In envisioning the frame of future Mars exploration missions, the need for a new series of communications services and performance has become essential. Future missions indeed will carry scientific instruments with higher resolution, higher performance producing higher data volumes to be transmitted to Earth for analysis. SAR, sounder or imaging and high resolution optical instruments are among the most generating data envisaged instruments.

In addition to orbiting systems, future users on the Mars planet will need a data exchange infrastructure and multiple access services. Landers, rovers, and possible human outposts will all need a communication service either local, within themselves, and or with Earth stations. Specifically for the surface, communications dedicated links are being studied to support both design simplicity and data transmission efficiency. These high data volumes, greater than 100 Gbit per day to be transmitted, necessitate of a dedicated communication system specifically designed to operate on Mars orbital ambient.

A system based on a Mars orbiter dedicated to communication - that could also include an on-board scientific payload - is being studied with analysis and definition of possible mission scenarios which will lead to definitions of main links:

• Direct to Earth (DTE) link: it will allow the exchange of large data volumes with Deep Space Network ground stations.

• Proximity Link: it will communicate with Mars surface, interacting with landers, rovers and future surface potential assets as well as connect the orbiter with other potential relay satellites of orbiters in Mars orbit.

DTE link are being defined operating primarily in X/Ka-band and with data transmission above 10 Mb/s. While for the proximity link on Mars both UHF and X-band are considered primary, Ka-band and optical links will be part of a trade-off study to be defined taking into account the evolution of the exploration mission.

As stated by a NASA administrator, “NASA, International Partners, and commercial partner are going forward to the moon. With Artemis, we will be exploring more of the Moon than ever before, and this time we are planning to stay. We will be demonstrating new technologies, capabilities, and business approaches needed for future exploration of Mars.” To support the complex, Artemis exploration campaign envisioned, the Gateway program is developing a communication network orbiting the Moon. Gateway will provide relay communication paths and radiometric tracking between crewed and robotic systems on the lunar surface or in cis-lunar space to mission control on the Earth. This paper is a high-level description of Gateway's communication and ranging capabilities, the motivation and use of internationally developed interoperability standards, potential upgrade opportunities, and challenges as Gateway enables technology to support future Mars exploration.

Human activity in the vicinity of the Moon is expected to increase in the near future. Gigabit-class communication links are needed that can handle the long distance between the Moon and the Earth. Optical communications offer a number of advantages compared with radio frequency communications. This paper proposes the first concept for providing continuous gigabit communication links between the Moon and a geosynchronous Earth orbit-based data relay platform along with link analyses for several link scenarios.

Leveraging a mixture of government-owned and commercial Satellite Communication (SATCOM) systems to provide global coverage with improved network throughputs and reliability has attracted attention from both academia and industry for years. However, utilizing multiple SATCOM services simultaneously through different satellite networks requires sophisticated traffic management due to large differences in connection properties. For example, commercial Non-GeoStationary Orbit (NGSO) Satellite Communication (SATCOM) networks have advantages of higher network throughputs, much lower propagation delay and more flexible on-demand services compared to Geosynchronous Equatorial Orbit (GEO) SATCOM systems. Global Network Access Terminal (GNAT) is considered herein as a potential solution designed and developed to provide Internet access utilizing multiple SATCOM services for improved throughput, delay, and reliability.

In this paper, we propose a novel intelligent dynamic network traffic management solution based on Deep Reinforcement Learning (DRL) to better distribute the application traffics to different SATCOM networks. Specifically, we employ DRL to the GNAT control unit to generate a policy that maps measured network states to the optimal traffic distribution. The GNAT system periodically measures the network states, in terms of bandwidth and latency and determines the actions on distributing the traffic flows toward better network performance. Besides, the DRL-based solution will initially learn a policy and then improve this policy by continuously interacting with the GNAT system. To evaluate our solution and facilitate further research, we implement a testbed consisted of the GNAT hardware integrated with our proposed solution and a simulated network environment. Evaluation results are presented to prove that our solution outperforms the state-of-the-art techniques.

We define satellite trunking services as the provision of high data rate point-to-point links for professional use (B2B). The review of the global market for high-speed satellite trunking services shows an expected and sustained growth in the next five to ten years. Among the seven market segments that we have identified, the fastest growing segment will be in-flight connectivity for passenger aircraft. The demand for better connectivity on board cruise ships will make this the second-largest segment. Clearly, there is an opportunity to develop a global satellite system to provide high-speed trunk services. The equatorial MEO constellation of O3b has already shown the way. Through an ESA supported study, “Next Generation High Data Rate Trunking Systems”, an inclined MEO constellation has been identified and studied. Technically innovative and performing, it has also shown that it is economically viable. The system includes a 24-satellite MEO constellation with three 50 deg.-inclined orbits and a distribution/feeder ground network of 80 gateways worldwide spread over 20 sites. Satellites carry a powerful payload (500kg/5kW) operating in Ka-band. Each payload provides a User mission connecting aircrafts and vessels with 175 agile narrow beams and a Feeder mission linking ground gateways in two steerable beams. The Ka-band allocated to NGSO systems is shared between User mission and Feeder mission. The payload is based on next generation technologies such as active planar Direct Radiating Antennas (DRA), Digital Beam-Formers Networks (DBFN) embedded in Digital Transparent Processor (DTP). The business model consists in the wholesale of volume of data (GByte) by the satellite operator, owner of the constellation and its feeder segment, to specialized Internet Service Providers who are active in aeronautical and maritime Internet Access markets. Although very expensive, the constellation and its large feeder ground network achieves profitability for wholesale prices of the same order of magnitude as those identified as affordable by service providers in the next five years. This paper describes the global satellite trunking services and traffics, the MEO constellation and its feeder segment and it demonstrates the economic viability.

