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PROPRIETARY1
Repeaters in CDMA and UMTS
Network Design Guidelines
Dr. Joseph [email protected]
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PROPRIETARY2
Contents
Definitions and classification
Repeater interaction with the network
Network planning with repeaters
Radio Hole Rural area
Hot Spot
Multiple repeaters: Star, cascade
Backhaul and interference cancellation
Indoor Service Pico repeaters
Optimization with repeaters
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PROPRIETARY3
Definitions
Repeater (3GPP): A device that receives, amplifies and
transmits the radiated or conducted RF carrier both in the
down-link direction (from the base station to the mobile
area) and in the up-link direction (from the mobile to the
base station).
Repeater is linked to the RF path and shares the BS resources
with the donor-serviced UEs.
Remote Sector is an access point that has its own resources
(bank of transceivers).
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PROPRIETARY4
CDMA repeatersDL, UL
GRR
FR
GB
FB
BTS Repeater
Tr
n
TD
RC
RR
Tc
RC0
m
GRR
FR
GB
FB
BTS Repeater
Tr
n
TD
RC
RR
Tc
RC0
m
GRF
FRFBTS Repeater
TRF
n
m
TDF
RCF
RRF
TcF
RC0
PA
GRF
FRFBTS Repeater
TRF
n
m
TDF
RCF
RRF
TcF
RC0
PA
Up-Link Down-Link
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PROPRIETARY5
Types of Repeaters
1. Embedded
2. Border extension
3. Remote
4. Cascaded
RR3
D3
D2
1
2
3
RR2
RR1
D1 RC
RR3
D3
D2
1
2
3
RR2
RR1
D1 RC
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PROPRIETARY6
Repeater coverage - DL
Coverage extension repeater
Signal received in mobile [dBm] Cell boundary
Hole filler repeaterBoundary repeater
Coverage extender Other cell
PBT(0)
PBT(0)yE
PBT(0)yB
PBT(0)yH
Cell coverage
Co
verage extension repeater
Signal received in mobile [dBm] Cell boundary
Hole filler repeaterBoundary repeater
Coverage extender Other cell
PBT(0)
PBT(0)yE
PBT(0)yB
PBT(0)yH
Cell coverage
The transmission-gain (T) slope depends on the antenna height and tilt
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PROPRIETARY7
Repeater Coverage - UL
Repeater embedded in a cell
Cell coverage
Pm[dB]
q
q/y
q/y
q
Repeater
coverage
Overlap
RC
RR
R0
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PROPRIETARY8
Cascaded (multi-hop) repeaters
Repeaters are cascaded to increase coverage
1. Along roads
maximal area/ length
2. Within an area/ campus
mixed large/ small areas
3. Within buildings
limited area, complex coverage
Distribution (backhaul):
Star
Cascade
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PROPRIETARY9
Repeater Interaction
Donor
antenna
Service
antenna
GF
GR
PF
PR RSSIR
RSSIF
DuplexDuplex
BTS
antenna
UE
antenna
yR=GRTDR
yF=GFTF
TDR
TUE R
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PROPRIETARY10
Impact of repeater on donor cell - RL
Apparent repeater noise factor
Effective cell noise factor
Effective repeater noise factor
Total load m+n
C
R
FFyF
FF
Fy
F
FFyFFF
C
R
C
CECERCCE
11;
GRR
FR
GB
FB
BTSRepeater
Tr
n
TD
RC
RR
Tc
RC0
m
GRR
FR
GB
FB
BTSRepeater
Tr
n
TD
RC
RR
Tc
RC0
m
yFFFyFFF CRCRERE11
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PROPRIETARY11
RL Impact of repeater on network
Loads the donor noise and reduces its coverage and/ or capacity
Overlap introduces diversity. Excess fingers introduce
interference.
