Satellite System Architecture Research Articles

COMPASSO mission and its iodine clock: outline of the clock design

One of the limiting factors for GNSS geolocation capabilities is the clock technology deployed on the satellites and the knowledge of the satellite position. Consequently, there are numerous ongoing efforts to improve the stability of space-deployable clocks for next-generation GNSS. The COMPASSO mission is a German Aerospace Center (DLR) project to demonstrate high-performance quantum optical technologies in space with two laser-based absolute frequency references, a frequency comb and a laser communication and ranging terminal establishing a link with the ground station located in Oberpfaffenhofen, Germany. A successful mission will strongly improve the timing stability of space-deployable clocks, demonstrate time transfer between different clocks and allow for ranging in the mm-range. Thus, the technology is a strong candidate for future GNSS satellite clocks and offers possibilities for novel satellite system architectures and can improve the performance of scientific instruments as well. The COMPASSO payload will be delivered to the international space station in 2025 for a mission time of 2 years. In this article, we will highlight the key systems and functionalities of COMPASSO, with the focus set to the absolute frequency references.

A Novel Dissemination Protocol to Deploy Opportunistic Services in Federated Satellite Systems

Earth Observation applications are demanding higher spatial resolution and shorter revisit times than existing systems, which can be met by ad-hoc constellations of Federated Satellite Systems. These systems are distributed satellite architectures which rely on the collaboration between satellites that share unused resources, such as memory storage, computing capabilities, or downlink opportunities. In the same context, the Internet of Satellites paradigm expands the federation concept to a multi-hop scenario, without predefining a particular satellite system architecture, and deploying temporal satellite networks. The basis of both concepts is the offer of unused satellite resources as services. Therefore, it is necessary that satellites notify their availability to the other satellites that compose the system. This work presents a novel Opportunistic Service Availability Dissemination Protocol, which allows a satellite to publish an available service to be consumed by others. Details of the protocol behavior, and packet formats are presented as part of the protocol definition. The protocol has been verified in a realistic scenario composed of Earth Observation satellites, and the Telesat mega-constellation as network backbone. The achieved results demonstrate the benefits of using a protocol as the proposed one, which in some cases even doubles the amount of data that can be downloaded. To the best of our knowledge, this proposal is the first protocol that allows deploying opportunistic services for Federated Satellite Systems.

Assessment of Satellite Contacts Using Predictive Algorithms for Autonomous Satellite Networks

Upcoming Low Earth Orbit Satellite Networks will provide low-latency and high downlink capacity necessary for future broadband communications and Earth Observation missions. This architecture was proposed at the beginning of the 90's, although it has just recently re-gained popularity thanks to the so-called Mega-Constellations. This network is composed of satellites that have Inter-Satellite Links (ISL) to communicate between them. Due to the satellite motion, an ISL is a temporal contact between two satellites characterized by a lifetime in which the communication remains feasible. The determination of a route between distant satellites is a challenging problem in this context. However, the satellite follows a well-known deterministic orbit trajectory, being feasible the prediction of its position by propagating a trajectory model over time. The Contact Graph Routing protocol uses this feature to determine the evolution of the routes by pre-computing on-ground a planning of the satellite contacts. This centralized ground-dependent solution cannot be directly applied in the Internet of Satellites paradigm, which proposes the autonomous deployment of heterogeneous satellite networks without pre-assuming any specific satellite system architecture. Following this concept, the present work proposes a distributed algorithm by which a satellite predicts neighbor contacts, and generates a global contact plan without trajectory propagation. To achieve this solution, an ISL has been modeled as a “close approach” between two satellites, which is characterized by their relative motion. The present work details the predictive algorithm, and evaluates its performance in two scenarios with a hybrid satellite constellation and a mega-constellation.

Interference-Aware Radio Resource Management for Cognitive High-Throughput Satellite Systems.

