m
Efficiency
"
Spect
r
um All
o
cation and
Utilization
"
Deployment
and
Net
w
o
r
k Planning
Issu
es
"
Comp
atibility
wi
th
eme
r
ging applicatio
ns and
all-IP ne
t
w
o
r
ks
with
a
s
y
m
m
e
tr
i
c
tra
f
f
i
c
"
Adaptability to advance
d
signal pro
c
e
s
sing
(ada
ptive
anten
na
s,
use
r
t
e
rminal
beam
-f
ormin
g
, et
c.
)
"
Field trials
December 3,
2
0
0
1
3 FDD –
F
requency Division Duplexing
!
Separ
a
te in frequency
the dow
n
stream and upstream
directions
of the traffic
!
Ratio betw
een dow
n
s
tream an
d upstream traffic fixed
by
...

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Tutorial on TD D Systems FCC O f fic e o f Engineer in g and Techn o logy Monday , De cember 3, 2 0 01 Part 1: Overview of Duplex Schemes Rém i Cha y er Chairman TDD Coali t io n http:/ /w w w .tddcoalition. org E- ma il: rc h a y e r@ h a rr is .co m The TD D Coalition It is th e po sition of the TDD Coalition th at wi th p r o p e r planning a n d reg u lato ry co nside r ation s , TDD and oth e r duple x ing t ech nologies can coe x ist in the sam e ge og ra phic a nd spe c t r al spa c e Aper to Ne t w orks LinkAir Malibu Netw orks Arra y c omm BeamRe ach Netw or ks Na v i ni Ne tw orks Caly Netw orks Pointred Te c hnologies Radian t Ne t w ork s Clear w i re Te chnologies Harri s Corpo r a t ion Raze Techn o logies InterDigi t al Wa v i on Ltd IP Wireless December 3, 2 0 0 1 2 Overview of the Duplex Schemes ! Definitions " FDD " TDD " Adaptive TD D ! Comparison of TDD vs FDD " Spect r u m Efficiency " Spect r um All o cation and Utilization " Deployment and Net w o r k Planning Issu es " Comp atibility wi th eme r ging applicatio ns and all-IP ne t w o r ks with a s y m m e tr i c tra f f i c " Adaptability to advance d signal pro c e s sing (ada ptive anten na s, use r t e rminal beam -f ormin g , et c. ) " Field trials December 3, 2 0 0 1 3 FDD – F requency Division Duplexing ! Separ a te in frequency the dow n stream and upstream directions of the traffic ! Ratio betw een dow n s tream an d upstream traffic fixed by equipment design " 1/2 - 1 / 2 fo r voice " 2/3 – 1 /3 f o r data (typical for 16 QAM do w n , 4 Q AM up ) ! FDD requires a guard band betw een the dow nstr eam and upstream F r equenc y Separati on: x MHz Do w n stre am Upstream Gua r d Band December 3, 2 0 0 1 4 TDD – T ime Division Duplexing ! Separ a te in time the dow nstr eam and upstream directions of the traffic An exa m ple o f TDD is h a lf-duplex t r an smission on a n HF com m uni cati on sy ste m u s ing a push - to -talk s w it ch ! Use a single frequency for both dow nstream and upstream ! Ratio betw een dow n s tream an d upstream traffic can be fixed or adaptive ! TDD requires a guard time betw een the dow nstr eam and upstream but no guard band December 3, 2 0 0 1 5 Data Traffic Asymmetry I nboun d & O u t bound T r a ffi c ( b p s ) LBL traffic is nearly 100 secs dur at i on, 1 sec bi ns symm e tric averag ed over 2 ed over 2 2. 0E + 0 6 hours (53/4 7 ) 1. 5E + 0 6 but but 1. 0E + 0 6 5. 0E + 0 5 as y mmetric 0. 0E + 0 0 over 1000 1010 1020 1030 1040 1050 1060 1070 10 80 1090 1100 shorter intervals Tim e (se c ) Statistics Averaged Over 2 H our T r ace: our T Aggreg ate: 392 kbps Aggreg Inboun d: 18 5 kbps Inboun Outbound: 20 7 kbps December 3, 2 0 0 1 6 Bits Pe r Se c Real-Time A daptive TDD ! Real-time adaptation provides highest transport efficiency " Milliseco nd re al-time a dap t a tion " 35% imp r ovement over FDD/TDMA ! TDD enabl es 100% use of available spectrum " Well-suited f o r wide , single block allocati ons and na rro w, d ual block allocati ons ! Min i mal latency variation enables prioritization of preferred subscriber s and critical applications December 3, 2 0 0 1 7 Spectral Efficiency P e r c e n t I m pr o v m e n t i n S p e c t r a l U t il iz a t io n 45 % 40 % 35 % 30 % 25 % 20 % 15 % 10 % 5% 0% 12 345 6789 1 0 R a t i o 1 : X of T r a f f i c L o a d With asy mme tric traffic (data), TDD sy ste m s use spe c t rum more effi cien tly than FDD systems. December 3, 2 0 0 1 8 P e r cen t Spectral Efficiency ! Minimize guard band ! Change sy mmetry on the fly de pending on subscriber ’s needs ! Adaptive dow n s tream/upstream ratio allow s for emerging new applications w i thout the need for spectrum re-farming ! Enables advanced technologies such as mesh netw or k and adaptive antenna array s ! Highly effective for b u rsty data traffic w h ile still supporting voice December 3, 2 0 0 1 9 Spectrum Allocation and Utilization ! TDD allow e d by the FCC, CEPT, Japan, Canada and many other countries ! Some countries still need to be convinced ! FDD absol u tely requires paired spectrum ! TDD can be used w i th paired and unpa ired spectrum “TDD can u s e eithe r sub - b and a nd t he middle gua rd band ” (f ro m an ITU-R Recom m en dation ) ! Block edge mask co ntributes to TDD/FDD coexisten ce ! New mitigation techniques are being dev e loped (Auton omo u s Freq uen cy Allocation – A F A for e x a m pl e) December 3, 2 0 0 1 10