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Transcript of Day1.2 WCDMA RAN Dimensioing
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1 Nokia Siemens Networks Presentation / Author / Date
For internal use
Radio Network Dimensioning
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Contents
Scope of RAN Dimensioing
Input parameters for RAN dimensioingLink Budget
Parameters
Cell Range Calculation
Load Calculation
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WCDMA Network Architecture
Circuit SwitchedCore Network
GGSN
3GSGSN
GPRS
USIMcard
WCDMAmobile
GSM/WCDMAmobile
RAN
WCDMABTS
WCDMABTS
RNC
RNC
MSC
HLR
MGW
IN SCP
SRR
PS Core Network
(PSTN/ISDN)
InternetTCP/IP)
GSM/WCDMAmobile
CBC
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UTRAN Elements and Interfaces
UTRAN
Iu
Uu
User Equipment(UE)
IurIub
RNC
WCDMABTS
WCDMABTS
WCDMABTS
WCDMABTS
RNC
Core Network(CN)
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RNC
3G-SGSN
GGSN
IP/MPLS/IPoATM-backbone
ApplicationServers
(co-locatedor remote)
support of 3GPP QoS-parametersand mechanisms in UE
UE support of different CH-types
internal delays generated byUE
UE memory [effects TCP kbps]
internal BTS-delays
interleaving/propagation delays
RNC internal delays, 3GPP QoS-support
protocol processing and trans-mission delays, 3GPP QoS-
support
internal processing/queuing delays.
3GPP QoS-support
internal processing/queuing and L1delays
memories/buffer sizes [TCP-effect]
internal delays in WAP-gateways/http-
proxies/servers/etc.
= terminal/NW element HW and SW effects
= network planning/dimensioning effects
site locations,
antenna directions/height/quality
cable length/quality
BTS-capacity
Iu-transmission resourcedimensioning, topology/distances
RNC capacity
HO thresholds
cell's traffic load thresholds
interference/transmission power thresholds
used packet scheduling criteria
used RLC buffer payload thresholds [TCP-effect]
used DCH bit rate allocation steps
allocation of dedicated NRT-capacity
packet core capacity
configuration of RT traffic limits
configuration of interactive queue weights
used HLR QoS-profiles
application server capacity
geographical location [e.g. localizedcontent caching vs. centralized server
transmission/router capacity
geographical locations/distance, number of hop
Example: What affects performance in WCDMA
= application software effects
UDP vs. TCP
supported HTTP/WAP-version
support of optimization features
supported HTTP/WAP-version
support of optimization features
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RAN Dimensioing Scope
DomainNameServer(DNS)
3GSGSN
GGSN
ChargingGateway(CG)
Backbonenetwork
(IP based)
BorderGateway(BG)
FireWall(FW)
LIG
Domain Host ConfigurationProtocol (DHCP)
PacketnetworkInter-PLMN
Network
MGW
Iub
Abis
BSC
NodeB
BTS
Iu-PS
Iu-CS(ATM)
RNC
Iub
IP/ATM/TDM
Backbone
PacketnetworkInternet
IN/SCP SMS
PacketnetworkIntranet
McRANAP(SIGTRAN)
MAP(SIGTRAN)
SS7 (E1)Gb
2GSGSN
BSSAP (E1)
CAP/MAP
(E1)
CAP/MAP(E1)
Exist Connect
New Connect
PSTN/PLMNNetwork
CDS
MSS
2G / 3GHLR
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Network planning process & relation to businessplanning
marketing
business
plan
traffic
assumptions
Network
dimensioning
Code & freq. &
interference plan
transmission
plan
final NW
topology/
architecture
parameter
planning
coverage
plan
Network
optimization
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Radio Network DimensioningOverview
COVERAGE CAPACITY
COMPROMISE BETWEEN COVERAGE AND CAPACITY
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Coverage VS Capacity Dimensioning:Cell Breathing [1/2]
This diagram showscells are unload
This diagram shows whensome cells are loaded
Cell-A
Cell-C
Cell-B
Resu lts =>Coverage Holes!
