Outage-Limit-Approaching Channel Coding for Future Wireless Communications: Root-Protograph Low-Density Parity-Check Codes

A block-fading (BF) channel, also known as a slow-fading channel, is a type of simple and practical channel model that can characterize the primary feature of a number of wireless-communication applications with low to moderate mobility. Although BF channels have received significant research attention in the past 20 years, designing low-complexity, outage-limit-approaching error-correction codes (ECCs) is still a challenging issue. For this reason, a novel family of protograph low-density parity-check (LDPC) codes, called root-protograph (RP) LDPC codes, has been conceived recently. The RP codes not only can realize linear-complexity encoding and highspeed decoding with the help of the quasi-cyclic (QC) structure but can also achieve near-outage-limit performance in different BF scenarios. In this article, we briefly review the design guidelines of such protograph codes with the aim of inspiring further research activities in this area.