The document discusses coverage and capacity concepts for WCDMA networks. It provides 3 key points: 1) WCDMA uses processing gain to provide different coverage levels for various services, with higher bit rate services requiring more power. Cell breathing and pole capacity concepts are also introduced. 2) Coverage is analyzed through uplink and downlink link budget comparisons to GSM. WCDMA is shown to provide better coverage for similar services. 3) Network capacity is maximized by optimizing the distribution of power between common and dedicated channels. Uneven user distributions and cell loading also impact achievable capacity. HSDPA is noted to further increase the average power utilization in the network.

1. Coverage and Capacity
Patrik Persson
Senior Specialist
WCDMA RAN System Management

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Outline
 Properties of WCDMA
– Processing gain
– Cell breathing
– Pole Capacity
– Orthogonal Channels
– Pooled DL power resources
– Soft Capacity
 Coverage: Link budget analysis
– UL and DL reference to GSM
 Capacity: Maximising air interface resources
– Common and dedicated power
– Effect of different user distribution
– Capacity and coverage
 HSDPA Considerations

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Properties of WCDMA
Processing gain (1/2)
 The processing gain allows
higher receiver sensitivity for
users with low bit rate
 Higher bit rate services
require more power since the
processing gain (sensitivity) is
lower
 The different sensitivity for
different services will
generate different coverage
Speech
PS 64
CS 64
PS 384
Decide which
service
to plan for

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Properties of WCDMA
Processing gain (2/2), downlink receiver sensitivity
Thermal noise -108 dBm/3.84 MHz
Sensitivity = Pth
Procesing
gain
- 10 log(Rchip/Rinfo)
UE Noise Figure ~9 dB in UE
+ NF
Eb/No
+ Eb/No
Sensitivity – minimum code power
required
-110 dBm
-120 dBm
-130 dBm
Speech
Packet 64
Packet 128
Packet 384
GSM Speech
UL DL
AMR 12.2 -125.2 -116.1
AMR 5.9 (SF=256) -125.8 -116.8
UDI -120.7 -109.8
I64/64 -121.2 -111.3
I64/128 -121.2 -109.1
I64/384 -121.2 -103.7
Example of sensitivity values

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PRx
UL sensitivity
Properties of WCDMA
Noise rise - single cell
-110 dBm
-120 dBm
-130 dBm
WCDMA UL
Pint,own
Own cell interference
Each new user decreases
the cell size – cell
“breathes” with load

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PRx
UL sensitivity
Properties of WCDMA
Noise rise - multi cell
-110 dBm
-120 dBm
-130 dBm
WCDMA UL
Pint,own
Own cell interference
Pinter,othe
r
Other cell cell interference

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Properties of WCDMA
Noise rise vs. load, Pole capacity
 Noise rise is directly
proportional to loading
 With 100% load the pole
capacity is reached
)
1
1
log(
10
Loading
Noiserise


High coverage
Low capacity
Low coverage
High capacity
Unstable
region
The anticipated load must be taken into
account in the cell planning process
Pole capacity
-No coverage
-Infinite power

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Properties of WCDMA
Impact of orthogonal channels
Pinterference
Th. Noise Th. Noise Th.Noise
No orthogonality
=1
Perfect orthogonality
=0
Reality
in between
Typical urban: =0,6
Rural area: =0,2
CC4,0=(0000)
CC4,1=(0011)
CC4,2=(0101)
PCCH
The orthogonality descibes the
capability of the UE to suppress
own cell interference in the
downlink

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Properties of WCDMA
Other cell interference, effect of cell overlap
 Cell overlap increases other cell
interference
– DL users consume more power
– UL users generates more
interference
 This results in
– Less coverage
– Increased drop rate (pilot pollution)
– Less capacity
Keeping confined cell is essential for
coverage and capacity
-the cell plan sets the limit of how
much traffic that can be carried in the
system
-Narrow beam width antennas and tilt
are needed to achieve low cell overlap
Cell overlap UL pole capacity
0% 150
20% 125
40% 107
60% 94
80% 83
100% 75
150% 60

