ID.No./Seat No.

MEHRAN UNIVERSITY OF ENGINEERING AND TECHNOLOGY,JAMSHORO.

FIRST TERM FINAL YEAR (7TH TERM) B.E.(ELECTRONIC) REGULAR EXAMINATION 2010 OF 07-BATCH.

Dated: 17-05-2010. Time Allowed: 03 Hours. Max.Marks-80. NOTE. ATTEMPT ANY FIVE QUESTIONS.

Q.No. Marks

01. Answer the following:1. What is a protocol?2. Define channel capacity.3. What is attenuation?4. Why are the wires twisted in twisted pair copper wire?5. Define flow and error control.6. What is echo cancellation?7. Why is multiplexing so cost effective?8. How is interfacing avoided by using frequency division

multiplexing?9. What is the relationship between the bandwidth of a signal before

and after it has been encoded using spread spectrum?10. What is CDMA?11. Why is it useful to have more than one possible path through a

network for each pair of station?12. How does ATM differ from frame relay?13. Why is a statistical time division multiplexer more efficient than a

synchronous time division multiplexer?14. List the layer of the OSI model.15. Distinguish between the baseband and broad band transmission.16. What are the differences between parallel and serial ransmission?

[16]

02 (a) Describe Open system Interconnection model for computer communication architecture. Describe the functions performed at each layer.

[08]

(b) What are network protocols? Why are they necessary? Describe the layered architecture of TCP/IP protocol suit in detail.

[08]

03 (a) How does NRZ-L differ from NRZ-I? [08]

(b) For Block coding, explain the steps in transformation. [08]

04. How does guided media differ from unguided media, also explain the three major classes of guided media?

[16]

Cont’d on P/-2….

COMPUTER COMMUNICATION & NETWORKING

( - 2 - )

05 (a) Explain the reason resulting lack of synchronization and discuss self synchronization to mitigate the problem incured.

[08]

(b) 1. Suppose that a sender and receiver use asynchronous transmission and agree not to use any stop elements could this work? If so, explain any necessary conditions.

2. Would you expect that the inclusion of a parity bit with each character would change the probability of receiving a correct message?

[08]

06 (a) Discuss the important characteristic of interface between the data terminal equipment and data communication equipment.

[06]

(b) List and briefly define some of the requirements for effective communication over a data link.

[05]

(c) Ten 9600-bps lines are to be multiplexed using TDM. Ignoring overhead bits in the TDM frame, what is the total capacity required for synchronous TDM? Assuming that we wish to limit average link utilization of 0.8 and assuming that each link is busy 50% of the time, what is the capacity required for statistical TDM?

[05]

07 (a) Design a stop and wait protocol and also write an algorithm for sender and receiver site for stop and wait protocol.

[10]

(b) 1. Assume that in a stop and wait ARQ system the bandwidth of the line is 1 Mbps and 1 bit takes 20 ms to make a round trip. What is the bandwidth delay product? If the system data frames are 1000 bits in length. What is the utilization percentage of the link?

2. What is the utilization percentage of the link in part (1) if we have a protocol that can send up to 15 frames before stopping and worrying about the acknowledgements?

[06]

08 (a) Discuss in detail the two quite different technologies used in wide area switched networks.

[06]

(b) 1. What is the difference between in-channel and common channel signaling?

2. Draw a flow chart showing the call establishment using virtual paths.

[04]

(c) Consider a simple telephone network consisting of two end offices and one intermediate switch with a1-MHz full duplex trunk between each end office and the intermediate switch. The average telephone is used to make four calls per 8-hour workday, with mean call duration of six minutes. Ten percent of the calls are long distance, What is the maximum number of telephones an end office can support?

[06]

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