No Rx diversityincreases UE_Tx and BS load, and reducescoverage
Change in Donor link gain causes change in coverage for both
repeater and donor
Imbalance DL-UL (excess offset) causes the P.C. open loop tobe noisy, and loss of capacity. Imbalance exceeding about
close loop range breaks the P.C. loop and drops RSUs
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PROPRIETARY12
Sensitivity and Noise Rise
q [dB]
q [dB]
1
1;;
1
Re
0
Tbtb
BTS
m SNRN
nWRNEquired
WFN
rTrPq
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PROPRIETARY13
Coverage-Capacity Trade-Off
The repeater coverage can be traded-off vs. Donor Capacity
Leaving donors coverage at nominal NR intact Donor Coverage
Maximizing the total capacity
User density in the area (coverage is linked to capacity)
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PROPRIETARY14
Capacity-Coverage Trade-off
Noise rise =
ST set limit
ST[dB]
Capacity loss
Max allowable
slope
][110 dBFLOG
30%coverage loss
17.5% capacity
loss
But recovered
and more-
by repeaters
10101
;;1
1dBNRT
nN
N
nFS
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PROPRIETARY15
Noise Rise vs Apparent Noise Figure
0
1
2
3
4
5
6
7
8
-25
-22
-19
-16
-13
-10
-7
-4
-1 2 5 8
Apparent Noise Figure [dB]
NoiseRise
[dB]
Noise Rise
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PROPRIETARY16
Repeater coverage - UL
11
11
1
0
0
00
00
IC
y
FWFN
rTrP
IC
FWFN
rTrP
IC
WFN
rTrP
BTS
RRm
BTS
CCm
CBTS
CCm
4UrrT
UL link budget
Baseline donor
Donor loaded with
repeater
Repeater
But
212
21
0
2
0
21
0
2
0
11
1
1
1
1
1
Uy
R
R
F
Uy
R
R
FR
R
C
R
CC
R
CC
C
T is transmission gain (between Tx and Rx antennas)
U is antenna height & diversity parameter
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PROPRIETARY17
Loss of Donors capacity and coverage
due to repeaters noise (no additional load)A Excess noise rise for fixed load limit (loss of coverage)B Loss of capacity for fixed noise rise limit
A B
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
Apparent repeater noise figure
Re
lativerangeandcoverage
Range (normalized) Coverage( normalized)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
-10 -8 -6 -4 -2 0 2 4 6 8
Apparent repeater noise figure
Donorcapacityrelativeto
nomin
al(max.loadfactorvs.
nominal)
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PROPRIETARY18
Repeater Noise RiseNRr,n fixed, N=40
0
5
10
15
20
25
30
35
40
45
50
1 4 7 10 13 16 19 22 25 28
Number of RSU
NRr[dB]
n=0;y=0 dB
n=0;y=-10 dB
n=0;y=-20 dB
n=5;y=0 dB
n=5;y=-10 dB
n=5;y=-20 dB
n=15;y=0 dB
n=15;y=-10 dB
n=15;y=-20 dB
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PROPRIETARY19
Down (Forward) Link
Relays all donor transmission ( plus other interfering sources)
No automatic balancing UL/DLHas to be controlled for coverage (gain) and saturation
(AMLC)
Reduces RSU (repeater-served-users) per-user power
Increases PiCH/TCH ratio for RSU (TCH is power-controlled)
RFDFF GTy
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PROPRIETARY20
Repeater specsPower (example)
Parameter Unit Assumed value
G dB 90 dB
Pout_DL_max dBm 30 dBm
Pout_UL_max dBm 12 dBm
NF dB 5 dB
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PROPRIETARY21
Power UL vs Power DL
Why is Max power DL higher than UL?(up to 18 dB)
TDR is higher than TUER (not true for pico) Coupling to the donor is designed to be high (LOS, high-gain
antennas)
Coupling to the UE determines the coverage, and is low.
DL transmits all BS transmission, ULonly RSUs
Headroom for PC (typical to 9 dB) on DL. May be on ULtoo in Pico.
Repeaters in SHO carry up to 50% more DL power perlink.
