Information Theory and Coding - Dec 2016

Information Technology (Semester 4)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks. 1(a) State properties of information? Explain types of Entropy, also derive expression for entropy.(10 marks) 1(a) What is Entropy? What are its types?(4 marks) 1(b) What is compression? Compare different type of compression with example?(10 marks) 1(b) Compare Lossy and Lossless compression.(4 marks) 1(c) Write a note on convolution code.(4 marks) 1(d) State Fermat's little theorem and its applications.(4 marks) 1(e) Explain cyclic codes.(4 marks) 2(a) Explain various error control strategies in brief.(10 marks) 2(a) What do you mean by symmetric key cryptography? Explain DES in detail.(10 marks) 2(b) Explain the following terms with example:
i) Hamming distance,
ii) Hamming weight,
iii) Syndrome,
iv) Linear code properties,
v) Code rate.(10 marks) 2(b) The generator polynomial for a (7, 4) cyclic code is given by G(D)= 1+D+D³. Compute all systematic codewords.(10 marks) 3(a) Explain LZW compression algorithm with example.(10 marks)

solve any one question from Q.3(a)(i) & Q3(a)(ii).

3(a)(i) Explain LZW compression technique with example(10 marks) 3(a)(ii) What is cyclic code? How it is generated? For a (7,4) cycle code, find out the generator matrix if G(D)=1+D+D^3(10 marks) 3(b) State Chinese Remainder theorem. Using it solve for X.
X=1 MOD 2
X=2 MOD3
X=2 MOD 5(10 marks)

solve any one question from Q.3(b)(i) & Q3(b)(ii).

3(b)(i) Explain Huffman encoding techinque. Encode the data pattern "accabbcdaad" using Huffman technique(10 marks) 3(b)(ii) Name the source coding techniques used in the following types of files & classify them as lossy or lossles:
.zip
.jpg
.mpg
.bmp
.gif(10 marks) 4(a) Consider the symbols {1,1,1,1,1,1,1,2,2,2,2,2,2,3,3,3,3,3,4,4,4,4,5,5,5,6,6,7}
i) Find efficient fixed length code.
ii) Find Huffman code
iii) Compare 2 codes.(10 marks)

solve any one question from Q.4(a)(i) & Q4(a)(ii).

4(a)(i) Define generator and parity check matrices of a (7,4) linear block code. Explain how to generate a linear block code using G-matrix. Explain with an example.(10 marks) 4(a)(ii) Explain Golay code in detail with example.(10 marks) 4(b) Explain Modular arithmetic with example.(5 marks)

solve any one question from Q.4(b)(i) & Q4(b)(ii).

4(b)(i) Explain convolution code in brief.(10 marks) 4(b)(ii) Which of the following (x) values guarantees that a single bit error is caught? In each case what is the error that cannot be caught? (i) x+1 (ii) x^3(10 marks) 4(c) Compare MD5 and SHA-1(5 marks) 5(a) Write short note on random number generation and state when is it needed.(10 marks) 5(a) Explain Diffie - Hellman algorithm. Which atttac, is it vulnerable to?(10 marks) 5(b) Describe Chinese Remainder Theorem and its applications(10 marks) 5(b) Explain the idea of Message Digest 5 (MD 5)(5 marks) 5(c) Explain speech compression.(5 marks)

Write a short note any two Q6.(a,b,c,d)

6(a) RSA(5 marks) 6(b) RLE(5 marks) 6(c) Channel Capacity(5 marks) 6(d) Data Encryption statndard (DES)(5 marks)