## Matlab code for repeat accumulate codes

I’ve uploaded some Matlab code for drawing EXIT chart, iterative decoding trajectories and BER plots for half-rate repeat accumulate codes. You can download it here.

Tags: BER, EXIT chart, iterative decoding, RA, repeat accumulate, trajectory

September 13th, 2011 at 4:02 am

3x a lot

November 28th, 2016 at 6:48 am

Hi! Can I change the coding rate of this RA codes? I found the solution for the encoding part, but I\\\’m not sure about the decoding part. Could you show me an example? Thx!

November 28th, 2016 at 10:30 pm

Hello Sol,

My Matlab code treats the RA code as a serial concatenation of a repetition code and a convolutional code.

You can reduce the coding rate by changing the number of repetitions performed by the repetition encoder - in the decoder, you just need to add all of the apriori LLRs for the repeated bits, in order to obtain the aposteriori LLRs. You can then convert to extrinsic LLRs by subtracting the apriori LLRs from the aposteriori LLRs.

You can increase the coding rate by performing puncturing at the output of the convolutional encoder. In the decoder, you just need to fill in the gaps left by these punctured bits using LLRs having the value of zero.

Take care, Rob.