Robotic Wireless Sensor Networks

In this chapter, we present a literature survey of an emerging, cutting-edge, and multi-disciplinary field of research at the intersection of Robotics and Wireless Sensor Networks (WSN) which we refer to as Robotic Wireless Sensor Networks (RWSN). We define a RWSN as an autonomous networked multi-robot system that aims to achieve certain sensing goals while meeting and maintaining certain communication performance requirements, through cooperative control, learning and adaptation. While both of the component areas, i.e., Robotics and WSN, are very well-known and well-explored, there exist a whole set of new opportunities and research directions at the intersection of these two fields which are relatively or even completely unexplored. One such example would be the use of a set of robotic routers to set up a temporary communication path between a sender and a receiver that uses the controlled mobility to the advantage of packet routing. We find that there exist only a limited number of articles to be directly categorized as RWSN related works whereas there exist a range of articles in the robotics and the WSN literature that are also relevant to this new field of research. To connect the dots, we first identify the core problems and research trends related to RWSN such as connectivity, localization, routing, and robust flow of information. Next, we classify the existing research on RWSN as well as the relevant state-of-the-arts from robotics and WSN community according to the problems and trends identified in the first step. Lastly, we analyze what is missing in the existing literature, and identify topics that require more research attention in the future

Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View

Small satellite systems enable whole new class of missions for navigation, communications, remote sensing and scientific research for both civilian and military purposes. As individual spacecraft are limited by the size, mass and power constraints, mass-produced small satellites in large constellations or clusters could be useful in many science missions such as gravity mapping, tracking of forest fires, finding water resources, etc. Constellation of satellites provide improved spatial and temporal resolution of the target. Small satellite constellations contribute innovative applications by replacing a single asset with several very capable spacecraft which opens the door to new applications. With increasing levels of autonomy, there will be a need for remote communication networks to enable communication between spacecraft. These space based networks will need to configure and maintain dynamic routes, manage intermediate nodes, and reconfigure themselves to achieve mission objectives. Hence, inter-satellite communication is a key aspect when satellites fly in formation. In this paper, we present the various researches being conducted in the small satellite community for implementing inter-satellite communications based on the Open System Interconnection (OSI) model. This paper also reviews the various design parameters applicable to the first three layers of the OSI model, i.e., physical, data link and network layer. Based on the survey, we also present a comprehensive list of design parameters useful for achieving inter-satellite communications for multiple small satellite missions. Specific topics include proposed solutions for some of the challenges faced by small satellite systems, enabling operations using a network of small satellites, and some examples of small satellite missions involving formation flying aspects.Comment: 51 pages, 21 Figures, 11 Tables, accepted in IEEE Communications Surveys and Tutorial

