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Published byGordon Griffith Modified over 9 years ago
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Rafael C Lavrado
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Fading Channels Alternative Representation PAM Analysis QAM Analysis Conclusion
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h(t) x(t) n(t) y(t) y(t)= x(t) + n(t)
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h(t) x(t) n(t) y(t) y(t)= αx(t) + n(t)
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Is a Random Variable Mean Square Value Ω = PDF dependent on the nature of the radio propagation environment
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As the carrier is attenuated by α, the signal power is attenuated by And then we will define the instantaneous SNR per bit by And the average SNR by
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Expected value of the probability of error taken over the RV α
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Rayleigh ◦ Mobile Systems with no LOS path between the transmitter and receiver Nakagami-m(Rice) ◦ Propagation path consist of one strong direct LOS Nakagami-q(Hoyt) ◦ Satellite Link subject to strong ionospheric scintillation
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Log Normal ◦ Caused by trees, buildings- Urban Nakagami-m ◦ Best fit to indoor mobile
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PDF In terms of SNR MGF
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General Expression For M=2
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Substituting for If we use the classical representation of the Q function we going to face some difficulties.
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Classical representation Alternative Representation Infinite Limit Variable in the Limit
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Remember
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: For the Rayleigh Fading channel
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General Expression For 4-QAM
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Substituting for So now, we need to calculate the integral for Q square
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Alternative representation for Q square
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So, = And, = Thus for
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The alternative form of Q-Function can help evaluate the error probability in Fading channels.
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