JNTU III B.Tech Supplimentary Examinations, Aug/Sep 2008
Telecommunication Switching Systems And Networks
( Common to Electronics & Communication Engineering and Electronics &
1. (a) List all the event sequences that occur for call setup , call maintenance and call termination in a telephone exchange environment for
i. Local call
ii. Trunk call.
(b) Estimate the number of the cross points required to design an exchange that supports 500 users on a non blocking basis and 50 transit , outgoing or incoming calls simultaneously.
2. (a) Explain the operation of input controlled and output controlled time division
space switch with the help neat sketches?
(b) A PABX is designed using an output-controlled digital time division space switch for supporting 128 subscribers. The transmission between the subscribers and the exchange is analog. On an average, 25 % of the subscribers are active simultaneously, compare the cost of output- controlled and memory controlled configurations.
3. (a) What are the major components of telecommunication network? Explain in detail about subscriber loop systems.
(b) An exchange uses a -40 V battery to derive subscriber lines. A resistance of 250 is placed in series with the battery to protect it from short circuits. The subscribers are required to use a standard telephone set which offers a d.c. resistance of 50. The microphone requires 23mA for proper functioning. Determine the farthest distance from the exchange at which a subscriber can be located if 26 AWG conductor is used.
4. (a) Define overload traffic and explain different ways of handling it.
(b) Over a 20-minute observation interval, 40 subscribers initiate calls. Total duration of the calls is 4800 seconds. Calculate the load offered to the network by the subscribers and the average subscriber traffic.
5. (a) Explain the functions and features of data communication network components.
(b) Discuss peer to peer client / server networks.
6. (a) Define open system interconnection. Name and explain functions of each of the Layers of the OSI model.
(b) Describe the operation of star, bus ring and hybrid Network topologies
7. (a) What are the principles of ISDN. Describe the evolution of ISDN.
(b) Explain the architecture of ISDN.
8. (a) Explain the terms Section, Line & Path related to SONET
(b) Explain Device- Layer relationship in SONET
(c) What is the Relationship between STS & STM signals?