HydRON (High thRoughput Optical Network) is a project of the European Space Agency (ESA) initiated in 2019. HydRON ambitions to extend high-capacity terrestrial networks into space, seamlessly and by interconnecting all kind of space assets across different orbits and terrestrial networks (i.e., 3-dimensional optical network). The targeted capacity performance is orders of magnitude greater compared to today's satcom systems (terabit/sec in contrast to gigabit/sec). This paper will present an overview of the HydRON-DS concept, including a summary of the technical baseline and associated programmatics submitted for approval at the ESA Ministerial Council in 2022.

In the last five years, the satellite community has witnessed growing interest in the delivery of Broadband Services from non-geostationary orbit (NGSO) systems. However, accessing the entire spectrum available without having to share it among the different operators is key for these systems to have a chance of breaking even, which makes for a challenging business case. This paper focuses on the challenges of spectrum coexistence of multiple satellite constellations for broadband communications and proposes a radio resource management algorithm to enable such coexistence.

In this paper, we investigate the possible satellite's role and technical solutions required for providing broadband services complementing the terrestrial fifth generation wireless standards. First, we review the satellite networks use cases, services, and system requirements. Then we investigate the satellite potential purpose for broadband service provision and the associated challenges with focus on the system and space/ground technological aspects. Different architectural satellite network solutions are illustrated jointly with the key system design trade-offs. Particular emphasis is dedicated to the payload architecture. Finally, we illustrate the space and ground segment technologies enabling the successful satellite contribution to broadband services provision.

The next generation of terrestrial radio communications, so-called fifth generation (5G) New Radio (NR), beyond the traditional bands below 6 GHz, has been also specified to operate over millimeter waves (mmWaves), in the so-called Frequency Range 2 (FR2). Such frequency bands have been since decades the `natural habitat' for fixed satellite services (FSS). In this new landscape, this paper preliminary investigates the feasibility of non-geostationary orbit (NGSO) satellites directly accessing NR-enabled User Equipment (UE) in mmWaves, from a regulatory, UE characteristics, space segment, link budget and system point of view. It also identifies future R&D needs in this area.

This paper presents a novel concept for offering payload resources flexibility in High Throughput Satellite (HTS) systems. The concepts makes joint use of two advanced techniques, namely beam hopping and precoding. The combination of these two techniques allows the system to really optimize the performance of beam hopping in terms of capability to follow the temporal and spatial variation of user traffic requests within the coverage. The performance of such an approach is demonstrated through computer simulations of an exemplary system. A similar approach can also be used by combing precoding with frequency flexible techniques. Additional combination of on-board power pooling techniques helps to further improve the system performance.

This paper focuses on frequency reuse schemes combined with the transmission on multiple polarizations in fixed satellite communication systems. A traditional 4 colours frequence reuse scheme realized on two orthogonal polarizations is compared to two alternative approaches allowing to increase drastically the achievable system throughput. The first alternative approach is using a 2 colors frequency reuse scheme on two orthogonal polarizations, while the proposed novel strategy is based on the use of 4 colours built transmitting signals on 4 nonorthogonal polarizations. The performance is estimated via a software simulator based on a link budget done over the service area. The main performance indicators are the coverage area and the total network capacity. The results of this analysis show a substantially equal capacity provided by the two alternative frequence reuse schemes, while an improvement of the service coverage is achieved by the non-orthogonal frequency reuse system.

The growing demand for two-way broadband satellite services has pushed for the development of the DVB-RCS2 standard to improve the performance of the reverse link. Among the enhancements brought by the new standard, a wide range of modulation and coding schemes allows Interference and Fading Mitigation Techniques (IFMTs) to more efficiently exploit the diverse temporal and geographical propagation channel attenuations. In addition, the rich intra-system interference environment typical of large multi-spot beam network with high frequency re-use, and the constraints on the desired user QoS, call for a clever combination of different techniques. However, the effective implementation of the techniques is not trivial and the consequent benefits require the exploitation of complex computer-based system simulation tools. In this paper we compare the performance obtained for a DVB-RCS2 system using Adaptive Coding and Modulation (ACM) with those ones achieved by combining Dynamic Rate Adaptation (DRA) and ACM. The considered reference system is ka-band multi-spot beam network, which is deemed to follow within the next few years the current generation of ka-band HTS (High Throughput Satellites) networks.

