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7/29/2019 GSM Rf Planning-PTT
http://slidepdf.com/reader/full/gsm-rf-planning-ptt 1/20
RF Network Design
& Planning
7/29/2019 GSM Rf Planning-PTT
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Introduction
The high level life cycle of the RF network planning process can besummarised as follows :-
• To help the operator to identify their RFdesign requirement
• Optional
• Discuss and agree RFdesign parameters,assumptions andobjectives with thecustomer
• Coverage requirement•Traffic requirement
• Various level of design(ROM to detail RFdesign)
• Issuing of search ring• Cand. assessment• Site survey, design,approval
• Drive test (optional)
• Frequency plan• Neighbour list• RF OMC data• Optimisation
Comparative Analysis
RF Designrequirement
RF Design
SiteRealisation
RF Design
Implementation
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Comparative Analysis
This is an optional step
This is intended to :-
• Help an existing operator in building/expanding their network
• Help a new operator in identifying their RF network requirement, e.g.
where their network should be built
For the comparative analysis, we would need to :-
• Identify all network that are competitors to the customer
• Design drive routes that take in the high density traffic areas of interest
• Include areas where the customer has no or poor service and the
competitors have service
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Coverage Design Inputs by BSNL
• Coverage Thresholds
– Indoor Coverage : Signal Level measured at street better than –65
dBm. Indoor coverage to be provided in commercial complexes,
hotels,technology parks etc.
– In Car Coverage: Signal Level measured at street better than –75 dBm.
In Car coverage to be provided in residential areas, highways, tourist
spots etc.
– Outdoor Coverage : Signal level measured at street better than –85
dBm. All remaining areas to be covered with Outdoor coverage.
– These are general guidelines for planning , specific areas not provided.
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Capacity Design Inputs by BSNL
• Frequency spectrum available 6.2 MHz (31 channels).
• Average traffic per sub for RF design : 50 mErlang.
• Synthesizer frequency hopping can be used.
• GOS: 2%
• Existing network Database
– Total No. of sites with configuration
– Site details eg location(Lat-Long), Antenna height ,azimuth,
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50mE = 3600* 50 * 10-3 = 180seconds = 3 min = Average
Voice call holding time (urban)Rural = 1.5min = 25mErlangs
1 Erlang of network traffic(TCHs)
= 20 no. of users with 50mEindividual traffic (call holding)
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RF Network Design
There are 2 parts to the RF network design to meet the :-
• Capacity requirement• Coverage requirement
For the RF Coverage Design
RF
Coverage
Design
Link
Budget
Propagation
Model
Digitised
DatabasesCW DriveTesting
Customer Requirements
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CW Drive Testing
CW drive test can be used for the following purposes :-
• Propagation model tuning• Assessment of the suitability of candidate sites, from both coverage and
interference aspect
CW drive test process can be broken down to :-
TestPreparation
Propagation
Test
Data
Processing
• Equipment required
• BTS antenna selection
• Channel selection
• Power setting
• Drive route planning
• Test site selection
• Transmitter setup
• Receiver setup
• Drive test
• Transmitter dismantle
• Measurement averaging
• Report generation
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CW Drive Testing - Propagation Test
Scanning Receiver Setup - HP 7475A Receiver Example
HP 7475A Receiver
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Propagation Model
Standard Macrocell Model for Asset
Lp (dB) = K1 + K2 log(d) + K3 Hm + K4 log(Hm) + K5 log(Heff)+ K6 log(Heff) log(d) + K7 Diffraction + Clutter factor
where Lp, Diffraction, Clutter factor are in dBd, Hm, Heff are in m
•It is based on the Okumura-Hata empirical model, with a number of additional features to enhance its flexibility
• Known to be valid for frequencies from 150MHz to 2GHz
• Applies in condition :-
– Base station height : 30 - 200 m – Mobile height : 1 - 10 m – Distance : 1 - 20 km
• An optional second intercept and slope (K1, K2) for the creation of a two-piece model with the slope changing at the specified breakpoint distance.
