Commercial Satellite Communications Research Articles

Current wideband MILSATCOM infrastructure and the future of bandwidth availability

The military satellite communications (MILSATCOM) infrastructure is typically broken into three categories: wideband, protected, and narrowband. Wideband systems emphasize high capacity, protected systems prioritize anti-jam features and covertness, and narrowband systems emphasize support to the disadvantaged user by providing low data rate communications to small / mobile users. This focuses on the existing wideband MILSATCOM infrastructure (namely the Defense Satellite Communications System and Global Broadcast Service), because the architecture that exists is aging technology that lacks the ability to provide the required bandwidth to the warfighters without relying on commercial satellites. Bandwidth is limited and expensive to purchase, resulting in the DoD leasing transponders on commercial communications satellites - a solution that may not always be an option. This also illustrates various technologies and future programs currently being investigated by the Department of Defense (DoD) in order to augment and/or replace existing systems, and the resulting capability and benefits provided to the warfighter. These programs include the Wideband Global SATCOM (WGS) (previously known as Wideband Gapflller Satellite System), and the Advanced Wideband System (AWS) / Transformational Satellite Communications System (TSAT). Both WGS and AWSITSAT will significantly increase the bandwidth capacity of the wideband MILSATCOM architecture. These military initiatives take advantage of nascent technology such as IP router technology and laser cross-links to maximize performance. Finally, thia describes several techniques to augment these MILSATCOM programs and increase their capacity and effectiveness, including: use of a network-style approach (vice point-to-point), combining space and terrestrial systems, use of near-space communication platforms (e.g., high-altitude. UAVs or balloons), operating at higher frequencies, use of multiple satellites and re-use frequencies, and use of IP accelerators. These techniques increase the bandwidth capacity and improve its effectiveness by providing diversity, better quality of service via multiple relays, improved link performance via network architecture, and increase the amount of effective bandwidth available by including airborne platforms as additional communications relays.

Beyond the Looking Glass: The Application of Public Choice Theory to U.S. Commercial Communication Satellite Export Controls

Resolving the future challenges of space law requires not only an understanding of the law itself, but also the process through which law and policy is chosen. As legal scholars, we should complement our legal knowledge with public administration and public choice theory. This article undertakes a public choice case-study of U.S. commercial communication satellite export control law and policy, focusing on two particular regulatory choices: the 1999 Strom Thurmond Defense Act Satellite Export Control Amendment and the 1990 Tiananmen Square Sanctions boycott on Chinese launch services. This case study analyzes both the initial choice to implement these regulations and also the choice to maintain them in light of strong empirical evidence against their cost-benefit effectiveness. Specific models of public choice are demonstrated to explain and predict future U.S. export control regulatory decision. The findings of this case study are thereafter extrapolated to examine how public choice may operate in light of future challenges in outer space.

The emergence of commercial digital satellite communications

In this article some of the factors responsible for the emergence of commercial digital satellite communication are discussed. Today most voice traffic across the Atlantic is carried by fiber optic undersea cable. Satellites remain competitive in broadcast and thin route applications. Video distribution remains strong for satellites, and in mobile applications such as maritime and military telecom requirements for voice, data, and video. In disaster situations (e.g. the earthquakes in Haiti and Chile) satellite trucks with generators and small Earth stations provide quick communications when terrestrial facilities are damaged or destroyed.

The start of commercial satellite communications [History of communications

The era of satellite communications, now going on fifty years in length, has in many ways only just begun. Perhaps one day we will see broadband commercial satellite systems operating to support telecommunications services for the Moon and Mars. But the excitement of the early years will be hard to beat.

