Network slicing architecture for SDM and analog-radio-over-fiber-based 5G fronthaul networks

\u3cp\u3eThe blueSPACE project focuses on the study of innovative technologies to overcome the limitations of current fronthaul networks. The key technology proposed is space-division multiplexing, which makes it possible to increase the capacity available in conventional single-mode fibers, effectively encompassing this capacity to the forecasted bandwidth demands imposed by 5G mobile communications. In this paper, we present the innovative optical fronthaul infrastructure proposed in the project and the tailored extensions to the European Telecommunications Standards Institute network function virtualization management and orchestration architecture for this enhanced infrastructure together with practical implementation considerations.\u3c/p\u3

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

Advanced modulation schemes and signal processing techniques for transmission in highly multimode fibers

In this dissertation, advanced modulation schemes and digital signal processing techniques are proposed and investigated through both numerical simulations as well as experiments, in order to overcome the limitations of multimode step index plastic optical fibers (SI-POF) to support data rates in the order of Gbps. In particular, novel multi-carrier modulation techniques with the inherent property of symbol spreading (spreading multicarrier modulation schemes) are proposed and applied. These schemes are Discrete Fourier Transform Spread Discrete Multitone (DFT-Spread DMT) and Code Division Multiple Access Discrete Multitone (CDMA-DMT), which, in this thesis, are suitably adapted for short-range IM/DD transmission via SI-POF and compared against conventional Discrete Multitone (DMT) in terms of achieved transmission rate given a target bit error rate. Evaluation is performed for links of 50m and 100m by exploring various cases affecting the overall performance, including rate adaptation and artificial PAPR reduction. In all cases it is found that the DFT-spread DMT perfoms better than all other schemes, followed by CDMA-DMT hence, paving the way for more elaborated research for optimizing its transmission properties.Στην παρούσα διδακτορική διατριβή, προηγμένα σχήματα διαμόρφωσης και τεχνικές επεξεργασίας σήματος μελετώνται με την βοήθεια προσομοιώσεων και με την ανάπτυξη πειραματικών διατάξεων, με στόχο να ξεπεραστούν οι περιορισμοί που εισάγουν οι πολύτροπες πλαστικές οπτικές ίνες με σκοπό να υποστηρίξουν ρυθμούς μετάδοσης της τάξης των Gbps. Ειδικότερα, σχήματα διαμόρφωσης, με εγγενές χαρακτηριστικό τη διάχυση των συμβόλων προτείνονται και εξετάζονται. Αυτά τα σχήματα είναι η Discrete Fourier Transform Spread Discrete Multitone (DFT-Spread DMT) and Code Division Multiple Access Discrete Multitone (CDMA-DMT), τα οποία προσαρμόζονται κατάλληλα για μετάδοση σε δίκτυα μικρής κλίμακας μέσω πλαστικών οπτικών ινών (SI-POF) με διαμόρφωση έντασης και άμεση φώραση (IM/DD) και συγκρίνονται με την κλασσική DMT διαμόρφωση ως προς τον παράγοντα της πιθανότητας σφάλματος bit (BER) για ένα δεδομένο ρυθμό μετάδοσης. Η σύγκριση πραγματοποιείται για μήκη ίνας 50 και 100μ, με χρήση και τεχνικών βελτιστοποίησης, όπως μείωσης του λόγου ισχύος κορυφής προς τη μέση ισχύ (PAPR) και δυναμικής προσαρμογής του ρυθμού μετάδοσης. Σε όλες τις υπό διερεύνηση περιπτώσεις η DFT-Spread DMT παρουσιάζει βελτιωμένη συμπεριφορά σε σύγκριση με τα υπόλοιπα υπόλοιπα σχήματα διαμόρφωσης

Gb/s One-Time-Pad Data Encryption With Synchronized Chaos-Based True Random Bit Generators

Ultrafast physical random bit generators based on broadband optical signals have been presented lately at astounding speeds. Some of the most popular mechanisms to obtain such random sequences are through signals that emerge from the coherence collapse operation of semiconductor lasers or from the photodetection signal beating of amplified spontaneous emission optical noise. Especially in the first case, the potential of chaotic signals to synchronize offers a great potential for secure communications. In this paper, we combine two unique properties of semiconductor lasers that operate at a chaotic regime: Their potential to become highly synchronized when optically coupled through appropriate configurations and their ability to seed ultrafast true random bit generators. The concurrent fulfillment of both conditions is shown in this paper and is used to demonstrate experimentally the one-time-pad encryption communication protocol. We report an error-free operation of such an encryption system, exceeding for the first time the Gb/s rate. Forward-error-correction coding is applied on the encryption scheme, in order to drastically reduce the errors of the synchronized true random bit sequences and optimize the decoding performance of the system, while securing the distribution of the random seed.The current work was supported by Greek General Secretariat for Research and Technology under the funding research action "ARISTEIA II" and the project "CONECT-4750" and was performed at the Department of Informatics and Telecommunications, National and Kapodistrian University of Athens, Panepistimiopolis, Ilisia, 15784, Greece.Peer reviewe