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PROPRIETARY22
SHO DL OverheadSHO Probability
(1, 2, 3 way) %
Average total DL
power [units]
UL noise rise
[dB]
67, 22, 11 4.37 1.7756, 25, 19 6.32 1.68
45, 27, 28 8.56 1.58
Ref: Laiho, A. Wacker, T. Novosad: Radio Network Planning and Optimization for UMTS, Wiley 2002
Repeaters in SHO carry up to 50% more DL power per link
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PROPRIETARY23
Impact of Repeaters on the Network - DL
Net gain (yF) determines coverage
Excess gain causes oscillations/spurii
ALC reduces coverage, causes imbalance and reduces capacity
Amplifying other sources may lead to ALCInstability of the BS-Repeater (BSR) link (e.g. directive antenna
nodding, fiber loss change with temperature, etc.) changes
coverage
Overlap with donors coverage adds multiple fingers to the MSreceiver, introduces interference (reduces orthogonality) and
diversity (if there are enough fingers).
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PROPRIETARY24
Coverage of repeaters
Embedded Border Remote
-10.00
-8.00
-6.00
-4.00
-2.00
0.00
2.00
4.00
6.00
8.00
10.00
0.02 0.
10.18
0.26
0.34
0.42 0.
50.58
0.66
0.74
0.82 0.
90.98
Distance from BTS (normalized)
Prs/Ps[dB]
-10.00
-8.00
-6.00
-4.00
-2.00
0.00
2.00
4.00
6.00
8.00
10.00
0.
46
0.
52
0.
58
0.
64
0.
7
0.
76
0.
82
0.
88
0.
94 1
1.
06
1.
12
1.
18
1.
24
1.
3
Distance from BTS (normalized)
Prs/Ps[dB]
-15.00
-13.00
-11.00
-9.00
-7.00
-5.00
-3.00
-1.00
1.00
3.00
5.00
0.9
0.98
1.06
1.14
1.22 1.
31.38
1.46
1.54
1.62 1.
71.78
1.86
1.94
Distance from BTS (normalized)
Prs/Ps[dB]
Cell border
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PROPRIETARY25
Multipath, rake receiver
and search window
Ch l t
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PROPRIETARY26
Channel response to an
ImpulseMultipath occurs in discrete
peaks (fingers)
The fingers follow a structured
path along UE motion.
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PROPRIETARY27
Rake ReceiverThe rake receiver is a series of correlators searching in time-
delay for signal peaks with the right code (multipaths).
Each finger extends over one chip (0.26 ms).
The number of fingers in the receiver is limited.
The time delay from the first-arriving peak (delay spread)that is searched in UMTS is 20ms ( but is adjustable insome vendors systems).
Multipath fingers captured by the receiver are MRC-
combined (Maximal ratio combiningphase-adjusted andSNR-weighted) to create diversity gain.
Excess multipath adds only noise.
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PROPRIETARY28
Repeater Delay and Multipath
(Fingers) Search WindowRSU excess delay
D=DR+ (dDR+dRUE-dDUE)/c
D
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PROPRIETARY29
AGCAGC is not a required feature for CDMA repeaters. The fast
power control maintains the coverage, both DL and UL.
AGC is used with low-power repeaters, loosely coupled to
the BS (y
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PROPRIETARY30
ALCALCAutomatic Level Controlis a guard measure against
amplifier saturation, signal distortion and generation ofspurious interference. It is used on the DL, and in somesystemson UL.
ALC reacts to amplifier saturation by reducing the gain whenthe amplifier reaches its limit, and maintaining a constanttransmission level. While in operationit biases the DL
power control and reduces coverage and functionality. Itretrieves the normal gain setting when the amplifieroverdrive is relaxed. Its operation is to be programmed by
the operator.ALC is a guard measure, not a normal mode of operation. Its
operation has to be limited and the respective problem (andassociated alarm) be addressed.
