We provide a broad overview of current quantum communication by analyzing the recent discoveries on the topic and by identifying the potential bottlenecks requiring further investigation. The analysis follows an industrial perspective, first identifying the state or the art in terms of protocols, systems, and devices for quantum communication. Next, we classify the applicative fields where short- and medium-term impact is expected by emphasizing the potential and challenges of different approaches. The direction and the methodology with which the scientific community is proceeding are discussed. Finally, with reference to the European guidelines within the Quantum Flagship initiative, we suggest a roadmap to match the effort community-wise, with the objective of maximizing the impact that quantum communication may have on our society.

This paper aims to give an outlook of future advanced antenna systems for 5G and 6G wireless networks. The trend to increase the peak data rate and to reduce latency and power consumption will continue in the future. This will be made possible by the exploitation of millimeter wave frequency bands and by the introduction of massive multiple-input multiple-output antenna technology which requires a transformation of the antenna hardware architectures and technologies. Advanced antenna systems based on arrays of several hundreds of antenna elements are under development and to keep the fronthaul throughput manageable, some digital signal processing functions have been moved inside the antenna, creating the need to distribute very big volumes of data at high bit rate across the antenna. The characteristics and hardware architecture of future advanced antenna systems are discussed and the relevant interconnect requirements are presented. A new type of monolithically integrated optical transceiver is presented, integrating electronic and photonic circuits on the same chip with high bandwidth density, high energy efficiency and low latency. The transceiver technology is discussed and results of experimental demonstrations are given.

The evolution beyond 5G towards 6G will accelerate the transformations begun by 5G to deploy new approaches to define delivery services. The network should be accessible anywhere, always-on and with the guarantee performances. This poses new challenges to the transport network that should assure available connectivity among the functions at different levels of granularity. The transport network should be so flexible to guarantee on-demand the connectivity among the processing functions that automatically will be required and, at the same time, should assure extreme performance. Optical network and Dense Wavelength Division Multiplexing technology are relevant candidates to match high bandwidth and low latency, but new challenges are required to assure the suitable cost and size for the wireless access networks. The current optical technology, suitable used in aggregation and long-haul transport network, cannot be simply downsized to be used in the access area, but novel paradigm should be considered for the optics as well. Integrated photonics seems a promising direction to realize low cost and low size optical components for the transport network. Moreover, this technology enables a certain level of remote tunability and reconfiguration of optical equipment that allow to simplify and reduce cost of installation in field and operation of the transport network. In this paper relevant optical components for transport networks are analyzed using the integrated photonics to assess the technology challenges.

In a central light seeded PON, it is shown that the resilience to the Rayleigh backscattering can be strongly different for NRZ or RZ-direct modulated R-SOAs at the OLT. It is experimentally demonstrated that the RZ modulated signal has an increased tolerance to the in-band crosstalk compared to NRZ format, thanks to the spurious chirp. Error-free uplink communications down to 10 dB signal-to-crosstalk level are obtained.

Here, we report on the design and performance of a silicon photonic micro-transceiver required to operate in 5G and 6G environments at high ambient temperatures above 105 °C. The four-channel “IOCore” micro-transceiver incorporates a 1310 nm quantum dot laser system and operates at a data rate of 25 Gbps and higher. The 5 × 5 mm micro-transceiver chip benefits from a multimode coupling interface for low-cost assembly and robust connectivity at high temperatures as well as an optical redundancy scheme, which increases reliability by over an order of magnitude.

The paper provides a review of the Xhaul network in terms of architecture, transmission, switching and service provisioning automation, with the objective to illustrate the state of the art and indicate the open issues to be addressed. Xhaul is the new transport network segment that covers the first 15-20 km from the access site, replacing today point-to-point fronthaul connections. Due to the high level of capillarity of deployed equipment in this network segment, a simple downsize of the technology used in metro and aggregation networks cannot achieve sufficient cost effectiveness: cost reduction, both in opex and capex, must indeed not compromise the demanding requirements of low latency and high bandwidth. Enabling service convergence is the key feature of Xhaul. The considered network scenario starts from an initial phase, where the Xhaul infrastructure is designed to carry only mobile fronthaul and backhaul traffic, evolving to support enterprises services, as well as vertical services. Such a convergent infrastructure has to support any kind of 5G service, including massive Machine Type Communication (mMTC), extreme Mobile Broad-Band (eMBB), and Ultra-Reliable Low Latency communication (URLLC). The most important challenges and significant features are illustrated through relevant examples and experiments.