By providing interactive broadband services to geographical areas underserved by terrestrial infrastructure, multi-beam satellite systems play a central role in future wireless communications. Targeting the terabit throughput requirements in satellite communications, we introduce a cognitive radio-based high-throughput satellite (HTS) system architecture where full frequency reuse is employed among beams. Moreover, by analyzing the characteristics of the considered architecture, we discuss the design challenges of radio resource management in cognitive HTS systems exposed to both intra-system and inter-system co-channel interference. Furthermore, to combat interference with low overhead, we propose a generic interference-aware resource management framework based on joint spatial division and multiplexing (JSDM). Under this framework, user grouping along with two-stage precoding is studied to achieve substantial improvement in the overall system throughput. Finally, some future research directions and challenges are also given.

Benefits of Using Mobile Ad-Hoc Network Protocols in Federated Satellite Systems for Polar Satellite Missions

The operational network of individual observation nodes project evaluated the benefits of applying distributed satellite system (DSS) architectures to Earth observation. One of its outcomes is the identification of Arctic services as top priority current user needs that require near-real-time observations. Using inter-satellite communications (ISC) capabilities, a federated satellite system (FSS) can establish a win-win collaboration between two spacecrafts to provide these services. However, as a FSS is established during the contact between two satellites, the service duration is limited. Therefore, the Internet of satellites (IoSat) paradigm promotes the use of multi-hop sporadic networks to deploy FSS. In this paper, the routing protocol (which identifies routes between a source-destination pair) becomes crucial. One of the most extended networks is the mobile ad-hoc network (MANET), in which nodes are constantly moving and changing the network topology. In principle, applying MANET technologies in the IoSat context would provide self-organization, self-configuration, and flexibility to satellite systems. The optimized link-state routing (OLSR) protocol is the predominant solution in MANET, because it quickly reacts against topology changes. This paper aims at studying the benefits of using satellite networks with MANET solutions (e.g. OLSR) for polar satellite missions. The results presented in this article demonstrate that the access time is significantly improved, and thus these new Arctic services can be achieved.

Trust Management Approach to Satellite System Telecommanding Security

This paper is concerned with the application of trust-management theory from the distributed information system domain to satellite system telecommanding operations. New standards in satellite system architecture afford more open and efficient mission operations. With these benefits come additional security threats to critical space assets. As one method to mitigate threats to space systems, this research develops, implements, and tests the consolidated trust-management system: a novel approach to satellite system security. The proposed trust-management system is implemented in a CubeSat test environment. Experimental results show promise for the proposed approach for telecommanding security with potential applicability to large, small, and federated satellites.

A Hybrid GNSS Integrity Design Leveraging a Priori Signal Noise Characteristics

The objective of this paper is to explore a hybrid Global Navigation Satellite System (GNSS) architecture that efficiently meets the stringent needs of safety of life systems. An architecture is proposed that allocates error bounding and alerting functionality between the space, ground and user segments based on refining the assumptions of the leading-order fault free error sources expected in the near future from developing GNSS technologies. By revisiting the first principles used to derive standard RAIM fault detection, a modified detection algorithm is developed to more accurately accommodate these new fault-free error distributions while supporting timely user alerts. The results of the analysis and simulation indicate that this optimized receiver algorithm and associated architecture can provide significant development and operational benefit for navigation users requiring high levels of integrity.

이동 위성 방송 시스템을 위한 협력적 전송 기법 연구

차세대 이동 위성 시스템의 주요 서비스중 하나는 멀티미디어 방송 및 멀티캐스팅 서비스가 될 것이다. 이러한 서비스를 효과적으로 제공하기 위해 통합 위성 지장 네트워크가 고려될 수 있다. 본 논문에서는 차세대 이동위성 시스템에 적합한 통합 위성 지상 시스템의 구조를 소개하고, 효율적인 이동 위성 멀티미디어 방송 및 멀티캐스팅 서비스를 제공하기 위한 위성과 지상 보조 장치 간의 협력적 전송 기법들을 제안하였다. 성능 분석 시뮬레이션 결과, 제안한 구조가 시스템 성능을 보다 향상시킬 수 있으며 효과적인 전송을 할 수 있음을 보여준다. One of major services for the next generation mobile satellite system will be multimedia broadcasting and multi-casting service(MBMS). An integrated satellite and terrestrial network can be considered to provide those services seamlessly and cooperatively. This paper presents efficient cooperative transmission architectures for integrated satellite and terrestrial network. First, an integrated satellite and terrestrial system architectures is introduced, and several cooperative transmission architectures for the integrated system are derived. Extensive performance simulation results reveal that the proposed architectures can improve the system performance and make an efficient transmission.

