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SPPU Electronics and Telecom Engineering (Semester 6)
Information Theory and Coding Techniques
June 2015
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

Answer any one question from Q1 and Q2
1 (a) Design a Shannon-Fano code for a source generating 5 different messages with probabilities 0.45, 0.3, 0.15, 0.05, 0.05. Find the coding efficiency.
7 M
1 (b) What are interleaved codes? Explain with suitable example.
7 M
1 (c) Write the procedure for decoding a cyclic code.
6 M

2 (a) What is Run length encoding? Explain how it is used in bitmap file formats.
7 M
2 (b) What are single parity check codes? Write about the decoding performance of these codes.
7 M
2 (c) What is CRC code? Explain how are they generated?
6 M

Answer any one question from Q3 and Q4
3 (a) Find the generator polynomial for (7, 4) BCH code. Use primitive polynomial x3+x+1.
10 M
3 (b) What are RS-codes? Write features & applications of Rs. Codes.
6 M

4 (a) The received code polynomial for a (7, 4) BCH code is r(x)=x6+x4+x3+x2. Find the corrected codeword polynomial if single error has occured.
8 M
4 (b) What are cyclic hamming codes? Give one example of cyclic hamming code.
4 M
4 (c) Explain stop-and-wait ARQ.
4 M

Answer any one question from Q5 and Q6
5 (a) Draw state diagram for following convolutional encoder.

6 M
5 (b) Explain with suitable example generator polynomial description of convolutional codes.
8 M
5 (c) Write a short note on Turbo codes.
4 M

6 (a) For the following convolutional encoder, find the coded output if input message is 10110000.

8 M
6 (b) What is sequential decoding? Explain in brief.
6 M
6 (c) Write a short note on LDPC codes.
4 M

Answer any one question from Q7 and Q8
7 (a) Explain how the goals of the communication system designer are conflicting.
6 M
7 (b) What is bandwidth efficiency plane? Explain different regions in the plane.
6 M
7 (c) Write Ungerboeck's TCM design rules.
4 M

8 (a) What is error probability plane? Indicate various trade-offs on this lane.
6 M
8 (b) What is coding gain inTCM encoder? How it is calculated?
6 M
8 (c) What are typical design specifications of communication system? What techniques are used when
i) Power is limited
ii) Bandwidth is limited
4 M

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