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# rayleighchan usage in MATLAB for Rayleigh channel

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#### mohamed_bakr

##### Newbie level 6
rayleighchan usage

Hello,

I would like to know some notes about using rayleighchan in Matlab in generating a frequency selective Rayleigh channel.

In the transmitter,

Ts=1e-6; % sample time of the input signal, in seconds
Fd=40; % maximum Doppler shift, in Hertz
TAU=[0]; % row vector of path delays, each specified in seconds
PDB=[0]; % row vector of average path gains, each specified in dB
Chan = rayleighchan(Ts,Fd,TAU,PDB);
Chan.StorePathGains=1;
Chan.ResetBeforeFiltering=0;

Output_Filtered_Symbols=filter(Chan,Input_Symbols);

So, how to recover the signal in the receiver after the filter,
I think I should use Chan.PathGains but should it be directly used as the time filter coefficients used in the filter ?? or it needs some processing to be considered as that??

Also, if I am talking about the channel frequency response, could I get it directly by using fft(Chan.PathGains) ??

Re: rayleighchan usage

There is a tool in MATLAB that sketch the frequency response and the impulse response of the channel.
You can use channel estimation and equalization.
The least square is the simplest method and it does not require an intensive processing, you can use it.

Added after 24 seconds:

The least square is very convenient in case of implementing a system that is using OFDM.

I am asking about usage of rayleighchan in case of 2 paths of more are used so how to extract my frequency channel response in the receiver for perfect channel estimation and to recover my signal back ?

I have the same problem with yours.

It makes me very confusing when I use the rayleighchan() in time/frequency domain.

I also want to implement ideal channel estimation by extract frequency channel response.

In the case of implementation on simulink, actually there is the same simulink block with rayleighchan() in simulink version, I could extract complex gains of the rayleigh channel in time domain. And I converted the coefficients into the frequency reponse by FFT.

Thus, I did the same method, but I couldn't find the same results. That is my confusing point.

If you found any solusion, could you inform me?

Thank you.

i think that the channel created by rayleighchan is in the time domain, so after cretaing teh channel object, u need to insert the significant path gains at the right place according to the channel delay, and then FFT the channel and multiply it by your input-symbols. u will obtain the received symbols directly in frequency domain

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