Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

curve of BER in ldpc codes in matlab

Status
Not open for further replies.
E

electronical

Advanced Member level 4
Full Member level 1
Joined
Nov 4, 2011
Messages
104
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,298
Activity points
1,975
hello every body.
I wrote a plan for ldpc code an get these result but it is different ehit result that recived from papaers.can any boby tell me why the result is different?
 

Attachments

  • BER.png
    BER.png
    87.1 KB · Views: 154

Hi electronical,

Please provide mode details about your code and what result do you expect.
By the way, it would be better to place this post in the "Digital Communication" forum.
Regards

Z
 

hello .
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);
LLR = demodulate(demodObj, receivedsig);

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

Attachments

  • Fats_Tanner5_10_fr500.jpg
    Fats_Tanner5_10_fr500.jpg
    17.2 KB · Views: 142

Hi,

it would be necessary to check the results against theory for this particular code (have you the theoretical result?)
Nevertheless, your first result seems to give a result better to the theoretical capacity limit for AWGN channel with rate=1/2 at Eb/No=0dB (see figure).
I would check the simulation.
Regards

Z
 
thanks zorro
my result is nearly linear but the result of theoretical is nonlinear.
I want to know my recieved result is true?
if not can you tell me why ?
the problem is about channel or my code?
my code is simple
by regegards
 
Last edited:

Hi electronical,

You result seems to violate an information theory limit (see my previous post).
In order to see if your simulation of the channel is correct, you should check its performance without coding (i.e. pure BPSK) and compare with the result of theory.
Regards

Z
 
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top