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Nirav Shah · Guest

Hi All,
I was wondering of anyone of you have tried using the function rayleighchan in MATLAB.
as it is a channel function I would expact it to generate uncorrelated channel everytime.
But surprizingly it generates identical channel realization.
So If I have two simulations.. I have identical channel for both of them.
I tried using rand('state',xx) & gave different state for initialization.
But i felt that seed to generate random numbers is hardcoded inside the subroutine.

Help says,

To generate a particular path gain hk, the function performs these steps:
a.. Generates white Gaussian noise
b.. Passes the noise through a filter whose power spectrum corresponds to the Jakes Doppler spectrum
c.. Interpolates values so that the sample period is consistent with that of the signal
d.. Adjusts accordingly to obtain the correct average path gain

But they don't say that this white gaussian noise has constant seed everytime .. . !

Has anyone faced this problem?
or know the solution to it?
I am doing something wrong?

Nirav Shah · Guest

Thanks Jerry.

I will make sure to post in text format next time

Regards
Nirav

"Jerry Avins" <jya@ieee.org> wrote in message
news:r7ednQn4S539gBPenZ2dnUVZ_sudnZ2d@rcn.net...

Jerry Avins · Guest

Nirav Shah wrote this mostly content-free HTML post:

This is a multi-part message in MIME format.

------=_NextPart_000_001E_01C5F5CC.4C393C00
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

Hi All,
I was wondering of anyone of you have tried using the function =
rayleighchan in MATLAB.=20
as it is a channel function I would expact it to generate uncorrelated =
channel everytime.
But surprizingly it generates identical channel realization.=20
So If I have two simulations.. I have identical channel for both of =
them.=20
I tried using rand('state',xx) & gave different state for =
initialization.
But i felt that seed to generate random numbers is hardcoded inside the =
subroutine.=20

Help says,

To generate a particular path gain hk, the function performs these =
steps:
a.. Generates white Gaussian noise
b.. Passes the noise through a filter whose power spectrum corresponds =
to the Jakes Doppler spectrum
c.. Interpolates values so that the sample period is consistent with =
that of the signal
d.. Adjusts accordingly to obtain the correct average path gain

But they don't say that this white gaussian noise has constant seed =
everytime .. . !

Has anyone faced this problem?
or know the solution to it?
I am doing something wrong?

------=_NextPart_000_001E_01C5F5CC.4C393C00
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charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

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<META http-equiv=3DContent-Type content=3D"text/html; =
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<BODY>
<DIV><FONT face=3DArial size=3D2>Hi All,</FONT></DIV>

<DIV><FONT face=3DArial size=3D2>I was wondering of anyone of you have =
tried using=20
the function rayleighchan in MATLAB. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>as it is a channel function I would =
expact it to=20
generate uncorrelated channel everytime.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>But surprizingly it generates identical =
channel=20
realization. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>So If I have two simulations.. I have =
identical=20
channel for both of them. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>I tried using rand('state',xx) & =
gave different=20
state for initialization.</FONT></DIV>

<DIV><FONT face=3DArial size=3D2>But i felt that seed to generate random =
numbers=20
is hardcoded inside the subroutine. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Help says,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>

<DIV><FONT face=3DArial size=3D2>To generate a particular path gain hk, =
the function=20
performs these steps:</FONT></DIV>
<UL>
<LI><FONT face=3DArial size=3D2>Generates white Gaussian =
noise</FONT></LI>
<LI><FONT face=3DArial size=3D2>Passes the noise through a filter =
whose power=20
spectrum corresponds to the Jakes Doppler spectrum</FONT></LI>
<LI><FONT face=3DArial size=3D2>Interpolates values so that the sample =
period is=20
consistent with that of the signal</FONT></LI>
<LI><FONT face=3DArial size=3D2>Adjusts accordingly to obtain the =
correct average=20
path gain</FONT></LI></UL>

<DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial =
size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>But they don't say that this white =
gaussian noise=20
has constant seed everytime .. . !</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Has anyone faced this =
problem?</FONT></DIV>

<DIV><FONT face=3DArial size=3D2>or know the solution to =
it?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>I am doing something =
wrong?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>

<DIV><FONT face=3DArial size=3D2></FONT> </DIV></BODY></HTML>

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Jerry
--
Engineering is the art of making what you want from things you can get.
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