Spatially Coupled Codes and Optical Fiber Communications: An Ideal Match?

In this paper, we highlight the class of spatially coupled codes and discuss their applicability to long-haul and submarine optical communication systems. We first demonstrate how to optimize irregular spatially coupled LDPC codes for their use in optical communications with limited decoding hardware complexity and then present simulation results with an FPGA-based decoder where we show that very low error rates can be achieved and that conventional block-based LDPC codes can be outperformed. In the second part of the paper, we focus on the combination of spatially coupled LDPC codes with different demodulators and detectors, important for future systems with adaptive modulation and for varying channel characteristics. We demonstrate that SC codes can be employed as universal, channel-agnostic coding schemes.Comment: Invited paper to be presented in the special session on "Signal Processing, Coding, and Information Theory for Optical Communications" at IEEE SPAWC 201

4-Fluoro-2-[(3-methyl­phen­yl)imino­meth­yl]phenol

The title compound, C14H12FNO, crystallizes as the trans phenol–imine tautomer. The two benzene rings are essentially coplanar, being inclined to one another by 9.28 (7)°. This is at least in part due to the intra­molecular O—H⋯N hydrogen bond between the hy­droxy O atom and the imine N atom. The crystal structure is stabilized by an array of weak C—H⋯O and C—H⋯F inter­actions, which link the mol­ecules into a stable three-dimensional network

2-(m-Tolyl­imino­meth­yl)phenol

The title compound, C14H13NO, is non-planar with a dihedral angle of 47.00 (6)° between the planes of the two aromatic rings. Intra­molecular hydrogen bonding is observed between the O—H group and the N atom, resulting in a phenol–imine tautomeric form

Tetra­ethyl­ammonium (acetyl­acetonato)bromidotricarbonyl­rhenate(I)

In the title compound, (C8H20N)[ReBr(C5H7O2)(CO)3], the ReI atom in the rhenate anion is surrounded by three carbonyl ligands orientated in a facial arrangement, a bromide ligand and an acetyl­acetonate ligand, leading to a distorted octa­hedral ReC3BrO2 coordination with a O—Re—O bite angle of 85.66 (7)°. An array of C—H⋯O and C—H⋯Br hydrogen-bonding inter­actions between the cations and the surrounding rhenate anions stabilize the crystal structure

Land Cover Change Monitoring Using Landsat MSS/TM Satellite Image Data over West Africa between 1975 and 1990

Abstract: Monitoring land cover changes from the 1970s in West Africa is important for assessing the dynamics between land cover types and understanding the anthropogenic impact during this period. Given the lack of historical land cover maps over such a large area, Landsat data is a reliable and consistent source of information on land cover dynamics from the 1970s. This study examines land cover changes occurring between 1975 and 1990 in West Africa using a systematic sample of satellite imagery. The primary data sources for the land cover classification were Landsat Multispectral Scanner (MSS) for 1975 and Landsat Thematic Mapper (TM) for the 1990 period. Dedicated selection of the appropriate image data for land cover change monitoring was performed for the year 1975. Based on this selected dataset, the land cover analysis is based on a systematic sample of 220 suitable Landsat image extracts (out of 246) of 20 km × 20 km at each one degree latitude/longitude intersection. Object-based classification, originally dedicated for Landsat TM land cover change monitoring and adapted for MSS, was used to produce land cover change information for four different land cover classes: dense tree cover, tree cover mosaic, other wooded land and other vegetation cover. Our results reveal that in 1975 about 6% of West Africa was covered by dense tree cover complemented with 12% of tree cover mosaic. Almost half of the area was covered by other wooded land and the remaining 32% was represented by other vegetation cover. Over the 1975–1990 period, the net annual change rate of dense tree cover was estimated at −0.95%, at −0.37% for the other wooded land and very low for tree cover mosaic (−0.05%). On the other side, other vegetation cover increased annually by 0.70%, most probably due to the expansion of agricultural areas. This study demonstrates the potential of Landsat MSS and TM data for large scale land cover change assessment in West Africa and highlights the importance of consistent and systematic data processing methods with targeted image acquisition procedures for long-term monitoring.JRC.H.5-Land Resources Managemen