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PROPRIETARY31
Network planning with repeaters
Major parameters:
Repeater location
Repeater UL/DL power, gain, dynamic range
(per channel, per location and purpose)
Height, beam-width, direction and tilt of
service antenna
Backhaul link
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PROPRIETARY32
Coverage-capacity limits vs user density
5161 ; lR
0.45
0.55
0.65
0.75
0.85
0.95
1.05
1.15
1.25
1.35
1.45
1.55
0.05 0.
20.
35 0.5
0.65 0.
80.
95 1.1
1.25 1.
41.
55 1.7
1.85 2
2.15 2.
32.
45 2.6
2.75 2.
9
User area density (normalized)
Cellrange(normalized)
Coverage-
limited
Capacity-
limited
Density Log scale)
Radius R (Log scale)
Forward link power limit
Reverse link
(interference) limit
Available zone
Rr
a b
0.45
0.55
0.65
0.75
0.85
0.95
1.05
1.15
1.25
1.35
1.45
1.55
0.05 0.
20.
35 0.5
0.65 0.
80.
95 1.1
1.25 1.
41.
55 1.7
1.85 2
2.15 2.
32.
45 2.6
2.75 2.
9
User area density (normalized)
Cellrange(normalized)
Coverage-
limited
Capacity-
limited
0.45
0.55
0.65
0.75
0.85
0.95
1.05
1.15
1.25
1.35
1.45
1.55
0.05 0.
20.
35 0.5
0.65 0.
80.
95 1.1
1.25 1.
41.
55 1.7
1.85 2
2.15 2.
32.
45 2.6
2.75 2.
9
User area density (normalized)
Cellrange(normalized)
Coverage-
limited
Capacity-
limited
Density Log scale)
Radius R (Log scale)
Forward link power limit
Reverse link
(interference) limit
Available zone
Rr
a b
121 ; lRDL UL
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PROPRIETARY33
Repeater parameters
42
C
R
C
R
C
R
C
R
t
t
H
H
g
g
G
GU
GR,C antenna gain
(note sectorization gain)
R,C repeater, cell
g diversity gain
H antenna height
t tilt parameter
Activity and interference Antennas and diversity
capacityPoleN
densityArea
N
Ns
R
C
C
RRC
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PROPRIETARY34
Beam-tilt and foot-print
kHh
Tilted Beam
Reference
Reduced power
R
H
tilt
Rtilt
LOG(Rtilt)
Cell boundary:
Reference
With tilt
Stronger and
shorter coverage
LOG (R)
Power received at MS[dB]- R-2 propagation law
Tilt (BW) 0.4 0.6 0.8
Range R=1000m 72 46 28
With tilt (%) R=500m 74 50 32
R=200m 78 55 38
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PROPRIETARY35
Directional donor/ repeater
If
the beamwidth of the donor
coverage is 1/n of a circle
the beamwidth of the repeatercoverage is 1/m of a circle
Then
smns
Un
mU
s
s
n1m1
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PROPRIETARY36
Rural Area
(extension/ remote repeater)User density in the area is allowed to have two values, both in
the donor and in the repeater, accounting for denser inner
cores.
s1 ratio of donors inner core density to the rest
sR ratio of repeaters density to donors
sR1 ratio of repeaters inner core density to rest
R1 radius of donors inner core
RR1 radius of repeaters inner core
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PROPRIETARY37
Rural AreaBase load=50%;s1=1;sr=0.5;sr1=1;r1=.3;rr1;=.1;F=0 dB
00.10.2
0.30.40.50.60.70.80.9
11.11.21.3
-30
-26
-22
-18
-14
-10
-6
-2 2
Donor coverage
Repeater coverage
Load
Coverage
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PROPRIETARY38
Radio Hole in a Dense AreaThe objective is coverage of a well defined area with minimum
loss of capacity and coverage. The repeater coverage isembedded within the cells/ sectors coverage.