Cell-A
Cell-C
Cell-B
Cellbreathing
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Coverage VS Capacity Dimensioning:Fixed Uplink Load - To avoid Coverage holes [2/2]
This diagram shows aFixed Uplink Load design
Results => No orMin CoverageHoles!
Cell-A
Cell-C
Cell-B
Cell-
A Cell-D
Cell-H
Cell-E
Cell-F
Cell-
C
Cell-B
Cell-
G
No (or minimum)
coverage holes problems
More cells required
Traffic mobility taken
into account. (Note:dimensioning assumes
uniform traffic
distribution)
eg. Actual ULload = 8%
eg. Fixed ULload = 30%
"actual" Loading,(ie from the traffic
inputs defined indimensioning)
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Input parameters overview
CAPACITY RELATED Spectrum Available
User Profile and Traffic GrowthForecast
Traffic Density Map
COVERAGE RELATED Coverage Regions
Area Type Information
QUALITY RELATED MS Class
Indoor Coverage
Location Probability
Blocking Probability
Gives an Estimation of theEquipment Necessary to Meet theNetwork Requirements
Network Dimensioning Activities
Radio Link Budget Calculation
Cell Size Calculation
Capacity Calculation
Number of Node B, RNCcalculation
Iub, Iur and Iu transmissionCapacity
Input Categories
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Capacity Related Input
The number of subscribers, user profile and spectrum available are the main requirements forcapacity dimensioning
Traffic forecast should be done by analysing the offered Busy Hour traffic per subscriber for different
service bit rates in each rollout phase.Traffic data:
Voice :
Erlang per subscriber during busy hour of the network
Codec bit rate, Voice activity
RT data :
Erlang per subscriber during busy hour of the network
Service bit rates
NRT data :
Average throughput (kbps) subscriber during busy hour of the network
Target bit rates
Asymmetry between UL an DL traffic for NRT Services (Downloading 1/10) should be taken intoconsideration.
Network and Subscribers evolution forecast is also needed.
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Coverage Related Input
Accurate coverage area information should be available
Total coverage area for each rollout phase (km2
) Percentage of the area for each morpho class (Dense Urban, Urban, Suburban andRural)
DENSE URBAN
URBAN
SUBURBAN
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Coverage Related Input
Area type information must be as accurate as possible:
coverage area for each rollout phase
percentage of the area for each morpho-class (DU,U,SU,R)
building penetration loss and fading margin
propagation models for path loss calculation
correction factors for the Propagation Model
Service Scenarios should be defined: which kind of service is to be offered and where (big impact onthe number of sites).
MorphoClass Build Pen Loss Stand Deviation Car Loss Stand Deviation
Dense Urban 18 dB 11 dB
Urban 15 dB 10 dB
Sub Urban 12 dB 9 dB
Rural 10 dB 9 dB
Road 6 dB 7 dB
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Quality Related Input
Blocking Probability: is blocking of call attempts due to lack of availableresources and for CS Services is usually between 1-2%
In the propagation models there is no place to cover the local fluctuations(slowfading) of the strength of the electromagnetic waves, caused mainly byshadowing. It should be done separately.
Fade margin is a function of location probability and standard deviation
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Quality Related Input
Penetration Losses
Signal levels inside the buildings are estimated by applying buildingpenetration loss margins. BPL may vary in different area types.
