RF 2G Interview questions

Q.1 How many time slots have in 2G?
8 time slots

Q.2 What is TRAU and its work?
Transport Rate Adaption Unit , work is to compress and decompress the speech.

Q.3 Which modulation used in GSM?
Pulse Width Modulation

Q.4 What is PLMN?
Public Land Mobile Network - its a group of BTS, BSC and MSC.

Q.5 What is BSIC?
Base Station Identity Code its depends on network color code and base station color code.

Q.6 Procedure for GPRS in 2G?

GSM: MS - BTS- BSC - SGSN- GPRS Backbone - GGSN

Q.7 How many pdp context can open by one MS.
7

Q.8 Types of channels in GSM with details?

Logical channels and physical channels.

Physical Channels-
1- Common Channel       2-Dedicated Channels

1- Common Channels classified in to 3 categories.
a)Common Control Channels
i) PCH-downlink channel Paging Channel use for incoming the call.
ii)RACH- Random Access Channel- uplink channel use for call request after user dial a number.
iii)AGCH- Access Grant Channel- downlink channel use for granting the call by BTS.

b)Broadcast Channels
i)FCCH- Frequency Correction Channel used to guide the mobile to match the frequency.
ii)SCH- Synchronization Channel - use to sending BSIC and give TDMA frame numbe to MS.
iii)BCCH- used for sending information to the mobile. like CGI

c)Dedicated Channels
i)SDCCH- Standalone Dedicated Control Channel its a signalling channel between MS and BTS.
its responsibilites are  location update, sms etc.
ii)FACCH- Fast Access Control Channel - use for handover
iii)SACH- Slow Access Control Channel- use for measurement of report during calls.

2- Dedicated Channel
a)Full Rate- user bit rate 13.4kbps data 9.6kbps bidirectional channel
b)Half Rate - user bit rate 6.7kbps data 4.8kbps bidriectional channel
c)Enhance Rate- user bitrate 12kbps data 9.6kbps - bidirectional channel.