881 research outputs found
Links Assignment Scheme based on Potential Edges Importance in Dual-layer Wavelength Routing Optical Satellite Networks
With the development of the massive satellite constellation and the on-orbit
laser-based communication equipment, the wavelength routing optical satellite
network (WROSN) becomes a potential solution for on-orbit, high-capacity, and
high-speed communication. Since the inter-satellite links (ISLs) are
time-varying, one of the fundamental considerations in the construction of the
WROSN is assigning limited laser communication terminals for each satellite to
establish ISLs with the visible satellites. Therefore, we propose a links
assignment scheme (LAS) based on the potential edges importance matrix (PEIM)
algorithm to construct a temporarily stable topology of the ISLs for a
dual-layer constellation. The simulation results showed that the LAS based on
the PEIM algorithm is better than LAS based on the random or Greedy algorithm
in terms of node-to-node distance, node pair connectivity, wavelength demand,
and transmission delay. The node pair connectivity and wavelength demand in
WROSN is a trade-off problem. The research in this paper also brings a novel
method for reduction of the cost of the on-board resources, that is through
designing topology of the ISLs with links assignment algorithm.Comment: This is the manuscript version that was submitted to the
International Journal of Satellite Communications and Networking
(SAT-23-0018
Proceedings of the Fifth International Mobile Satellite Conference 1997
Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial communications services. While previous International Mobile Satellite Conferences have concentrated on technical advances and the increasing worldwide commercial activities, this conference focuses on the next generation of mobile satellite services. The approximately 80 papers included here cover sessions in the following areas: networking and protocols; code division multiple access technologies; demand, economics and technology issues; current and planned systems; propagation; terminal technology; modulation and coding advances; spacecraft technology; advanced systems; and applications and experiments
Virtual Satellite Network Simulator (VSNeS) - A novel engine to evaluate satellite networks over virtual infrastructure and networks
Space has been populated by a wide range of satellite systems from governmental and private space entities. Monolithic satellites have been ruling it by providing a custom design that accomplishes a specific mission. Nevertheless, novel user demands emerged have required global coverage, low revisit time, and ubiquitous service. The possibility to integrate in-orbit infrastructure to support current communications systems has been discussed persistently during the last years. Specifically, the concept of deploying networks composed of aircraft and spacecraft (creating the so-called Non-Terrestrial Networks), has emerged as a potential architecture to satisfy this new demand. This novel concept has enabled to investigate mobile technologies in space infrastructure. For example, this is the case of the Software-Defined Satellite, which aims at managing in-orbit infrastructure by using Software-Defined Network techniques. These novel concepts pose multiple challenges which dedicated developments shall address. Likewise, specific equipment and simulation environments shall support them. Currently, open source satellite network emulators have certain limitations or are not easily accessible. This project aims at presenting the Virtual Satellite Network Simulator, a novel simulation engine capable to represent satellites as well as ground nodes in virtual machines and deploy a virtual network that depicts the channel effects and dynamics. VSNeS has been generated from different modules, that thanks to the joint work is able to generate the virtualization. First of all, a Python3 program has been developed, which works as a manager and is responsible for running the rest of the modules according to the virtualized scenario. Furthermore, Kernel-based Virtual Machine has been implemented for the execution of the virtual machines. The channel management is done with the NetEm emulator. Finally, a graphical user interface is delivered by Cesium. This dissertation presents formally a preliminary design with the essential steps to select each technology. Then, the networking design is also discussed. Different tests are also shown in order to verify the correct functioning of the tool. In addition, tests about the performance of the final release have been performed. The program has been tested with the following protocols in different realistic scenarios: TCP, UDP, and ICMP. This allowed us to verify the correct operation of the program, checking the delays and channel losses. Moreover, it is empirically demonstrated that some protocols are not functional for geostationary satellites, due to the long latency caused by the large distances
