# curve of BER in ldpc codes in matlab

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#### electronical

hello every body.
I wrote a plan for ldpc code an get these result but it is different the result that recieved from papaers.can any boby tell me why the result is different?

I wrote these code for n=1210 and frame_num=2000, code rate=0.5;
I used these code for channel
[m,n]=size(H);
sigma=sqrt(10^(-SNRindB1/10));
msg = randint(1,n-m);
c=rem(msg*G,2);
modObj = modem.pskmod('M',2,'InputType','Bit');
modulatedsig = modulate(modObj, c);
receivedsig = awgn(modulatedsig, SNRindB1(I), 0); ...
% Compute log-likelihood ratios (AWGN channel)
demodObj = modem.pskdemod(modObj,'DecisionType','LLR', ...
'NoiseVariance',sigma);

and I expect nearly these result(fast QC codes figure) :at low value SNR ,bit error rate value be about 10^(-1)

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Last edited:

#### iamjin

##### Newbie level 3
can u write BER performance of non binary LDPC min sum decoding???pls help me....i tried a lot..

#### electronical

hi. I just worked on binary decoding

iamjin

### iamjin

Points: 2

#### iamjin

##### Newbie level 3
it differs from binary....

#### cwjcwjcwj

##### Full Member level 5
Don't get what you mean. We normally compare BER at 10^-5. If you have a simulation results similar to the paper one at 10^-3 to 10^-5. Then, likely you're doing something right. Bear in mind, BER of coded system is often worse than uncoded system at low SNR.

#### Mohamedabuhelala

##### Newbie level 2
Hello every body,
any one can help me how to write a code can plot y axis in log scale and x axis in normal scale.

thanks,

- - - Updated - - -

What i am trying to say is i've got results displayed for BER using matlab simulink but i don't know how to plot curve of BER.

i would be so appreciated if someone could help out,

thanks

#### cwjcwjcwj

##### Full Member level 5
Use Microsoft Excel.

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