RADIATION & PROPAGATION - diversity

Diversity techniques for mobile wireless radio systems ,[object Object],[object Object],[object Object],AJAL.A.J Assistant Professor , ECE DEPARTMENT MET’S SCHOOL OF ENGINEERING - MALA BY SLIDES SHARED ON

Communication - Mobile Telephone Exchange Subscriber Line Inter-Exchange Junction Mobile Switching Centre ( MSC ) BSC BTS MS

HOW DO WE OVERCOME LIMITATIONS IMPOSED BY THE RADIO CHANNEL? • Flat Fading Countermeasures – Fade Margin – Diversity – Coding and Interleaving – Adaptive Techniques • Delay Spread Countermeasures – Equalization – Multicarrier – Spread Spectrum – Antenna Solutions 8C32810.104-Cimini-7/98

Cultural Dimensions UNITY IN DIVERSITY PERSONAL CORPORATE ETHNIC GENERATIONAL RELIGIOUS CLASS GENDER REGIONAL NATIONAL PROFESSIONAL / EDUCATIONAL

What is Diversity? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

DIVERSITY as far as mobile wireless radio systems are ,[object Object]

Common assumption: ,[object Object],[object Object]

How / when diversity is created ? ,[object Object],[object Object],Examples: RAKE receiver - - separates paths by delay [PATH DIVERSITY] Multi beam antenna - - separates paths by angle [ANGLE DIVERSITY]

Why the name rake receiver ? ,[object Object]

Multi-path Energy Capture ,[object Object],[object Object],[object Object]

Multipath ,[object Object],[object Object]

Rake Receiver – Multipath fading ,[object Object],[object Object],x(t) y(t) = a 0 x(t) y(t) = a 0 x(t)+a 1 x(t-d 1 ) y(t) = a 0 x(t)+a 1 x(t-d 1 )+a 2 x(t-d 2 )

RAKE Receiver: Basic Idea ,[object Object],[object Object],[object Object]

Overview of Rake Receiver ,[object Object],[object Object],[object Object]

RAKE Receiver Continued ,[object Object],[object Object]

Maximum Ratio Combining of Symbols ,[object Object],[object Object]

End Result of RAKE Receiver ,[object Object]

Another ways to create diversity: ?

Another way to create diversity: change the relative phases of the multi path signals ,[object Object],[object Object],[object Object],[object Object],[object Object]

Still other ways to generate diversity: ,[object Object]

Fading VS Diversity ,[object Object],[object Object],[object Object],[object Object],[object Object]

Introduction (cont’d) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Spatial diversity ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The following classes of diversity schemes can be identified: ,[object Object],[object Object],[object Object],[object Object],[object Object]

1] Space diversity ,[object Object],[object Object],[object Object],[object Object]

2] Polarization diversity ,[object Object],[object Object]

3] Frequency diversity ,[object Object],[object Object],[object Object],[object Object]

4] Time diversity ,[object Object]

Terrestrial microwave radio system with two antenna arrays configured for space-diversity

Diversity Combining ,[object Object],[object Object]

Spatial diversity (cont’d) ,[object Object],h 1 h 2 h 1 * h 2 *  y x

Combining schemes: ,[object Object],h 1 h 2 y x Monitor SNR Select branch

[object Object],[object Object],[object Object],h 1 h 2 x Comparator Channel estimator switching threshold

[object Object],[object Object],[object Object],[object Object]

What are all the needs of diversity techniques?? ,[object Object],[object Object]

CONCEPTS OF DIVERSITY BRANCH AND SIGNAL PATH

(a) Branch Construction method using frequency diversity

(b) Branch Construction method using Time diversity

COMBINING AND SWITCHNING METHODS

COMBINING AND SWITCHNING METHODS FOR COHERENT DETECTION FOR NON - COHERENT DETECTION

FOR COHERENT DETECTION ,[object Object],FOR NON-COHERENT DETECTION ,[object Object]

(a) Maximal ratio combining (MRC)

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

(b) Equal Gain Combining (EGC)

[object Object],[object Object]

For VHF, UHF and microwave wireless radio applications ,[object Object],[object Object]

(c) Selection or Switching Combining

[object Object],[object Object],[object Object]

SWITCHNING METHODS FIXED THERSHOLD VARIABLE THERSHOLD

(a) Switching Methods with Fixed threshold

[object Object],[object Object],[object Object],FIXED THERSHOLD

(b) Switching Methods with Variable threshold

[object Object],[object Object],[object Object],VARIABLE THERSHOLD

Conclusions ,[object Object],[object Object],[object Object]

[object Object],Mail: [email_address]

RADIATION & PROPAGATION - diversity

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