The core of this research is conceptual aspects for the optimization of RRM in heterogeneous networks (HetNets) based on small cells providing high data rates with low rate requirements to mobile broadband and machine traffic at a reduced cost. CONQUEST addresses the optimization of the capacity trade-off in Small Cells for the 5G technology and investigates aspects of spectrum sharing in both terrestrial cellular scenarios and heterogeneous networks (HetNets) with drone small cells. It is an exploratory research collaboration between Prof. Jon Peha team in CMU (Departments of Electrical and Computer Engineering / Engineering and Public Policy), and two main Portuguese research teams, one from Instituto de Telecomunicações (IT), led by Prof. Fernando Velez, from IT-UBI, and another from University of Coimbra (CISUC), led by Prof. Edmundo Monteiro. The CMU team will mainly contribute with knowledge on spectrum sharing and public policy in the management of spectrum.

Two scenarios are addressed. In the first scenario, a C-RAN architecture, with a full centralize structure, with RRH connected to a virtualized BBU pool is consider. This scenario explores several advantages from a C-RAN architecture with CA between non- contiguous frequency bands. The level of performance achievable using CA over fragmented spectrum will be compared to the performance achievable with independent carriers over multiple non-contiguous blocks. Above and beyond LTEAdvanced systems applying Orthogonal Frequency Division Multiplexing Access (OFDMA), the research will also address new air interfaces based on filter bank technology, referred to as Filter Bank Modulation Carrier (FBMC), as it shows much better much better interference behaviour than its predecessor, based on OFDM modulation. Differently form LTE-A, considering FBMC will facilitate to use bandwidths, wider than 20 MHz, thus allowing for SC operation with bandwidths of the order of 100 MHz (or more), at the millimetre wavebands (e.g., 28, 40 or 60 GHz).

As the scarcity of available spectrum comes from the outdated spectrum policies, where current allocated spectrum is highly underutilized, in the second scenario, rather than spectrum splitting, the research will explore spectrum sharing between SCs, with or without coordination, considering licensed spectrum, licensed shared spectrum and unlicensed spectrum, within an environment where two mobile operators operate at the macro cellular layer of the mobile network in dedicated spectrum. Here sharing can be cooperative or coexistence/opportunistic, regarding to the user application QoS requirements. CONQUEST addresses the optimization of the capacity trade-off in Small Cells for the 5G technology and investigates aspects of spectrum sharing in both terrestrial cellular scenarios and heterogeneous networks (HetNets) with drone small cells.

In the Portuguese side, the IT-ISCTE team will mainly contribute on drones small cells and their real demonstration, business strategies and entrepreneurship, IT-Covilhã (Cv) will contribute in the remaining key areas of the project research, implementation and demonstration (including hardware programming of the solutions, e.g., in USRPs). CISUC, the team form University of Coimbra will mainly contribute on aspects of opportunistic access and cognitive radio (sensing, MAC sub-layer protocols).

Achievements of the CONQUEST exploratory project include not only aspects of Licensed Shared Access in HEtNets with Small Cells but also the investigation of the impact in the system capacity of considering the two-slope characteristic of the propagation (and the comparison of the promising millimeter wavebands, for the shortest coverage distances, in Small Cell deployments). Efforts also includes the in depth research on the increase of efficiency in the use of spectrum and infrastructure for multi-network access, as well as answering to the challenges of spectrum management in 5G Drone Small Cells, the research conducted by Prof. Pedro Sebastião, from IT. A Workshop and Tutorial Day on "Communications, Public Safety and Innovative Applications with Aerial Drones" is being organized by the CONQUEST team, to be held in the Heaquarters of Ordem dos Engenheiros, in Lisbon, co-located with ConfTele 2019 (June 26th-28th).

The six main tasks of the CONQUEST project are the following ones:

1-Project Management, Communication and Scientific Dissemination.

2-Analytical Formulation for the Carrier-to-Noise-plus-Interference Ratio:

In this task, we will perform analytical formulation for signal-to-interference-plus-noise ratio (SINR) in a macro and micro-urban environment, where the macro/micro-cellular layer of an HetNet is populated with different small cells, from one or several operators, either considering that the spectrum resources are exclusively by one operator/carrier or there is a mix of exclusive ownership and shared spectrum (which can be used for carrier aggregation purposes).

3-Carrier Aggregation Between Two Licensed Frequency Bands in Hetnets with Small Cells:

This research addresses the optimization of multi-band scheduling for CA in an HetNet with either a macro (or micro) cellular on top of the SC layer. This scenario considers dedicated frequency bands in both layers (SC and macro/micro) where a C-RAN architecture, as addressed in 3GPP scenario 4 is considered.

4-Implications of RRH and Small Cells in Spectrum Sharing:

This WP will analyse the characteristics of baseband architectures on spectrum sharing scenarios with SCs. Subtasks are identified in 4a - Exclusively Shared Band (3.5 GHz, mmWaves). Shared Licensed Spectrum/Coordinated Shared Access.

5-Computational Geometry and Mapping Tool for the Planning/Optimization of SCell Deployment and Frequency Assignment:

As operators/carriers intend to locate their Small Cells close to the users that close by hotspots of the multimedia traffic, one will use an approach where the geographic information of current eNBs, base stations and WiFi Access Points will be considered. By means of considering the MATLAB mapping tool (or another similar to this one), the position of the existing infrastructure will be determined, and then considered for the choice of the placement/deployment of the SC cell layer eNBs (i.e., pico-cells).

6-Optimization of the Cost/Revenue Trade-off and Business Strategies: