Dtn and non-dtn routing protocols for inter-cubesat communications: A comprehensive survey

CubeSats, which are limited by size and mass, have limited functionality. These miniaturised satellites suffer from a low power budget, short radio range, low transmission speeds, and limited data storage capacity. Regardless of these limitations, CubeSats have been deployed to carry out many research missions, such as gravity mapping and the tracking of forest fires. One method of increasing their functionality and reducing their limitations is to form CubeSat networks, or swarms, where many CubeSats work together to carry out a mission. Nevertheless, the network might have intermittent connectivity and, accordingly, data communication becomes challenging in such a disjointed network where there is no contemporaneous path between source and destination due to satellites’ mobility pattern and given the limitations of range. In this survey, various inter-satellite routing protocols that are Delay Tolerant (DTN) and Non Delay Tolerant (Non-DTN) are considered. DTN routing protocols are considered for the scenarios where the network is disjointed with no contemporaneous path between a source and a destination. We qualitatively compare all of the above routing protocols to highlight the positive and negative points under different network constraints. We conclude that the performance of routing protocols used in aerospace communications is highly dependent on the evolving topology of the network over time. Additionally, the Non-DTN routing protocols will work efficiently if the network is dense enough to establish reliable links between CubeSats. Emphasis is also given to network capacity in terms of how buffer, energy, bandwidth, and contact duration influence the performance of DTN routing protocols, where, for example, flooding-based DTN protocols can provide superior performance in terms of maximizing delivery ratio and minimizing a delivery delay. However, such protocols are not suitable for CubeSat networks, as they harvest the limited resources of these tiny satellites and they are contrasted with forwarding-based DTN routing protocols, which are resource-friendly and produce minimum overheads on the cost of degraded delivery probability. From the literature, we found that quota-based DTN routing protocols can provide the necessary balance between delivery delay and overhead costs in many CubeSat missions

Antenna and Random Access Solutions for nano-satellite and 5G networks operating in the millimiter-wave domain

L\u2019obiettivo di questa tesi \ue8 la discussione di soluzioni per reti satellitari basate su nano-satelliti e reti 5G, operanti in onde millimetriche. I contributi originali di questo lavoro interessano due settori che ricoprono un ruolo chiave nel contesto delle comunicazioni digitali ad alta velocit\ue0 e alta capacit\ue0: i meccanismi di condivisione del mezzo trasmissivo basati sull\u2019accesso casuale e le antenne a schiera riconfigurabili e compatte. I risultati ottenuti in questi due ambiti sono poi applicati in un\u2019architettura di rete che integra sistemi 5G terrestri e una costellazione di nanosatelliti in orbita bassa. Le comunicazioni satellitari sono sempre pi\uf9 parte integrante della vita quotidiana. Negli ultimi anni, si \ue8 registrata una crescita notevole dei piccoli satelliti (da 1 a 100 kg), sia in termini di tecnologia, che di frequenza di utilizzo. Non solo vengono lanciati in gran numero, ma si \ue8 iniziato ad utilizzarli in costellazioni da diverse decine di unit\ue0. Questa attivit\ue0 \ue8 l\u2019indicatore di una prospettiva ormai prossima: gli sviluppi nel settore dell\u2019Information and Communication Technology hanno avviato diverse iniziative che puntano ad utilizzare megacostellazioni di satelliti come reti per la fornitura di servizi di comunicazione a banda larga. Lo sfruttamento delle onde millimetriche rappresenta quindi un punto cardine per soddisfare la crescente richiesta di capacit\ue0 dei sistemi radio di prossima generazione. Inoltre, lo scenario che ne risulta \ue8 tale da richiedere una connettivit\ue0 completa, cos\uec che ogni satellite operi come un nodo di rete a tutto tondo, con possibilit\ue0 di collegamento tra la terra e lo spazio, e da satellite a satellite. In tale contesto, il ricorso a moderne tecniche di accesso casuale \ue8 particolarmente indicato. Negli ultimi anni si \ue8 assistito a un rinnovato interesse per i protocolli di tipo Aloha, grazie alla possibilit\ue0 di dotare i ricevitori di sistemi di cancellazione dell\u2019interferenza. A tale proposito, viene presentato un nuovo algoritmo che affianca alla cancellazione iterativa di interferenza lo sfruttamento dell\u2019effetto cattura, tenendo al tempo stesso presente la possibile non idealit\ue0 della cancellazione, e quindi la presenza di un residuo. Le sue prestazioni sono confrontate con i metodi attualmente adottati negli standard, mostrando un miglioramento del throughput pari al 31%. Viene inoltre presentata la sintesi di un\u2019antenna a schiera operante in banda Ka adatta per l\u2019uso su nanosatelliti. La schiera risultante offre interessanti benefici in termini di larghezza di banda, polarizzazione e versatilit\ue0, essendo possibile un utilizzo dual-task (downlink verso terra e collegamentointersatellitare). I risultati cos\uec ottenuti sono poi utilizzati per dimostrare, in un simulatore tempo discreto ed evento discreto, le prestazioni ottenibili da un\u2019architettura di rete integrante segmenti di rete radiomobile 5G con una dorsale costituita da una costellazione di nanosatellti. Il simulatore si avvale inoltre di un modello teorico per valutare l\u2019impatto della distribuzione geometrica dei nodi interferenti su una comunicazione in onde millimetriche di tipo line-of-sight. Tale modello, validato con simulazioni di tipo Monte Carlo, contempla i diagrammi di radiazione delle antenne e i recenti modelli di canale in onde millimetriche, che tengono in considerazione rumore, dispersione angolare, fading e bounded path loss. Sono state ricavate delle formulazioni analitiche per la distribuzione della potenza di rumore e interferenza, che consentono di valutare in forma chiusa la probabilit\ue0 di cattura. Tale impostazione \ue8 stata infine usata per discutere gli effetti dell\u2019interferenza sulla capacit\ue0 di Shannon di un collegamento in uplink operante in onde millimetriche, prendendo in considerazione delle condizioni realistiche per il canale

An Integrated Thermal-Electrical Model for Simulations of Battery Behavior in CubeSats

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Fault-tolerant satellite computing with modern semiconductors

Miniaturized satellites enable a variety space missions which were in the past infeasible, impractical or uneconomical with traditionally-designed heavier spacecraft. Especially CubeSats can be launched and manufactured rapidly at low cost from commercial components, even in academic environments. However, due to their low reliability and brief lifetime, they are usually not considered suitable for life- and safety-critical services, complex multi-phased solar-system-exploration missions, and missions with a longer duration. Commercial electronics are key to satellite miniaturization, but also responsible for their low reliability: Until 2019, there existed no reliable or fault-tolerant computer architectures suitable for very small satellites. To overcome this deficit, a novel on-board-computer architecture is described in this thesis.Robustness is assured without resorting to radiation hardening, but through software measures implemented within a robust-by-design multiprocessor-system-on-chip. This fault-tolerant architecture is component-wise simple and can dynamically adapt to changing performance requirements throughout a mission. It can support graceful aging by exploiting FPGA-reconfiguration and mixed-criticality.  Experimentally, we achieve 1.94W power consumption at 300Mhz with a Xilinx Kintex Ultrascale+ proof-of-concept, which is well within the powerbudget range of current 2U CubeSats. To our knowledge, this is the first COTS-based, reproducible on-board-computer architecture that can offer strong fault coverage even for small CubeSats.European Space AgencyComputer Systems, Imagery and Medi

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 Non-Terrestrial Networks From 5G to 6G: A Survey

Non-terrestrial networks (NTNs) traditionally have certain limited applications. However, the recent technological advancements and manufacturing cost reduction opened up myriad applications of NTNs for 5G and beyond networks, especially when integrated into terrestrial networks (TNs). This article comprehensively surveys the evolution of NTNs highlighting their relevance to 5G networks and essentially, how it will play a pivotal role in the development of 6G ecosystem. We discuss important features of NTNs integration into TNs and the synergies by delving into the new range of services and use cases, various architectures, technological enablers, and higher layer aspects pertinent to NTNs integration. Moreover, we review the corresponding challenges arising from the technical peculiarities and the new approaches being adopted to develop efficient integrated ground-air-space (GAS) networks. Our survey further includes the major progress and outcomes from academic research as well as industrial efforts representing the main industrial trends, field trials, and prototyping towards the 6G networks

Evolution of Non-Terrestrial Networks From 5G to 6G: A Survey

Non-terrestrial networks (NTNs) traditionally have certain limited applications. However, the recent technological advancements and manufacturing cost reduction opened up myriad applications of NTNs for 5G and beyond networks, especially when integrated into terrestrial networks (TNs). This article comprehensively surveys the evolution of NTNs highlighting their relevance to 5G networks and essentially, how it will play a pivotal role in the development of 6G ecosystem. We discuss important features of NTNs integration into TNs and the synergies by delving into the new range of services and use cases, various architectures, technological enablers, and higher layer aspects pertinent to NTNs integration. Moreover, we review the corresponding challenges arising from the technical peculiarities and the new approaches being adopted to develop efficient integrated ground-air-space (GAS) networks. Our survey further includes the major progress and outcomes from academic research as well as industrial efforts representing the main industrial trends, field trials, and prototyping towards the 6G networks

New Waves of IoT Technologies Research – Transcending Intelligence and Senses at the Edge to Create Multi Experience Environments

The next wave of Internet of Things (IoT) and Industrial Internet of Things (IIoT) brings new technological developments that incorporate radical advances in Artificial Intelligence (AI), edge computing processing, new sensing capabilities, more security protection and autonomous functions accelerating progress towards the ability for IoT systems to self-develop, self-maintain and self-optimise. The emergence of hyper autonomous IoT applications with enhanced sensing, distributed intelligence, edge processing and connectivity, combined with human augmentation, has the potential to power the transformation and optimisation of industrial sectors and to change the innovation landscape. This chapter is reviewing the most recent advances in the next wave of the IoT by looking not only at the technology enabling the IoT but also at the platforms and smart data aspects that will bring intelligence, sustainability, dependability, autonomy, and will support human-centric solutions.acceptedVersio