Multifold calculations for LLRs in interative turbo decoding

To proceed iterative decoding by choosing every output sequence of the constituent encoders as the start sequence in turn, multiple different extrinsic information sequences can be obtained due to the existence of interleavers as well as different initial decoding conditions and tail-bit lengths. To assemble them before making decision, more extrinsic information can be gathered. This results in more precise final decision-making than in the conventional decoding scheme. Simulation results show that the proposed decoding scheme is capable of not only obtaining lower BER at the same iteration number but lowering the error floor of turbo codes compared to the conventional one. Furthermore, the coding gain and the improvement in performance are growing generally with the increment of SNR. In this text, the coding gain can be obtained up to 1.5 dB.