Towards 6G Through SDN and NFV-Based Solutions for Terrestrial and Non-Terrestrial Networks
As societal needs continue to evolve, there has been a marked rise in a wide variety of emerging use cases that cannot be served adequately by existing networks. For example, increasing industrial automation has not only resulted in a massive rise in the number of connected devices, but has also brought forth the need for remote monitoring and reconnaissance at scale, often in remote locations characterized by a lack of connectivity options. Going beyond 5G, which has largely focused on enhancing the quality-of-experience for end devices, the next generation of wireless communications is expected to be centered around the idea of "wireless ubiquity". The concept of wireless ubiquity mandates that the quality of connectivity is not only determined by classical metrics such as throughput, reliability, and latency, but also by the level of coverage offered by the network. In other words, the upcoming sixth generation of wireless communications should be characterized by networks that exhibit high throughput and reliability with low latency, while also providing robust connectivity to a multitude of devices spread across the surface of the Earth, without any geographical constraints. The objective of this PhD thesis is to design novel architectural solutions for the upcoming sixth generation of cellular and space communications systems with a view to enabling wireless ubiquity with software-defined networking and network function virtualization at its core. Towards this goal, this thesis introduces a novel end-to-end system architecture for cellular communications characterized by innovations such as the AirHYPE wireless hypervisor. Furthermore, within the cellular systems domain, solutions for radio access network design with software-defined mobility management, and containerized core network design optimization have also been presented. On the other hand, within the space systems domain, this thesis introduces the concept of the Internet of Space Things (IoST). IoST is a novel cyber-physical system centered on nanosatellites and is capable of delivering ubiquitous connectivity for a wide variety of use cases, ranging from monitoring and reconnaissance to in-space backhauling. In this direction, contributions relating to constellation design, routing, and automatic network slicing form a key aspect of this thesis.Ph.D
Evolution of High Throughput Satellite Systems: Vision, Requirements, and Key Technologies
High throughput satellites (HTS), with their digital payload technology, are
expected to play a key role as enablers of the upcoming 6G networks. HTS are
mainly designed to provide higher data rates and capacities. Fueled by
technological advancements including beamforming, advanced modulation
techniques, reconfigurable phased array technologies, and electronically
steerable antennas, HTS have emerged as a fundamental component for future
network generation. This paper offers a comprehensive state-of-the-art of HTS
systems, with a focus on standardization, patents, channel multiple access
techniques, routing, load balancing, and the role of software-defined
networking (SDN). In addition, we provide a vision for next-satellite systems
that we named as extremely-HTS (EHTS) toward autonomous satellites supported by
the main requirements and key technologies expected for these systems. The EHTS
system will be designed such that it maximizes spectrum reuse and data rates,
and flexibly steers the capacity to satisfy user demand. We introduce a novel
architecture for future regenerative payloads while summarizing the challenges
imposed by this architecture
Inter-Plane Inter-Satellite Connectivity in Dense LEO Constellations
With numerous ongoing deployments owned by private companies and startups,
dense satellite constellations deployed in low Earth orbit (LEO) will play a
major role in the near future of wireless communications. In addition, the 3rd
Generation Partnership Project (3GPP) has ongoing efforts to integrate
satellites into 5G and beyond-5G networks. Nevertheless, numerous challenges
must be overcome to fully exploit the connectivity capabilities of satellite
constellations. These challenges are mainly a consequence of the low
capabilities of individual small satellites, along with their high orbital
speeds and small coverage due to the low altitude of deployment. In particular,
inter-plane inter-satellite links (ISLs), which connect satellites from
different orbital planes, are greatly dynamic and may be considerably affected
by the Doppler shift. In this paper, we present a framework and the
corresponding algorithms for the dynamic establishment of the inter-plane ISLs
in LEO constellations. Our results show that the proposed algorithms increase
the sum of rates in the constellation 1) by up to 115% with respect to the
state-of-the-art benchmark schemes in an interference-free environment and 2)
by up to 71% when compared to random resource allocation in a worst-case
scenario for interference.Comment: To be published in IEEE Transactions on Wireless Communication
Distributed satellite communications system design : first-order interactions between system and network architectures
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2005.Includes bibliographical references (p. 159-165).Humanity now exists in the midst of the fast-moving Information Age, a period of history characterized by fast travel and even faster information transfer. As data becomes seemingly more valuable than physical possessions, the introduction of exciting applications for communications services becomes ever more critical for the success - and in some cases, survival - of businesses and even nations. While the majority of these innovations have occurred over cable and fiber, a number of the most socially significant have occurred due to the introduction of satellites. Terrestrial fiber and cable systems have a number of advantages, but the extent of their reach and the cost of installation - in terms of both capital and time - favor industrialized nations over more remote and underdeveloped communities. Even as satellites offer the only real chance for ultimate communications ubiquity and true global unity, there remains a significant cost-benefit barrier. Few commercial satellite systems have succeeded economically without first falling victim to bankruptcy. The upfront capital required to implement a satellite communications system is staggering, and historically satellite companies have failed to adequately match capacity and service options to the current and actual future demand. The design process itself is an inherent limiting factor to the achievable cost and performance of a system.(cont.) Traditionally, the first step toward designing satellite communication systems - as well as terrestrial, sensor web, and ad hoc networks - has been to specify the system topology (e.g., the orbits of the satellites and the locations of the ground stations) based on the desired market and then to design the network protocols to make the most of the available resources. Such a sequential process assumes that the design of the network architecture (e.g., protocols, packet structure, etc) does not drive the design of the system architecture (e.g., constellation topology, spacecraft design, etc). This thesis will show that in the case of Ka-band distributed satellite communication systems this fundamental assumption is not valid, and can have a significant impact on the success (cost, capacity, customer satisfaction) of the resulting satellite communication system. Furthermore, this thesis will show that how a designer values performance during the design and decision process can have a substantial impact on the quality of the design path taken through the trade space of possible joint architectures.by Jennifer E. Underwood.S.M
Performance Analysis of Protocol Independent Multicasting-Dense Mode in Low Earth Orbit Satellite Networks
This research explored the implementation of Protocol Independent Multicasting - Dense Mode (PIM-DM) in a LEO satellite constellation. PIM-DM is a terrestrial protocol for distributing traffic efficiently between subscriber nodes by combining data streams into a tree-based structure, spreading from the root of the tree to the branches. Using this structure, a minimum number of connections are required to transfer data, decreasing the load on intermediate satellite routers. The PIM-DM protocol was developed for terrestrial systems and this research implemented an adaptation of this protocol in a satellite system. This research examined the PIM-DM performance characteristics which were compared to earlier work for On- Demand Multicast Routing Protocol (ODMRP) and Distance Vector Multicasting Routing Protocol (DVMRP) - all in a LEO satellite network environment. Experimental results show that PIM-DM is extremely scalable and has equivalent performance across diverse workloads. Three performance metrics are used to determine protocol performance in the dynamic LEO satellite environment, including Data-to- Overhead ratio, Received-to-Sent ratio, and End-to-End Delay. The OPNET® simulations show that the PIM-DM Data-to-Overhead ratio is approximately 80% and the protocol reliability is extremely high, achieving a Receive-to-Sent ratio of 99.98% across all loading levels. Finally, the PIM-DM protocol introduces minimal delay, exhibiting an average End-to-End Delay of approximately 76 ms; this is well within the time necessary to support real-time communications. Though fundamental differences between the DVMRP, ODMRP, and PIM-DM implementations precluded a direct comparison for each experiment, by comparing average values, PIM-DM generally provides equivalent or better performance
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
Uncoded space-time labelling diversity : data rate & reliability enhancements and application to real-world satellite broadcasting.
Doctoral Degree. University of KwaZulu-Natal, Durban.Abstract available in PDF
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