Guest Editorial: Nanophotonics for Space Applications

The application of cutting-edge photonics technology for improving the performance of space-based assets has resulted in a myriad of success stories. As early as 1981, the first photonics-based active fiber optic data links aboard the NASA Long Duration Exposure Facility (Air Force Experiment, AFWL Experiment 701, Fiber Optic Space Effects), during a 69-month orbital period in the Van Allen radiation belts convincingly demonstrated that optical fibers, III-IV laser diodes and detectors, and other photonics technology to follow would have a major role in reducing the dependency on expensive, complexly-wired system technologies, while reducing weight and volume. The proof-of-concept experiment verified the contention that reduced-size photonic systems could reduce satellite weight and volumes while dramatically increasing the bandwidth, reliability, and survivability of commercial and military satellite communication and data acquisition systems. Most importantly, the experiment provided the first conclusive evidence that properly designed photonic systems could provide excellent resistance to the natural space radiation and temperature environment. More recently, QD and nanostructure-based photovoltaic and nonlinear components and sensor arrays operating from visible wavelengths to far-IR are under investigation for near-term application in space systems. Cutting-edge photonic-nanophotonic components, materials, and systems under investigation include radiation-resistant, QD-based chip-sized nonlinear inertial guidance systems, focal plane arrays, thin film solar cells, polymer detectors, polymer modulators, active-smart optical windows, and specialized coatings, to name but a few applications, several of which are presented in this special section. The recent evolution of exotic photonic technology involving integration of nanotechnology with polymers and new molecular-hybrid nanomaterials have shown a high potential for potentially improving specific extra-terrestrial applications, as discussed in this special section. The diverse potential applications are well represented in this section and include papers on protective optical limiting coatings for spacebased sensors (Sarkar et al.), radiation-resistant properties of photovoltaic solar cells (Hubbard et al.), mitigation of Lunar regolith using nanoparticle smart coatings (Pirich et al.), and evolving radiationresistant EO polymer modulator materials (Zhang and Taylor). Recently announced plans by NASA to return to the Moon in 2020 as well as other potential interplanetary space missions will require lightweight polymer-based shielding materials for crew cabins and the protection of astronauts and components from galactic cosmic rays (GCR) during lunar surface exploration and interplanetary missions. Nanotechnology is expected to play a role in the development of some of these materials. Traditional radiation high-Z shielding materials such as lead and other heavy elements are not suitable for GCR protection since the interaction of GCR with these materials results in the production of secondary radiation which is harmful to humans and can degrade photonic and electronic components. Radiation transport calculations have shown that hydrogen-rich low-Z materials are more effective per unit mass of shield than heavier shielding elements for xor gamma-ray absorption because of their lower cross sections, and because heavier elements can serve as the sources of dose-producing secondary particles such as short-range heavy nuclear fragments and penetrating neutrons. Thus, a challenge to develop new nano-based materials and radiation-resistant photonic components for space applications appears to be well under way. Hopefully the initial sampling of papers presented in this special section on Nanophotonics for Space Applications will be well received and provide new ideas from the readership for addressing the special needs of the photonics space community. Journal of Nanophotonics, Vol. 3, 031899 (19 November 2009)

Optimal Layout Design of a Satellite Module Using a Coevolutionary Method with Heuristic Rules

The layout design of a satellite module belongs to a three-dimensional (3D) packing problem with mutual-conflicting performance constraints. Taking the layout design of a simplified commercial communication satellite as a background, based on the cooperative coevolutionary framework, this paper presents a coevolutionary method with heuristic rules for the optimal layout design of a satellite module. First, a whole satellite module layout problem is decomposed into several sublayout problems according to the multisubphysical structure of a satellite module. Second, a relaxation model is adopted to distribute all objects among subspaces. Third, a coevolutionary genetic algorithm is adopted to solve the detailed layout design within the subspaces. Finally, a heuristic combination-rotation (CR) method is adopted to adjust the constraints to obtain the final whole layout scheme. Compared with the coevolutionary approach and the all-at-once optimization approaches, computational results show that the CR method ...

