Transition technologies towards 6G networks

[EN] The sixth generation (6G) mobile systems will create new markets, services, and industries making possible a plethora of new opportunities and solutions. Commercially successful rollouts will involve scaling enabling technologies, such as cloud radio access networks, virtualization, and artificial intelligence. This paper addresses the principal technologies in the transition towards next generation mobile networks. The convergence of 6G key-performance indicators along with evaluation methodologies and use cases are also addressed. Free-space optics, Terahertz systems, photonic integrated circuits, softwarization, massive multiple-input multiple-output signaling, and multi-core fibers, are among the technologies identified and discussed. Finally, some of these technologies are showcased in an experimental demonstration of a mobile fronthaul system based on millimeter 5G NR OFDM signaling compliant with 3GPP Rel. 15. The signals are generated by a bespoke 5G baseband unit and transmitted through both a 10 km prototype multi-core fiber and 4 m wireless V-band link using a pair of directional 60 GHz antennas with 10 degrees beamwidth. Results shown that the 5G and beyond fronthaul system can successfully transmit signals with both wide bandwidth (up to 800 MHz) and fully centralized signal processing. As a result, this system can support large capacity and accommodate several simultaneous users as a key candidate for next generation mobile networks. Thus, these technologies will be needed for fully integrated, heterogeneous solutions to benefit from hardware commoditization and softwarization. They will ensure the ultimate user experience, while also anticipating the quality-of-service demands that future applications and services will put on 6G networks.This work was partially funded by the blueSPACE and 5G-PHOS 5G-PPP phase 2 projects, which have received funding from the European Union's Horizon 2020 programme under Grant Agreements Number 762055 and 761989. D. PerezGalacho acknowledges the funding of the Spanish Science Ministry through the Juan de la Cierva programme.Raddo, TR.; Rommel, S.; Cimoli, B.; Vagionas, C.; Pérez-Galacho, D.; Pikasis, E.; Grivas, E.... (2021). Transition technologies towards 6G networks. EURASIP Journal on Wireless Communications and Networking. 2021(1):1-22. https://doi.org/10.1186/s13638-021-01973-91222021

Roadmap on multimode photonics

Multimode devices and components have attracted considerable attention in the last years, and different research topics and themes have emerged very recently. The multimodality can be seen as an additional degree of freedom in designing devices, thus allowing for the development of more complex and sophisticated components. The propagation of different modes can be used to increase the fiber optic capacity, but also to introduce novel intermodal interactions, as well as allowing for complex manipulation of optical modes for a variety of applications. In this roadmap we would like to give to the readers a comprehensive overview of the most recent developments in the field, presenting contributions coming from different research topics, including optical fiber technologies, integrated optics, basic physics and telecommunications

All Optical Signal Processing Technologies in Optical Fiber Communication

Due to continued growth of internet at starling rate and the introduction of new broadband services, such as cloud computing, IPTV and high-definition media streaming, there is a requirement for flexible bandwidth infrastructure that supports mobility of data at peta-scale. Elastic networking based on gridless spectrum technology is evolving as a favorable solution for the flexible optical networking supportive next generation traffic requirements. Recently, research is centered on a more elastic spectrum provision methodology than the traditional ITU-T grid. The main issue is the requirement for a transmission connect, capable of accommodating and handling a variety of signals with distinct modulation format, baud rate and spectral occupancy. Segmented use of the spectrum could lead to the shortage of availableness of sufficiently extensive spectrum spaces for high bitrate channels, resulting in wavelength contention. On-demand space assignment creates not only deviation from the ideal course but also have spectrum fragmentation, which reduces spectrum resource utilization. This chapter reviewed the recent research development of feasible solutions for the efficient transport of heterogeneous traffic by enhancing the flexibility of the optical layer for performing allocation of network resources as well as implementation of optical node by all optical signal processing in optical fiber communication

All-optically untangling light propagation through multimode fibres

When light propagates through a complex medium, such as a multimode optical fibre (MMF), the spatial information it carries is scrambled. In this work we experimentally demonstrate an all-optical strategy to unscramble this light again. We first create a digital model capturing the way light has been scattered, and then use this model to inverse-design and build a complementary optical system - which we call an optical inverter - that reverses this scattering process. Our implementation of this concept is based on multi-plane light conversion, and can also be understood as a diffractive artificial neural network or a physical matrix pre-conditioner. We present three design strategies allowing different aspects of device performance to be prioritised. We experimentally demonstrate a prototype optical inverter capable of simultaneously unscrambling up to 30 spatial modes that have propagated through a 1m long MMF, and show how this enables near instantaneous incoherent imaging, without the need for any beam scanning or computational processing. We also demonstrate the reconfigurable nature of this prototype, allowing it to adapt and deliver a new optical transformation if the MMF it is matched to changes configuration. Our work represents a first step towards a new way to see through scattering media. Beyond imaging, this concept may also have applications to the fields of optical communications, optical computing and quantum photonics.Comment: 18 pages, 11 figure