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Iterative decoding....

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venkat3271

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HI,
When i implement Turbo code in MATLAB and plot the graph for BER of each iteration(I computed BER after every iteration and i performed 10 iteration), i thought the plot should be monotonically decrease and reach minimum. . But to my surprise, i am getting randomly increasing and decreasing plot..

Can anybody help , y this occurs and spot the error...

To my knowledge my algo is right and i am getting good results for some other set of data..
 

i think you should use a very larger number of iterations to get the right result.
According to Monte Carlo simulation method , to estimate a given BER, the number of iterations must be very larger than 1/BER and as a rule of thumb we can choose N>10/BER

for example , if you want to estimate a BER of 1e-5 then you must at least have N=1000,000 iterations.

regards
 

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    venkat3271

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first of all i m bit shocked to read that u have implemented iterative decoding on MATLAB. because it involves lot of memory access, indirections and pointers are unavoidable in the implementation of decoding.

i wonder to wat extent the code is correct.

recently i have developed turbo encoder and decoder on C. as for as algo is concerned it is working fine, but because the turbo decoder wants soft bits as inputs right now i m focused on soft demapper.

once i m done with that i will surely get back to ur issue.
 

Hi,

This problem occurs when the data is not enough. So, you have to increase your data; especially for high SNR.

Ahmed
 

HI...am looking for bcjr algorithm implementation...if any one can help thts gr8..arunshowry19@gmail.com
 

Hi guys plz send me matlab code for iterative decoding
 

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