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Link Budget
Link Budget Element of a GSM Network
BTS Antenna Gain Max. Path Loss Fade Margin
LNA
(optional)
Feeder Loss
Diversity
Gain
BTS ReceiverSensitivity
ACE
Loss
BTS TransmitPower
Penetration Loss
MS Antenna Gain,
Body and Cable Loss
Mobile Transmit
Power
Mobile Receiver
Sensitivity
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Link Budget
BTS Transmit Power • Maximum transmit power • GSM900 and 1800 networks use radios with 46dBm maximum transmit
power
ACE Loss• Includes all diplexers, combiners and connectors.• Depends on the ACE configuration• The ACE configuration depends on the number of TRXs and combiners
used
No of TRXs
Network ACE Configuration Downlink ACELoss (dB)
1 or 2 GSM900 2 antennas per cell, diplexer 1.0
1 or 2 GSM1800 2 antennas per cell, diplexer 1.2
3 or 4 GSM900 2 antennas per cell, diplexer + hybrid combiner 4.43 or 4 GSM1800 2 antennas per cell, diplexer + hybrid combiner 4.4
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Link Budget
Penetration Loss
• Penetration loss depends on the building structure and material• Penetration loss is included for in-building link budget
• Typical value used for Asia-Pacific environment (if country specificinformation is not available) :-
– Dense Urban : 20 dB – Urban : 18 dB – Suburban : 15 dB – Rural : 9 dB
Body Loss
• Typical value of 2dB body loss is used
MS Antenna Gain
• A typical mobile antenna gain of 2.2 dBi is used
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Link Budget
Link Budget Example (GSM900)
UPLINK DOWNLINKMS Transmit Power 33 dBm BTS Transmit Power 46 dBm
Cable Loss 0 dB ACE Loss ZMS Antenna Gain 2.2 dBi Feeder Loss 2 dB
Body Loss 2 dB LNA Gain 0 dBPenetration Loss W BTS Antenna Gain 18 dBi
Slow Fade Margin X Max. Path Loss YMax. Path Loss Y Slow Fade Margin XBTS Antenna Gain 18 dBi Penetration Loss WLNA Gain 0 dB Body Loss 2 dB
Feeder Loss 2 dB MS Antenna Gain 2.2 dBi
ACE Loss 0 dB Cable Loss 0 dB
Diversity Gain 4 dB Diversity Gain 0 dB
BTS Receiver Sensitivity -107 dBm MS Receiver Sensitivity -102 dBm
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Site Realisation
Candidate Assessment Report-Site Survey Forms
• Site survey Forms for all suitable candidates for the search ring• For each candidates :-
– Location (latitude/longitude)
– Location map showing the relative location of the candidates and also
the search ring
– Candidate information (height, owner etc)
– Photographs (360º set, rooftop, access, building)
– Possible antenna orientations
– Possible base station equipment location
– Information for any existing antennas
– Planning reports/comments (restrictions, possibilities of approval etc.)
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Site Realisation-Site Survey Form
Final RF Configuration Form
• Base Station configuration
– Azimuth
– Antenna height
– Antenna type
– Down tilt
– Antenna location
– Feeder type and length
– BTS type
– Transmit power
– Transceiver configuration
Date
BSNL Circle
CITY / SSA
Site ID
Site Name
Owner Name
Address & Contact No.
Construction
Tower Type Bldg. Hgt
Tower Hgt Antenna Ht
Coordinate LAT N LONG E
GSM ANTENNA:
AZ M -TILT
SECTOR 1 85° +1.9 Spheroid:
SECTOR 2 185° +0.7
SECTOR 3 307° +1.3
Candidate No.
Assess: Priority
Morphology/Clutter
Site Blockage if Any
Remark
Name: Name:
Signature: Signature:
BSNL/ NBSNL
20 m.
GBT / Rooftop 10 m.
6 m.
