Digital Switching System(DSS) Model Question Paper-1

B.E Fifth Semester Examination, Dec-10/Jan-11

Model Set-1

On

Digital Switching System

1          a. Briefly explain the different network structures used in communication.  (8)

            b. Explain Frequency division multiplexing with respect to a suitable block diagram.                                                                                                          (8 Marks)

            c. What are various types of network structure.                                 (4 Marks)

2          a. Explain the working od distribution frame in strowger exchange. (8 Marks)

            b. Highlight the advantages and disadvantages of crossbar switch.  (6 Marks)

            c. Define:        i) Traffic          ii) Congestion              iii) Lost call system.

                                                                                                                        (6 Marks)

3          a. What is Grading? Describe various type of Gradings.                   (5 Marks)

            b. Explain in Brief different types of system function.                      (8 Marks)

            c. Deduce the total number of cross points to three stage switching network with N incoming and M outgoing trunks.                                                                      (7 Marks)

4          a. Derive second Erlang’s distribution formula.                                 (8 Marks)

            b. A group of 40 trunks provides a grade of service of 0.05 when offered 12E of traffic,

            i) How much is the GOS improved if one of extra trunk is added to the group?

            ii) How much does the GOS deteriorate if one trunk is out of service?

                                                                                                                        (6 Marks)

            c. Define the following terms:

                        i) Traffic Intensity       ii) Grade of service    

                        iii) Busy hour              iv) Blocking Network

                        v) Blocking probability                                                           (6 Marks)

5          a. Explain time-space-time-switch with suitable diagram.                  (8 Marks)

            b. Discuss the need for frame alignment in time division switching networks. Explain double ended unilateral and bilateral synchronization system. (12 Marks)

6          a. Explain the working of OS indicating the basic software architecture of a typical digital switching system.                                                                        (12 Marks)

            b. Explain the three modes of operation for call forwarding using simple floe diagram.                                                                                                       (8 Marks)

7                    a. Explain the organizational interface of a typical DSS central office. (10)

b. Explain the interface of digital switching central office.         (10 Marks)

8                    a. Explain the generic switch software with respect to a suitable block diagram

(10 Marks)

            b. Explain in brief the common characteristics of a digital Switching system.

                                                                                                                        (10 Marks)

                                               

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