The solutions of navigation observation equations for CAPS

Chinese scientists invent the navigation and positioning system based on commercial communications satellites and develop them successfully into China Area Positioning System (CAPS). In principle, this system is different from the GPS broadcasting satellite navigation class, where the propagation epoch of original navigation signals for pseudo-range measurement is from a ground master control station rather than from satellite transponders. This paper addresses the establishment of the three observation equation models for the navigation and positioning system based on communications satellites, and expresses them identically to operator equations and optimized models. Furthermore, both algorithms of the linear solution for the observable characteristic equation and the least-squares solution for the condition number more than 4 are discussed, with several methods for the exact solution, such as improving the behavior of coefficient matrices, right estimation for the weighted right hand side and selection of iteration forms of solutions, and the influence of the condition number on improving navigation and positioning accuracy is also analyzed carefully. Hopefully, all the works would be contributive to further development of the navigation and positioning system based on communications satellites, and be potentially valuable to other satellite navigation and positioning systems.

Commercial Communications Satellites for the Moon

NASA is planning to rely on commercial communications and navigation services to support missions to the moon in the next decade, say engineers at Johnson Space Center, in Houston. The network, consisting of moon-orbiting satellites and ground stations on Earth, would initially serve robotic lunar missions by NASA, other governments, and private ventures. It would expand to provide 70 percent of the communication requirements for human space missions by the end of 2020, according to NASA documents.

정지궤도 위성의 자동운용을 위한 위치결정 시스템의 개념연구

현재 240여기의 상업용 정지궤도 통신위성이 운용 중에 있지만, GPS 등의 위치항법 위성의 고도보다 높을 뿐만 아니라 나쁜 가시성으로 인하여 중궤도 위치항법시스템을 사용할 수 없으므로 반드시 지상관제소에 의해 추적되어야 한다. 또한 지상관제소에서 관측할 경우 정지궤도 위성은 거의 움직이지 않는 것처럼 보이기 때문에 수 미터급의 정지궤도위성의 위치결정 정밀도를 높이기 위해서 충분히 멀리 떨어진 2곳 이상의 추적안테나를 사용하여야 한다. 따라서 본 논문에서는 정지궤도 위성의 궤도결정과 자동운용을 위해서 정지궤도 고도보다 높은 2일 주기의 원형궤도를 사용하는 GSPS(Geostationary Satellite Positioning System)을 제안하였다. GSPS는 지상추적소에서 정밀하게 위치가 결정된 자기 자신의 위치정보 및 시각정보, 보정데이터와 정지궤도 위성의 운용을 위한 명령을 GSPS 위성에 전송하여 정지궤도위성에 위치정보를 제공하는 기능을 한다. Even more than 240 commercial geostationary communication satellites currently on orbit at the higher location than the GPS orbit altitude perform their own missions only by the support of the ground segment because of weak visibility from GPS. In addition, the orbit determination accuracy is very low without using two or more dedicated ground tracking antennas in intercontinental ground segment, since the satellite hardly moves with respect to the ground station. In this paper, we propose the GSPS(Geostationary Satellite Positioning System) in circular orbits of two sidereal days period higher than the geosynchronous orbit for orbit determination and autonomous satellite operation. The GSPS is conceived as a ranging system in that unknown positions of a geostationary satellite can be acquired from the known positions of the GSPS satellites. Each GSPS satellite transmits navigation data, clock data, correction data, and geostationary satellite command to control a geostationary satellite.

A 500-W Coupled-Cavity TWT for Ka-Band Communication

Worldwide demand for high-power amplifiers for digital satellite communication at Ka-band frequencies between 27 and 31 GHz is steadily increasing (2003). Communication and Power Industries (CPI) has developed a 500-W periodic permanent magnet focused coupled-cavity traveling wave tube (TWT) for conduction-cooled amplifier systems, which is being introduced into the commercial satellite communication market. The TWT is capable of greater than 500-MHz instantaneous bandwidth and is cathode voltage tunable from 28.3 to 30 GHz. The TWT may be operated saturated at the 500-W output power level or backed off from saturation in the linear mode. CPI's Satcom Division has integrated the TWT into a conduction-cooled transmitter box suitable for antenna hub-mount applications. The amplifier uses predistortion networks to provide a high degree of linear response when operated in output power back-off mode.

