phase noise

Dear all,

I am modelling phase noise for OFDM systems. At the receiver

r=s*exp(j*phi)+w

r= received signal
s=transmitted signal
phi=random phase
w = AWGN noise

I have studied in the literature that phase noise can be described as
sampled version of wiener process, but for the purpose of analysis and
simulations a discrete time random walk or weiner levy process is used.
What exactly is this weiner levy process, how could i model it in matlab?

aamer wrote:

> I have studied in the literature that phase noise can be described as
> sampled version of wiener process, but for the purpose of analysis and
> simulations a discrete time random walk or weiner levy process is used.
> What exactly is this weiner levy process, how could i model it in matlab?

The Wiener process is a special case of the Levy process.
For your purposes, it's probably sufficient to generate a Wiener
process by:

 x = randn(N.1);
 h = some filter with the appropriate Fourier transform
 y = conv(x,h);

Basically generate a discrete-time white Gaussian sequence and then
filter it using filter h.  Choose h according to what you want.  I have
seen
phase noise models where h is a lowpass filter, for example.

Hope that helps,
Julius