Simulating a system in which Turbo code can be adjusted

[fielix]

hi I need help on turbo code.

Is there anybody who have simulated such a system in which the code rate can be adjusted, namely 1/2, 1/3, 3/4 and so on?

thank you for your help!

 

[cwjcwjcwj]

Re: turbo code

yes i do.....

 

[fielix]

Re: turbo code

I would like to see the matlab code for turbo coding described above, thank you!

hello448@163.com

 

[cwjcwjcwj]

Re: turbo code

The matlab code for turbo code can be found in YuFei website. She did a good job in writting Matlab version turbo code. For different coding rate, you can simply puntured the parity bits.

**broken link removed**

 

[fielix]

Re: turbo code

I am not familiar with turbo code, are there any files that demonstrate the concrete procedure of implementing different code rate?

thank you!

 

[cwjcwjcwj]

Re: turbo code

rate-1/2 turbo code

information bit: I1 I2 I3 I4
parity bit 1 : A1 X A3 X
parity bit 2 : X B2 X B4

rate-1/3 turbo code

information bit: I1 I2 I3 I4
parity bit 1 : A1 A2 A3 A4
parity bit 2 : B1 B2 B3 B4

rate-3/4 turbo code

information bit: I1 I2 I3 I4 I5 I6
parity bit 1 : A1 X X X X X
parity bit 2 : X X X B4 X X

X denoted the corresponding bit is being puntured.

You should follow above puncturing pattern until the end of your frame size. If you need further information you can refers to the Error Correcting Code from ShuLin. Hope this help you.......

 

[fielix]

Re: turbo code

Thank you for your kind reply, I am still wondering what is the punturing pattern of code rate (= 1/4) ?

The last question is arrangement of the output sequence, take the code rate (=1/2) for example, the output should be I1 A1 I2 B2 I3 A3 I4 B4, is it right?

 

[cwjcwjcwj]

Re: turbo code

I don't think you can directly obtained a turbo code with rate-1/4 by puncturing the rate-1/3 mother code, as it is a very low rate. I believe you need some modifications on your chanel code, which i am not very sure as well. Try search 'low rate turbo code' from any search engines.

Yes, you are right...the output should be like that..

 

[fielix]

Re: turbo code

The code rate (=1/4) can be obtained from mother code (=1/3) by repetiton.

Is there anybody who knows how to implemente the process ?

Thank you in advance!

 

[lordsathish]

Re: turbo code

HI everybody ,
how to use the extrinsic information for the next iteration? ,in turbo coding....
I think there ll be change in Gamma calculation.. But dont know , how that formula comes,....

 

[sundarmeenakshi]

Re: turbo code

hi I need help on turbo code.

Is there anybody who have simulated such a system in which the code rate can be adjusted, namely 1/2, 1/3, 3/4 and so on?

thank you for your help!

before implementation read sklar example problem

 

[venkat3271]

Re: turbo code

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..