Bandwidth on demand for deployed-IP users

The increased expectation for instantaneous, global communications is at odds with the existence of areas that have little or no communications infrastructure. Telephones and their supporting ground-based systems are not as ubiquitous as first-world enterprises might believe. Cell phones require some minimal number of support systems, whether ground or satellite based. Even in areas that have a considerable communications infrastructure, consider what would happen if disaster struck, as it unfortunately did in Sumatra and Indonesia in late December 2004. Restoring communications might require a quickly deployable, temporary communications system. In these situations, commercial satellite communications (satcom) has some unique advantages. With the advent of IP services characterized by short messages such as Internet packets, satcom transmission technologies such as MF TDMA provide a very effective means of quickly deploying a communications infrastructure. The bandwidth-on-demand concept uses the dynamic and flexible allocation of bandwidth across a range of frequencies and a large pool of timeslots. This is the most advanced step toward the nirvana of transmissions at any time across any and all frequencies. Commercial satcom is already beginning to provide direct TV and IP capability into planes, trains, buses, ships, and automobiles. A move to ultra-small satcom terminals for the busy executive is on the horizon. This would be one suitcase-sized package with easy setup, permitting a user to quickly go on the air. In the future, commercial satcom might use other techniques-such as bandwidth reuse, spread spectrum, multifrequency, and echo cancellation - for greater efficiency.

Particle swarm optimization based on pyramid model for satellite module layout

To improve the global search ability of particle swarm optimization (PSO), a multi-population PSO based on pyramid model (PPSO) is presented. Then, it is applied to solve the layout optimization problems against the background of an international commercial communication satellite (INTELSAT-Ⅲ) module. Three improvements are developed, including multi-population search based on pyramid model, adaptive collision avoidance among particles, and mutation of degraded particles. In the numerical examples of the layout design of this simplified satellite module, the performance of PPSO is compared to global version PSO and local version PSO (ring and Neumann PSO). The results show that PPSO has higher computational accuracy, efficiency and success ratio.

System design, capacity dimensioning and revenue estimation for aeronautical communications via satellite

AbstractThe paper discusses various system aspects of commercial aeronautical broadband satellite communications (AirCom). An integrated global system design approach is presented, and key R&D issues along this path are discussed. Some focus is laid on geographic satellite coverage and constellation alternatives. A capacity dimensioning method for global aeronautical communications is developed, using a global flight database, and numerical results from computer simulations are presented. Finally, we estimate the revenues that airlines can expect from passenger telephone and Internet services offered on North Atlantic flights, under the assumption of an existing wireless cabin infrastructure, supporting wireless Internet and GSM telephony. Copyright © 2004 John Wiley & Sons, Ltd.

연안 어장에서의 불법 조업 어선의 탐지, 식별 및 감시 시스템 개발

A real-time surveillance system of the inshore fishing ground was constructed to identify and detect discrete targets, such as illegal fishing vessels. This paper describes measurements made with a combination of sensors, such as radar, CCTV camera, and GPS receivers, for monitoring the fishing activity of small vessels within the fishing limit zones of the inshore waters. The CCTV camera system was used to confirm detection and to classify the type of target. The location of legal vessels distributed in coastal waters was acquired from each GPS system of ships connected to commercial satellite communication network. The surveillance system was networked via LAN to one host PC with the use of electronic navigational charts (ENC) and a radar link. Radar Target Extractor (RTX) for radar signal processing can be remotely accessed and controlled on existing PC via the internet, from anywhere, at any time. Results are presented that demonstrate the effectiveness of the newly constructed fisheries monitoring system for conducting continuous surveillance of illegal fishing vessels in the inshore fishing ground. The identification of illegal fishing vessels was achieved by comparing radar positions of illegal fishing vessels exceeding the warning limits in the surveillance area with GPS position reports transmitted from legal fishing vessels, and the illegal fishing vessels were marked with red symbols on the ENC screen of a PC. The methods to track the activities of all vessels intruding or leaving the fishing limit zones also were discussed.

