WCDMA

1. Radio Network Planning
Strategy
Patrik Persson
Senior Specialist
WCDMA RAN System Management

2. Commercial in confidence Radio Network Planning Strategy 2005-09-27
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Outline
 Basic cell planning principles
– Securing coverage
– Achieving confined cells
– Selecting strategic sites
– Code planning
– Power planning
– Neighbour planning
 Combining GSM and WCDMA
– Using IRAT to enhance service area
 HSDPA scenarios
 Micro cells and indoor solutions
 Deploying 2nd carrier
– Strategies for 1900/1900, 850/1900 with fallback to GSM
 Capacity paths

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Cell planning principles
Securing Coverage
 High gain antennas (20-22
dBi)
 Use TMA
– With Enhanced Uplink
this will be even more
important
 Avoid long feeder runs and
complex antenna installations
– 10-20% of installations
are incorrect
 Plan for network load
 Consider service coverage
18 dBi 23 dBi
 Path loss
[dB]
 Range
[%]

Coverage
[%]
 Path
loss
[dB]
 Range
[%]

Coverage
[%]
+1 +7 +14 –1 –6 -12
+3 +22 +48 –3 –18 -32
Higher antenna gain Longer feederloss

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Cell planning principles
Securing Coverage - using modular high gain antennas
 Modular
– Standard sector antennas
stacked vertically
– Custom mounting frame
for easy and accurate
assembly
– Scalable to suit different
propagation
environments
 Radiation Performance
– High gain
– Improved link budget
within main beam
– Null-filling for coverage
below the horizon
Ideal for suburban and rural applications
MHGA compared to standard antenna

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Cell planning principles
Achieving confined cells (1/2)
 Electrical Antenna tilt
 Use RET
– For efficient capacity
tuning
 High Gain antennas (small
vertical BW)
– To achieve maximum
benefit of tilt
 Separate antenna systems
recommended
– GSM and WCDMA
requires different tilt
0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
20%
0 1 2 3 4 5 6 7
Tilt
Capacity
gain
Example of capacity gain vs tilt
Recommended tilt: one beamwidth at
cell border, more in city areas
Ideal capacity when –3 dB
point at cell border

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Cell planning principles
Achieving Confined cells (2/2)
 Narrow horisontal beam
antennas
 In areas with high capacity
needs reducing the cell
overlap is essential
 City environment: <65
degrees
 Rural environment: <90
degrees

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Cell planning principles
Selecting strategic sites
 Avoid high sites
– Harder to confine coverage
– Generate interference far
away from service area
 Place sites close to traffic
– Ensures high air interface
capacity
 Don’t be afraid to remove sectors
– Fast deployment can
sometime require sector
removal
High sites generate interference
outside the planned coverage area
Placing sites close to traffic ensures
high capacity

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Cell planning principles
Code Planning
A1
B3
B2
B1
G3
G2
A1
C3
C2
C1
B3
B2
B1
G3
G2
Monitored set
13
13
Call will/may be dropped
(UE dependent)
Same code must not appear in
the same monitred set
Code planning is important and
must not be neglected

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Cell planning principles
Power planning
 Power = Capacity
– Correct initial values are
of essence
 Common channel power
should be balanced towards
speech
– Ensures efficient power
usage
 Individual cell tuning should
be avoided
– Ripple effects difficult to
foresee
0
200
400
600
800
1000
1200
-4 -5 -6 -8 -12 -17 -23
Ec/No (unloaded)
Throughput
[kbps]
20W_10%
20W_5%
30W_10%
30W_5%
Example of Capacity benefits of tuning CPICH
20% capacity
gain close to site

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Cell planning principles
Neighbour planning
 A good neighbour plan is
essential for a well functioning
radio network
– 20 - 50% of dropped calls
occur due to missing
neighbours
 The challenge with WCDMA is
that you have to consider soft
handover.
– A relation should be present
for cells that are 3-5 dB
weaker than target cell
 More relations needed compared
to GSM (for intra frequency)
– Neighbours neighbour is
required
Cell A
Cell B
Add cell B Delete cell B
A1
C3
C2
C1
B3
B2
B1
G3
G2

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Combining WCDMA and GSM
Allowing IRAT everywhere
 Good for initial deployment
– Allows immediate service
coverage
 Potential ”cost” of
compressed mode
manageable
WCDMA
GSM
GSM network
WCDMA
gsmpref gsmpref

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Combining WCDMA and GSM
Selected areas with IRAT
 When 3G network has
contiguous coverage
 IRAT handover allowed only
in border areas or selected
sites
 Ensures efficient compressed
mode usage
– Increase capacity
GSM network
WCDMA
IRAT allowed only in
border areas
none
WCDMA
GSM
gsmpref gsmpref

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Combining WCDMA and GSM
Terminating calls in GSM – Camping on 3G where possible
 If GSM has better coverage it
can be advantageous to
terminate the call (speech) in
GSM
– In order to minimize
handover
 This can be achieved by:
– Not allowing GSMUMTS
– Only allow handover when
there is significant load in
GSM
 Strategy only possible for CS
services
– PS services use cell
reselection mechanism 
moves to 3G where possible
WCDMA
GSM
gsmpref
GSMUMTS only if GSM under load