The support of high capacity broadband multi-beam satellite networks requires the implementation of a large number of gateways to cope with the high feeder link throughput generated by the large number of satellite user beams. Although today the state-of-the-art satellite broadband systems exploit Ka-band for the feeder link, to further increase the system capacity Q/V-band exploitation will be required. When exploiting Ka or Q/V-band (the latter in particular) gateway site diversity becomes a must to ensure the required high feeder link availability. Conventional site diversity is too onerous when the number of gateways is large as it is doubling the number of system gateways. The novel Smart Gateway Diversity Concepts (SGC) described in the paper are representing possible ways to exploit the inherent presence of multiple physically separated gateways in high capacity systems to achieve the required feeder link capacity minimizing the number of required gateways. The key idea is to exploit the inherent presence of several spatially separated gateways to cope with the required large feeder link bandwidth to achieve the required fading link availability. This requires gateway interconnection and ad-hoc payload architectures allowing seamless user traffic hand-off from the faded gateway(s) to the unfaded ones. In current systems each gateway serves a distinct cluster of beams thus this approach is not possible. The proposed smart gateway schemes allow to significantly reducing the cost of the ground segment (number of gateway antennas and associated RF front-end). Depending on the SGC scheme, a certain level of the transparent payload complexity increase is required. Some payload reconfigurability will be in any case required to support the need for gateway switchover to a redundant one in case of failure. Furthermore, all the proposed payload architectures are all analogue and exploits technologies readily available. The paper provides a detailed description of the different Smart Gateway Diversity Concepts and associated architecture for the ground and space segment.

SAT-AIS is gaining momentum thanks to the push of the users and to the different ongoing institutional and private initiatives. System performance characterization is a central task for the system design, as the constellation has to be sized efficiently to meet the user requirements. However due to the complexity of the systems, often composed of more than 10 satellites in a LEO constellation, this characterization can be extremely time consuming when a full processing approach is undertaken. This paper presents a method for extrapolating the system performance of a SAT-AIS constellation based on a partial characterization of the detection technology onboard the satellites of the constellation. An extensive validation of the extrapolation technique was carried out thanks to the valuable data collected by ESA in the frame of the Comparative Performance Assessment (CPA) carried out between the end of 2011 and beginning of 2012. Thanks to these data, the method was tested against full processing simulations for different systems, and was proven to be extremely accurate.

Reliable communications are a fundamental means to manage in an effective manner public protection and disaster relief (PPDR) operations, especially in the first hours during the response phase. This paper investigates the expected performance of a physical layer for mobile satellite services based on the LTE specifications, properly adapted to suit the mobile satellite channel and thought to satisfy the current needs of PPDR users. In particular, the effect of the land mobile satellite (LMS) channel frequency selectivity is considered in terms of impacts on the LTE uplink PHY layer performance, as LMS greatly differs in this aspect with respect to the terrestrial mobile channel.

The paper addresses the integration architecture (I-concept) between a terrestrial technology—TETRA (TErrestrial Trunked Radio)—and satellite systems. This approach, that enhances and harmonises the features of both technologies, could provide an interesting contribution to the effectiveness of the International Mobile Telecommunications-Advanced (IMT-A) and, hence, to the 4G vision. TETRA can represent an interesting building block of an integrated network devoted to both civil and military scenarios; it meets the “suitable technological capability” requirement for integration, because it represents a consolidated terrestrial technology that can be trusted, hence focusing the integration effort on the definition, design and implementation of proper interfaces. System architectures are here proposed referring to short, medium term and long term scenarios.

The future of systems and applications to be developed on either a global or a local scale is increasingly related to an advanced implementation of the so called "Integration concept" (I-concept). The latter can be defined as an approach to the conceivement of systems and applications that is not polarised in terms of technology and medium. The I-concept envisages, for instance, the effective exploitation of wireless or wired connections, the wise mix of satellite, terrestrial and stratospheric technologies to provide optimal system performance at both user and provider level. In this frame, TETRA (terrestrial trunked radio) can be an interesting building block of an I-concept-based network devoted to both civil and military scenarios. In particular, TETRA meets the "suitable technological capability" requirement for integration, because it represents a consolidated terrestrial technology that can be trusted, hence focusing the integration effort on the definition, design and implementation of proper interfaces. In this paper the present status of TETRA technology and its integration with other platforms is presented and framed in the I-concept based general vision. A system analysis is also carried out proposing system architectures referring to two different scenarios, in a medium term and long term perspective.

In this paper, the main trends of the latest space missions will be outlined, dealing with the advantages of using W-band in space communication systems. In the first part, an overview of the current projects involved in the study of W-band is shown, highlighting the reasons of its future widespread.([1][2])