Protection of Commercial Satellite Communications Infrastructure

Although a nation's interest in protecting its commercial assets in space would seem obvious, the task of protecting commercial satellites is inherently complicated. Protection of commercial space infrastructure requires coordination among multiple actors in the public and private sectors. Although most public sector actors ultimately report to the same political leadership, the process of establishing coherent policies across agencies can take time. Coordination is even more complicated in the private sector, where multi-national firms compete against each other for profits by serving a wide range of customers. Given the complexities of this process, it is not surprising that efforts to protect commercial satellite communications (SATCOM) networks have been slow in coming. At the same time, recent progress in the U.S. may pave the way for a more coherent approach to commercial SATCOM protection. If successful, these efforts can provide increased assurance of uninterrupted satellite connectivity, thus benefiting the economic and national security interests of America, its allies and its trading partners.

Exploiting Commercial SATCOM: A BetterWay

Since the late 1980s, elements of the Department of Defense and the US intelligence community have used commercial satellite communications (SATCOM) augment their organic SATCOM capabilities. Following the Persian Gulf Conflict of 1990-91, Congress directed the DOD pursue greater use of commercial SATCOM, providing $15 million in the fiscal year 1992 Defense appropriation in order for DOD to study ways of using commercial communication satellite and begin moving aggressively toward maximum utilization of commercial satellite communications (1) In 1997, the senior communications flag officers of the military services committed the military the long-term employment of commercial satellite communications augment military owned and operated SATCOM systems. (2) The Joint Requirements Oversight Council (JROC) endorsed this decision in October 1997. (3) Today, the Defense Department continues expand its use of commercial satellite communications; however, DOD's approach for leasing commercial SATCOM is inefficient and expensive. Joint Vision 2020 identifies continuous information superiority as an essential element of US warfighting for the first part of the current century. (4) The various service requirements pass information between dispersed, mobile elements, as in the Army's concept for the Future Force and the Navy's vision for Network-Centric Warfare, rely on information superiority. (5) The result is that the US military's need pass large amounts of information (hundreds and soon thousands of megabits per second) will continue grow. Only space-based communications can meet this need. Although the military is undertaking an effort greatly increase the information-carrying capacity of its organic military SATCOM (MILSATCOM) systems, the Transformational Communications Office will not be able deliver a functional worldwide system until sometime in the second decade of this century. (6) Until such new capabilities are available--and quite probably even after they are, the Defense Department will require commercial SATCOM complement its military systems fully meet its needs for transmitting information among deployed forces and between deployed forces and the sustaining base in the United States. In 1997, military communications planners projected that the growing demand within the military for satellite communications would consistently exceed the capacity of available military systems. Operation Enduring Freedom in Afghanistan and Operation Iraqi Freedom have more than validated this projection. Before Operation Enduring Freedom, the greatest demand US Central Command (CENTCOM) projected for information transfer using SATCOM was 500 megabits (million bits) per second (Mbps) and it routinely used about 100 Mbps. Shortly after the operation commenced, however, CENTCOM identified that its forces needed not less than 500 Mbps and potentially more than one gigabit (one billion bits) per second (Gbps). The required increase in SATCOM capacity was met by leasing it from commercial industry. As shown in Figure 1, the demand for SATCOM by deployed military forces has grown markedly since Operation Desert Storm in 1991. This has been the case even though the number of deployed forces in operations since Desert Storm has been smaller, often much smaller. A good way assess the trend in the military's demand for satellite communications is look at the amount of SATCOM required support a consistently-sized increment of military forces. Figure 1 and Figure 2 are based on historical information regarding the SATCOM actually used, which is available from US Strategic Command, DOD's SATCOM operational manager. They show that since 1991 the satellite communications required support an increment, or force package, of 5,000 deployed military members has increased from 1 Mbps during Operation Desert Storm an initial assessment of about 51 Mbps during Operation Iraqi Freedom. …

