Mobile technologies

Question 1

How do you register a phone on a network

Answer 1

Sim: Subscriber Identification Module
…Identifies subscribers account which is mapped to a phone number
Special channels for comms between tower/mast and the handsets… detect if a channel is in use
Pick the strongest mast signal
Register ith mast which then serves the handset

Question 2

How does a Call Happen

Answer 2

-Mast covers an area known as cells
-Cells overlap to cover large areas
Handset transmits call requests to its serving mast
The mast will use its base station to communicate with the mobile switching centre
If the number is registered with another mast
Two masks communicate
Channels are assigned between masts and handsets (one per call)
Mast transmits between each other via base stations and PSTN

Question 3

How does a handover occur when moving during a call

Answer 3

Handover: Travelling while on cell, moving from one cell to another
As the handset moves further from mast controlling it
… this is sensed by mast
Checks with neighbouring masts…which neighbour is detecting handset

Question 4

What are the stages of Handover

Answer 4

May need to assign a new channel
Must be free on each mast
Both mast transits call simultaneously for short time period
The first mast dumps out of call

Question 5

Describe the Terms Cell, Mast, Base Station Controller, PSTN and Mobile switching centre

Answer 5

Cell: Geographical area controlled by a mast
Mast: Radio Transmitter sending/receiving mobile phone communications
Base Station Controller: Links the mast to the PSTN
It can serve multiple masts, which may not have access to PSTN which will forward messages to its neighbouring mats
PSTN: Public Switched Telephone Network
Mobile Switching Centre: Service providers (Vodafone, orange etc)
Maintain a database of sims, masts, locations etc..
Registers and tracks phone geographical location, controlling mast
Routes all calls + data around mobile network