The increasing demand for high-rate broadcast and multicast services over satellite networks has pushed for the development of High Throughput Satellites characterized by a large number of beams (e.g., more than 100). This, together with the variable distribution of data traffic request across beams and over time, has called for the design of a new generation of satellite payloads, able to flexibly allocate bandwidth and power. In this context, this paper studies the problem of radio resource allocation in the forward link of multibeam satellite networks adopting the Digital Video Broadcasting -Satellite -Second Generation (DVB-S2) standard. We propose a novel objective function with the aim to meet as close as possible the requested traffic across the beams while taking fairness into account. The resulting non-convex optimization problem is solved using a modified version of the simulated annealing algorithm, for which a detailed complexity analysis is presented. Simulation results obtained under realistic conditions confirm the effectiveness of the proposed approach and shed some light on possible payload design implications.

SUMMARYMulti-user multiple-input multiple-output (MU-MIMO) has allowed recent releases of terrestrial long-term evolution (LTE) standards to achieve significant improvements in terms of offered system capacity. The publication of the DVB-S2X standard and particularly of its novel superframe structure is a key enabler for applying similar interference management techniques -such as precoding-to multibeam high throughput satellite (HTS) systems. This paper presents results from the European Space Agency-funded R&D activities concerning the practical issues that arise when precoding is applied over an aggressive frequency re-use HTS network. In addressing these issues, the paper also proposes pragmatic solutions that have been developed in order to overcome these limitations. Through the application of a comprehensive system simulator, it is demonstrated that important capacity gains (beyond 40%) are to be expected from applying precoding even after introducing a number of significant practical impairments.

In this paper, interference-aware radio resource management (RRM) algorithms are presented for the forward and return links of geostationary orbit (GEO) high throughput satellite (HTS) communication system. For the feeder link, satellite-switched smart gateway diversity is combined with two scheduling methods to improve the feeder link availability in rain conditions. For the user link, interference-aware scheduling (IAS) for the forward link and scheduling based on multi-partite graph matching for the return link are shown to enable full frequency reuse (FR) multi-beam satellite systems. The performance assessment of scheduling algorithms is carried out in a system-level simulator with realistic channel models and system assumptions. The improvements of the system capacity and user rates are evaluated

DVB-RCS2 is the second generation of DVB standards for the return link in interactive satellite systems, which is combined with the well consolidated DVB-S2 standard, applicable to forward links. This paper presents a DVB-S2/RCS2 testbed, able to reproduce all functionalities specified for higher and lower layers (HL and LL) of the protocol stack, down to the physical layer characteristics, which are instead accounted by means of a channel emulator for both return and forward links. The presented testbed turns out to be a formidable tool for research investigation and overall system design thanks to the implemented features and the flexible architecture, allowing easy reconfiguration and extensions of functionalities according to specific purposes. Some merit figures shown at the end of the paper also prove the possibility to plug the testbed to external systems and carry out performance monitoring/tracking tasks through regular Simple Network Management Protocol (SNMP) agents.

This paper studies the sum throughput maximization of the return-link in multi-beam satellite systems. Considering bursty communication scenarios with different users' data request probabilities, we develop an efficient scheduling scheme using genetic algorithms (GAs). Moreover, we consider co-channel interference (CCI) and adjacent channel interference (ACI). We consider a receiver with and without interference cancelation. Using a simplified channel model, we evaluate the proposed scheduler in a multi-beam system. The proposed GA-based scheduler approaches the throughput of an optimal scheduler based on exhaustive search with substantially less implementation complexity.