Optimal layout design of a satellite module

Layout design of a satellite module directly concerns its structure, performance, service life, and cost of assembly and maintenance. It is an important and NP-complete problem. The main difficulties consist of combinatorial optimizations in mathematics and system complexity in engineering practice, and relevant researches are far from enough. This paper proposes a basic solution strategy for the optimal layout design of a satellite module, which consists of two stages, global (or loose) layout design and detailed layout design. Corresponding algorithms are then developed while taking the layout design of an international commercial communication satellite as an example. They are the centripetal balancing method for global layout design and a quasi Traveling Salesman Problem (TSP) model-based Ant Colony Optimization (ACO) algorithm for layout optimization. The proposed method demonstrates its feasibility and validity on an application instance. Existing problems and further research directions are finally discussed.

Iridium satellites help map electrical currents in space

The satellite constellation of Iridium LLC, which filed for Chapter 11 bankruptcy in 1999 after it failed to win enough business for its commercial satellite communications services, is still orbiting at an altitude of about 780 kilometers. Now, however, the satellites are helping to write a new chapter in understanding space weather.Magnetometers onboard each of the system's 66 polar‐orbiting satellites are working in conjunction with the high‐frequency, multinational Super Dual Auroral Radar Network, or SuperDARN, to provide the first continuous measurements of electrical currents between Earth's upper atmosphere and space. These tools also are generating the first global maps of electrical power flowing into the polar upper atmosphere.

Global satellite communications technology and systems - An overview

The National Aeronautics and Space Administration (NASA) and the National Science Foundation (NSF) commissioned a panel of scientists and engineers in 1997 to benchmark the global status of commercial communications satellite technology, markets and regulatory and policy issues. After visiting or interviewing over 60 manufacturing, R&D laboratory, service provider and government institutions in North and South America, Europe and Asia, the review panel concluded as follows: Many European and Asian governments are increasing their satellite communications R&D programs and supporting demonstrations and space marketing efforts, relative to the US. The US is currently the leader in new technology and its insertion into commercial satellite systems, but ambitious foreign efforts threaten this position. Global commercial satellite communications is a large and rapidly growing business. New technology is being inserted into satellites at an increasingly rapid pace with an increasing number of international participants. Aerospace communications companies, worldwide, are consolidating their efforts and are expanding into the end user service business. The Direct-to-End User mass consumer satellite service industry has the potential to be quite large and is changing the way satellites are manufactured and deployed and is creating a potentially large satellite terminal industry. Satellite manufacturing is increasingly becoming a design, assembly and test operation with parts and sub-systems obtained from global suppliers. This increased use of satellites for communications services is creating a shortage of spectrum and orbital slots and is resulting in spectrum utilization conflicts with terrestrial wireless service providers. Future development of commercial satellite communications is dependent on the resolution of key regulatory, trade, spectrum, inter-operability and standards issues and government leadership is vitally needed. There are opportunities for international cooperation to facilitate the development of satellites technologies, systems, standards and protocols. There is concern that unless several issues are addressed, particularly an increase in long term oriented R&D and trade and regulatory issues, the US may experience a deterioration of its leading position in the manufacture of satellites for global service providers and the initiation of new services, much in the way that it lost its leading position in the launch of commercial satellites.

Not so Great Lakes?

In 1965, Frank Sinatra won the Grammy Award for his album, “September of My Years;” “Early Bird,” the first commercial communications satellite, was launched; and Dr. Martin Luther King, Jr. was arrested in Selma, Alabama, during demonstrations against voter‐registration rules.The year 1965 was also the last time water levels in the U.S. Great Lakes were as low as they are now.