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Combing WCDMA and GSM
Considerations with WCDMA 850
 With WCDMA 850Mhz widely
deployed coverage will be
better than GSM
– Less likely to do IRAT
handover to GSM
 Same strategy shall apply
– GSM handover shall only
be allowed where
necessary (in case GSM
will be better)
gsmpref WCDMA 850
GSM 850

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HS Bitrate
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
0 500 1000 1500 2000 2500 3000
HS Bitrate [kbps]
C.D.F.
HSDPA Scenarios
Single carrier
 Two reasons to deploy HSDPA
1. Provide high bitrate services
 Configure high
profile areas with
HSDPA in an initial
phase
2. Enhance packet capacity
 To get largest
benefit install
HSDPA on cluster
base (10-12 sites)
where traffic
demand is high
 Significant amount
of packet users are
required
Example of user throughput distribution with HSDPA
Max R99 user rate
0
200
400
600
800
1000
1200
1400
1600
1800
2000
130 135 140 145 150
Lsa [dB]
Cell
average
throughput
[kbps]
8.7 W 12.5 W 22.3 W
DCH 8.7 W DCH 12.5W DCH 22.3 W
High capacity potential
with many packet users
Example of capacity benefit compared to R99 with
100% packet users

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HSDPA Scenarios
Islands of HSDPA vs network wide deployment
 Island coverage
– HSDPA only where
needed (high profile
areas with high capacity
need)
– Instances of data flow
reductions during
HSR99
 Network wide
– High bitrate services
available in wider area
– Reduce the effect of data
flow reduction (fewer
border areas
Ideal for indoor solutions
with little mobility

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Micro cells and indoor solutions
Planning considerations for micro cells
 Primary application for micro
is outdoor hotspot areas
– Essential to place site
close to traffic
 Micro cell coverage area
depends on distance to
macro base station Smaller coverage area
close to site
Large coverage area
Higher interference limits
coverage area close to site

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Micro cells and indoor solutions
Indoor solutions
 Good for high traffic density
areas and corporate users
with high
 Indoor signal level must be
strong to avoid interaction
with outside macro network
 Use embedded indoor cells
initially
 Keep same IRAT strategies Close to macro site
lower floors
a
Macro site
Macro cell coverage
Signal
strength
frommacro
cell
Close to macro site
upper floors
Close to cell border
upper floors
Close to cell border
lower floors
b
c
d
Signal
strength
frommacro
cell
Use indoor systems in these locations

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Deploying Second Carrier
WCDMA in same frequency band
gsmpref none none
none
1st carrier
2nd carrier
GSM
gsmpref
IFHO Load sharing enabled
gsmpref
IFHOpref
Cell edge for 1st and 2nd carrier
- gsmpref on both carriers

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Deploying second carrier
Different frequency bands
 With WCDMA 850 coverage
will be better than GSM
 IRAT handover should only
be allowed at network edges
 IFHO on higher frequency
layer
 With a good cell plan cell
confinement (outdoor) can be
the same for 1900 and 850
– CPICH planning and
neighbour planning
should be the same for
both bands
GSM
gsmpref none
IFHOpref
IFHOpref
IFHO Load sharing enabled
gsmpref
IFHOpref
WCDMA 850 MHz
WCDMA 1900MHz

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R99 +HS
R99 + HS
R99 +HS
R99 + HS
Deploying second carrier
HSDPA alternatives
1st carrier
2nd carrier
HSDPA on
both carriers
R99
R99 + HS
R99
R99 + HS
1st carrier
2nd carrier
HSDPA on 2nd
carrier only R99 traffic can be
pushed to 1st carrier
by
load sharing or
idle mode offsets
HSDPA UE

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Capacity paths
 Single carrier scenario
1. Macro cell deployment
2. HSDPA
3. Cell split
4. Micro cells and indoor
solution
 Multi carrier scenario
1. Selected sites with 2nd
carrier
2. Wide second carrier
deployment
3. HSDPA on both carriers
4. Cell split
PS data capacity 10 - 15 MHz
0
2 000
4 000
6 000
8 000
10 000
12 000
14 000
PS R99 Tuning HSDPA Grake / RX div
(Ue)
6-sector 2nd carrier 3rd carrier
Mbps/sector
area
(in
3
sector
sites)
- Antenna tilt
- 80%
admission
Terminal
dependen
t
6 sector*
3 sector
3x1
Carrier
expansion
6x2*
6x1*
3x2
3x3
3x1
* throughput (Mbps) per 2 sectors
Also to keep in mind:
*Advanced receivers (GRAKE)
*Narrowband AMR (speech
capacity)
*Advanced HS terminals (more
codes, EUL)

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Summary
 Cell planning
– Use high gain antennas and avoid long feeder runs to
secure good coverage
– Keeping cells confined is the key to high cap networks
– Code planning, power planning, neighbour planning is
essential for a well working system
 Use fallback to GSM to enhance the service coverage
– Terminate CS calls in GSM
 Use HSDPA to provide high bit rate services and
enhance packet capacity
 2nd carrier deployment can lead to enhanced coverage
and capacity
– Be sure to use 850 and 1900 MHz spectrum

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