Microwave and High-Speed Photonics Applications to 6G Systems

The evolution towards the 6th mobile systems Generation (6G) will be characterized by several factors, among which it is possible to identify two significant trends for the topics of this paper: i) the always increasing Bandwidth (BW) and high data rates, and ii) the increasingly complex radio systems architecture. The former will lead to exploit centimeter-wave (∼ 7-15 GHz), millimeter-wave (∼ 26-43 GHz) and sub-Terahertz (∼ 90-300 GHz) frequencies to achieve ultra-high data rates on air. This means that radio hardware platforms will have to support processing volumes of the order of several hundred Gbit/s up to 1 Tbit/s. The latter will make more intensive use of massive Multiple-Input Multiple-Output (MIMO) and beamforming technologies, already introduced in the 5th mobile systems Generation (5G), which will require a very high number of radiating elements, leading to high complexity and energy consuming radio systems. In this scenario, high-speed optical transmission systems, integrated photonics for interconnection systems in high-bandwidth-density hardware platforms, co-packaged optics, advanced photonic communication systems on integrated optical waveguides, radio-over-fiber transmission systems, and microwave photonics components for implementing radio functions (currently dominated by microwave technologies) will all play a critical role, and in some cases, drive disruptive innovation for future 6G radio systems. Extending its traditional definition, in this paper we will refer to all these technologies as Microwave Photonics (MWP), intended as the set of critical photonic technologies, often associated with integrated photonic technologies, contributing to the realization of future radio systems.