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 paritycheck (LDPC) codes, called rootprotograph (RP) LDPC codes, has been conceived recently. The RP codes not only can realize linearcomplexity 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.