Re-Polarization Processing in Extended Polar Codes

Yu-Ming HUANG  Hsie-Chia CHANG  Hsiang-Pang LI  

IEICE TRANSACTIONS on Communications   Vol.E100-B   No.10   pp.1765-1777
Publication Date: 2017/10/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2016EBP3307
Type of Manuscript: PAPER
Category: Fundamental Theories for Communications
polar codes,  length-compatible,  rate-compatible,  length-adaptation,  extending,  

Full Text: PDF(1.3MB)>>
Buy this Article

In this paper, extended polar codes based on re-polarization technique are proposed. The presented schemes extend a conventional polar code of length N to length N+q, which stand in contrast to known length-compatible schemes such as puncturing and shortening techniques that reduce the length from N to N-q. For certain specific lengths, the waterfall region performance of our extended polar code is superior to that of other length-compatible polar codes. It provides better reliability and reduces the management overhead in several storage devices and communications systems. In essence, extended polar codes are created by re-polarizing the q least reliable nonfrozen bit-channels with the help of q additional frozen bit-channels. It is proved that this re-polarization enhances the reliability of these bits. Moreover, the extended schemes can be not only modified to improve decoding performance, but generalized as a m-stage scheme to improve throughput significantly. With parallel operation, the throughput is improved around 2m-1 times when q is small. Compared to a shortened polar code with length 1536, the encoding and decoding complexities of an extended polar code are only 50% and 60.5%, respectively.