TITLE:
Half Rate Quasi Cyclic Low Density Parity Check Codes Based on Combinatorial Designs
AUTHORS:
Sina Vafi, Narges Rezvani Majid
KEYWORDS:
Quasi-Cyclic LDPC Codes, Combinatorial Designs, Circulant Matrix
JOURNAL NAME:
Journal of Computer and Communications,
Vol.4 No.12,
October
18,
2016
ABSTRACT: This paper presents new half rate Quasi
Cyclic Low Density Parity Check (QC- LDPC) codes formed on the basis of
combinatorial designs. In these codes, circulant matrices of the parity check
matrix are formed on the basis of subsets in which the difference between any
two elements of a subset is unique with all differences obtained from the same
or different subsets. This structure of circulant matrices guarantees
non-existence of cycle-4 in the Tanner graph of QC-LDPC codes. First, an
irregular code with girth 6 constituted by two rows of circulant matrices is
proposed. Then, more criteria will be considered on the structure of subsets
with the mentioned feature aiming to represent a new scheme of regular QC-LPDC
codes with girth at least 8. From simulations, it is confirmed that codes have
similar to or better performance than other well-known half rate codes, while
require lower complexity in their design.