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 UNIVERSITY OF MAURITIUS

FACULTY OF ENGINEERING

SECOND SEMESTER EXAMINATIONSSECOND SEMESTER EXAMINATIONSSECOND SEMESTER EXAMINATIONSSECOND SEMESTER EXAMINATIONS 

MAY 2010MAY 2010MAY 2010MAY 2010

PROGRAMME BEng (Hons) Electronic & Communication Engineering

MODULE NAME Wireless Technologies

DATE Thursday

13 May 2010

MODULE CODE ELEC 4023Y(5)

TIME 09.30 – 12.30 Hrs DURATION 3 Hrs

NO. OFQUESTIONS SET

4 NO. OF QUESTIONSTO BE ATTEMPTED

4

INSTRUCTIONS TO CANDIDATES 

Answer ALL questions.

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WIRELESS TECHNOLOGIES – ELEC 4023Y(5) 

Question 1

(a) What is the function and features of a wireless repeater? [5 marks]

(b) Explain how the use of wireless repeaters reduces throughput. [3 marks]

(c) Differentiate between visual line of sight and RF line of sight. [5 marks]

(d) Explain what you understand by the term adjacent channel interference.Illustrate your answer with an appropriate diagram. [5 marks]

(e) Explain what is an Intentional Radiator.  [4 marks]

(f) An access point is transmitting at 50 mW. The signal loss between the accesspoint and the antenna is –1 dB, and the access point is using a 5 dBi antenna.Calculate the IR and the EIRP values.  [3 marks]

Question 2

(a) Write short notes on the following standards:(i) 802.11(ii) 802.11b(iii) 802.11g(iv) 802.11n [3 x 4 marks ]

(b) Explain what you understand by B/G mode (mixed mode).  [3 marks]

(c) Explain 802.11b Direct Sequence Modulation. Illustrate your answer with anexample. [6 marks]

(d) Explain 802.11b Scalability.  [4 marks]

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WIRELESS TECHNOLOGIES – ELEC 4023Y(5) 

Question 3 

(a) What are the advantages and disadvantages of FDMA with respect to TDMAor CDMA? [6 marks] 

(b) What are the three distinct states in the process of authentication andassociation? Elaborate on each of these. [9 marks] 

(c) Distinguish between Continuous Aware Mode and Power Save Polling.[5 marks]

(d) Explain briefly the steps followed by stations in order to pass traffic betweenpeers. [5 marks] 

Question 4

(a) Explain roaming. [3 marks] 

(b) Briefly explain how too much cell overlap may cause roaming problems.[3 marks]

(c) Briefly describe 3 methods can be used to fix a hidden node problem.[3 marks]

(d) Explain what you understand by the Near/Far Problem, and what can bedone to correct the problem.  [8 marks] 

(e) What devices cause RF Interference? [5 marks] 

(f) What is the purpose of Control Frames in wireless communications? Giveexamples of control frames. [3 marks] 

END OF QUESTION PAPER 

 /ph