Анализ оперативности информационных взаимодействий в низкоорбитальных многоспутниковых группировках

The objects of the research are networks and information interactions in low-orbit satellite constellations performing tasks of remote sensing of the Earth. Research of network creation questions in this case is a necessary condition as opportunities and efficiency of information interaction directly depend on opportunities of a network. DTN (Delay-and-Disruption Tolerant Networking) technology is a basis of the network creation and CGR (Contact Graph Routing) approach is a basis of message routing. DTN technology and CGR approach are originally developed and used to provide communication with spacecraft located in a deep space. Therefore, the article discusses issues and problems arising in the context of their use in relation to low-orbit satellite constellations. The purpose of the information interaction study is development of effective interaction schemes (protocols). In the paper, the schemes of information interaction that can be used by a group of satellites in case of autonomous planning are considered. Along with autonomous planning, the paper also considers information interaction that can be used to implement network control of a satellite constellation in the case of ground planning. The effectiveness of the information interaction schemes are assessed by efficiency of orders’ execution. Measurement of efficiency is estimated via simulation of the communication network and the corresponding scheme of information interaction.Исследуются коммуникационные сети и информационные взаимодействия в низкоорбитальных многоспутниковых группировках, выполняющих задачи дистанционного зондирования Земли. Исследования вопросов создания коммуникационной сети в данном случае является необходимым условием, так как возможности и эффективность информационного взаимодействия непосредственно зависят от возможностей сети связи. В основе создания коммуникационной сети, устойчивой к разрывам и задержкам в каналах связи, рассматривается DTN (от англ. Delay-and-Disruption Tolerant Networking) технология, а в основе маршрутизации сообщений — CGR (от англ. Contact Graph Routing) подход. Эти технология и подход в оригинале разрабатываются и используются для обеспечения связи с космическими аппаратами, находящимися в далеком космосе. Поэтому в работе рассматриваются вопросы и задачи, возникающие в связи с использованием DTN технологии и CGR метода маршрутизации применительно к низкоорбитальным спутниковым группировкам. Целью исследования информационного взаимодействия является разработка эффективных схем (протоколов) взаимодействия. Анализируются схемы информационного взаимодействия, которые могут использоваться группировкой спутников при автономном планировании поступающих заявок на дистанционное зондирование Земли. Наряду с автономным планированием также исследуется информационное взаимодействие, которое может использоваться для реализации сетевого управления группировкой спутников в случае наземного планирования. Эффективность схем информационного взаимодействия оценивается оперативностью выполнения заявок. Измерение оценок оперативности выполняется на основе имитационного моделирования коммуникационной сети и соответствующей схемы информационного взаимодействия

Анализ оперативности информационных взаимодействий в низкоорбитальных многоспутниковых группировках

Исследуются коммуникационные сети и информационные взаимодействия в низкоорбитальных многоспутниковых группировках, выполняющих задачи дистанционного зондирования Земли. Исследования вопросов создания коммуникационной сети в данном случае является необходимым условием, так как возможности и эффективность информационного взаимодействия непосредственно зависят от возможностей сети связи. В основе создания коммуникационной сети, устойчивой к разрывам и задержкам в каналах связи, рассматривается DTN (от англ. Delay-and-Disruption Tolerant Networking) технология, а в основе маршрутизации сообщений — CGR (от англ. Contact Graph Routing) подход. Эти технология и подход в оригинале разрабатываются и используются для обеспечения связи с космическими аппаратами, находящимися в далеком космосе. Поэтому в работе рассматриваются вопросы и задачи, возникающие в связи с использованием DTN технологии и CGR метода маршрутизации применительно к низкоорбитальным спутниковым группировкам. Целью исследования информационного взаимодействия является разработка эффективных схем (протоколов) взаимодействия. Анализируются схемы информационного взаимодействия, которые могут использоваться группировкой спутников при автономном планировании поступающих заявок на дистанционное зондирование Земли. Наряду с автономным планированием также исследуется информационное взаимодействие, которое может использоваться для реализации сетевого управления группировкой спутников в случае наземного планирования. Эффективность схем информационного взаимодействия оценивается оперативностью выполнения заявок. Измерение оценок оперативности выполняется на основе имитационного моделирования коммуникационной сети и соответствующей схемы информационного взаимодействия

Queuing Game Theory Based Optimal Routing Scheme for Heterogeneous Users over Space Information Networks

An optimal routing scheme in space information networks was presented to balance network loads for heterogeneous users. According to the competition among the nodes, the model was built based on queuing game theory. The virtual routing platform was in charge of resources allocation and route selection. It got user’s gain to decide which node the user joined in. Owning to the existing of heterogeneous users, an optimal admission fee needed to be obtained to avoid congestion. In our model, firstly, the whole welfare of the system was formulated. Then the optimal admission fee was calculated through maximizing the whole welfare. Meanwhile, the average maximum queue length was generated to set the buffer space of the node. At last, a routing factor was introduced into the route algorithm in order that the optimal routing could be selected by heterogeneous users. As a result, the system welfare reaches the maximum

Small satellites and CubeSats: survey of structures, architectures, and protocols

