Question (a) A CRC is constructed to generate a 4-bit FCS for an 11-bit message. The divisor polynomial is X⁴ + X³ + 1

(i) Encode the data bit sequence 00111011001 using polynomial division and give the code word.

(ii) Assume that 7^th MSB in the data bit sequence above gets corrupted during transmission, show how the detection algorithm detects the error.

Question (b) What is the difference between Synchronous TDM and Statistical TDM?

(c) In respect to HDLC:

(i) State the three data transfer modes of operation.
(ii) Give the structure of generic HDLC frame.
(iii) Explain why HDLC uses 'bit stuffing'.

Question (d) With the aid of sketches, explain the difference between the following two transmission modes used with optical fibre:

(i) Graded-index Multi-mode and

(ii) Mono-mode.