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RF Optimization (Drive Test)
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Objective (brief)
Understanding Optimization
Overview H/w used in TEMS Using TEMS
Question in Interview
Review
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Objective Understanding meaning of RF Optimization
H/w & S/W used in TEMS
Understand GSM protocol
Understand LAP-Dm
Using TEMS Drop Call Analysis
Handover Analysis
Troubleshooting with TEMS
Question in Interview
Review
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Understanding Optimization
Optimization is the process of improving operationof the network to better utilise available Infra.
to provide customers of the service the best possible
quality of service.
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H/w & S/W used in TEMS
TEMS Dongle
TEMS software
Laptop GPS
Mobile
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TMES Dongle
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GPS
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Latitude
Longitude
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Latitude parallel to equator
Longitude parallel to meridian
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lat=19.187055N
lon=72.970878E
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TEMS
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Understand GSM protocol
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Understand GSM protocol
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Layer 3 Messages
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Layer 3 Message System Information Type 1
System Information Type 2
System Information Type 3
System Information Type 4
System Information Type 5
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SYSTEM INFORMATION TYPE 1
sent on the BCCH
Information of control of the RACH
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SYSTEM INFORMATION TYPE 2 sent on the BCCH
BCCH allocation in the neighbour cells.
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SYSTEM INFORMATION TYPE 3
The location area identification,
The cell identity
various other information about cell
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System information type 5 sent on the SACCH by the network
Any change in the neighbour cells
description
Mobile station must analyse all
correctly received messages.
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PAGING REQUEST TYPE 1
sent on the CCCH by the network
Up to two mobile stations
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PAGING REQUEST TYPE 2
Three mobile stations
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Understanding LAP-Dm
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Layer 2 Messages
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Using TEMS
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Serving Cell
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Cell ID 16bit identifier
CGI = Cell ID + MCC + MNC +LAC
LAC < 65535
(Cell Global Identity).
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Base Station Identity Code
Important in border areas
3-bit network color code (NCC) assigned by regulatory authority
3-bit base-station color code (BCC) assigned by the network operator
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Serving and Nighbouring cell
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RxLEV
Measured in dBm units
Rxlev (-110 to – 47) dbm
RxLEV (0 to 63)GSM unit
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Cell selection For example,
If the minimum allowed level is -100dBm
Average received signal level is - 80dBm
The terminal evaluates C1 as +20.
The terminal always selects for attach the cell
with highest C1.
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Mobile allocation index offset (MAIO)
Time delay separating traffic channels.
Hopping sequence number (HSN).
The hopping pattern must be known both by thereceiver and the transmitter.
The smallest amount of interference on a site
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Frame Erasure Rate
Speech Quality Index
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Troubleshooting With TEMS
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Troubleshooting With
TEMS
Call drop
Hand Over
Congestion
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Troubleshooting Call Drop
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Check Interference Internal
Co-channel Interference Change Frequency
MS power
Turn on Frequency Hopping Put more TRU
External wireless alarm system
Check Antenna Direction & Position
Low Signal Strength
Timing Advance
Ping-pong Handover Call dropped on the TCH.
Call dropped on the SDCCH
DRAGON site
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Excessive Timing advance TA value is higher than TALIM
Reducing the coverage If cell is really covering far away from BTS
Tilting the antennas,
Reducing antenna height
Changing antenna
Reducing output power
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Excessive Timing advance The maximum BTS radius of 35 Km
is divided into 64 TA steps
i.e. 1 TA = 547 Meter OR 550 Meter
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Excessive Timing advance
Check the BTS error log
Run commands: RXELP & RXMFP
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Low signal strength Received signal level,
Measured in dBm units
Rxlev (-110 to –
47) dbm RxLEV (0 to 63)GSM unit.
Either BCCH channel in idle mode
both BCCH and TCH
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Handover Analysis
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Handover Analysis No or few handover attempts:
whether the target cell is congested, ifcongested, solves the congestion problem.
Check if BTS is defined but might not be inservice.
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Handover Analysis
(BTS Log)
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Question in Interview – 1
How to connect gps and mobile?
GPS components used?
whic mobiles are been used?
Laptop which pin is used to connect the gps?what parameters are used to measure call drop?
what parameters are used to measure handoff?
what u mean by RX-LEVEL?
what u mean by RX-QUAL?what does the term power budget mean?
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Assignment for Student
How can you calculate the coverage and capacity of a GSM
network?
How do you make a link budget? Which parameters are included in “System Information”?
How can you increase coverage and capacity?
How does the choice of antennas affect network performance?
What are C/I, C/A ?
How can repeaters improve the network performance?
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Thank you
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