Anna University Chennai 2009-8th Sem B.E Electronics & Tele-Communication Engineering ECE, ester, EC 1451 – MOBILE COMMUNICATION, /E . - Question Paper

B. E. / B. Tech. DEGREE EXAMINATION, MAY/JUNE 2009.

Eighth Semester
(Regulation 2004)

Electronics and Communication Engineering
EC 1451 – MOBILE COMMUNICATION
(Common to B.E. (Part – Time) 7th Semester Regulation 2005)

Time : 3 hours Maximum : 100 marks
ans ALL ques..

PART A – (10 X two = 20 marks)
1. Define coherence bandwith.
2. Define grade of service?
3. What is meant by soft handoff? elaborate the advantages does it have?
4. What are piconets?
5. What is air interference.
6. Draw the frame structure of GSM.
7. What are the advantages of the two ray ground reflection model in the analysis of path loss?
8. What is Doppler shift?
9. Explain adjkacent channel interface.
10. In an FDMA system the total spectrum bandwidth is 12.5 mHZ. every channel is of 30 kHZ and the guard band is 10 k?HZ. obtain the total number of channels available in the system.

PART B – (5 X 16 = 80 marks)]
11. (a) (i) discuss the different methods of increasing the capacity of users in cellular system.
(ii) Show that the frequency reuse factor for a celluar system is provided by k/S, where k is the avg. number of channels per call and S is the total no of channels available.
(OR)
(b) (i) discuss the procedure for making a call from a mobile to a different mobile.
(ii) discuss how the interference ranging from the base and the mobile transmission is decreased in PCS.
12. (a) (i) discuss how the diffraction affects the signal propagation using knife edge diffraction model.
(ii) discuss the propagation of signal in outdoor using Durkin’s Model.
(OR)
(b) elaborate the kinds of small scale fading. discuss every fading effects in detail.
13. (a) (i) discuss the generation and detection of GMSK signal.
(ii) explain the nonlinear equalization methods using Maximum likelihood sequence estimation (MLSE).
(OR)
(b) (i) elaborate the benefits of RAKE receiver?
(ii) Draw the constellation points of 16-QAM signal and derive the avg. probability fault.
14. (a) (i) discuss the LPC vocoder and determine the predictive coefficients.
(ii) discuss the working of GSM codec with block diagram.
(OR)
(b) (i) Draw the frame structure of TDMA and derive its efficiency.
(ii) Derive the formula to compute the number of users in a CDMA cellular system.

15. (a) (i) elaborate the advantages and disadvantages of WLL.
(ii) Draw the functional block of DECT systems and discuss its working principle.
(OR)
(b) (i) discuss the forward and reverse channel parameters in IS-95 CDMA.
(ii) discuss the GSM system architecture and provide its protocol specifications.

Earning:   Approval pending.