2G/3G Network Interview Questions: Field Problems & Call Flow

Interview 1 ( montaser ) & emad
2g
Field problem ( cross sector – cross feeder ) physically and theoretically – overshooting
Blocked call – droped call and their causes and their event . –missing neighbor – ho failure
Why we use Power control in 2g
h.o scenario and who responsible for make h.o .
call flow scenario ( physical channel – layer3 message )
cell selection & Reselection ( c1 & c2 criteria )
TX-RX
3g
Field problem ( coss sector & feeder ) how we can detect coss feeder (RTWP – uplink
interference from sib7 )
Blocked call – droped call – pilot pollution – interference (downlink & uplink )
TX-RX
Ue states and it’s connection between ue and node b and core network
Call flow
Power control why we use it
How we can detect interferer cell (using mapinfo)
Type of H.O (hard – soft – softer )and Difference between soft and softer and why we use softer
and why it’s better than soft h.o
When hard h.o happened (from I rat and from f1 to f2 )

Interview 2 ( emad )
2g
Cross feeder TX-RX physically how trx can change with each other and how bcch change with
tch , how we can detect it when cross feeder on tchs .
Cross sector
Service problem ( droped and blocked call ho failure overshooting missing neighbor)
Call flow and ho flow
Difference between electrical and mechanical tilt
Intra cell ho why we need this technique
Frequence hooping why we need it
Power control
Sd and tch congestion
3g
Rl congestion causes ( codes – power – iub connection between node b )
What’s type of codes ? and what’s tree
What’s cell breathing
Why power control in 3g is very important and dynamic (cuz it’s important resourse and cause
3g network is interfered network )
Pilot pollution – interference
SNR Criteria in 3g
Modulation qpsk -qam
Ho from utran failure
TX-RX
MIMO Technology (42mb/s)
Cross feeder how we can detect it and see it ( from rwtp and sib 7 uplink interference

Limitation of hsdpa :
1- Resources2
2- Radio condition
3- User equipment (usb modem)
4- Sim limitation  from layer 3 message  pdp context acceptance  bit for uplink &
downlink
2g :-
Call scenario – Ho scenario – hardware problem - service problem – overshooting -