Various information and materials about OFDM

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Re: any thing about OFDM

Hi everbody!

I have done simulation the Huffman coding on 16-QAM/OFDM that shows smaller PAPR than without coding.

So, I am going to simulate SLM (Selective Mapping) idea for Huffman, however, the problem which I couldn't understand PAPR choosing part.

For ex. I chose the smallest PAPR of subcarriers in OFDM symbol, then I should transmit with this PAPR, but I am confusing that I understand to transmit only one subcarrier.

How about others? I lost other subcarriers.
How can I apply one PAPR point for all subcarriers?

Any explanations pls!

Thanks in advance!
 

any thing about OFDM

informative mates
i am new over here. hopefully we will share and learn alot from ehre
 

any thing about OFDM

so you want us to tell you about OFDM so that you can write that in your report? 70 pages worth?

Why don't you just go ahead and copy somebody else's work? [sarcastic, not advising you to do it! :| ]

Have you considered reading a book?
 

    Aya2002

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Re: any thing about OFDM

Hi,

OFDM is a powerful technique employed in communications systems suffering from frequency selectivity. Combined with multiple antennas at the transmitter and receiver as well as adaptive modulation, OFDM proves to be robust against channel delay spread. Furthermore, it leads to significant data rates with improved bit error performance over links having only a single antenna at both the transmitter and receiver.

Good Luck!

Ahmed
 

    Aya2002

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Re: any thing about OFDM

hi all!

pls write here essential information about Selective Mapping (for any codes) for reduction of PAPR in OFDM.

thnks!
 

Re: any thing about OFDM

Selected Mapping (SLM), is simply to generate D - symbols all carry the same information (copy from the original symbol), then generate a phase rotation sequences then multiply each copy by its corresponding phase rotation sequence, you will have D - values of the PAPR values, choose the lowest value then send its corresponding phase rotated symbol and the number of the phase rotation sequence as a side information to the receiver.
regards
 

Re: any thing about OFDM

I've studied OFDM and PAPR basics. Now i'm trying to work with PAPR Reduction. I need instruction.
 

Re: any thing about OFDM

masudranaks said:
I've studied OFDM and PAPR basics. Now i'm trying to work with PAPR Reduction. I need instruction.
Click to expand...

what type of instruction do you need?
 

Re: any thing about OFDM

hello sir
i m new in ofdm.i want to do a research on papr reduction of ofdm. now my main problem is that i need a good ofdm simulation code using matlab,so that i can carry my future research based on that code.in my code i need - usefull symbol duration+CP insertions +fft based ofdm
plz sir help me on this.
thank you
 

Re: any thing about OFDM


I am currently working on PAPR reduction of OFDM system, and MC - CDMA system ( PhD study), but you must do the code yourself. I can help you step by step but not to give you the code directly
 
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    sayfee

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Re: any thing about OFDM

ofdm generation code needed.:-(
 
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Re: any thing about OFDM

Aya2002 said:
I am currently working on PAPR reduction of OFDM system, and MC - CDMA system ( PhD study), but you must do the code yourself. I can help you step by step but not to give you the code directly
Click to expand...

sir i want a ofdm code based on what i will do my future research.currently i m using this code OFDM signal generation, transmission and reception - File Exchange - MATLAB Central
this code does not have: carrier separation,Symbol duration and up conversion. now my question is that do i need these for papr reduction tecnique? as far i know i need to show ccdf vs snr graph to prove my technique..correct me if i m wrong..reply me soon plz
 
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Re: any thing about OFDM

do the code by yourself as follows:
step by step i will be with you
generate data (any number you want lets say 1000 binary bits)
map the data using any baseband modulation such as PSK, QAM ....
zero pad the data to be of length 2^n
IFFT
cp
channel
remove cp
FFT
remove zeros
demap
compare the bits (BER)
----------------------------
after you finish the code we will see how to calculate the papr
ok?
if you need any help on the above steps, contact me here on edaboard.com by replying this message or **broken link removed**
 
Re: any thing about OFDM

thank you sir for your reply..i am done with what you said..i can calculate the papr as well ,now i am stuck with ccdf.would u tell me how to plot ccdf??
 

Re: any thing about OFDM

sayfee said:
thank you sir for your reply..i am done with what you said..i can calculate the papr as well ,now i am stuck with ccdf.would u tell me how to plot ccdf??
Click to expand...

Here you are a sample for the CCDF plot for the PAPR

iterations=1000;
t=1;
for z=0:0.25:18-0.25
if min(par_ss_z8r4)>10^(z/10)
cdata_ss_z8r4(t)=cdata_ss_z8r4(t)+1;
end
t=t+1;
end

_______________________________________________________________________________________________________________
end of main loop
cdata_ss_z8r4=cdata_ss_z8r4/iterations;
semilogy(t,cdata_ss_z8r4,'-b^','LineWidth',1,'MarkerEdgeColor','b','MarkerFaceColor','b','MarkerSize',5)



_________________________________________________________________________________________________________________

put all your code inside a loop for the Iterations (make them 1000) and put this code at the end of the loop then plot the results. but you must specify the vector cdata_ss_z8r4 at the beginning to be as cdata_ss_z48r4=zeros(1,72).


the attachment is a sample from my work
 

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i am little bit confused about this code,
1. what is par_ss_z8r4 ?? is it the papr of ofdm signal?is its size is 1000?
2. what is cdata_ss_z8r4?
3. why here so many thing like line width,markeredgecolor.... {semilogy(t,cdata_ss_z8r4,'-b^','LineWidth',1,'MarkerEdgeColor','b','MarkerFac eColor','b','MarkerSize',5)}
thank you sir for your reply

---------- Post added at 11:28 ---------- Previous post was at 11:25 ----------

did you mean something like this??

clc
clear all
close all
cdata_ss_z8r4=zeros(1,72);
for i=1:1000
data=randsrc(1,64,0:1);
data_mod=pskmod(data,2);
ofdm_signal=ifft(data_mod,64);
N1x=length(ofdm_signal);x1I=real(ofdm_signal); x1Q=imag(ofdm_signal);Power1 = x1I.*x1I + x1Q.*x1Q; %power calculation
Avg1P = sum(Power1)/N1x;
Peak1P = max(Power1);
PAPR_without_phs_dB(i) = (Peak1P/Avg1P);

t=1;
for z=0:0.25:18-0.25
if min(PAPR_without_phs_dB)>10^(z/10)
cdata_ss_z8r4(t)=cdata_ss_z8r4(t)+1;
end
t=t+1;
end

end

cdata_ss_z8r4=cdata_ss_z8r4/1000;
semilogy(cdata_ss_z8r4)
 

yes, that is right
go ahead
 

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