Efficient encoding of quasi-cyclic LDPC codes with continuously variable length

In this paper, we present a class of QC-LDPC codes with continuously variable length (CVL), which can be encoded in linear time. The method combines CVL codes [1] with approximate lower triangle structure. Thus the parity-check matrix can achieve girth of 10, and the block length can vary continuously. Significantly, only cyclic-shifting and XOR operations are needed to realize the linear time encoding.