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Thread Subject:
How to similate QPSK in Rician fading channel???

Subject: How to similate QPSK in Rician fading channel???

From: Dae Il Kang

Date: 13 Jul, 1999 08:00:53

Message: 1 of 5

Hi everyone!!

Now, i would like to simulate QPSK or 16 Square-QAM under Rician fading
channel.
but, i have no idea to generate Rician fading process.
As i know, Rician distribution is non-central chi square distribution
and Rayleigh is central chi square...
but i can't apply this concept in my simulation..

Please help me..

Subject: How to similate QPSK in Rician fading channel???

From: Matthias Unbehaun

Date: 15 Jul, 1999 16:59:39

Message: 2 of 5

Hi,

there is a function
  ncx2rnd
    Random matrices from the noncentral chi-square distribution.

which generates Ricean distributed random variables.
  But:
Although the degrees of freedom are obvious, I don't know
how to use the non-centrality parameter V. Proakis defines it as
s^2 = m^2 + n^2 with m and n being the mean of the two random
variables. Is V == s or V == s^2?

In the help files 2 references are given
- Evans, M., N. Hastings, and B. Peacock, Statistical Distributions, Second
Edition,
  John Wiley and Sons, 1993. p. 50-52.
- Johnson, N., and S. Kotz, Distributions in Statistics: Continuous
Univariate Distributions-2,
  John Wiley and Sons, 1970. pp. 130-148.

but I couldn't get a hold of them.
Any help welcome.

Matthias.
KTH Stockholm/Sweden, Dept. Radio Comm. Systems

Dae Il Kang wrote:

> Hi everyone!!
>
> Now, i would like to simulate QPSK or 16 Square-QAM under Rician fading
> channel.
> but, i have no idea to generate Rician fading process.
> As i know, Rician distribution is non-central chi square distribution
> and Rayleigh is central chi square...
> but i can't apply this concept in my simulation..
>
> Please help me..

Subject: How to similate QPSK in Rician fading channel???

From: Dave Harvatin

Date: 17 Jul, 1999 23:45:10

Message: 3 of 5

It appears you want to simulate flat Ricean fading, so you need to generate
Ricean distributed pseudorandom variables and multiply them by your data
symbols. You want to make sure that the (noncentral) second moment of your
Ricean distribution is unity; otherwise, your fading channel would alter the
average energy of your data symbols and yield erroneous results. You also
want to control what is sometimes called the Rice factor or the K factor,
which is the specular-to-diffuse ratio of the received signal. Unlike
Rayleigh fading, Ricean fading models a direct signal path (the specular
component) in addition to reflected signals (the diffuse component). The
higher the Rice factor, the less severe is the fading. Here is how it is
done for a case that generates 10,000 pseudorandom Ricean variables:

Let mu = sqrt( K/(2*(K+1)) ) and s = sqrt( 1/(2*(K+1)) )

r = ( s*randn(1,10000 ) + mu ) + j*( s*randn(1,10000 ) + mu );
R = abs(r);

R is your Ricean variable, and if you compute mean(R.^2), you should get a
number fairly close to unity. For specular-to-diffuse ratio <= -6 dB (K <=
1/4), the fading statistics very closely approximate Rayleigh fading; which
is a good way to check your simulation since theoretical reults are more
readily available for flat Rayleigh fading than for flat Ricean fading.

Hope this helped,
Dave Harvatin

Dae Il Kang <kdi902@bjko.changwon.ac.kr> wrote in message
news:378A73A5.E35495DB@bjko.changwon.ac.kr...
> Hi everyone!!
>
> Now, i would like to simulate QPSK or 16 Square-QAM under Rician fading
> channel.
> but, i have no idea to generate Rician fading process.
> As i know, Rician distribution is non-central chi square distribution
> and Rayleigh is central chi square...
> but i can't apply this concept in my simulation..
>
> Please help me..
>
>

Subject: matlab file

From: eymli@ntu.edu.sg (Youmingli)

Date: 20 Jul, 1999 07:15:47

Message: 4 of 5

How to simulate QPSK in Rician fading
channel??

Subject: How to similate QPSK in Rician fading channel???

From: Mathuranathan Viswanathan

Date: 18 Oct, 2012 14:52:12

Message: 5 of 5

You can check my simulation code for simulation a Rician Fading model in baseband.
I have written it for BPSK and you can extend it to QPSK/16QAM

http://www.gaussianwaves.com/2012/07/ebn0-vs-ber-for-bpsk-over-rician-fading-channel/

Regards
Mathuranathan

Dae Il Kang <kdi902@bjko.changwon.ac.kr> wrote in message <378A73A5.E35495DB@bjko.changwon.ac.kr>...
> Hi everyone!!
>
> Now, i would like to simulate QPSK or 16 Square-QAM under Rician fading
> channel.
> but, i have no idea to generate Rician fading process.
> As i know, Rician distribution is non-central chi square distribution
> and Rayleigh is central chi square...
> but i can't apply this concept in my simulation..
>
> Please help me..
>
>

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