# What is the relation between AWGN & Rayleigh fading chan

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#### almasbd

##### Newbie level 3
Channel

Hi all,

i m not clear about AWGN channel . most paper and book consider that
channel is Gaussian and it has zero mean and N0/2 noise spectral
desnsity for eatch side.
i just clear channel is random it has normal valriable(zero mean) and
noise

what is the meaning of two sided spectral density is it transmitter
side as well as receiver side noise level.

What is the relation between AWGN channel and rayleigh fading channel
?

could u possible to little bit implent what exactly that........if
possible give a example.

#### tiger_shark

##### Member level 1
Channel

AWGN and rayleigh?

AWGN effect is additive wheras rayleigh is multiplicative (that is why it fades some data).

AWGN means additive white gaussian noise. so the noise is assumed to be normally distributed with mean zero.

Now, imagin the random variable Z = X + j Y where X and Y are both normally distributted (gaussian) with zero mean. Then one can prove that

|z^2| = X^2 + Y2 has a Chi distribution and its square root :
|z| = sqrt( X^2 + Y2 ) has Rayleigh distribution. That is how you generate Rayleigh using 'randn' function in matlab.

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