Telecom lect 2
- 1. By: Muhammad Naveed Shaikh INSTRUCTED BY MUHAMMAD NAVEED SHAIKH Telecom Systems & Networks Lecture 1
- 2. By: Muhammad Naveed Shaikh Definition : Telecommunication • Communications at a distance • The transmission of signals over long distance, such as by telegraph, radio or television. • Telecommunication encompasses the electrical communication at a distance of voice, data, and image information
- 3. By: Muhammad Naveed Shaikh Applications of Telecommunications Business Telecommunications Telecommunications Architectures Electronic commu- nications system Electronic meeting systems Business process systems • Centralized • Distributed • Client/server • Interorganizational • Global • Electronic mail • Voice mail • Bulletin Board systems • Videotex • Fascimile • Public Information Service • Desktop Video conferencing • Decision room conferencing • Computer conferencing • Teleconferencing • Online transaction processing • Inquiry/Response • EDI / XML • Electronic Funds Transfer • Activity monitoring • Process control • Telecommuting
- 4. By: Muhammad Naveed Shaikh INTRODUCTORY TOPICS IN TELECOMMUNICATIONS End-Users • End-users, as the term tells us, provide the inputs to the network and are recipients of network outputs. • The end-user employs what is called an I/O, standing for input/ output (device).
- 5. By: Muhammad Naveed Shaikh Long Distance Network
- 6. By: Muhammad Naveed Shaikh Nodes & Connectivity • Nodes – End-users usually connect to nodes. – A node is a point or junction in a transmission system where lines and trunks meet. – A node usually carries out a switching function. • Connectivity – connects an end-user to a node, and from there possibly through other nodes to some final end-user destination with which the initiating end-user wants to communicate.
- 7. By: Muhammad Naveed Shaikh End users, Nodes & Connectivity
- 8. By: Muhammad Naveed Shaikh • The IEEE (Ref. 2) defines a connection as “an association of channels, switching systems, and other functional units set up to provide means for a transfer of information between two or more points in a telecommunications network.”
- 9. By: Muhammad Naveed Shaikh Stages to telephone call • There are three sequential stages to a telephone call: 1. Call setup; 2. Information exchange; and 3. Call take down.
- 10. By: Muhammad Naveed Shaikh • Call setup is the stage where a circuit is established and activated. The setup is facilitated by signaling, • It is initiated by the calling subscriber (user) going off- hook. • “the action of taking the telephone instrument out of its cradle.” • Two little knobs in the cradle pop up, pushed by a spring action, causing an electrical closure.
- 11. By: Muhammad Naveed Shaikh • If we turn a light on, we have an electrical closure allowing electrical current to pass. • The same thing happens with our telephone set; it now passes current. • The current source is a “battery” that resides at the local serving switch. • It is connected by the subscriber loop. • This is just a pair of copper wires connecting the battery and switch out to the subscriber premises and then to the subscriber instrument.
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- 13. By: Muhammad Naveed Shaikh • Suppose now that a subscriber wishes to call another telephone subscriber outside the local serving area of her/ his switch. • The call setup will be similar as before, except that at the calling subscriber serving switch the call will be connected to an outgoing trunk. • Trunks are transmission pathways that interconnect switches. • To repeat: subscriber loops connect end-users (subscriber) to a local serving switch; trunks interconnect exchanges or switches.
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- 15. By: Muhammad Naveed Shaikh Telephone Numbering and Routing • Every subscriber in the world is identified by a number, which is geographically tied to a physical location. This is the telephone number. The telephone number, as we used it here, is seven digits long. For example: 234 − 5678 • The last four digits identify the subscriber line; the first three digits (i.e., 234) identify • the serving switch (or exchange).
- 16. By: Muhammad Naveed Shaikh Telephone Numbering and Routing
- 17. By: Muhammad Naveed Shaikh • Routing through a tandem switch is an important economic expedient for a telephone company or administration. • We could call a tandem switch a traffic concentrator.
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- 19. By: Muhammad Naveed Shaikh • Trunks can be configured for either one- way or two-way operation. A third option is a hybrid,
- 20. By: Muhammad Naveed Shaikh