Gsm Architecture

Question 1

Expand GSM

Answer 1

Global system for mobile communications

Question 2

What is the gsm mobile phone know as ?

Answer 2

Mobile station or ms

Question 3

What two elements does a mobile station (MS) have ?

Answer 3

The mobile equipment (ME)

Subscriber Identity Module (SIM)

Question 4

What is the air interface ?

Answer 4

It is the radio frequency link between the mobile station and the tower

Question 5

What information can a sim contain ?

Answer 5

Phone book 
Imsi 
Tmsi 
Authentication and encryption keys 
Services available 
Msisdn

Question 6

Expand MSISDN

Answer 6

Mobile station interested services digital network number

Question 7

Expand IMSI

Answer 7

International mobile subscriber identification

Question 8

Expand TMSI

Answer 8

Temporary mobile subscriber identification

Question 9

Expand IMEI

Answer 9

International mobile equipment identification

Question 10

What is the msisdn ?

Answer 10

Mobile stations phone number

Question 11

How many digits is the msisdn made up of ?

Answer 11

A maximum of 15 digits

Question 12

How is a msisdn broken down ?

Answer 12

First 2 digits = country code

Next 3 digits = the national destination code

Remaining digits = unique serial number

Question 13

Expand NDC

Answer 13

National destination code

Question 14

Expand PLMN

Answer 14

Public land mobile network

Question 15

What is the national destination code identifying?

Answer 15

Which public land mobile network the ms is associated with

O2 or EE

Question 16

Expand SNR

Answer 16

Unique serial number

Question 17

How is a international mobile subscriber identity broken down ?

Answer 17

First 3 digits = mobile country code

Next 2 digits = mobile network code

Remaining digits = operator specific

Question 18

Expand MCC

Answer 18

Mobile country code

Question 19

Expand MNC

Answer 19

Mobile network code

Question 20

What identity is the most commonly sent between the MS and the network

Answer 20

True tmsi or temporary Mobile subscriber identity

Question 21

How is a tmsi generated ?

Answer 21

It is a randomly allocated hexadecimal number that is given to the ms after initial authentication

Question 22

Why effects the tmsi ? When is it updated?

Answer 22

Each time the mobile moves to a new geographical area

Question 23

How can the network use a tmsi

Answer 23

As a security feature, to ensure the subscribers identity remains secure and is not tracked while accessing the network

Question 24

Where is international mobile subscriber or imsi held ?

Answer 24

On the SIM card

Question 25

What is associated with the imsi

Answer 25

All subscriber related information like billing

Question 26

Expand imei

Answer 26

International mobile equipment identity

Question 27

What could a imei also be known as ?

Answer 27

Eir or equipment identity register

Question 28

How is a imei broken down ?

Answer 28

First 8 digits = type allocation code (tac). Next 6 digits = serial number Last digit = check digit

Question 29

How is the type allocation (tac) broken down ?

Answer 29

First 2 digits = reporting body identifier Next 6 = mobile equipment type identifier

Question 30

Expand SNR and what is it used for ?

Answer 30

Serial number Used to uniquely identify each individual mobile equipment

Question 31

What is the purpose of a check digit

Answer 31

To help guard against incorrect entries into the equipment identity register

Question 32

When is the imei broadcast ?

Answer 32

Powering on the mobile station Change of SIM card

Question 33

Expand BTS

Answer 33

Base transceiver station

Question 34

What role does the Bts play ? What will it typically have ?

Answer 34

It is responsible for the radio functions associated with connection to and from the ms Several transceivers

Question 35

What is bts commonly referred to as ?

Answer 35

Mobile phone Mast

Question 36

What functions does a bts provide ?

Answer 36

``` Radio frequency carriers Modulation and demodulation of rf carriers Data processing Error coding Ciphering Channel mapping ```

Question 37

What is the link between the mobile station and base transceiver station know as ?

Answer 37

Um or air interface and is an encrypted radio frequency link

Question 38

What are the most common antenna types used in gsm ?

Answer 38

Macro - range < 35km Micro - range < 5 km Pico - around a hundred meters Micro wave radio relay - link bts to other bts