Design Guidelines of Low-Density Parity-Check Codes for Magnetic Recording Systems

Abstract

As one of the most classical data-storage systems, magnetic recording (MR) systems have attracted a significant amount of research attention in the past several decades due to the advantages of low cost and high storage density. Along with the continual increase of areal density of modern MR devices, more severe inter-symbol interference (ISI) and noise appear and thus reliable storage becomes more difficult. To address this challenging problem, turbo detections and errorcorrection codes (ECCs) have been applied to MR systems so as to significantly improve the overall data-storage reliability. Among all the existing ECCs, low-density parity-check (LDPC) codes are of particular interest because they can offer excellent error performance with relatively low encoding and decoding complexity. This paper presents a comprehensive survey of the latest research advancements in LDPC-code design for MR systems from the perspectives of code construction, decoder design, as well as asymptotic performance-evaluation methodology. More specifically, we summarize the design guidelines of LDPC encoder and decoder over both one-dimensional (OD) ISI and two-dimensional (TD) ISI channels, which are commonly used to characterize MR systems with different areal densities. We also concisely portray the research progress in the design of some LDPC-code variants, such as protograph codes, repeataccumulate (RA) codes, spatially-coupled (SC) codes, and their non-binary counterparts over the aforementioned ISI channels. In particular, we restrict our attention to the reading process and ignore the written-in errors in MR systems unless otherwise stated. Hopefully, this survey will inspire more research activities in the area of LDPC-coded MR systems.

Multilevel High-Rate Coding With Twofold Concatenation for IoTs in Wireless Mesh Networks

“…Several promising channel coding designs for wireless communication systems are well presented in [23], [24], including the variants of physical-layer network codingaided wireless communications and root protograph (RP) codes which belong to the novel family of protograph lowdensity parity check (LDPC) codes, over block-fading (BF) channels. Readers are advised to read these references for a comprehensive survey of the latest research advancements in channel coding designs [23]- [25]. In many cases, IoTs devices are battery powered and may need to be deployed in some remote and harsh areas where a power source is not available.…”

Joint Channel Estimation and Power Allocation for the CRS‐NOMA

“…The strong user acts as a relay to forward information for the weak user. The channel coefficients of S-to-U 1 and U 1 -to-U 2 links are respectively denoted as h 1 and h 2 , which are assumed to be zero-mean circular symmetric complex Gaussian random variables with variances δ 2 1 and δ 2 2 , respectively. Thus, we have…”

Congestion‐Optimal WiFi Offloading with User Mobility Management in Smart Communications

“…With the proliferation of smart devices such as smartphones and tablets, cellular networks are facing an exponential growth of mobile data traffic. According to Cisco's forecast, global mobile data traffic is expected to grow to 49 megabytes per month by 2021, a sevenfold increase over 2016 [1][2][3][4]. With the limited licensed bandwidth, the cellular network capacity, however, can not keep up with the explosive data growth [5][6][7][8][9].…”