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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)

PDF

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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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