Pref= 0 dB
Pindoor = -3 ...-15 dB
Pindoor= -7 ...-18 dB
-15 ...-25 dB no coverage
rear side :
-18 ...-30 dB
signal level increases with floor
number :~1,5 dB/floor (for 1st
..10th floor)
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Summary of Dimensioning Inputs
Dense Urban Urban Suburban Rural
Voice # of subs & mErl per sub # of subs & mErl per sub # of subs & mErl per sub # of subs & mErl per sub
CS data # of subs & mErl per sub # of subs & mErl per sub # of subs & mErl per sub # of subs & mErl per sub
PS data # of subs & kbps per sub # of subs & kbps per sub # of subs & kbps per sub # of subs & kbps per sub
Coverage area km2 km2 km2 km2
Location probability % % % %
Standard deviation dB dB dB dB
Fade margin dB dB dB dB
Penetration loss dB dB dB dB
Area correctionfactor
dB dB dB dB
MS / Node Bantenna height
m m m m
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RF Dimensioning Process Flow
Link Budget Calculation
Radio link specific :- Data rate (processing gain)- Average Eb/No- SHO gain in dB
Equipment specific :- MS Power class- MS/BS calc. sensitivity- Antenna gainetc
Load factorcalculation
Propagation specific :- Antenna height- BPL and BPL deviation- Area correction factor
- Lognormal shadowingmargin
Max. allowed path loss
Cell Range Calculation
Max. Cell Range in each areatype
Capacity Estimate
No. of sites / Total supported trafficin each area type
Equipment Requirement
BS HWs / Transmission / RNC
Service specific :-blocking rate- throughput factor
1st guessof amountof trafficper CU
InterferenceMargin
Max. traffic per CU
If fulfill the operator need
If too low capacity
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WCDMA Link Budget
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Link Budget Overview
Building penetrationloss
Body loss
Cable losses
Antenna gain
Noise figure
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WCDMA Link Budget
MS transmit power = 21 dBm
Antenna Gain (example):
18 dBi, X-pol, 650horizontal beamwidth,variable electrical tilt
Cable Losses
Body proximity Loss
3 dB for voice services 0 dB for data services
WCDMA Link Budget
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WCDMA Link Budget
Soft HO
Softer HO
Soft HO MDC gain is actually the gain due to less powerrequirement when multiple radio links are there
(relative to that of a single link )This gain is mainly in DL and in UL this gain is negligible
WCDMA Li k B d
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WCDMA Link Budget
MDC Gain: In DL there is some combining gain dueto UE maximal ratio combining:
Soft/softer handovers are included
Average is calculated over all theconnections taking into account theaverage difference of the received signalbranches (and UE speed)
Nokia recommended value = 1.2 dB
MHA gain is used to compensate for the cable
losses
WCDMA Li k B d t
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WCDMA Link Budget
Total noise power in the receiver is a function of:
Boltzmans constant
Temperature
Bandwidth
Thermal Noise = kTB
Noise figure
Nokia recommended values:
Node B MS
Noise Figure 3 dB 8 dB
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WCDMA Link Budget
Processing gain is a function of the system chiprate and service bit rate
Service bit rate Processing Gain
Voice 12.2 kbps 24.98 ~ 25 dB
CS 64 kbps 17.78 ~ 18 dB
PS 128 kbps 14.77 ~ 15 dB
PS 384 kbps 10 dB
WCDMA Link B dget
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WCDMA Link Budget
Interference margin calculated from the UL/DLloading () values. This parameter shows in DL
how much the BTS "sensitivity" is decreased due tothe network load (subscribers in the network) & inUL indicates the loss in link budget due to load.
dBLog 110 10IMargin = dBLog 110 10IMargin =
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WCDMA Link Budget
In order to meet the defined quality requirements (BLER)a certain average bit-energy divided by total
noise+interference spectral density (Eb/N0) is needed.Eb/No depends on:
Service
MS speed
Radio channel
Service bit rate UL Eb/No [3kph] DL Eb/No [3kph]
Voice 12.2 kbps 4.4 7.9
CS 64 kbps 2.0 5.0
PS 64 kbps 2.0 5.0
PS 128 kbps 1.4 4.7
PS 384 kbps 1.7 4.8
* Nokia recommendedvalues
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WCDMA Link Budget
Soft handover gain is the gain against shadow fading.
