Comments on: Deriving PDF of Rayleigh random variable

By: Krishna Sankar

Krishna Sankar — Thu, 26 Jan 2012 01:39:07 +0000

@Sami: Good questions. Am trying to recall why I did it that way… quite likely as you said, it might be due to the continuous vs discrete sample aspect. Will revert back if i find a better explanation…
Thanks again.

By: Sami Aldalahmeh

Sami Aldalahmeh — Mon, 16 Jan 2012 14:03:03 +0000

Hi,
I looked at the code and noticed in line 34, when you plot the histogram of the simulated Rayleigh pdf, you divided by 0.01 that is the step of the zBin variable. Is there any intuitive explanation for this? Furthermore, if you sum, approximately integrate, the value for both theoretical pdfs of the Rayleigh distribution you don’t get one. However, if you don’t divide with 0.01 and multiply the theoretical pdf with 0.01 instead, you get one when sum. Maybe this is due MATLAB being not able to purely represent continuous functions? What do you think?

By: Krishna Sankar

Krishna Sankar — Mon, 02 Jan 2012 23:44:20 +0000

@mohsen: This is generate complex gaussian noise with zero mean and unit variance.

By: mohsen

mohsen — Wed, 21 Dec 2011 07:34:06 +0000

Dear Krishna
would you please send me the reference which u use to get this:
h = 1/sqrt(2)*(randn(1,1000) + j*randn(1,1000)) % rayleigh random variable

By: Krishna Sankar

Krishna Sankar — Sat, 03 Apr 2010 22:49:46 +0000

@PeterRay: My replies
a) You can use the histogram (hist function in Matlab) to obtain the PDF.
b) One needs to the write the equations to figure out the nature of the PDF
c) Did you mean, you want to add correlation to the channel coefficients?

By: PeterRay

PeterRay — Wed, 17 Feb 2010 16:01:57 +0000

Hello Krishna,
I am new to matlab. I need some help. Suppose we have ‘Nr x Nt’ MIMO channel matrix.And we assume iid rayleigh fading. So the magnitude of every entry will be rayleigh distributed. Now at the receiver side we have ‘Nr’ receive antennas and at every antenna we will have a set of values for every transmitted symbol. I wish to plot the pdf of the output values. (like the output SNR). How do I find the pdf then ? What kind of pdf will it be ? Further if I have to toss independent and non identical channels how to I do that ? we usually write “(1/sqrt(2))*(randn(Nr,Nt)+j*randn(Nr,Nt))” for a typical unit variance zero mean channel.Please correct me if my understanding is wrong. Any help would be appreciated.

By: Krishna Sankar

Krishna Sankar — Thu, 10 Dec 2009 01:05:23 +0000

@mesange: Hope the following code snippet helps
>>h = 1/sqrt(2)*(randn(1,1000) + j*randn(1,1000)) % rayleigh random variable
>>hP = h.*conj(h); % finding the power
>>hist(hP) % plotting the histogram