Non-geostationary orbit (NGSO) constellations, represented by Low and Medium Earth Orbit (LEO and MEO) satellites, require resource-Allocation frameworks that jointly address payload flexibility and communication performance. This work presents a hierarchical three-stage framework for resource allocation: demand-driven satellite cell coloring (SCC), topology-Aware satellite-cell association (S2C), and multi-satellite beam hopping (BH). Our framework halves the downlink power required to reach 10% unserved capacity (UC) and reduces the peak load on inter-satellite links (ISLs) by approximately 40% compared to a baseline strategy, while controlling cell handovers. The results further show that architectural parameters dominate performance: increasing the number of beams, refining cell granularity, and scaling constellation density enable approximately × , × , and × reductions in power consumption, respectively. These reductions in the required downlink (DL) power and ISL load for a given performance target can be directly translated into system-level gains at payload or constellation size level. The proposed framework provides a scalable foundation for end-To-end optimization of next-generation NGSO satellite networks.

The paper presents a novel optimization approach for resource allocation in non-geostationary orbit (NGSO) satellite constellations employing beam-hopping (BH) payloads for large-scale broadband services. Current literature has proposed several optimization strategies to deal with the intricacies of BH applied to large satellite constellations. However, most works limit their study to only sub-portions of the complete problem, often fixing certain variables, such as frequency or power, or disregarding specific objectives, such as user fairness or excess of allocated resources. To address this gap, this work introduces a novel mixed-integer linear programming (MILP) formulation that integrates all available degrees of freedom, namely, power, frequency, and beam illumination, while optimizing for performance, quality of service and fairness through three objectives: unserved capacity (UC), extra-served capacity (EC), and time-to-serve (TTS). To reduce the computational complexity, an alternative time-split MILP is proposed by partitioning the problem into smaller time-based subproblems. The time-split MILP maintains the performance of the full MILP formulation in larger user scenarios and balances execution time with superior computational performance. Simulations demonstrate that the time-split MILP method surpasses other approaches, including deterministic (DB) and meta-heuristic (GA) solutions. It achieves up to a 6% reduction in UC, maintains EC levels below those of DB and GA in low-user scenarios, and nearly halves the TTS, highlighting its efficiency in resource allocation and service optimization.

Existing research on resource allocation in satellite networks incorporating beam-hopping (BH) focuses predominantly on the performance analysis of diverse algorithms and techniques. However, studies evaluating the architectural and economic impacts of implemented BH-based technical solutions have not yet been addressed. Aiming to close this gap, this contribution quantifies the impact of BH and orbital parameters on the satellite platform and constellation size, considering specific traffic demand and service time indicators. The paper proposes a low complexity, instantaneous demand-based BH resource allocation technique, and presents a comprehensive analysis of LEO and VLEO scenarios using small platforms, lying on 5G/6G Non-Terrestrial Network (NTN) specifications. Given a joint set of traffic demand and time-to-serve indicators, and based on a feasible multibeam on-board antenna architecture, the paper compares the RF transmit power requirements in fixed and variable grid LEO schemes, and in VLEO with different minimum elevation angles, to assess the feasibility of these orbits. For a fixed minimum elevation and number of users, the RF transmit power and satellite platform requirements are significantly reduced when transitioning into lower altitudes with narrower satellite coverage areas. The relevant trade-off between the satellite platform and the size of the constellation required for global coverage is presented, to fulfill a set of traffic demand and time to serve indicators: approximately, 1156 3U satellites are required for VLEO constellation and 182 12U satellites for LEO. Once platform and constellation sizing trade-off is quantified, the paper estimates the economic costs for each of the deployments, showing a total cost of almost the double for the presented VLEO constellation compared to the LEO one. The article aims to provide system engineers and satellite operators with crucial information for satellite system design, dimensioning and cost assessment.

In this paper, the experience of ETSIT-UPM in hands-on nanosatellite activities is presented. Innovate methodologies based on the active participation of students are presented. Projects with the participation of students have proven to be successful if students are motivated and assume responsibilities. Aspects as international collaboration and students motivation are described.

Earth stations for downloading data from LEO satellites use large reflector antennas (usually, with diameters over 12 m for telemetry links). These antennas pose a number of impairments regarding their mechanical complexity, flexibility, network efficiency (only one satellite can be tracked at a time) and cost. In order to improve the performance of traditional earth stations, the feasibility of other antenna technologies must be evaluated. This paper presents a prototype for an antenna array receiver based on software radio applied to satellite communications. The aim of the prototype is to prove the concept of antenna arrays for tracking LEO satellites under different conditions and beamforming algorithms.

Adaptive type smart antennas have not been implemented yet on the deployed UMTS systems, although UTRA-UMTS preview their operation and they also could improve capacity especially in a multiservice environment. This paper describes a set of novel measurement techniques that must be performed to evaluate the correct operation of a smart antenna system in an anechoic chamber. The validity of these new techniques are supported by the measurement results obtained from a real smart antenna prototype for WCDMA.