TECHNICAL SITE SURVEY FORM
June 12, 2004
BHPAT-09
Bihar
Container/Room
BSNL Survey Team RepresentativeNokia Representative
Accept/ Reject
85° 48 ' 31.2"
AP909014-2
AP909014-2
Patna 09
26° 21' 25.9"
TYPE
AP909014-2
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Traffic Engineering
Spectrum
AvailableReuse factor
Maximum number of
TRX per cell
No of TCH
availableTraffic offered
Traffic
Requirement
Subscriber
supported
Channel
loading
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Traffic Engineering
•Traffic Requirement
•The Erlang per subscriber
•Grade of Service (GoS)
• GoS is expressed as the percentage of call attempts that are blocked
during peak traffic
• Most cellular systems are designed to a blocking rate of 1% to 5% duringbusy hour
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Traffic Engineering
After determining the number of TCH available and the trafficrequirements, the traffic offered is calculated using the Erlang B table
• For example, for a 2% GoS and 3 TRX configuration, the traffic offered is14 Erlang
• If the traffic per subscriber is 50mE/subscriber, then the total subscriberssupported per sector = 280
For a uniform traffic distribution network, the number of sites requiredfor the traffic requirement is :-
site per supportedSubscriber
ssubscriber Total sitesTotal
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Traffic Engineering
Erlang B Table
N 1% 1.20% 1.50% 2% 3% 5% 7% 10% 15% 20% 30% 40% 50%1 0.01 0.01 0.02 0 .02 0.03 0.05 0.1 0.11 0.18 0.25 0.43 0.67 1
2 0.15 0.17 0.19 0.22 0.28 0.38 0.5 0.6 0.8 1 1.45 2 2.73
3 0.46 0.49 0.54 0.6 0.72 0.9 1.1 1.27 1.6 1 .93 2.63 3.48 4.59
4 0.87 0.92 0.99 1.09 1.26 1.52 1.8 2.05 2.5 2.95 3.89 5.02 6.5
5 1.36 1.43 1.52 1.66 1.88 2.22 2.5 2.88 3.45 4.01 5.19 6.6 8.44
6 1.91 2 2.11 2 .28 2.54 2.96 3.3 3.76 4.44 5.11 6.51 8.19 10.4
7 2.5 2.6 2.74 2.94 3.25 3.74 4.1 4.67 5.46 6.23 7.86 9.8 12.4
8 3.13 3.25 3.4 3.63 3.99 4.54 5 5.6 6.5 7.37 9.21 11.4 14.3
9 3.78 3.92 4.09 4.34 4.75 5.37 5.9 6.55 7.55 8.52 10.6 13 16.3
10 4.46 4.61 4.81 5.08 5.53 6.22 6.8 7.51 8.62 9.68 12 14.7 18.3
11 5.16 5.32 5.54 5.84 6.33 7.08 7.7 8.49 9.69 10.9 13.3 16.3 20.3
12 5.88 6.05 6.29 6 .61 7.14 7.95 8.6 9.47 10.8 12 14.7 18 22.2
13 6.61 6.8 7.05 7.4 7.97 8.83 9.5 10.5 11.9 13.2 16.1 19.6 24.2
14 7.35 7.56 7.82 8.2 8.8 9.73 10.5 11.5 13 14.4 17.5 21.2 26.2
15 8.11 8.33 8.61 9.01 9.65 10.6 11.4 12.5 14.1 15.6 18.9 22.9 28.2
16 8.88 9.11 9.41 9.83 10.5 11.5 12.4 13.5 15.2 16.8 20.3 24.5 30.2
17 9.65 9.89 10.2 10.7 11.4 12.5 13.4 14.5 16.3 18 21.7 26.2 32.2
18 10.4 10.7 11 11.5 12.2 13.4 14.3 15.5 17.4 19.2 23.1 27.8 34.2
19 11.2 11.5 11.8 12.3 13.1 14.3 15.3 16.6 18.5 20.4 24.5 29.5 36.2
20 12 12.3 12.7 13.2 14.0 15.2 16.3 17.6 19.6 21.6 25.9 31.2 38.2
21 12.8 13.1 13.5 14 14.9 16.2 17.3 18.7 20.8 22.8 27.3 32.8 40.2
22 13.7 14 14.3 14.9 15.8 17.1 18.2 19.7 21.9 24.1 28.7 34.5 42.1
23 14.5 14.8 15.2 15.8 16.7 18.1 19.2 20.7 23 25.3 30.1 36.1 44.1