members of our presentation (bsts09-08) hafiz umer ejaz (bsts09-09) rai-habib ullah (bsts09-31)...
TRANSCRIPT
Members of our Presentation
(Bsts09-08) Hafiz Umer Ejaz
(Bsts09-09) Rai-Habib Ullah
(Bsts09-31) M.Arsalan Qureshi
(Bsts09-32) Shoaib Ansari
(Bsts09-34) Talal Rashid
Presentation
Why do we need cellular phones?
We can freely move and in contact with people at anytime.
It helps to organize our life.
If someone lost, it can give you directions.
Advantages of cellular phone
Advantages to Mobile User
Advantages to Network Provider
Different technologies of Cellular phones
First Generation -Analog Mobile Telephone System
Second Generation-Digital Mobile Communication System
Third Generation-IMT-2000
Cellular technologies overview
First Generation Cellular Systems
The predominant technology of first generation was Advanced Mobile Phone System or AMPS.
First generation cellular systems made its entrance in 1979, work in 1980’s were based on analog communication.
On October 12, 1983 the regional Bell operating company began the first United States commercial cellular service in Chicago.
Advanced Mobile Phone System (AMPS) is one of the leading analog cellular systems in North America.
It uses FDMA to separate channels in a link.
BAND
AMPS was released in 1983 using the 800-MHz to 900-MHz frequency band
The System uses two separate analog channels
The band between 824 and 849 MHZ carries reverse communication and the band between 869 and 894 MHZ carries forward communications
Total Access Communications Service
The original European 900 MHz analog system launched in 1985 by Vodafone.
Still used in Austria, Bahrain, China, Japan etc
Uses a protocol known as Frequency Division Multiple Access (FDMA).
Nordic mobile telephony (NMT)
It uses 450 and 900 MHz band.
Still used in parts of Europe and Asia, including Algeria, Andorra, Bangladesh etc.
It was the first cellular system to be used commercially.
Problems in First Generation
As 1G was based on (FDMA) for transfer between cells, it was very vague and had a low capacity.
It has a low degree of safety, Low security, easy to fake
Poor data communication.
Bulky equipment.,
Do you remember 1G phones?
Do you remember 1G phones?
Basic technologies
CDMA (Code division multiple access)
TDMA (Time division multiple access)
History & Introduction of GSM
In 1982, the European Conference of Postal and Telecommunications Administrations (CEPT) created the GSM.
In 1989, GSM responsibility was transferred to the European Telecommunications Standards Institute (ETSI).
The first GSM network was launched in 1991 in Finland.
Main features of GSM
Compatibility with other systems
Flexibility and Increased Capacity
Improved Security and privacy
ISDN Compatibility
GSM Services
Speech Services
Bearer or Data Services
Supplementary services
Speech Services
Telephony
Emergency Calls
Dual Personal and Business Numbers
Bearer Data Services
Short Message Service (SMS).
Text files and fax.
Voice mail.
Supplementary Services
Number Identification
Call Forwarding
Call Waiting
Call Hold etc
GSM Specifications
GSM 900* Mobile to BTS (uplink): 890-915 MHz* BTS to Mobile (downlink):935-960 MHz EGSM900* Mobile to BTS (uplink): 880~915MHz * BTS to Mobile (downlink): 925~960MHz
EGSM
880 890 915 925 935 960 MHz
GSM EGSM GSM
GSM Specifications
DCS (Digital Communication System) 1800
* Mobile to BTS (uplink): 1710-1785 MHz * BTS to Mobile (downlink) 1805-1880 MHz
Base Station Receive
1710 1785 1805 1880MHz
Base Station Transmit
GSM System Architecture Overview
(MS) Mobile Station
(BSS) Base Station Sub-system
(NSS) Network and Switching Sub-system
The GSM Mobile Station (MS)
Mobile Equipment (ME)
Subscriber Identity Module (SIM)
Mobile Equipment
International Mobile Equipment Identifier (IMEI)
160 character long SMS
The IMEI may be used to block stolen equipment
Subscriber Identity Module (SIM)
International mobile subscriber identifier (IMSI)
Allows user to send and receive calls and receive other subscribed services
SIM is Protected by 4-8 digit PIN
PUK – Personal/Pin Unlocking Key
Base Station Subsystem (BSS)
(BTS) Base Transceiver Station
(BSC) Base Station Controller
(XCDR) The Transcoder
Base Transceiver Station (BTS)
General Architecture
*Radio Transceivers*Combiner*Duplexer*Antennas and feeder cables
Rack Structure
Signal Flow in BTS Rack
CSBCMB
DTRU(0~2)
B8018机柜
DTRU(3~5) DTRU(6~8)
LAYER 1 LAYER 2 LAYER 3
AEM AEM AEM
天馈
BSCEIB
Base Station Controller (BSC)
Main functions of BSC* Allocates a channel for the duration of a call* Handles call set up* Maintains the call* Monitoring quality* It communicates with MSC ,BTS & NSS.*Controls one or more BTSs
The Transcoder
Network and Switching Sub-system
(MSC) Mobile Switching Center(HLR) Home Location Register(VLR) Visitor Location Register(EIR) Equipment Identity Register(AUC) Authentication Center(GMSC) Gateway Mobile Switching Centre(EC) Echo CancellerBilling
Mobile Switching Center (MSC)
Heart of the networkManages communication between GSM and
other networksCall setup function and basic switchingCall routing Billing information and collectionMobility management* Location Updating
Home Location Registers (HLR)
Permanent database about mobile users in a large service area
Database contains Subscriber ID Current subscriber VLR Subscriber status Authentication key
Visitor Location Registers (VLR)
Temporary database which updates whenever new MS enters its area, by HLR database
Controls those mobiles roaming in its area Reduces number of queries to HLR Database contains Mobile StatusLocation Area Identity(LAI)
Equipment Identity Register (EIR)
Database that is used to track handsets using the IMEI (International Mobile Equipment Identity)
Made up of three sub-classes: * White List * Black List * Gray List
Authentication Center (AUC)
Protects against intruders in air interface
Maintains authentication keys and algorithms and provides security.
Generally associated with HLR
Gateway Mobile Switching Centre
The GMSC is a device which routes traffic entering a mobile network to the correct destination.
The GMSC accesses the network’s HLR to find the location of the required mobile user.
A particular MSC can be assigned to act as a GMSC.
The operator may decide to assign more than one GMSC.
The GMSC routes calls out of the network and is the point of access for calls entering the network from outside.
Echo Canceller
An echo canceller models the voice signal passing through it
As the voice passes back through the canceller it applies signal to remove it dynamically.
Billing
The MSC/GMSC that originates a call generates a record (Call Detail Record which contains:
> Subscriber identity> Number called> Call length> Routing of the callThe record passes along the backbone to the
home networkBilling computer generates bills to be sent to
the user.