Satellite communication (SatCom) systems operations centers currently require high human intervention, which leads to increased operational expenditure (OPEX) and implicit latency in human action that causes degradation in the quality of service (QoS). Consequently, new SatCom systems leverage artificial intelligence and machine learning (AI/ML) to provide higher levels of autonomy and control. Onboard processing for advanced AI/ML algorithms, especially deep learning algorithms, requires an improvement of several magnitudes in computing power compared to what is available with legacy, radiation-tolerant, space-grade processors in space vehicles today. The next generation of onboard AI/ML space processors will likely include a diverse landscape of heterogeneous systems. This manuscript identifies the key requirements for onboard AI/ML processing, defines a reference architecture, evaluates different use case scenarios, and assesses the hardware landscape for current and next-generation space AI processors.

Onboard satellite communication systems generate and manage coverage beams over the Earth. Depending on data traffic requirements, the number of beams, side lobe levels, nulls, and EIRP, their beamwidth must be efficiently generated and managed. Therefore, this paper describes an approach for beam pattern synthesis applied to geostationary satellite communication systems. The beam pattern synthesis can generate beams with a beamwidth variation from 0.45° to 1.5°, which can be controlled independently for the two principal cuts. In addition, other requirements have been considered, e.g., latitude, and longitude, required EIRP, minimum and maximum side love levels for the two principal cuts, and nulling direction. The output of the synthesizer is a weight matrix with beamforming coefficients of the required beam. The direct radiating array in this contribution utilizes an open-ended waveguide antenna as unit cell elements with a period of 0.875λ ₀ designed to work in left-hand circular polarization in the frequency band from 17.7 to 20.1 GHz. Since this design is intended for high-data rates applications, the minimum beamwidth requirements are very narrow. Therefore, 36 × 36 sub-arrays of 4 × 4 unit cells with a period of 3.5λ are considered to accomplish the beamwidth requirements while maintaining reduced computational and time resources for the weight matrix calculation compared to the conventional counterpart of 144×144 unit cells. The results show that the algorithm, which uses the surrogate optimizer, can compute the weight matrix and synthesize the beam with a slight deviation from the input data.

Recent advancements in onboard satellite communication have enhanced the capability of dynamically modifying the radiation pattern of a Direct Radiating Array (DRA). This is crucial not only for conventional communication satellites like Geostationary Orbit (GEO) but also for those in lower orbits such as Low Earth Orbit (LEO). Key design factors include the number of beams, beamwidth, Effective Isotropic Radiated Power (EIRP), and Side Lobe Level (SLL) for each beam. However, a challenge arises in multibeam scenarios when trying to simultaneously meet requirements for the aforementioned design factors which are reflected as uneven power distribution. This leads to over-saturation, especially in centrally located antenna elements due to the activation times per beam, commonly referred to as activation instances. In response to this challenge, this paper presents a method to balance the activation instances across antenna elements for each required beam. Our focus is on beams operating at 19 GHz on a CubeSat positioned 500 km above the Earth’s surface. We introduce a Genetic Algorithm (GA)-based algorithm to optimize the beamforming coefficients by modulating the amplitude component of the weight matrix for each antenna element. A key constraint of this algorithm is a limit on activation instances per element, which avoids over-saturation in the Radio Frequency (RF) chain. Additionally, the algorithm accommodates beam requirements such as beamwidth, SLL, pointing direction, and total available power. With the previous key design factors, the algorithm will optimize the required genes to address the desired beam characteristics and constraints. We tested the algorithm’s effectiveness in three scenarios using an $8\times 8$ DRA patch antenna with circular polarization, arranged in a triangular lattice. The results demonstrate that our algorithm not only meets the required beam pattern specifications but also ensures a uniform activation distribution across the antenna array.

Current trends in non-geostationary orbit (NGSO) satellite communications pose the challenge of attaining high spectral efficiency with low-complexity user terminals (UTs). In this context, this letter investigates the downlink/forward transmission of linear space-time block coded (STBC) signals through multiple geographically distributed NGSO satellites. As such, by combining the signals through multiple satellites, STBC provides a diversity advantage, which helps in combating the adverse effects of fading and interference at the UT. The main challenge of implementing such a scheme is the lack of time synchronization and the interference effect through a multi-satellite system toward the UT. To address this issue, we propose a digital receiver structure with multiple branches specifically designed to lock onto each satellite of the multi-satellite system, thus providing a solution for simple UT without requiring additional complexity in terms of radio-frequency components. Herein, we consider the zero-forcing (ZF) based diversity combining scheme while deriving the signal-to-interference-plus-noise ratio (SINR) expression at UT. Our results demonstrate the SINR improvement brought by the ZF combiner.

The non-terrestrial communication industry is required to optimize the use of the available radio frequency (RF) spectrum and, in turn, lower the cost per delivered bit. Full-Duplex (FD) is a widely studied technology in the terrestrial domain, which allows the data transmission simultaneously in both directions of the same frequency channel. In this work, we study and evaluate the feasibility of using FD techniques within SatCom networks. First, a survey of the current state of the art for self-interference cancellation (SIC) techniques and technology is presented, to set the baseline of achievable interference cancellation with currently available technology. Subsequently, different SatCom use cases are identified, including different satellite orbits and types of links, and a detailed feasibility evaluation is carried out through analytical models and simulations. The most promising scenarios are shown to be both LEO feeder and downlink in Q/V and Ka band, respectively, and an on-ground FD between terrestrial and satellite backhauling in Ka-band. To conclude, we identify the technological shortcomings and outline a possible roadmap for developing and implementing the necessary self-interference cancellation methods to facilitate FD communications in the selected use cases.

The Industry 4.0 paradigm conceives a cyber-physical supporting framework for the manufacturing processes in smart factories. In this context, solutions concerning the wired communications at the field-level have been reported which utilize either fieldbuses, which exhibit a huge distance range but a reduced data rate in a bus topology, or Ethernet-based technologies, which provide an increased data rate but reduced distance in a ring topology. To overcome this shortage, we propose the use of orthogonal frequency division multiplexing (OFDM) to significantly increase the achievable data rates over large distances in industrial bus systems. Also, we establish a novel methodology to compute the signal-to-noise ratio between arbitrary pairs of nodes, which in turn allows to compute the communication capacity. Our wideband system was validated by connecting up to 32 nodes in the distance range 100 m–1 km. Compared to fieldbuses, the results of the proposal exhibit an amazing improvement in data rate of about fifty times for 100m distance and more than ten times for 0.5 km. Moreover, with respect to Ethernet-based solutions, the results show a relevant improvement in the data rate of around five times for 100m distance, but Ethernet-based systems cannot go beyond this distance, to which our proposal is not limited.