4.2 concepts of diversity

1. CONCEPTS
OF
DIVERSITY

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3. Basic - Understanding
Dispersive
Channels

4. Diversity - Understanding
Dispersive
Channels

5. Diversity - Principle
• The principle of diversity is to ensure that the same
information reaches the receiver on a statistically
independent channels.

6. Diversity
• This is a technique implemented to improve the channel quality
and performance.
• This is achieved by placing the Tx signals in a statistically
independent channels.
• This reduces the over all fading of the received signals at the
receiver side.
• This technique mainly addresses the fading problems.

7. Correlation Coefficient
• Diversity is most efficient when the different
transmission channels carry independently faded
copies of the same signals.
• The correlation coefficient characterises the
correlation between signals on different diversity
branches .
• Correlation can be done on different parameters
such as complex part of the signal, phase relations
etc,
• Most important one is correlation between the
signal envelopes.

8. Lack of Correlation - Understanding
Dispersive
Channels

9. • The correlation coefficient is given by:
• Where x and y are the envelope of the signals.
• The signals are said to be “effectively” decorrelated if , ρ
is between a certain threshold value (typically 0.5 or
0.7)

10. Types of Diversity
• How to obtain the diversity in the signals ?
• Diversity are classified based on the fading methods.
•Small scale fading
• Microscopic diversity techniques are used.
•Large scale fading
• Macroscopic diversity techniques are used.