Ricerc@Sapienza

We consider the problem of managing a 5G network composed of virtualized entities, called Reusable Functional Blocks (RFBs), as proposed by the Horizon 2020 SUPERFLUIDITY project. The RFBs are used to decompose network functions and services, and are deployed on top of physical nodes, in order to realize the 5G functionalities. After formally modelling the RFBs in a 5G network, as well as the physical nodes hosting them, we formulate the problem of managing the 5G network through the RFBs, in order to satisfy different Key Performance Indicators (KPIs) to users.

We target the problem of providing 5G network connectivity in rural zones by means of Base Stations (BSs) carried by Unmanned Aerial Vehicles (UAVs). Our goal is to schedule the UAVs missions to: i) limit the amount of energy consumed by each UAV, ii) ensure the coverage of selected zones over the territory, ii) decide where and when each UAV has to be recharged in a ground site, iii) deal with the amount of energy provided by Solar Panels (SPs) and batteries installed in each ground site.

5G-specific features, such as massive deployment, heterogeneity, and coexistence, call for innovative dynamic spectrum management mechanisms. Context-aware interoperability and interference control, and their integration, may be crucial to comply with spectrum efficiency and service optimization 5G requirements.

Motivated by recent theoretical challenges for 5G, this study aims to position relevant results in the literature on codedomain non-orthogonal multiple access (NOMA) from an information-theoretic perspective, given that most of the recent intuition of NOMA relies on another domain, that is, the power domain. Theoretical derivations for several code-domain NOMA schemes are reported and interpreted, adopting a unified framework that focuses on the analysis of the NOMA spreading matrix, in terms of load, sparsity, and regularity features.

Spectral efficiency of low-density spreading nonorthogonal multiple access channels in the presence of fading is derived for linear detection with independent decoding as well as optimum decoding. The large system limit, where both the number of users and number of signal dimensions grow with fixed ratio, called load, is considered. In the case of optimum decoding, it is found that low-density spreading underperforms dense spreading for all loads. Conversely, linear detection is characterized by different behaviors in the underloaded vs. overloaded regimes.

A novel dielectric resonator antenna (DRA), working at 28 GHz with a peak gain of 12.4 dBi over a fractional bandwidth of 12.6%, is presented. The novel design achieves side-lobe levels below -10 dB for both the E and H-planes so to meet the requirements of the new generation 5G wireless communications systems.