The space environment is still challenging but is becoming more and more attractive for an increasing number of entities. In the second half of the 20th century, a huge amount of funds was required to build satellites and gain access to space. Nowadays, it is no longer so. The advancement of technologies allows producing very small hardware components able to survive the strict conditions of the outer space. Consequently, small satellites can be designed for a wide set of missions keeping low design times, production costs, and deployment costs. One widely used type of small satellite is the CubeSat, whose different aspects are surveyed in the following: mission goals, hardware subsystems and components, possible network topologies, channel models, and suitable communication protocols. We also show some future challenges related to the employment of CubeSat networks

Space mission resilience with inter-satellite networking

Satellites typically operate in isolation from their orbiting counterparts, but communicating only with ground-based infrastructure leaves them susceptible to the consequences of on-board anomalies. Loss of payload, communication system, or other sub-system function could render the entire satellite inoperable. This susceptibility can be partially mitigated through the addition of an inter-satellite networking capability, which offers value in terms of increased general performance and an increased resilience to on-board anomalies. While a typical platform can be modelled to exhibit only two fundamental states: operational and failed, a networking-capable platform (specifically one with an inter-satellite communication capability) exhibits six states, each reached through a unique combination of sub-system malfunctions. The result of this added resilience is a reduction in the likelihood of the satellite reaching a fully-failed state. Simulations for independent and networking-capable systems are presented that illustrate the benefits and limitations of inter-satellite networking in terms of failure resilience. It is shown that whilst a networked system can be expected to reach greater levels of performance utility, sub-system anomalies are found to result in greater percentage levels of performance degradation compared to a non-networking-capable system with similar characteristics

Application of Contact Graph Routing to LEO Satellite DTN Communications

Delay-/Disruption- Tolerant Networking, which originated from research on deep space communications, has enlarged its scope to encompass all challenged networks, including LEO satellite communications. Focusing on single satellite or incomplete constellation cases, the advantages of DTN mainly relate to its ability to cope with disruption and intermittent connectivity, typical of LEOs. This, however, requires the adoption of routing solutions specifically designed for DTNs. Among the many proposals, Contact Graph Routing, designed by NASA for deep space, seems particularly appealing, as it takes advantage of the a priori knowledge of \u201ccontacts\u201d between DTN nodes, a characteristic peculiar to both deep space and LEO environments. This paper aims to investigate the suitability of CGR in LEO satellite DTN communications, by focusing on two practical application scenarios: Earth observation and data mule. Results, obtained through a Linux testbed running ION, the DTN Bundle protocol and CGR implementation developed by NASA, highlight the advantages of CGR when applied to LEO satellite communications

低軌道周回衛星における衛星回線の大容量化に関する研究

Tohoku University加藤寧課

Methodologies for the analysis of value from delay-tolerant inter-satellite networking

In a world that is becoming increasingly connected, both in the sense of people and devices, it is of no surprise that users of the data enabled by satellites are exploring the potential brought about from a more connected Earth orbit environment. Lower data latency, higher revisit rates and higher volumes of information are the order of the day, and inter-connectivity is one of the ways in which this could be achieved. Within this dissertation, three main topics are investigated and built upon. First, the process of routing data through intermittently connected delay-tolerant networks is examined and a new routing protocol introduced, called Spae. The consideration of downstream resource limitations forms the heart of this novel approach which is shown to provide improvements in data routing that closely match that of a theoretically optimal scheme. Next, the value of inter-satellite networking is derived in such a way that removes the difficult task of costing the enabling inter-satellite link technology. Instead, value is defined as the price one should be willing to pay for the technology while retaining a mission value greater than its non-networking counterpart. This is achieved through the use of multi-attribute utility theory, trade-space analysis and system modelling, and demonstrated in two case studies. Finally, the effects of uncertainty in the form of sub-system failure are considered. Inter-satellite networking is shown to increase a system's resilience to failure through introduction of additional, partially failed states, made possible by data relay. The lifetime value of a system is then captured using a semi-analytical approach exploiting Markov chains, validated with a numerical Monte Carlo simulation approach. It is evident that while inter-satellite networking may offer more value in general, it does not necessarily result in a decrease in the loss of utility over the lifetime.In a world that is becoming increasingly connected, both in the sense of people and devices, it is of no surprise that users of the data enabled by satellites are exploring the potential brought about from a more connected Earth orbit environment. Lower data latency, higher revisit rates and higher volumes of information are the order of the day, and inter-connectivity is one of the ways in which this could be achieved. Within this dissertation, three main topics are investigated and built upon. First, the process of routing data through intermittently connected delay-tolerant networks is examined and a new routing protocol introduced, called Spae. The consideration of downstream resource limitations forms the heart of this novel approach which is shown to provide improvements in data routing that closely match that of a theoretically optimal scheme. Next, the value of inter-satellite networking is derived in such a way that removes the difficult task of costing the enabling inter-satellite link technology. Instead, value is defined as the price one should be willing to pay for the technology while retaining a mission value greater than its non-networking counterpart. This is achieved through the use of multi-attribute utility theory, trade-space analysis and system modelling, and demonstrated in two case studies. Finally, the effects of uncertainty in the form of sub-system failure are considered. Inter-satellite networking is shown to increase a system's resilience to failure through introduction of additional, partially failed states, made possible by data relay. The lifetime value of a system is then captured using a semi-analytical approach exploiting Markov chains, validated with a numerical Monte Carlo simulation approach. It is evident that while inter-satellite networking may offer more value in general, it does not necessarily result in a decrease in the loss of utility over the lifetime