DIG 6206 Lecture 7 OFDM

________ occurs due to the gradual reduction of the transmitted signal's power as it propagates through space.

• Multipath

• Shadowing

• Pathloss

• Fading

________ carry frequency and phase synchronisation information for the receiver to be able to decode the data with the correct timing

• Continual Pilots

• Scattered Pilots

The positions of _____ vary from symbol to symbol in alternating and predictable pattern.

• Continual pilots

• Scattered pilots

The car stops at a red stop light and radio reception ceases. If one were to

select another station or move the car slightly forward, reception would be

restored. What is the cause of this effect?

• Doppler effect

• Gaussian Noise

• Fading

• Shadowing

Coded OFDM (COFDM) is a powerful combination of OFDM and __________.

• Frequency Modulation

• Time Division Multiplexing

• Error Correction Coding

• Phase Shift Keying

To avoid interference between adjacent carriers:

carriers placed such that each carrier spacing is equal to

• T (symbol duration)

• 1 / T

• Twice the symbol duration

OFDM is a ______ method with thousands of overlapping carriers which do not interfere because they are _________

• Single carrier, orthogonal

• Multi-carrier, phase shifter

• Multi-carrier, orthognal

The reason the overlapping frequencies do not interfere in OFDM is that the peak of each carrier coincides with the _______ of the adjacent carrier's tails.

• Side-band

• Null point

• Lowest point