Dear Colleagues,

The developed mobile 5G systems and networks as well as the planned 6G are some of the most important elements of modern communication. The technologies of 5G/6G mobile systems and networks have become so demanding that they cannot be constructed and implemented without advanced optical technologies. Core network, backhaul, midhaul, and fronthaul are the components that together form mobile systems and 5G/6G networks. Each of these components can be seen as an Xhaul integrated network service that can be run in a hybrid configuration based on DWDM, EON, or PON fiber-optic technologies. The sixth generation of mobile networks will use not only optical fiber networks, but also optical wireless Li-Fi connections. The increasing density of base stations operating at higher and higher radio frequencies will therefore force the introduction of Li-Fi, which will be dictated by the popularization of mIoT services and the evolution of Industry 4.0 towards Industry 5.0. Given that the RAN domain of 5G/6G systems is evolving towards Open-RAN architecture, Heterogeneous, multi-domain, and multi-vendor optical networks will have to work coherently to ensure the efficient transport of very differentiated network traffic. In many situations, only synchronous networks with all-optical links and very effective management of optical resources will be able to cope with these challenges. The search for optical and photonic solutions, useful in 5G/6G networks, concerns not only transmission systems, but also systems supporting the operation of effective antenna array systems, which in the O-RAN architecture are most often connected in FTTA configuration. In order to manage the shape of the radio beam for wireless path, FBG techniques, optical delay lines, or multi-core optical fibers are used. Currently, optical networks and systems are widely available, but the optimal use of their capabilities and resources in terms of transmission and energy consumption leaves much to be desired. In order to dynamically manage these resources, it is necessary to introduce machine learning techniques and elements of artificial intelligence. The intelligence of future universal optical networks will make mobile network and radio access planning automated and very optimal.

We invite scientists to submit original papers presenting the results of research on new optical technologies, which may be of key importance in future 5G/6G mobile networks. The potential topics of this Special Issue include, but are not limited to:

• evolution of the optical Xhaul architecture;
• optical O-RAN supporting QoS services;
• smart all-optical paths for O-RAN and 5G/6G core network;
• optical resource management tools dedicated to the mobile and access networks;
• new protocols and techniques for optical slicing;
• elastic optical networking in radio and core domain;
• D-RoF and A-RoF techniques dedicated to effective O-RANs;
• optical networks based on multicore fibers in O-RAN domains;
• effective integration of mobile systems and passive optical networks;
• BBU/CU cloud based on all-optical elastic network;
• RRH/RU as an optical node for radio-fiber services;
• O-RAN DU as optical network cloud service;
• optical eCPRI/NGFI evolution and adaptation to 6G mobile networks controlled by AI;
• ML methods and algorithms for DU service localization and optimization in optical network;
• smart optical nodes recognizing and managing the radio traffic;
• new smart optical TSNs for Industry 4.0/5.0 based on wireless systems;
• highly efficient TSON services for mobile next generation backhaul;
• optical mixed networks for mIoT services;
• Li-Fi connections as radio-over-light services;
• synchronous fronthaul ethernet optical links/paths with high QoS;
• photonics antenna array connected directly to the fiber-optic/light network;
• fiber-optic beamforming techniques for mobile smart antenna systems;
• new modulation and coding formats for radio-fiber services.

Dr. Zbigniew Zakrzewski
Prof. Dr. Mariusz Głąbowski
Prof. Dr. Piotr Zwierzykowski
Prof. Dr. Vincenzo Eramo
Dr. Francesco Giacinto Lavacca
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Photonics is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• xhaul
• optical backhaul
• optical fronthaul
• midhaul
• digitized radio-over-fiber
• analogue radio-over-fiber
• optical 5G/6G core
• radio-fiber technique
• optical O-RAN
• photonics antenna
• fiber-optic beamforming
• microwave photonics
• optical slicing
• TSON
• Li-Fi connection
• VLC
• all-optical radio transport network
• optical RRH/RU
• radio-over-ethernet-over-fiber
• multicore fibers for O-RAN
• radio-over-PON