Physical layer one-time-pad data encryption through synchronized semiconductor laser networks

Semiconductor lasers (SL) have been proven to be a key device in the generation of ultrafast true random bit streams. Their potential to emit chaotic signals under conditions with desirable statistics, establish them as a low cost solution to cover various needs, from large volume key generation to real-time encrypted communications. Usually, only undemanding post-processing is needed to convert the acquired analog timeseries to digital sequences that pass all established tests of randomness. A novel architecture that can generate and exploit these true random sequences is through a fiber network in which the nodes are semiconductor lasers that are coupled and synchronized to central hub laser. In this work we show experimentally that laser nodes in such a star network topology can synchronize with each other through complex broadband signals that are the seed to true random bit sequences (TRBS) generated at several Gb/s. The potential for each node to access real-time generated and synchronized with the rest of the nodes random bit streams, through the fiber optic network, allows to implement an one-time-pad encryption protocol that mixes the synchronized true random bit sequence with real data at Gb/s rates. Forward-error correction methods are used to reduce the errors in the TRBS and the final error rate at the data decoding level. An appropriate selection in the sampling methodology and properties, as well as in the physical properties of the chaotic seed signal through which network locks in synchronization, allows an error free performance

Performance enhancement of point-to-point diffuse links at 265 nm under fog conditions

It is known that the tempting features of free space Non-Line-Of-Sight (NLOS) communications systems operating in the Ultraviolet C-band between 200 and 280 nm are the significantly reduced solar irradiance on ground level, the intense scattering and its combination with strong absorption which ensures the covertness against distant eavesdroppers or jammers. In the majority of the experimental surveys that have been published so far, the performance of point-to-point links has been evaluated under clear atmosphere without taking into account the weather conditions. In this work, it is shown that harsh atmospheric conditions due to fog appearance can be advantageous to short distance NLOS transmissions at 265 nm. Initially, the impact of fog on the losses of the diffuse wireless channels was investigated theoretically. Afterwards, an experimental survey of both the losses and the performance of low rate amplitude signals' transmissions for two atmosphere cases followed. Initially, the satisfactory relation between scattering and absorption at 265 nm was verified by deploying outdoor NLOS point-to-point links under clear atmosphere. The transmitter consisted of 4 Light Emitting Diodes and the optical part of the receiver included a filter and a Photo-Multiplier tube. Then, the beneficial impact of artificially generated fog on scattering was exploited not only to enhance the system performance but also to identify the modification of the conditions. The experimental results showed a clear decrease of both the losses and the Bit Error Rate under fog conditions making such a system a perfect candidate for low rate communications under dense atmosphere

Real-time high-bandwidth mm-wave 5G NR signal transmission with analog radio-over-fiber fronthaul over multi-core fiber

This article presents an experimental demonstration of a high-capacity millimeter-wave 5G NR signal transmission with analog radio-over-fiber (ARoF) fronthaul over multi-core fiber and full real-time processing. The demonstration validates the core of the blueSPACE fronthaul architecture which combines ARoF fronthaul with space division multiplexing in the optical distribution network to alleviate the fronthaul capacity bottleneck and maintain a centralized radio access network with fully centralized signal processing. The introduction of optical beamforming in the blueSPACE architecture brings true multi-beam transmission and enables full spatial control over the RF signal. The proposed ARoF architecture features a transmitter that generates the ARoF signal and an optical signal carrying a reference local oscillator employed for downconversion at the remote unit from a single RF reference at the central office. A space division multiplexing based radio access network with multi-core fibre allows parallel transport of the uplink ARoF signal and reference local oscillator at the same wavelength over separate cores. A complete description of the real-time signal processing and experimental setup is provided and system performance is evaluated. Transmission of an 800 MHz wide extended 5G NR fronthaul signal over a 7-core fibre is shown with full real-time signal processing, achieving 1.4 Gbit/s with a bit error rate < 3.8 × 10 - 3 and thus below the limit for hard-decision forward error correction with 7% overhead