In this paper, we propose a gateway selection algorithm for radio and optical hybrid satellites considering weather condi-tion to maximize system throughput. To accommodate large number of communication requests, more and more capacity of satellite communication systems has been required to pro-vide communication links for remote area. To this end, com-bining radio and optical links can improve system throughput with high reliability. In radio and optical hybrid satellite com-munication systems, it is important to utilize site diversity technology and to change network structure according to weather condition and link status. In this paper, the radio and optical hybrid system is firstly modelled and problem setting to obtain gateway selection is described. Then, we propose an algorithm to solve the gateway selection problem based on weather condition and desired utilization ratio of radio and op-tical links. Finally, we conducted numerical simulations and verified the basic functions of the proposed algorithm.

Dr. Claude Shannon developed his famous channel capacity theorem for additive white Gaussian noise (AWGN) channels. In a multi-beam high throughput satellite (HTS) system with colour reuse, channel induced impairments are not limited to noise but include substantial intra-system colour reuse interference that corrupts the intended signal. In this article, I examine HTS system channels, signals and interferers, and derive the HTS system Shannon channel capacities in theory. In the process, I clarify the theoretic foundation for the interference Gaussian distribution assumption from information theory perspective which is missing in the HTS capacity literature. I then apply probability theory to obtain average channel capacities over traffic and mobility caused interference power level uncertainties. The work extends original Shannon capacity theory to the HTS systems which allows HTS channel and system capacity estimation without the costly measurements data. It completes the study by including sample examples from a simulated HTS system with a user service coverage area of continental US to showcase the application of the theoretic development. The paper complements and refines the studies on the topic in similar works in the HTS literature.

In trending satellite communication applications, the traffic demand is not only rapidly increasing, it is also spatiotemporally evolving. This motivates the deployment of high throughput satellite systems with flexible radio resource management and transmission techniques. In contrast to regular beam layout plans (RBLP) currently used in GEO payloads, future flexible payloads are capable of dynamic beamforming (DBF) in order to illuminate the coverage area using highly-directive and traffic-adaptive beampatterns. The beampatterns in an adaptive beam layout plan (ABLP) can have irregular shapes and mutual overlaps, potentially causing excessive inter-beam interferences (IBI) compared to the RBLP case. In this work, we evaluate the combination of DBF and precoding as the latter promises high throughputs in interference-limited conditions and is supported by the recent DVB-S2X norm. Under realistic non-uniform traffic patterns, we compare a typical RBLP against an ABLP in terms of their traffic matching performances with and without precoding. Through the comparisons, we show that DBF enables to significantly reduce the capacity mismatches using an ABLP that uniformly balances the demand distribution across beams. Noting that the ABLP is IBI agnostic, an unpredictable interference environment is built. In such conditions, precoding enables to reliably provide high throughputs through full frequency reuse.

Phased array antennas are widely used in LEO communication systems. This hold for ground terminal antennas and LEO satellite antennas. Main purpose of phased array antennas is the electrical steering of the antenna without using mechanical devices. The drawback of such configurations is the discrete set of pointing vectors among the antenna controller can select the best suited steering. This paper shows how discrete beam pointing can reduce the average data rate of LEO satellite downlink connections.

The Narrowband Internet Of Things, better known by the acronym NB- IoT, is spearheading 3GPP's effort to address the massive Machine Type Communication (mMTC) segment of 5G. With 103 deployments in more than 40 countries, NBIoT's performance in terms of cell capacity, battery life and coverage are well established in the terrestrial world. Recognizing the capability of satellite systems to offer wide coverage and enable cross-countries deployment, 3GPP is considering 5G technologies to support Non-Terrestrial Network (NTN). However, the performance of NB-IoT has to be re-evaluated in a satellite context, especially because there are so many different systems. In this paper, we consider the necessary adaptations to the NB-IoT mechanisms to support the satellite context and we assess its performance for different satellite systems, focusing on the capacity and the energy consumption. Finally, we compare the systems in terms of power and cost efficiency, taking into account a wide range of system metrics such as service lifetime and usage ratio.