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ClassNotes7 - ECE595 Wireless Communications Lecture 7...

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ECE595 Wireless Communications Lecture 7 Spring 2009 [Diversity] Goal : Improve signal quality by providing alternatives for mitigating fading. Different types: Space ± RX TX Time Frequency Polarization This RX space diversity : putting multiple antennas at uncorrelated distance in the receiver Microscopic diversity: mitigate small-scale fading. Macroscopic diversity: mitigate large-scale fading.
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2 Lecture 7 [Microscopic diversity] Instantaneous γ i = SNR i = | ch | 2 P T N R , r ( t ) : | ch ( t ) | u ( t ) : TX baseband linear combiner N R : receiver noise power P T : TX power P T = E [ u 2 ( t )]
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Wireless Communications 3 Received signal at the output of the combiner is M X i =1 α i r i e i u ( t ) | {z } signal + M X i =1 α i n i , n i : RX noise at the i th branch Then the received SNR is γ Σ = Total instantaneous SNR = P T | M i =1 α i e i r i | 2 N R M i =1 | α i | 2 1) Selection Combining: γ Σ : maximum SNR i is chosen. The cumulative distribution function (cdf) of
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This note was uploaded on 10/07/2009 for the course ECE 595 taught by Professor Sen during the Spring '07 term at New Mexico.

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ClassNotes7 - ECE595 Wireless Communications Lecture 7...

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