14-08-2012, 01:22 PM
Public switched telephone network
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INTRODUCTION
1.1 Revolution in telecom
The telephone has long been important in modern living, but it use has been constrained by connecting wires. The advent of mobile radio telephony and particularly the cellular radio has removed this restriction and led to explosive growth in mobile throughout the world. The phone is really on move now.
With the phenomenal and unprecedented growth of more than forty fold in just ten years, a strong demand for mobile cellular services has created an industry which now accounts for more than one third of all telephone lines. It is expected that mobile phone will soon exceed the traditional fixed line phones. In fact the trend of fixed and mobile convergence is already being talked about.
1.2 Concept of mobile communication
Fixed telephones, using wired access network, are meant to be used at a particular location only. We can have telephones at our office/business and our residence. The fixed telephones are linked to a place but the modern day life style demands that we should have telephone facility while on move also. Mobile communication facilitates telephonic conversation in a fast moving vehicle. This means that phones moves along with a person thereby moving telephone is linked to a person and not to a place. In these words our reach becomes broader and world shrinks into a Global village. Wireless communication is all around us. The day is not far off; the future generations will wonder as to “why wires are required for a telephone to work!!!”
1.3 Mobile communication objectives
The important objectives of the mobile communication are
•Any time anywhere communication
•Mobility & Roaming
•High capacity & subs. density
•Efficient use of radio spectrum
•Seamless Network Architecture
•Low cost
•Innovative Services
•Standard Interfaces
1.4 History of mobile communication
•1946 Appeared in St .Louis USA (By AT & T) at 150 MHz band – FM – 120 KHz BW
•1960 450 MHz Band FM – 30 KHz BW
•1970 BELL LAB introduced Cellular Principle
•1979 Advanced Mobile Phone System in US
•1985 Total Access Communication System (TACs in UK) •1986 Nordic Mobile Telephony Systems (NMT)
•1990 Digital Systems
1.5 Different generations – Analog and digital systems
• 1946- 1960s 1980s 1990s 2000s
Appearance 1G 2G 3G
Analog Digital Digital
Multi Standard
Multi Standard
Unified Standard
. Terrestrial Terrestrial
Terrestrial & Satellite
1 G – I Generation --Analog (cellular revolution)
-only mobile voice services
2 G – II Generation -- digital (breaking digital barrier)
- Mostly for voice services & data delivery possible
3 G - Voice & data (breaking data barrier) –mainly data
INTERNATIONAL MOBILE TELECOM 2000. (IMT-2000)
THIRD GENERATION (3 G) STANDARD
A future standard in which a single inexpensive mobile terminal can truly provide communications any time and any where.
INTERNATIONAL MOBILE TELECOM 2000. (IMT-2000)
INTERNATIONAL MOBILE TELECOM 2000. (IMT-2000) is an initiative of ITU that seeks to integrate the various satellites, terrestrial, fixed and mobile systems currently being deployed and developed under a single standard to promote global service capabilities and interoperability.
1.6 DEVELOPMENT AND INTRODUCTION OF THE GSM STANDARD
The chronological development of GSM standard is given below.
YEAR EVENTS/DECISIONS/ACHIVEMENTS
1982 CEPT (CONFERENCE EUROPEAN POSTS AND TELEGRAPHS) Decides to establish Grouped special mobile (the initial origin of the GSM) to develop a set of common standards for future pan European cellular mobile network.
1984 Establishment of three working parties (WP1-3) to define and describe the services offered in a GSM PLMN (GSM Public Land Mobile Network) the radio interface, transmission, signaling protocols, interfaces and network architecture.
1986 A so called permanent nucleus is established to continuously coordinate the work, which is intensely supported by industry delegates.
1987 Initial memorandum of understanding (MOU) signed by network operator organizations (representing 12 countries) with major objectives as:
* coordinating the introduction of the standard and time scales.
*Planning of service introduction
*Routing, billing, and tariff coordination.
1988/89 with the establishment of the European telecommunication
To Standards Institute (ETSI), the specification work was mooted to
1991/92 this international body.GSM becomes a technical committee within ETSI and splits up to into GSM groups 1-4, later called Special Mobile Groups (SMG) 1-4, which are technical sub Committees. GSM finally stands for Global system for Mobile Communications
1990 The GSM specifications for 900 MHz band are also applied to a Digital cellular system on the 1800 MHz band (DCS1800), a PCN application initiated in the United Kingdom.
1991 The GSM Recommendations comprise more than 130 single documents including more than 5000 pages.
1992 Official commercial launch of GSM service in Europe.
1993 The GSM- MOU has 62 members (signatories) in 39 countries worldwide.
1993 The end of 1993 shows one million subscribers to GSM networks, however more than 80% of them is to be found in Germany alone.
1993 First commercial services also start outside Europe: Australia, Hongkong.
The features and benefits expected in the new system were
Superior speech quality
Low terminal, operational, and service costs
A high level of security (confidentiality and fraud prevention)
International roaming
Support of low terminal hand portable terminals
A variety of new services and network facilities.