Cross‐layer protocols for satellite communication networks: part II

Cross‐layer protocols for satellite communication networks: part II

Cross‐layer protocols for satellite communication networks: part I

Cross‐layer protocols for satellite communication networks: part I

Cross‐layer protocol optimization for satellite communications networks: a survey

AbstractSatellite links are expected to be one important component of the next‐generation Internet. New satellite system architectures are being envisaged to be fully IP based and support digital video broadcasting and return channel protocols (e.g. DVB‐S, DVB‐S2 and DVB‐RCS). To make the upcoming satellite network systems fully realizable, meeting new services and application requirements, a complete system optimization is needed spanning the different layers of the OSI, and TCP/IP protocol stack. This paper deals with the cross‐layer approach to be adopted in novel satellite systems and architectures. Different cross‐layer techniques will be discussed, addressing the interactions among application, transport, MAC and physical layers. The impacts of these techniques will be investigated and numerical examples dealing with the joint optimization of different transport control schemes and lower layers will be considered referring to a geostationary‐based architecture. Our aim is to prove that the interaction of different layers can permit to improve the higher‐layer goodput as well as user satisfaction. Copyright © 2006 John Wiley & Sons, Ltd.

Performance evaluation of an optimized intersegment handover procedure for hybrid constellation satellite systems

AbstractSatellite system architectures based on geostationary or Low Earth Orbit (LEO)/Medium Earth Orbit (MEO) constellation suffer from their intrinsic limitations in terms of coverage or flexibility. Traffic requirements concerning broadband services are expected to be very uneven both in time and space. To match this requirement and to improve coverage an innovative satellite system architecture, composed of a LEO/MEO segment to complement a Geostationary Earth Orbit (GEO) segment, has been proposed. In this scenario, to achieve interworking and to make it possible to hold the call while switching between the two segments, efficient intersegment handover (ISHO) procedures must be identified.The paper, after introducing the classical ISHO schemes, aims at defining and analysing an ISHO procedure developed to perform handover in case of hybrid constellations based on the use of both GEO and LEO/MEO orbits. Performance evaluation will be carried out for different system configurations utilizing a dynamic satellite constellation simulator in the time domain. The execution delay and its complementary cumulative distribution have been evaluated for different constellation geometry at different distances from the gateway. Copyright © 2002 John Wiley & Sons, Ltd.

Development of versatile small satellite

This paper introduces the versatile small satellite system architecture developed by NEC. The versatile small satellite design features the standardization concept both in the electrical functional interface and also the physical interface and the modular configuration which results in the reduction of not only the delivery time but also the cost of the satellite. Several key features of the system together with the system description and the considerable example of the applications are described.

Data collection from the Antarctic region through a W‐band low Earth orbit satellite

AbstractThe DAVID (DAta and Video Interactive Distribution) mission is being carried out in the framework of the Science Small Missions Program of the Italian Space Agency. The mission is aimed at the deployment of two scientific telecommunication experiments through a low Earth orbit (LEO) satellite. The paper will focus on one of these experiments, that will test a satellite system architecture for the exchange of a large amount of data and high definition images through a W‐band link and a Ka‐band inter‐satellite link between the LEO and the ARTEMIS satellite. The proposed architecture, that will explore various innovative aspects, will also allow for the first time the distribution of large volumes of scientific data collected from the Antarctic region and other extremely remote areas of the Earth. The availability of a return link in the envisaged system will also allow interactive control of the various laboratories located in the remote sites. Copyright © 2001 John Wiley & Sons, Ltd.

Advanced Communications Technology Satellite (ACTS): four-year system performance

The Advanced Communications Technology Satellite (ACTS) was conceived at the National Aeronautics and Space Administration (NASA) in the late 1970s as a follow-on program to ATS and CTS to continue NASA's long history of satellite communications projects. The ACTS project set the stage for the C-band satellites that started the industry, and later the ACTS project established the use of Ku-band for video distribution and direct-to-home broadcasting. ACTS, launched in September 1993 from the Space Shuttle, created a revolution in satellite system architecture by using digital communications techniques employing key technologies such as a fast hopping multibeam antenna, an on-board baseband processor, a wide-band microwave switch matrix, adaptive rain fade compensation, and the use of 900 MHz transponders operating at Ka-band frequencies. This paper describes the lessons learned in each of the key ACTS technology areas, as well as in propagation investigations.

