The performances of interleavers used in turbo codes

A new type of interleaver, block-random interleaver, is proposed and compared with the principal types of interleavers on the basis of the BER (bit error rate) performances of the turbo code. A recursive systematic convolutional code, 1/3 rate, unpunctured turbo code was used. The convolutional code has the constraint length, K=4 with generator matrix [1, 15/13], in octal representation. The MAP algorithm, 12 iterations were used. A log likelihood ratio (LLR) stop criterion was selected. The BER and FER (frame error rate) for different interleaver lengths were obtained.