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Properties of WCDMA
Pooled power resources in downlink
 Mobiles share the available
power in the cell
 The power usage depends on
– Distance to cell
– Radio environment
(channel dispertion)
– Interference
– Service type
High power usage
far from cell or with
high data rate
service
Low power usage
close to site in good
radio condition
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
Required
power
(W)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Distance to cell (km)
Indoor
Outdoor
Example of power requirement for outdoor and indoor
speech users at various distances from cell

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Effects of soft capacity
Equally loaded cells
Less loading in surrounding cells
 Higher capacity in middle cell
Equally loaded cells
Less loading in surrounding cells
 Higher capacity in middle cell
0
200
400
600
800
1000
1200
130 135 140 145 150
Lsa [dB]
Cell
border
throughput
[kbps]
0% 25% 50% 75% 100%
Example of cell border throughput
Equally loaded
No load in neighbouring cells
Maximum cell capacity and user
throughput can be significantly
higher in an unevenly loaded
network
 All networks are
unevenly loaded
Cell pole capacity
Equal load Unloaded neighbour
85
125
Upto 50% more capacity

12. Coverage
Linkbudget analysis

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Coverage
Uplink Linkbudget, comparison between GSM/WCDMA
GSM WCDMA
Continuous transmission in WCDMA
1900 1900
21 21
- -
17 17
incl Eb/No incl Eb/No
- -
3 0
0.3 0.3
- -
7.5 7.5
0.7 0.7
- -
1.5 1.5
-125 -121
150.0 149.1
0 0
150.0 149.1
150.0 149.1
2.9 2.7
Frequency (MHz) 1900
TX power (MS & RBS) 30
TX antenna gain -
RX antenna gain 17
Rx diversity 3.5
TMA/ASC insertion Loss 0
Body loss 3
Lf+Lj loss 0.3
Interference margin 1
LNF margin 8.4
PC margin (at cell border) -
Rayleigh fading margin 3
Noise rise due to loading -
RX sensitivity -111.5
path loss 146.2
Building penetration loss 0
Path Loss (Lp) 146.2
Max Path Loss (Lp)+clutter freq delta(dB) 146.2
Cell range (km) 2.2
RX diversity gain included in
Sensitivity value
Soft handover reduces the effect of
fading
Fast power control counters the effect of
fast fading
Interference due to load (1-5 dB)
WCDMA has better coverage than GSM
Speech Speech P64

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Coverage
Downlink Linkbudget, comparison with GSM/WCDMA
GSM WCDMA
Frequency (MHz) 1900
TX power (MS & RBS) 40
TX antenna gain or WCDMA DL Pout (W) 17
RX antenna gain -
Rx diversity 0
TMA/ASC insertion Loss 0.3
Body loss 3
Lf+Lj loss 3.0
Interference margin 1
LNF margin 8.4
PC margin (at cell border) -
Rayleigh fading margin 3
Noise rise due to loading -
RX sensitivity -104
path loss 142.3
Building penetration loss 0
Path Loss (Lp) 142.3
Max Path Loss (Lp)+clutter freq delta(dB) 142.3
Cell range (km) 1.7
Possible to control the coverage by allowing
higher power for high bitrate services
Soft handover reduces the effect of
fading
Fast power control counters the effect of
fast fading
Interference due to load (1-5 dB)
1900 1900
34.1 35.6
17 17
- -
0.3 0.3
3 0
3.0 3.0
- -
7.0 7.0
0.7 0.7
- -
3.0 3.0
-116 -111
150.2 149.9
0 0
150.2 149.9
150.2 149.9
2.9 2.9
WCDMA has better coverage than GSM
Same coverage for speech and I64
Speech Speech P64