This is actually the gain in required Eb/No relative to thatof a single link and it is averaged over all radio links inthe SHO area
Nokia recommended value = 2 dB
IPL Correction Factor. This parameter describesthe ratio between the maximum and the averagepathloss. Usually all subscribers are not located atthe cell edge but are distributed through the wholecell coverage area. That is why some gain can beadded in power budget calculation.
Nokia recommended value = 6 dB
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IPL Correction Factor
Worst case scenario Reality MS distributed over the whole area
Users at the cell edge require high power; users closeto the base station need much less power at the
same time
WCDMA Link Budget
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WCDMA Link Budget
UL Power Control Headroom is the parameter todescribe the margin against fast fading. This
parameter is needed because at the cell edge theUE does not have enough power to follow the fastfading dips. This is especially important for the slowmoving UEs.
Nokia recommended value = 1.8 dB
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Load Calculation
L d C l l ti
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Load Calculation
Load factor () predicts the amount of noise rise by treatinginterference as wideband noise.
It is based on Eb/No, number of users, their service bit rate and activity,other cell to own cell interference ratio, the amount of uplink noiserise and orthogonality factor.
Load Calculation
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In order to meet the defined quality requirements (BLER) a certain average bit-energydivided by total noise+interference spectral density (Eb/N0) is needed. So for every userj
and for given bit rate Rjwe have:
, where Ij is the received signal power of user j
Of course subscriberj is not active all the time, that is why the special activity factorjshould be introduced:
jjtot
j
jj
b
II
I
RW
NE
1
0
jtot
j
jj
b
II
I
R
W
N
E
0
Load Calculation
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Using the previous equation we can express the load caused by one subscriberas a part ofthe total load:
, where:
For N subscribers, the load caused in the cell (so called load factor) is:
jjbj
j
NE
RWload
11
1
0
totjj IloadI
N
jjload
Little i
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Little i
The load factor calculation the other cell interferences takes into account theinterference from other cells.
This can be introduced by means of the little ivalue, which describes how muchtwo cells overlap (bigger overlapping more inter-cell interferences).
Iother
Sector Little i
Omni 0.55
3 0.65* Nokia recommended
values
Intereference in DL
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Interference in UL
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Orthogonality
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Orthogonality
Orthogonality [] is a measure how well separate code signals areuncorrelated
In DL the own cell interference are reduced by factor (1-). This is due to thesynchronised orthogonal channelisation codes, which are used in DL.
Nokia recommended value: [] = 50%
Load Calculation
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After introduction of the little i the load factor in the cell will be:
In DL the own cell interference is reduced by factor (1-). This is due to the synchronisedorthogonal channelisation codes, which are used in DL:
N
j
jloadi1
N
j
jjDL loadi 1
Ortogonality factorj is between 0.4 and 0.9Typical values:
ITU vehicular subscriber (Macro Cell) j=0.6
ITU pedestrian subscriber (Micro Cell) j=0.9
Power Rise
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Power Rise
For UEs located in the other cells the power increase caused by Fast LoopPC procedure is harmful for the own cell interference conditions
Non-fad ing channel Fad ing channel
Transmitted power
Received power
Power rise
Average transmitted power
Non-fad ing channel Fad ing channel
Transmitted power
Received power
Power rise
Average transmitted power
Nokia recommended value:[pwr_r ise] = 0.7 dB
Load Calculation
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Because of power rise in the UL load calculation, the little ishould be corrected (little iismultiplied by pw_r iseparameter)
UL load affects the noise level at the Node B receiver. Noise Rise
A typical cell load value for dimensioning ranges from 30% to 70 %.
50% is a good compromise between the number of sites and the offered capacity.
Breathing effect: UL load limits the Coverage.
