LLR processing of polar codes in concatenation systems

This paper studies the decoding performance of low-density parity-check (LDPC) codes in a serial concatenation system with polar codes employing the successive cancellation (SC) decoding. It is known that the absolute incorrect log-likelihood ratio (LLR) values from the SC decoding can be very large. This phenomenon dramatically deteriorates the error correcting performance of the outer LDPC codes. In this paper, the LLR values of polar codes are regulated by a log processing before being sent to the LDPC decoder. Simulation results show that the log processing is an efficient approach with a low optimization complexity compared with the existing procedures to improve the performance of the serial concatenation systems.