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Coverage
CPICH linkbudget
Fading margin is higher since there
is no soft handover
CPICH coverage should
match UL speech
Frequency (MHz) 1900 1900 1900
TX power (MS & RBS) 21 21 34.5
TX antenna gain - - 17
RX antenna gain 17 17
Rx diversity incl Eb/No incl Eb/No -
TMA/ASC insertion Loss - - 0.3
Body loss 3 0 3
Lf+Lj loss 0.3 0.3 3.0
Interference margin - - -
LNF margin 7.5 7.5 8.4
PC margin (at cell border) 0.7 0.7 -
Rayleigh fading margin - - -
Noise rise due to loading 1.5 1.5 2.0
RX sensitivity -125 -121 -115.1
path loss 150.0 149.1 149.9
Building penetration loss 0 0 0
Path Loss (Lp) 150.0 149.1 149.9
Max Path Loss (Lp)+clutter freq delta(dB) 150.0 149.1 149.9
Cell range (km) 2.9 2.7 2.9

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Setting the CPICH power
 Matching the UL coverage
– UE max power
– Service rate
– Load
 Considering PA power
– Higher PA  less relative
power to CPICH since the
UL remains the same
 CPICH settings range from 6% -
16%
– Low setting for 20W high
capacity
– High power too avoid
camping on GSM, setting at
wrong reference point
The CPICH must support UL coverage
for high load and low load cases
Higher power PA means more
interference at cell edge. Increase in
interference less than PA increase
relative CPICH setting can be reduced

17. Capacity
Maximising air interface resources

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Power distribution
FACH-2
3%
FACH-1
1%
P-CPICH
8%
P-SCH
0%
PCH
1%
BCH
3%
AICH
0%
PICH
1%
S-SCH
0%
CCH pow er
22%
PCH
Capacity
Shared power between dedicated and common channels
Pilot, BCH use
approx 60% of
CCH power
FACH and
PCH are traffic
dependednt
Max 25% to
Common
channels
Remaining
power to be
used for traffic

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Capacity
Shared power between dedicated and common channels
Settable powersettings on common channels
Sync channels and Broadcast channel are multiplexed
Traffic based
P-SCH
S-SCH
P-CCPCH
Time slot
Common channel
Offset from
CPICH (dB)
Activity
factor
P-SCH -1.8 10%
S-SCH -3.5 10%
BCH -3.1 90%
P-CPICH 100%
PICH -7 96%
FACH-1 1.8 10%
FACH-2 1.5 30%
PCH -0.4 20%
AICH -6 7%

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Capacity
Effect of different user distribution
High power usage
Low capacity
Low power usage
High code usage
Code limited scenario
Power limited scenario

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Capacity
DL ftp throughput vs. distance to site capacity (field
measurement)
0%
20%
40%
60%
80%
100%
120%
-14
-12
-10
-8
-6
-4
-2
Ec/No measured without load in cell
kbps
0
200
400
600
800
1000
1200
1400
Relative gain 60W_20W
Relative gain 30W_20W
Throughput_20W
Throughput_30W
Throughput_60W
Example of aggregated throughput for 6 UE at different positions in the cell
Close to cell Cell border
Power limited
Code limited

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Capacity
Cell range impact on capacity
Load vs air pathloss (fixed CPICH)
0
10
20
30
40
50
60
70
80
120
122
124
126
128
130
132
134
136
138
140
142
144
146
148
150
152
Lsa (CPICH)
Number
of
simultaneous
use
rs
Max UL load 20W 30W 40W
Maximum capacity
drops with
increasing site-site
distance

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Capacity
Mpole values and max cell capacity
UL noise rise limitations
Uneven cell load- soft capacity
Pole capacity
equal load
AMR 5.9 109
AMR 12.2 84
UDI 19
I64/64 21
I64/128 21
I64/384 21
75%/25%
163
125
28
31
31
31
Max cell capacity
low pathloss
65
50
11
12
12
12
high pathloss
22
17
4
4
4
4
Pole capacity
equal load
AMR 5.9 93
AMR 12.2 66
UDI 8
I64/64 11
I64/128 6
I64/384 2
75%/25%
158
111
13
19
11
3
Max cell capacity
low pathloss
66
48
6
7
4
1
high pathloss
31
24
4
5
3
1
Code limitation
Uplink Capacity
Downlink Capacity
Max downlink Code Capacity
AMR 5.9
AMR 12.2
UDI
I64/64
I64/128
I64/384
31
15
7
Max code capacity
246
123
31

