RF Optimization (Drive Test)

Objective (brief)

Understanding Optimization Overview H/w used in TEMS Using TEMS Question in Interview Review

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

Understanding Optimization

Optimization is the process of improving operationof the network to better utilise available

Infra.to provide customers of the service the best

possiblequality of service. 

H/w & S/W used in TEMS

TEMS Dongle TEMS software Laptop GPS

Mobile

TMES Dongle

GPS

Latitude

Longitude

Latitude parallel to equator

Longitude parallel to meridian

lat=19.187055Nlon=72.970878E

TEMS

Understand GSM protocol

Understand GSM protocol

Layer 3 Messages

Layer 3 Message System Information Type 1 System Information Type 2 System Information Type 3 System Information Type 4 System Information Type 5

SYSTEM INFORMATION TYPE 1

sent on the BCCH Information of control of the RACH

SYSTEM INFORMATION TYPE 2 sent on the BCCH BCCH allocation in the neighbour cells.

SYSTEM INFORMATION TYPE 3 The location area identification, The cell identity various other information about cell

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.

PAGING REQUEST TYPE 1

sent on the CCCH by the network Up to two mobile stations

PAGING REQUEST TYPE 2

Three mobile stations

Understanding LAP-Dm

Layer 2 Messages

Using TEMS

Serving Cell

Cell ID 16bit identifier

CGI = Cell ID + MCC + MNC +LAC

LAC < 65535

(Cell Global Identity).

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

Serving and Nighbouring cell

RxLEV

Measured in dBm units Rxlev (-110 to – 47) dbm RxLEV (0 to 63)GSM unit

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.

Mobile allocation index offset (MAIO)

Time delay separating traffic channels.

Hopping sequence number (HSN).

The hopping pattern must be known both by the receiver and the transmitter.

The smallest amount of interference on a site

Frame Erasure Rate

Speech Quality Index

Troubleshooting With TEMS

Troubleshooting With TEMS

Call drop

Hand Over

Congestion

Troubleshooting Call Drop

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

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

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

Excessive Timing advance

Check the BTS error log Run commands: RXELP & RXMFP

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

Handover Analysis

Handover Analysis No or few handover attempts:

whether the target cell is congested, if congested, solves the congestion problem.

Check if BTS is defined but might not be in service.

Handover Analysis

(BTS Log) PDF

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?

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?

Thank you

Design by Mahesh

Tawade