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Modeling of Rayleigh Fading Channel

Started by zohreh January 4, 2008
Hello Dear,

I'm looking for a accurate and simple way to model Rayleigh distributed
sequences for modeling a wireless communication channel. I've already made
a model by filtering white noise sequence but it doesn't work well and it
is not accurate.

Thanks.
Rayleigh distribution can be generated from uniform distribution
using the following formula.

Z   = a + sqrt(b*log[1 - U]); % log is natural log.

where U is uniformly distributed random number in the range
[0 <= U < 1]; In matlab rand function can be used to generate
pseudo random numbers. In hardware we use LFSR to generate
pseudo random numbers.

mean of generated rayleigh distribution is given by

m   = a + sqrt(pi*b/4);        ...... eq 2

and variance is given by 

var = b*(4-pi)/4;              ...... eq 3

you can reverse calculate parameters a and b using eq 2 and 3, 
based on the desired mean and variance of rayleigh distribution.

Regards
Bharat Pathak
Founder and CEO
Arithos Designs
www.arithos.com


>Hello Dear, > >I'm looking for a accurate and simple way to model Rayleigh distributed >sequences for modeling a wireless communication channel. I've already
made
>a model by filtering white noise sequence but it doesn't work well and
it
>is not accurate. > >Thanks. >
On Jan 4, 4:32 pm, "zohreh" <zand2...@gmail.com> wrote:
> Hello Dear, > > I'm looking for a accurate and simple way to model Rayleigh distributed > sequences for modeling a wireless communication channel. I've already made > a model by filtering white noise sequence but it doesn't work well and it > is not accurate. > > Thanks.
If you have Matlab's Communications Toolbox, you can use its Rayleigh channel function. Darol Klawetter
Thanks a lot. Now I have another problem. How the Doppler spread can affect
the mean and variance of that? I mean how I can generate Rayleigh sequence
by given Doppler spread and the variance (from Jakes's model)?

 >Rayleigh distribution can be generated from uniform distribution
>using the following formula. > >Z = a + sqrt(b*log[1 - U]); % log is natural log. > >where U is uniformly distributed random number in the range >[0 <= U < 1]; In matlab rand function can be used to generate >pseudo random numbers. In hardware we use LFSR to generate >pseudo random numbers. > >mean of generated rayleigh distribution is given by > >m = a + sqrt(pi*b/4); ...... eq 2 > >and variance is given by > >var = b*(4-pi)/4; ...... eq 3 > >you can reverse calculate parameters a and b using eq 2 and 3, >based on the desired mean and variance of rayleigh distribution. > >Regards >Bharat Pathak >Founder and CEO >Arithos Designs >www.arithos.com > > >>Hello Dear, >> >>I'm looking for a accurate and simple way to model Rayleigh distributed >>sequences for modeling a wireless communication channel. I've already >made >>a model by filtering white noise sequence but it doesn't work well and >it >>is not accurate. >> >>Thanks. >> >