Biblio
Ze the quality of channels into either completely noisy or noieseless channels. This paper presents extrinsic information transfer (EXIT) analysis for iterative decoding of Polar codes to reveal the mechanism of channel transformation. The purpose of understanding the transformation process are to comprehend the placement process of information bit and frozen bit and to comprehend the security standard of Polar codes. Mutual information derived based on the concept of EXIT chart for check nodes and variable nodes of low density parity check (LDPC) codes and applied to Polar codes. This paper explores the quality of the polarized channels in finite blocklength. The finite block-length is of our interest since in the fifth telecommunications generation (5G) the block length is limited. This paper reveals the EXIT curve changes of Polar codes and explores the polarization characteristics, thus, high value of mutual informations for frozen bit are needed to be detectable. If it is the other way, the error correction capability of Polar codes would be drastically decreases. These results are expected to be a reference for developments of Polar codes for 5G technologies and beyond.
In this paper, we propose a frozen bit selection scheme for polar coding scheme combined with physical layer security that enhances the security of two legitimate users on a wiretap channel. By flipping certain frozen bits, the bit-error rate (BER) of an eavesdropper is maximized while the BER of the legitimate receiver is unaffected. An ARQ protocol is proposed that only feeds back a small proportion of the frozen bits to the transmitter, which increases the secrecy rate. The scheme is evaluated on a wiretap channel affected by impulsive noise and we consider cases where the eavesdropper's channel is actually more impulsive than the main channel. Simulation results show that the proposed scheme ensures the eavesdropper's BER is high even when only one frozen bit is flipped and this is achieved even when their channel is more impulsive than the main channel.