The cell base load is 70%
The radio hole covers 1% of the cells/ sectors area
Required density in the repeaters area sR=1
Antenna - U=.1 (U is a coverage-control parameter)
The working point is set to cover the required area.
y=-26dB Cov.=15% ; Donor cov.=98% ; Load=70%
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PROPRIETARY39
Coverage of a radio hole
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
-30
-26
-22
-18
-14
-10
-6
-2 2 6
10
Net gain y
Lnearvalues
Coverage
Repeater fractional
coverage
Repeater coverage
repeater load
Total load
Normalized total load
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PROPRIETARY40
Hot Spot
Hot spotthe density within the hot spot is high. The BS
power may not suffice, if the link to the hot spot is weak.
The working point is chosen so that the repeater coverage
exceeds the hot spot area, with a minimum effect on the
donors coverage.
Example presented: Hot Spot area 5%
Base Load s U HS cov. Fr [dB] y [dB] Load Cov.
0.3 10 0.10 0.07 0.00 -9.00 0.61 0.720
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PROPRIETARY41
Hot Spot repeater
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
-30
-26
-22
-18
-14
-10
-6
-2 2 6
10
Net gain y
Lnearvalues
Coverage
Repeater fractional
coverage
Repeater coverage
repeater load
Total load
Normalized total load
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PROPRIETARY42
Multiple Repeaters - Star/ Cascade
Star
Each repeater may be controlledindependently
The aggregate apparent noise factorcounts. Optimal settingsame net gainto each.
Cascade
The gain setting of each repeaterinfluence the rest of the chain. Thecoverage is successively smaller. Optimal
settingsame net gain (y) to all repeatersbut the first (preferablyy=1). Control thechain by the net gain of the first.
RC R1 R2 R3 R4
Total range
RC R1 R2 R3 R4
Total range
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PROPRIETARY43
Coverage area vs. number of repeaters
Uniform density of users
4
664
0 ;;
nn
R
R
R
p
P
nRpRrdrrP
2
22
n
nR
RnRnRCoverage
Power limitation, DL
nCoveragen
Coverage
F
Fn
nR
R
n Fnn
1
2
1
;
1
1
1
2
1
2
1
212
Noise Rise limitation , UL
Coverage advantage to multiple repeaters for low-density
coverage, both UL and DL
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PROPRIETARY44
Star Coverage
Uniform user density, very light load
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
-20
-18
-16
-14
-12
-10 -8 -6 -4 -2 0 2 4 6 8 10
net gain y[dB] per repeater
Totalcov
erage
n=1 n=2 n=3 n=4 n=5
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PROPRIETARY45
STAR coverage5 repeaters
Coverage dependence on the load
uniform densityCoverage, n=5, U=1, s=1
1.000
1.200
1.400
1.600
1.800
2.000
2.200
2.400
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2 0 2 4 6 8
10
y[dB]
Coverage
5%
30%
50%
60%
40%
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PROPRIETARY46
Coverage, n=5, U=1, s=0.1
1.000
1.200
1.400
1.600
1.800
2.000
2.200
2.400
2.600
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2 0 2 4 6 8
10
y[dB]
Coverage
5%
30%
50%
60%
40%
Coverage dependence on the loadRepeaters density s=0.1
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PROPRIETARY47
Total length including donor
1.5
2
2.5
3
3.5
4
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5
y=repeater + link gain
to
tallength
1 repeater 2 3 4 5
Road Coverage with Cascaded RepeatersVery light load
Donor cell radius shrinkage
0.40
0.500.60
0.70
0.80
0.90
1.00
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5
y=repeater +link gain
Don
orcellradius
5 4 3 2 1 repeater
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PROPRIETARY48
Diversity GainSignal fading below threshold increases the
Bit Error Rate (BER)
Correlated fading: gain 3 dB
Threshold
Rx Diversity
MS
SDiversity gain is the rise of the average signal
level for the same BER (for the same fraction of
time below the threshold)
Uncorrelated fading: gain 7 dB
(at 1% FER)
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PROPRIETARY49
Cumulative Distribution Function (CDF)
for Diversity Combining
Single Branch
Diversity Gain (dB)
Signal [dB]
CDF
10%
100%
Prob. Signal
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