MOBLIE PHONE NETWORKS Dr. Hassan Nojumi

Mobile Phone Networks Dr. Hassan Nojumi 1

MOBLIE PHONE NETWORKSDr. Hassan Nojumi


Functions of Mobile Phones



• Send/Receive Voice Message



• Send/Receive Voice Message

• Send/Receive E-Mail



• Send/Receive Voice Messages


• Internet Connection



• Send/Receive Voice Messages


• Internet Connection

• Complementing PDAs, GPS Receivers, etc.


Functionality

Combination of

. . .

And

. . .


Functionality

Combination of

Telephone Technology

And

. . .


Functionality

Combination of

Telephone Technology

And

Wireless Communication


Basic Notion

Geographical Division into

Cells


Basic Notion

Geographical Division into

Cells

Result:

Possibility of simultaneous use of frequency bands by users


Basic Technology

Each Cell

• About 10 square miles About 26 square kilometers


Basic Technology

Each Cell

• About 10 square miles About 26 square kilometers

• With a Base Station with transmission equipment and antenna


Basic Technology

• Communication can be made using the same frequencies in different cells.


Basic Technology

• Communication can be made using the same frequencies in different cells.

• Several service providers may use one Tower.


Basic Notion: Cellular


Communication Channels

Simplex: One-Way



Half-Duplex: Two-Way

One at a time



Full-Duplex: Two-Way

Simultaneously



Full-Duplex: Two-Way

Simultaneously



Each cell

• About 56 Voice Channels (Full-Duplex)



Each cell


• Several Control Channels



Each cell


• Several Control Channels

• Three-fold increase possible by TDMA


Analog Versus Digital

Digital signals can be manipulated, compressed, etc., more easily.


Analog Versus Digital

Digital signals can be manipulated, compressed, etc., more easily.

FSK (Frequency Shift Keying) for Tower/Phone Connection


Access Technologies


Access Technologies

FDMA

Frequency Division

Multiple Access


Access Technologies

FDMA

Frequency Division

Multiple Access

Available frequency band is divided and each part assigned separately.


Access Technologies

FDMA


Access Technologies

FDMA

• Traditional radio transmission


Access Technologies

FDMA

• Traditional radio transmission

• Not efficient for digital transmission


Access Technologies

TDMA

Time Division

Multiple Access


Access Technologies

TDMA

Time Division

Multiple Access

Available time is divided and each part assigned separately.


Access Technologies

TDMA


Access Technologies

TDMA

Suitable for digital transmission as compression techniques can greatly reduce needed transmission time.


Access Technologies

TDMA

• “Multiprogramming” idea


Access Technologies

TDMA

• “Multiprogramming” idea

• Has typically three times the capacity of an analog system


Access Technologies

TDMA

• IS- 54: 800 MHz Band


Access Technologies

TDMA


• IS-136: 1900 MHz Band


Access Technologies

TDMA


• IS-136: 1900 MHz Band

• Dual-Band phones can operate in both bands.


Access Technologies

TDMA/GSM

Global System for

Mobile Communications

Specialized TDMA used for mobile phone communication


Access Technologies

TDMA/GSM

Encryption methods are used to make the call more secure.


Access Technologies

TDMA/GSM

To Connect to different service providers, users change their

SIM (Subscriber Identification Module) Cards that contain necessary data for connection


Access Technologies

CDMA

Code Division

Multiple Access


Access Technologies

CDMA

Code Division

Multiple Access

Communication data is digitized and distributed

over the available band.


Access Technologies

CDMA

Code Division

Multiple Access

Each call is assigned a Sequence Code. Calls are

overlaid over available band.


Access Technologies

CDMA


Communication Cells

• Each cell About 26 Km 2


Communication Cells

• Each cell About 26 Km

• Many Base Stations and Transmission Towers required for a large city (paid off by many customers)

2


Communication Cells

All Base Stations in a region are controlled by an MTSO (Mobile Telephone Switching Office)


Cell Phone Codes

ESN

Electronic Serial Number

Unique 32-bit number programmed into the phone at manufacture

- Permanent and Unchangeable -


Cell Phone Codes

MIN

Mobile Identification Number

10-digit number derived from

mobile phone number

- Assigned When Phone Activated -


Cell Phone Codes

SID

System Identification Number

5-Digit Carrier Code

- Assigned When Phone Activated -


Cell Phone Codes

Each phone user has a unique MIN&ESN identification, used by the phone company for billing.


Cell Phone Codes

MIN&ESN identification may be captured by scanning the call and used by a third party for making fraudulent calls.


Cell Phone Communication

Startup



Startup

• Phone turned on.



Startup


• Device sends Registration Request to MTSO



Startup


• Device sends Registration Request to MTSO

• An SID is looked for on a Control Channel.



Startup

If SID not found, Out of Range.



Startup


If SID found, comparison is made with the programmed SID in the phone device



Startup


If SID found, comparison is made with the programmed SID in the phone device

Matched SID Means Home



Startup

If SID Not matched, MTSO contacts the Home MTSO to verify that SID in the phone device is valid.



Connection

Destination is dialed.



Connection

Destination is dialed.

MTSO selects and assigns a frequency channel for call



Connection

Cell Change is done by coordination between cells and MTSO using signal strengths.


Basic Notion: Cellular


Other Cellular Phone Details:



• Hardware/Software




• Analog-to-Digital Conversion





• Digital-to-Analog Conversion






• Display






• Display

• Power/Batteries



• Cell Phone Etiquette

Documents

MOBLIE PHONE NETWORKS Dr. Hassan Nojumi