0
2
4
6
8
10
12
14
16
18
10
20
30
40
50
60
70
80
90
95
98
loading/%
loss/dB
N
j
jUL loadirisepw_1
Interference Margin vs Load Factor
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Interference Margin vs Load Factor
20
10
6
1.25
3
25% 50% 75% 99%
IMargin [dB]
Load factor
20
10
6
1.25
3
25% 50% 75% 99%
IMargin [dB]
Load factor
The graph showsrelationship betweenthe interference marginand the load factor.
Nokia recommendsloading between 30% to
70% for optimumperformance
50% uplink loadingrepresents a good
trade-off betweencoverage and capacity
Cell Loading Calculation
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Cell Loading Calculation
1. Traffic per CellErlang or kbit/s
4. Interfering Channels(=physical channels*activity factor)
5. Fractional Load
3. Physical Channels(=traffic channels*SHO)
2. Traffic Channels
Traffic per cell is usually defined in terms of Erlang forvoice and real time (RT) data services and in terms ofkbits/s for non real time (NRT) data
The blocking probability is typically assumed to be 2% forcircuit switched services.
Cell Loading Calculation
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g
Evaluation of the physical channel requirement per carrierfor each service class. This is completed separately forUL and DL.
Evaluation of interfering channels per cell for each serviceclass. This requires a direct multiplication of thephysical channel requirement with the correspondingservice activity factor.
1. Traffic per CellErlang or kbit/s
4. Interfering Channels(=physical channels*activity factor)
5. Fractional Load
3. Physical Channels(=traffic channels*SHO)
2. Traffic Channels
Soft handover overhead (SHO)
Nokia value = 40%
assumption: 30% = 2-wayconnections
5% = 3-way connections
Therefore: (1 * 0.65) + (2 * 0.30) + (3* 0.05) = 1.4
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Code Channels Calculation
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1. Traffic per CellErlang or kbit/s
4. Interfering Channels(=physical channels*activity factor)
5. Fractional Load
3. Physical Channels(=traffic channels*SHO)
2. Traffic Channels
Hardware Channels
HW channels are implemented on channel cards(WSP cards)
The signal processing unit (WSP) in the Node B
performs RX and TX code channel processing,coding and decoding functions.
Amount of WSPs shall be planned according to thetraffic on the BTS.
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BTS Power
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The link budget provides the average BTS TX power per connection for eachservice class. The BTS TX power per connection is defined from the averageDL isotropic path loss.
The total BTS TX power is obtained by summing up the TX power required for allservice classes and common channels
For dimensioning, the amount of power allocated for common channels is 20% ofthe maximum BTS TX power.
NODE B POWER
COMMON CHANNELS
TRAFFIC
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Dimensioning Results
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Required HW channels (BTS processing capacity)
LoadRequired BTS TX
power
TRAFFICErlang or kbit/s
TRAFFICErlang or kbit/s
TRAFFIC CHANNELSTRAFFIC CHANNELS
PHYSICAL CHANNELSPHYSICAL CHANNELS
INTERFERING CHANNELSINTERFERING CHANNELS
FRACTIONAL LOADFRACTIONAL LOAD
FRAC. LOAD OF THESERVICE CLASSES
FRAC. LOAD OF THESERVICE CLASSES
TOTAL LOADUL & DL
TOTAL LOADUL & DL
REQUIRED BTS TXPOWER
REQUIRED BTS TXPOWER
Limiting factors:
The following criteria should be considered:
Uplink load < Maximum uplink load
DL load < 1
BTS TX power < Maximum BTS TX power
Number of channel units < Max number of channelunits
Dimensioning Results
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RF DIMENSIONINGRESULTS
Number of base stations
Configuration of base stations
Number of subscribers per area
mErl / subs for voice and RT data
mErl / sub for NRT data
Iub/Iur/Iu INTERFACEDIMENSIONING
RNC
DIMENSIONING
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Cell Loading Calculation
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UL Fractional Load Calculation
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Cell Load Calculation
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