VOCATIONAL TRAINING - BHARAT SANCHAR NIGAM LIMITED
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STUDY OF TRENDS TECHNOLOGIES IN COMMUNICATION AND NETWORKING
Bharat Sanchar Nigam Ltd. formed on 1 st October ‘2000, is one of the largest & leading public sector units providing comprehensive range of telecom services in India.
Apart from vast network expansions, especial emphasis has given for introducing latest technologies and new services like I-NET, INTERNET, ISDN (INTEGRATED SERVICES DIGITAL NETWORK), IN (INTELLIGENT NETWORK), GSM and WLL (WIRELESS IN LOCAL LOOP) services etc
WIRELESS IN LOCAL LOOP (WLL) MOBILE
WLL is a communication system that connects customers to the Public Switch Telephone
Network (PSTN) using radio frequency signals as substitutes of conventional wires for all
part of connection between the subscribers and the telephone exchange.
It works on CDMA technique.
The radio technology is able to provide same quality of services as that provided by the wires line.
WLL is based on CDMA technique and is entirely different from GSM. The system for WLL services can be divided in to following parts:-
BSC (Base Switching Centre):- It provides links between BTS & BSM; it consists of different processors, in BSNL it is of SUN Polaris of LG Company.
BTS (Base Transreceiver System):- As it is clear from its name it transmits as well as receive signal, it works as an amplifier (router) to overcome the loss in signal in transmission.
BSM (Base Station Management):- It controls and manages the WLL services. It can troubleshoot the problem; add new users as well as capable to block service given to user. It is basically a computer system, which manages the whole process of WLL service.
CODE DIVISION MULTIPLE ACCESS (CDMA):
CONCEPT OF MULTIPLE ACCESSES:
- Multiple access system allows a large number of
users to share a common pool of radio telephone circuits, like sharing of trunked radio
facility. Multiple access radio has similarity to the LAN in which the common channel is
available to all users. The circuits are demands assigned i.e. assigned on demand
first-cum-first-served basis. The provision of access to the radio circuits methods of
multiple accesses are:
CDMA: - Where large number of transmission are combined on the same channel
at the same time and separated by the codes.
FDMA (Frequency Division Multiple Access):- Where individual transmission
separated by each other by the time
The GSM Association is a unique organization, with a truly global reach, offering a full range of business and technical services to its members
GSM divides the frequency bands into multiple channels so that more than one user can place a call through a tower at the same time;
Global system for mobile communication (GSM) is a globally accepted standard for digital cellular communication. GSM is the name of a standardization group established in 1982 to create a common European mobile telephone standard that would formulae the specifications for a pan-European mobile cellular radio system operating at 900 MHz. It is estimated that many country outside of Europe will join the GSM partnership.