Cost per Billable Minute Metric for Comparing Satellite Systems

The cost per billable minute is the metric to compare the efŽ ciency of different mobile satellite system architectures. The cost per billable minute to achieve a speciŽ ed rate of return is determined from estimates of the useful system capacity and life cycle costs. To evaluate the useful system capacity, a computer simulation was developed to model the complex interaction between satellites, gateways, capacity limits, and an expected market model. The major capacity limiting factors addressed include frequency reuse, constellation design, link availability,spotbeam patterns, multiple access schemes, and satellite power. The life cycle costs were estimated for the satellites, launch vehicles, gateways, public switched telephone network hardware connections, operations, and launch insurance. The metric is evaluated for six model systems in low, medium, and geostationary Earth orbits to demonstrate the usefulness of the metric in the design process.

AN ATM‐LIKE SYSTEM ARCHITECTURE FOR SATELLITE COMMUNICATIONS INCLUDING ON‐BOARD SWITCHING

In this paper, an ATM system architecture for satellite communications is described. The proposed architecture includes an on-board switch and implements the adaptation of real-time services (e.g. voice and video) and non-real-time services (e.g. data) to the satellite communication link, while achieving statistical advantage. To this end, the ATM traffic categories defined in recent specifications1,2 are utilized. Real-time and non-real-time traffic components are simultaneously supported by a TDMA/TDM on the satellite uplink/downlink, respectively. By exploiting the burstiness of real-time traffic, the proposed satellite system architecture achieves a significant increase of the overall system throughput. After describing the satellite system architecture and addressing scheme, we derive analytical models, by using sophisticated queueing models that allow a very accurate performance evaluation and an easy dimensioning of the data buffers. The proposed model is validated with simulations. The main result is the assessed feasibility of on-board buffers with current technology, even under very strict performance requirements on cell loss ratio and for quite high load values (e.g. 80 per cent of the downlink capacity). Finally, a congestion control scheme, based on a combination of preventive and reactive strategies, is proposed and analysed.

QuickStar: Rapid access to space for small scientific payloads

At the advent of the United States space program, small low-cost satellite systems permitted scientific researchers timely access to space to perform a wide range of scientific experiments. More recently, however, high cost and the lack of launch opportunities have precluded most space experimentors, whether they are student scientists at the university level of government agency researchers, from ever participating in an actual space flight experiment. This paper discusses the development of a small highly capable, low-cost, light-weight satellite system using modern design techniques capable of carrying scientific experiments into space at a tenth the cost of current much larger and more costly space systems. Included are system design, technology applications, and the payload capabilities range (mass, power, data rate, pointing, volume, etc.) of this light-weight spacecraft. Also, as part of the overall small satellite system architecture, we have designed and constructed a low-cost multi-purpose transportable ground station to support production, test, launch, and orbit operations of the space segment. Finally, the paper will address the first flight of the prototype satellite system and its performance while on orbit.

Space Applications of GPS

The country's space systems ground command and control network is rapidly becoming antiquated, and will not be able to handle the expansion of space traffic projected for the twenty-first century. There is a heavy reliance on vulnerable overseas ground locations that are not guaranteed. A cooperative satellite system architecture based on GPS would significantly alleviate the complexity of a future command and control structure. Specifically, if each satellite were to carry a GPS receiver as part of its telemetry, tracking, and command subsystem, all space vehicles could maintain accurate and reliable time, ephemeris, and pointing estimates. This satellite navigation and status data could then be transmitted on a regularly scheduled basis to a ground monitoring station or a Tracking and Data-Relay Satellite System (TDRSS) Satellite. In this way, normal operations would be reduced to merely reviewing the telemetered data. In case of anomalies in the data or a space emergency, a dwell mode would be initiated in which the ground segment would begin active tracking of the space vehicle. This paper outlines the structure of such a GPS-based cooperative satellite monitoring system.