NATIONAL OPEN UNIVERSITY OF NIGERIA
14/16 AHMADU BELLO WAY, VICTORIA ISLAND, LAGOS
SCHOOL OF SCIENCE AND TECHNOLOGY
MARCH/APRIL 2014 EXAMINATION
COURSE CODE: CIT 755
COURSE TITLE: WIRELESS COMMUNICATION I
TIME ALLOWED: 21/2 HOURS
INSTRUCTION: ANSWER ANY FIVE (5) QUESTIONS. EACH QUESTION CARRIES 14 MARKS
Instruction: Answer any five (5) questions. Each question carries 14 marks
1. (a) What is the difference between a Local Area Network (LAN) and a Metropolitan Area
Network (4 marks)
(b) List and explain the classifications of wireless data networks (10 marks)
2. (a) Define Fixed channel assignment (2 marks)
(b) Describe 3 techniques that can be used to combine customers on to fixed channel
radio links. Illustrate your description with diagrams (12 marks)
3. (a) What do you understand by the term Channel Model (2 marks)
(b) Differentiate between wired channels and radio or wireless channel (4 marks)
(c) State and explain four techniques used to mitigate RF multipath problems (8 marks)
4. (a) Briefly explain the concept of diversity for fading channels (2 marks)
(b) Describe the following classes of diversity schemes (12 marks)
(i) Time Diversity (ii) Frequency Diversity (iii) Multiuser Diversity (iv) Space Diversity
5. (a) Define Amplitude modulation, illustrate your answer with diagrams (8 marks)
(b) List four types of Amplitude modulation techniques (6 marks)
6. (a) The antenna current of an AM transmitter is 8 A if only the carrier is sent, but it
increases to 8.93 A if the carrier is modulated by a single sinusoidal wave. Determine
the percentage modulation. Also find the antenna current if the percent of modulation
changes to 0.8.
(b) State three problems with conventional AM transmission
7. (a) Define Rayleigh Fading with the aid of a diagram (5 marks)
(b) Describe the following: (9 marks)
(i) Trellis Coded Modulation
(ii) Wavelet Modulation
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