NATIONAL OPEN UNIVERSITY OF NIGERIA

UNIVERSITY VILLAGE, PLOT 91, CASDASTRAL ZONE, NNAMDI AZIKIWE EXPRESS WAY, JABI, ABUJA.
FACULTY OF SCIENCES
APRIL 2019 EXAMINATION

COURSE CODE: CIT 755

COURSE CREDIT: 3

COURSE TITLE: WIRELESS COMMUNICATION I

TIME ALLOWED: 2½ HOURS

INSTRUCTION: ANSWER QUESTION ONE (1) AND ANY OTHER FOUR (4)  QUESTIONS

QUESTIONS

1a. The maximum dimension of an antenna is 1m and its operating frequency is  900 MHz, determine the far field distance for this antenna, outlining the steps involved in determining this distance.   (8 marks)

1b.Ordinarily, digital systems offer a number of benefits. Enumerate any four (4) of these benefits.   (4 marks)

1c. State the main role of a satellite television.  (2 marks)

1d. List the four (4) factors that affect small-scale fading in the radio propagation channels.   (4 marks)

1e. Briefly explain the following within the context of wireless communication:

1. Baby monitor
2. General Packet Radio Service       ) 2 marks each; 2x 2 = 4 marks      

 [Total =22 marks]

2a. Distinguish between the Frequency Division Multiple Access and Code Division Multiple Access using the following as the parameters of comparison:

1. Diversity
2. Modulation   ) 2 marks each; 2 x 3 = 6 marks         
3. Multiple-Access Interference

2b. Within the context of mobile radio channels, briefly mention and describe the three (3) mutually multiplicative propagation phenomena. (6 marks)                                [Total =12 marks]

3a. Enumerate four (4) common fading models employed in wireless communication.  (4 marks)

3b. Determine the modulation index of an FM signal having a carrier swing of 100 kHz if the modulating signal has a frequency of 8kHz?  (6marks)                                                                                   

3c. Write down two (2) common types of frequency modulation in wireless communication   (2 marks)

 [Total =12 marks]

4a. State the three (3) main mechanisms responsible for electromagnetic wave propagation.    (3 marks)

4b. Write short notes on the following notions:

1. Scattering
2. Microcell                                          ) 3 marks each; 3 x 3 = 9 marks
3. Code Division Multiple Access

 [Total =12 marks]

5a. Determine the system capacity of a cellular system which has 1001 radio channels available for handling traffic, cell area of 6 km² and the area of the entire system as   2100 km².    (8 marks)

5b. You have just been recruited as a Network Administrator in a national Engineering firm using wired technology. Based on your proficiency in   Wireless Communication, you are expected to encourage this firm to adopt the wireless technology rather than the existing wired technology. State four (4) good reasons which you would give in order to convince the firm to switch to the wireless technology.(4 marks)

[Total =12 marks]

6a. If a cellular system has a total bandwidth of 30 MHz and uses two 25 kHz  simplex channels to provide full duplex voice and control channels. If that system uses a nine-cell reuse pattern and 1 MHz of the total bandwidth allocated for control channels. Calculate:   

6ai. The total number of available channels;  (2 marks)

6a ii. The total number of control channels      (2 marks)

6b. Give a concise description of the following widespread notions in wireless communication:

1. Wireless Fidelity
2. Wireless Application Protocol            ) 2 marks each; 2 x 4 = 8 marks
3. Wireless Energy Transfer                                                 
4. Universal Mobile Telecommunications System

[Total =12 marks]