24. HSDPA Considerations
Coverage and Capacity Impacts with HSDPA

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HSDPA Considerations
Higher PA utilization
 HSDPA will take
whatever power that is
left in RBS after common
channels and dedicated
channels has taken their
part
 The average power
utilization in the network
will increase with
HSDPA
Power
time
CCH power
HSDPA power
DCH power
Admission control threshold
Max cell power
Power
time
CCH power
HSDPA power
DCH power
Admission control threshold
Max cell power
0%
25%
50%
75%
100%
1
Time
Average
cluster
power
utilisation
(%)
Network deployment – low load
High traffic R99 only
HSDPA deployment
High traffic with
majority of UE
HSDPA capable

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HSDPA Considerations
High bitrate possible in good radio conditions
0,00
0,50
1,00
1,50
2,00
2,50
3,00
3,50
4,00
4,50
-12 -10 -8 -6 -4 -2 0 2 4 6 8
C/I [dB]
Throughput
[Mbps]
16QAM QPSK
Max. rate 3.36 Mbps, class 5 & 6 UE
Max. rate 1.6 Mbps, class 12 UE
0,00
0,50
1,00
1,50
2,00
2,50
3,00
3,50
4,00
4,50
-12 -10 -8 -6 -4 -2 0 2 4 6 8
C/I [dB]
Throughput
[Mbps]
16QAM QPSK
Max. rate 3.36 Mbps, class 5 & 6 UE
Max user throughput for R99
thermal
own
other
HSDPA
P
P
P
P
I
C





Simulated throughput vs received C/I

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HSDPA FOA results
Throughput distribution
1km
Throughput Distribution
0
2
4
6
8
10
12
14
16
100 300 500 700 900 1100 1300 1500 1700
Throughput Range, kbps
%PDF
0
10
20
30
40
50
60
70
80
90
100
%CDF
PDF CDF

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0
200
400
600
800
1000
1200
130 135 140 145 150
Lsa [dB]
Cell
average
throughput
[kbps]
8.7 W 12.5 W 22.3 W
DCH 8.7W DCH 12.5W DCH 22.3W
HSDPA Considerations
Higher Packet Capacity with HSDPA
HSDPA cell average throughput
DCH cell average throughput
Lsa = 141.8dB, corresponding to PS 64 kbps in UL
About 2.5 times more capacity for HSDPA
Example of average cell throughput on TU-3 channel comparing R99 and HSDPA

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HSDPA Considerations
Common channel settings
 HSDPA will increase the
average power utilisation and
thus uncrease the general
interference level in the
system
increase the need for
higher CPICH power
 Average power utilisation per
cluster will NOT be 100%
 It is expected that maximum
power utilisation (on cluster
level) will go from 50% (R99)
 75% (HSDPA) in a real
network
CPICH required for coverage at low UL load
(30%) and 75% average power utilisation over a
cluster.
RBS
class percent dB
20 W 10.0% –10.0 dB
30 W 8.7% –10.6 dB
40 W* 7.7% –11.1 dB
60 W 7.2% –11.4 dB
20 W 7.8% –11.1 dB
30 W 7.0% –11.5 dB
40 W* 6.6% –12.3 dB
60 W 6.3% –12.0 dB
P-CPICH share of total output power
UE
power
With ASC
24 dBm
21 dBm
Recommended CPICH settings for
different configurations

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Summary
 WCDMA has better sensitivity than GSM  better coverage
 Coverage is dependent on number of users (cell breathing)
– Load must be considered when planning
 Different services has different coverage
– Decide which service to plan for
 Cell overlap influences both coverage and capacity
– The cell plan sets the limit of how much capacity the network can
deliver
 User distribution influences maximum cell capacity
– Placing cell as close to traffic as possible is key
 HSDPA will increase the PA utilisation in the system
– Common channel power must consider this effect

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