DATA COMPRESSION AND ENCRYPTION (DCE) DECEMBER 2009 [ELECTIVE] ELECTRONICS AND TELECOMMUNICATION SEMESTER 7

DATA COMPRESSION AND ENCRYPTION (DCE) DECEMBER 2009 [ELECTIVE]  ELECTRONICS AND TELECOMMUNICATION SEMESTER 7

Con.5900-09.                                                                                         SP-6632

                                                      (3 Hours)                               [Total Marks:-100]

N.B:- (1) Question No.1 is compulsory.
          (2) Attempt any four questions out of remaining six questions.

1. (a) Compare lossy and lossless compression. [5 Marks]
    (b) Explain relative encoding for Fax and Telemetry. [5 Marks]
    (c) Compare conventional and public key encryption. [5 Marks]
    (d) Explain JPEG compression method for Image Compression. [5 Marks]

2. (a) What is data compression? Explain parameters to measure the performance of data
          compression techniques. [10 Marks]
    (b) Encode the following input stream using with and without move to front coding and compare
          the average code word length for both coding methods. Assume alphabets
          A=(a, b, c, d, m, n, o, p). Input stream 'C' = "abcddcbamnopponm". [10 Marks]

3. (a) Explain the Kraft Macmillan Inequality Criterion for variable size codes. Explain Ternary
         and Canonical Huffman codes. [10 Marks]
     (b) What is idea behind context based PPM algorithm? State the principle and how it can
           achieve saving in terms of rates. Explain PPM method for text compression. [10 Marks]

4. (a) Explain the concepts of static and dynamic dictionary. Show the encoding with example
         using LZ 77. [10 Marks]
    (b) A source and its letters form an alphabet  A=with probabilities
         P = {0.15, 0.06, 0.24, 0.05, 0.5} respectively. Calculate:- [10 Marks]
            (i) Standard Huffman code.
           (ii) Minimum Variance Huffman code.
          (iii) Variance in both codes and compare them.
          (iv) Average length and Redundancy of both the codes.
          (v) Draw the binary code tree for both the codes and also prove that they are prefix codes.

5. (a) Explain various approaches for compassing images of various types. [10 Marks]
    (b) Describe the features of video compression as compared to image compression. Explain
          the MPEG industry standard for video compression. [10 Marks]  

6. (a) Explain hybrid speech coders. In speech coding how the quality of speech can be improved
         by using CELP and other sinusoidal coders over LPC. [10 Marks] 
    (b) Explain how key management and distribution is a problem and how it is solved. Explain the
          various key management techniques. [10 Marks]

7. Write short notes on the following (any two):- [20 Marks]
     (a) RSA algorithm
     (b) HMAC design objectives and structures
     (c) Data Encryption Standard Algorithms.