The next frontier towards truly ubiquitous connectivity is the use of Low Earth Orbit (LEO) small-satellite constellations to support 5G and Beyond-5G (B5G) networks. Besides enhanced mobile broadband (eMBB) massive machine-type communications (mMTC), LEO can ultra-reliable (URC) with relaxed latency requirements a few tens milliseconds. Small-satellite impairments low orbits pose major challenges design performance these networks, but also open new innovation opportunities. This paper...

Systems of small distributed satellites in low Earth orbit (LEO) transmitting cooperatively to a multiple antenna ground station (GS) are investigated. These satellite swarms have the benefit much higher spatial separation transmit antennas than traditional big with arrays, promising massive increase spectral efficiency. However, this would require instantaneous perfect channel state information (CSI) and strong cooperation between satellites. In practice, orbital velocities around 7.5 km/s...

Non-geostationary orbit (NGSO) satellite constellations represent a cornerstone in the NewSpace paradigm and thus have become one of hottest topics for industry, academia, but also national space agencies regulators. For instance, numerous companies worldwide, including Starlink, OneWeb, Kepler, SPUTNIX, Amazon started or will soon start to deploy their own NGSO constellations, which aim provide either broadband IoT services. One major drivers such high interest on is that, with an...

Low Earth orbit (LEO) satellite constellations rely on inter-satellite links (ISLs) to provide global connectivity. However, one significant challenge is establish and maintain inter-plane ISLs, which support communication between different orbital planes. This due the fast movement of infrastructure limited computation capabilities satellites. In this paper, we make use antenna arrays with either Butler matrix beam switching networks or digital steering ISLs in a LEO constellation....

Satellite communication systems are expected to play an important role in the fifth generation mobile network (5G) for global broadband coverage and service continuity. Constellations with many cooperating small satellites offer great advantages terms of scalability flexibility over traditional satellite few large satellites. Small means less power low complexity per while delivering 5G services as enhanced Mobile Broadband (eMBB) by exploiting Thus, we derive a Distributed Precoding (DiP)...

Direct Low Earth Orbit satellite-to-handheld links are expected to be part of a new era in satellite communications. Space-Division Multiple Access precoding is technique that reduces interference among beams, therefore increasing spectral efficiency by allowing cooperating satellites reuse frequency. Over the past decades, optimal solutions with perfect channel state information have been proposed for several scenarios, whereas robust imperfect has mostly studied simplified models. Such...

The uplink from a very small aperture terminal (VSAT) towards multiple satellites is considered, in this paper. VSATs can be equipped with antennas, allowing parallel transmission to satellites. A low-complexity precoder based on imperfect positional information of the presented. probability distribution position uncertainty and statistics channel elements are related by characteristic function uncertainty. This knowledge included design maximize mean signal-to-leakage-and-noise ratio (SLNR)...

In this paper, we propose a novel approach for downlink transmission from satellite swarm towards ground station (GS). These swarms have the benefit of much higher spatial separation in transmit antennas than traditional satellites with antenna arrays, promising massive increase spectral efficiency. The resulting precoder and equalizer very low demands on computational complexity, inter-satellite coordination channel estimation. This is achieved by taking knowledge about geometry between GS...

Non-terrestrial networks (NTNs), particularly satel-lite networks, are key factors for ubiquitous connectivity in today's 5G terrestrial (TNs) and future 6G networks. They can bring great benefits, but also challenges. The direct-to-cell (D2C) use case, i.e., direct from satellites to common low-gain user terminals (UTs), such as handheld or IoT devices, is currently gaining strong interest. This paper focuses on innovative distributed implementations of the space segment using swarms...

Low Earth Orbit (LEO) satellite-to-handheld connections herald a new era in satellite communications. Space-Division Multiple Access (SDMA) precoding is method that mitigates interference among beams, boosting spectral efficiency. While optimal SDMA solutions have been proposed for ideal channel knowledge various scenarios, addressing robust with imperfect information has primarily limited to simplified models. However, these models might not capture the complexity of LEO applications. We...

The rapid growth of non-terrestrial communication necessitates its integration with existing terrestrial networks, as highlighted in 3GPP Releases 16 and 17. This paper analyses the concept functional splits 3D-Networks. To manage this complex structure effectively, adoption a Radio Access Network (RAN) architecture Functional Split (FS) offers advantages flexibility, scalability, cost-efficiency. RAN achieves by disaggregating functionalities into three separate units. Analogous to network...

Low Earth orbit (LEO) satellite systems enable close to global coverage and are therefore expected become important pillars of future communication standards. However, a particular challenge faced by LEO satellites is the high orbital velocities due which precise channel estimation difficult. We model this influence as an erroneous angle departure (AoD), corresponds imperfect state information (CSI) at transmitter (CSIT). Poor CSIT non-orthogonal user channels degrade performance...

In this paper, a novel distributed precoding (DiP) algorithm for ultra-dense small cell (SC) networks is developed, where the SCs cooperate to perform joint transmission users (UEs) with limited and individual transmit powers. Different most state of art (SotA) DiP algorithms, proposed precoder design based on assumption that each SC has only local channel information (CSI) available. Additionally, there are no constraints number antennas SC, but one constraint sum all antennas. A solution...

The uplink from a very small aperture terminal (VSAT) towards multiple satellites is considered, in this paper. VSATs can be equipped with antennas, allowing parallel transmission to satellites. A low-complexity precoder based on imperfect positional information of the presented. probability distribution position uncertainty and statistics channel elements are related by characteristic function uncertainty. This knowledge included design maximize mean signal-to-leakage-and-noise ratio (SLNR)...

Direct Low Earth Orbit satellite-to-handheld links are expected to be part of a new era in satellite communications. Space-Division Multiple Access precoding is technique that reduces interference among beams, therefore increasing spectral efficiency by allowing cooperating satellites reuse frequency. Over the past decades, optimal solutions with perfect channel state information have been proposed for several scenarios, whereas robust only imperfect has mostly studied simplified models. In...

The next frontier towards truly ubiquitous connectivity is the use of Low Earth Orbit (LEO) small-satellite constellations to support 5G and Beyond-5G (B5G) networks. Besides enhanced mobile broadband (eMBB) massive machine-type communications (mMTC), LEO can ultra-reliable (URC) with relaxed latency requirements a few tens milliseconds. Small-satellite impairments low orbits pose major challenges design performance these networks, but also open new innovation opportunities. This paper...

Systems of small distributed satellites in low Earth orbit (LEO) transmitting cooperatively to a multiple antenna ground station (GS) are investigated. These satellite swarms have the benefit much higher spatial separation transmit antennas than traditional big with arrays, promising massive increase spectral efficiency. However, this would require instantaneous perfect channel state information (CSI) and strong cooperation between satellites. In practice, orbital velocities around 7.5 km/s...

Low Earth orbit (LEO) satellite constellations rely on inter-satellite links (ISLs) to provide global connectivity. However, one significant challenge is establish and maintain inter-plane ISLs, which support communication between different orbital planes. This due the fast movement of infrastructure limited computation capabilities satellites. In this paper, we make use antenna arrays with either Butler matrix beam switching networks or digital steering ISLs in a LEO constellation....