Routing for Flying Networks using Software-Defined Networking

Nos últimos anos, os Veículos Aéreos Não Tripulados (UAVs) estão a ser usados de forma crescente em inúmeras aplicações, tanto militares como civis. A sua miniaturização e o preço reduzido abriram o caminho para o uso de enxames de UAVs, que permitem melhores resultados na realização de tarefas em relação a UAVs independentes. Contudo, para permitir a cooperação entre UAVs, devem ser asseguradas comunicações contínuas e fiáveis.Além disso, os enxames de UAVs foram identificados pela comunidade científica como meio para permitir o acesso à Internet a utilizadores terrestres em cenários como prestação de socorros e Eventos Temporários Lotados (TCEs), tirando partido da sua capacidade para transportar Pontos de Acesso (APs) Wi-Fi e células Long-Term Evolution (LTE). Soluções que dependem de uma Estação de Controlo (CS) capaz de posicionar os UAVs de acordo com as necessidades de tráfego dos utilizadores demonstraram aumentar a Qualidade de Serviço (QoS) oferecida pela rede. No entanto, estas soluções introduzem desafios importantes no que diz respeito ao encaminhamento do tráfego.Recentemente, foi proposta uma solução que tira partido do conhecimento da CS sobre o estado futuro da rede para atualizar dinamicamente as tabelas de encaminhamento de modo a que as ligações na rede voadora não sejam interrompidas, em vez de se recuperar da sua interrupção, como é o caso na maioria dos protocolos de encaminhamento existentes. Apesar de não considerar o impacto das reconfigurações na rede de acesso, como consequência da mobilidade dos APs, ou o balanceamento da carga na rede, esta abordagem é promissora e merece ser desenvolvida e implementada num sistema real.Esta dissertação tem como foco a implementação de um protocolo de encaminhamento para redes voadoras baseado em Software-Defined Networking (SDN). Especificamente, aborda os problemas de mobilidade e de balanceamento da carga na rede de uma perspetiva centralizada, garantindo simultaneamente comunicações ininterruptas e de banda-larga entre utilizadores terrestres e a Internet, permitindo assim que os UAVs se possam reposicionar e reconfigurar sem interferir com as ligações dos terminais à rede.In recent years, Unmanned Aerial Vehicles (UAVs) are being increasingly used in various applications, both military and civilian. Their miniaturisation and low cost paved the way to the usage of swarms of UAVs, which provide better results when performing tasks compared to single UAVs. However, to enable cooperation between the UAVs, always-on and reliable communications must be ensured.Moreover, swarms of UAVs are being targeted by the scientific community as a way to provide Internet access to ground users in scenarios such as disaster reliefs and Temporary Crowded Events (TCEs), taking advantage of the capability of UAVs to carry Wi-Fi Access Points (APs) or Long-Term Evolution (LTE) cells. Solutions relying on a Control Station (CS) capable of positioning the UAVs according to the users' traffic demands have been shown to improve the Quality of Service (QoS) provided by the network. However, they introduce important challenges regarding network routing.Recently, a solution was proposed to take advantage of the knowledge provided by a CS regarding how the network will change, by dynamically updating the forwarding tables before links in the flying network are disrupted, rather than recovering from link failure, as is the case in most of the existing routing protocols. Although it does not consider the impact of reconfigurations on the access network due to the mobility of the APs, it is a promising approach worthy of being improved and implemented in a real system.This dissertation focuses on implementing a routing solution for flying networks based on Software-Defined Networking (SDN). Specifically, it addresses the mobility management and network load balancing issues from a centralised perspective, while simultaneously enabling uninterruptible and broadband communications between ground users and the Internet, thus allowing UAVs to reposition and reconfigure themselves without interfering with the terminals' connections to the network

Lunar Relay Satellite Network for Space Exploration: Architecture, Technologies and Challenges

NASA is planning a series of short and long duration human and robotic missions to explore the Moon and then Mars. A key objective of these missions is to grow, through a series of launches, a system of systems infrastructure with the capability for safe and sustainable autonomous operations at minimum cost while maximizing the exploration capabilities and science return. An incremental implementation process will enable a buildup of the communication, navigation, networking, computing, and informatics architectures to support human exploration missions in the vicinities and on the surfaces of the Moon and Mars. These architectures will support all space and surface nodes, including other orbiters, lander vehicles, humans in spacesuits, robots, rovers, human habitats, and pressurized vehicles. This paper describes the integration of an innovative MAC and networking technology with an equally innovative position-dependent, data routing, network technology. The MAC technology provides the relay spacecraft with the capability to autonomously discover neighbor spacecraft and surface nodes, establish variable-rate links and communicate simultaneously with multiple in-space and surface clients at varying and rapidly changing distances while making optimum use of the available power. The networking technology uses attitude sensors, a time synchronization protocol and occasional orbit-corrections to maintain awareness of its instantaneous position and attitude in space as well as the orbital or surface location of its communication clients. A position-dependent data routing capability is used in the communication relay satellites to handle the movement of data among any of multiple clients (including Earth) that may be simultaneously in view; and if not in view, the relay will temporarily store the data from a client source and download it when the destination client comes into view. The integration of the MAC and data routing networking technologies would enable a relay satellite system to provide end-to-end communication services for robotic and human missions in the vicinity, or on the surface of the Moon with a minimum of Earth-based operational support