Question:

a) Describe the following two approaches used towards wireless frequency regulation.

i. Regulated Band
ii. Unlicensed Band

b) An antenna is an electrical conductor or system of conductors to send and receive radio signals. Describe the omni-directional and the directional antennas.

c) Radiations after leaving an antenna are propagated by using one of the three modes of propagation.

i. List down and explain the different signal propagation behaviours that radio waves exhibit.

ii. Which technique is used for cellular phone communication, submarine communication and amateur radio?

iii. Describe two transmission effects that affect the technique used for cellular phone communication you presented in section ii above.

d) In wireless systems, just like wired systems, the users of channels need special mechanisms to avoid interference and collisions.

Describe the following three common mechanisms.

i. Frequency Division Multiple Access
ii. Code Division Multiple Access
iii. Time Division Multiple Access