About the Turbo Encoder/Decoder in Communication tool box

I ran the simulation using the comm.TurboEncoder/comm.TurboDecoder in Communication tool box with code rate 1/3. But it always shows some error bits after decoding, which makes me confused. Could anybody help me with this issue? Thanks in advance!

I attached my codes below:

N = 10000; bits = randint(N,1); pattern = randperm(N); maxIter = 5;

hTurboEnc = comm.TurboEncoder('TrellisStructure', poly2trellis(4, [13 15], 13),'InterleaverIndicesSource','input port');

hTurboDec = comm.TurboDecoder('TrellisStructure', poly2trellis(4, [13 15], 13),'InterleaverIndicesSource','Input port', 'NumIterations', maxIter);

codedBits = step(hTurboEnc, bits, pattern);

decBits = step(hTurboDec, codedBits, pattern);

e = sum(xor(decBits,bits))

Answer 1

[Mochan Yang]

• - codedBits ,,,,, Miuns (-) should be added?????