Characterization and Modeling of UHF Wireless Channel in Terrestrial SFN Environments: Urban Fading Profiles

[EN] This paper proposes several realistic fading channel models to describe the signal distortions that arise in single frequency network (SFN) environments. The proposed models characterize ultra-high frequency (UHF) wireless channels based on measurements from operating networks in metropolitan areas. In this paper, the unique features of SFN transmission are identified compared to the conventional, single antenna transmission channels. The impacts of urban propagation, tower configuration, and mobile and terrain effects are considered based on the tapped delay line structure. The proposed models can provide a useful reference to facilitate the SFN system design, network planning, verification, and receiver performance test. Free MATLAB source code of the fading simulator is available at https://github.com/ETRI-KMOU/FadingChannelSimulatorThis work was supported by the Institute of Information and Communications Technology Planning and Evaluation (IITP) Grant funded by the Korea Government (MSIT, Development of Convergence Transmission and Technology for 5G and ATSC 3.0 Networks) under Grant 2020-0-00846. This work was partially presented at IEEE BMSB in 2022 [DOI: 10.1109/BMSB55706.2022.9828617].Ahn, S.; Kim, J.; Ahn, S.; Kwon, S.; Jeon, S.; Gomez-Barquero, D.; Angueira, P.... (2022). Characterization and Modeling of UHF Wireless Channel in Terrestrial SFN Environments: Urban Fading Profiles. IEEE Transactions on Broadcasting (Online). 68(4):803-818. https://doi.org/10.1109/TBC.2022.321038280381868

An overview of preharvest factors influencing mango fruit growth, quality and postharvest behaviour

International audienceMango, a tropical fruit of great economic importance, is generally harvested green and then commercialised after a period of storage. Unfortunately, the final quality of mango batches is highly heterogeneous, in fruit size as well as in gustatory quality and postharvest behaviour. A large amount of knowledge has been gathered on the effects of the maturity stage at harvest and postharvest conditions on the final quality of mango. Considerably less attention has been paid to the influence of environmental factors on mango growth, quality traits, and postharvest behaviour. In this paper, we provide a review of studies on mango showing how environmental factors influence the accumulation of water, structural and non-structural dry matter in the fruit during its development. These changes are discussed with respect to the evolution of quality attributes on the tree and after harvest. The preharvest factors presented here are light, temperature, carbon and water availabilities, which can be controlled by various cultural practices such as tree pruning, fruit thinning and irrigation management. We also discuss recent advances in modelling mango function on the tree according to environmental conditions that, combined with experimental studies, can improve our understanding of how these preharvest conditions affect mango growth and quality. (Résumé d'auteur)Manga, um fruto tropical de grande importância, é geralmente colhido verde e comercializado após um período de armazenamento. Infelizmente, a qualidade final da manga na prateleira é altamente heterogênea, em termos de tamanho do fruto, qualidade do paladar e comportamento pós-colheita. Tem-se obtido uma quantidade expressiva de informações sobre os efeitos do estádio de maturação e condições pós-colheita sobre a qualidade final da manga. Contudo, tem-se dado atenção consideravelmente menor à influência dos fatores ambientes sobre o crescimento da manga, características de qualidade e comportamento pós-colheita. Neste artigo, faz-se uma revisão dos estudos sobre manga, evidenciando-se como fatores ambientes afetam o acúmulo de água e de matéria seca estrutural e não-estrutural nos frutos durante o seu desenvolvimento. Discutem-se essas alterações com relação à evolução de atributos de qualidade dos frutos ainda nas plantas e após a colheita. Os fatores de pré-colheita abordados são luz, temperatura, disponibilidades de água e de carbono, raleio de frutos e manejo da irrigação. Discutem-se também recentes avanços sobre modelagem associada à função do fruto na planta, conforme as condições ambientes que, combinados com estudos experimentais, pode melhorar a nossa compreensão sobre como as condições de pré-colheita afetam o crescimento e a qualidade da manga