coverage session slides
TRANSCRIPT
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Objectives
Review distributed files Setting up the tools for coverage analysis
Prioritizing your work Selecting top coverage issues
Categorizing In-building, In car, On-street coverage Identifying potential interference locations
Walk through on coverage examples Probable coverage holes scenario
Probable multi server scenario
Design changes
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What is the Right Coverage?
Creating Dominant Servers Each location ideally has one dominant server
Eliminating coverage gaps
Minimizing interference
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What Limits the Coverage?
Downlink Maximum downlink power allocated for a
traffic channel
Uplink Max uplink transmit power from MS
Discuss other factors!
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Coverage scenarios
On street In Car
In building (1-wall)
In building (3-wall)
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Interference
Minimizing interference Definition:
4 or more servers within 5 dB of strongest, inclusive
Example:
Impacts:Access failures
High HO reduced capacity Drops in extreme cases
Impact to throughput (for GPRS/EDGE)
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Coverage Optimization Process
Input Scanner Data
Mobile Camped On Cell RxLevIdle
Prediction Tool Plots Test transmitter (site selection)
Tasks
Identify each sectors coverage pattern Eliminate over-spray where sector is dominant
(and shouldnt be)
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Per Sector Coverage Data
AnalysisAnswer the following for each sectors coverage
pattern:
What is the design intent of this sectors coverage?
Where is this sector dominant?
Where shouldthis sector be dominant?
Is this sector over- (or under-) covering?
Is this sector contributing to excessive coverage? Is this sector under-performing (network stats)?
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Summary
Other useful plots RxLev Sub Plots
C1 Plots
Use of coverage plotsAccess failure analysis
Dropped call analysis
Throughput analysis
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Interference
Confidential
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Interference
Types of Interference Sources of Interference
Detecting Interference
Confidential
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Types of Interference
Types of Interference
External Interference
Internal Interference Co-Channel Interference
Adjacent Channel Interference
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External Interference
Sources of External Interference
Noise from other RF sources
Man made noiseAutomobiles, Machines, Power Lines, etc.,Galactic Noise
From Sun, Stars etc.,
Atmospheric NoiseMostly from Lightning..
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Co-Channel Interference
Co Channel interference: It is the relation between thedesired signal C and undesired (Interfering or re-used) signal I,both using the same carrier frequency.
Carrier, F1 Interferer,F1
CI
C/I > 12 dB (Design criteria)
C/I > 9 dB ( GSM Rec.)
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Types of Co-Channel Interference
Downlink Co-Channel Interference
Uplink Co-Channel Interference
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Frequency re-use
A1
A2A3
B1
B2B3
C1
C2C3
D3
D2D1
A1
A2A3
B1
B2B3
C1
C2C3
D3
D2D1
A1
A2A3
B1
B2B3
C1
C2C3
D3
D2D1
A1
A2A3
B1
B2B3
C1
C2C3
D3
D2D1
A1
A2A3
B1
B2B3
C1
C2C3
D3
D2D1
A1
A2A3
B1
B2B3
C1
C2C3
D3
D2D1
A1
A2A3
B1
B2B3
C1
C2C3
D3
D2D1
Potential
Interferers
PotentialInterferers
PotentialInterferers
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Internal Interference
BCCH BCCH interference TCH TCH interference
BCCH BCCH interference: Can be identified by poor call origination rate in the
interfered cell
More call drops in the BCCH Carrier
BCCH interference is not always dependent on theamount of traffic in the cell
Difficult to detect which cell is interfering, if there aremore cells with the same BCCH around the interferedcell
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TCH TCH Interference
TCH carriers are reused contribute to co-channelinterference.
It will be present only when these TCH carriers have callactivity
To check this type of interference calls are originated oneach timeslot of suspected reused TCH carriers & the C/Ivalues are measured
Easiest method to solve this measurement problem is to
make Delta (difference) measurements, that is Instead ofmeasuring C/I on the T1 (common TCH carrier frequency),we make a delta measurement of B2 / B1 , which is nearto the C/I value of T1
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TCH TCH Interference
Cell 1 has BCCH carrier on ARFCN B1 and cell 2 hasBCCH carrier on ARFCH B2 while both have TCH carrierson ARFCN T1
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Adjacent Channel Interference
Adjacent - Channel interference: It is the relationbetween the desired signal C and undesired signal A, bothusing the adjacent carrier frequency.
Carrier, F1Interferer
F1+1 or F1-1
CA
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Adjacent Channel Interference
Adjacent Channel interference: It is the relation betweenthe desired signal C and undesired signal A, both separated by200Khz
fx fx+200khz
C
AC/A > -9 dB
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Time Dispersion
C = Direct signalR = Reflected signalC/R > 9 dB
The Reflected signal that are delayed more than 15 micro secmust be at least 9 dB below the direct signal received at thattime instant.
C
R
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Detecting Interference
Detecting Interference
Detecting External interference
Detecting internal interferenceTools for detecting interference
Methods of detecting interference
D t ti E t l I t f
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Detecting External Interference
Other RFSources:
SpectrumAnalyzer
Directional
Antenna(Operating in the
required band)
Confidential
Source: www.Agilent.com
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Interference Analyzer
Detecting Interference using Interference Analyzer:
Racal - SmartAIR
Rohde & Schwarz - Roger TS 9958
Agilent E6474A / E7475A
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Interference Analyzer
Detecting Interference in the network
Measurement of Interfered and Interfering Signal
Identifying to which cell the interfered and interferingsignal belongs to.
G l C l i
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General Coverage Analysis processStudy RSSI from scanner and Idle phone RxLev plots.
Compare with the intended (planned) coverage and identify
serving with neighboring cells. Look for potential interference.Plot serving BCCH for camped on cell.
Plot individual coverage (from scanner ) to see per cellcoverage/containment.
In Mapinfo, plot serving with neighbors in idle mode and identifypotential interference.
Per cell, look at the individual tilts/height with general field clutterinformation
Look at stats for per cell usage and performance during busy
hour.Discuss recommendations for any changes required.
Simulate possible changes in Frequency planning tool forintended coverage
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Objectives for 15/02/10
Introduction on Drive Test tool and Actix post-processing tool.
Drive test process, different test set ups
Validating drive logs.
Initial set-up in Actix Loading drive data into Actix tool
Analysis windows/options in Actix
Using MapInfo
Site database ,Network Site level statistics.
Examples review