Normally-Off Computing Design Methodology Using Spintronics: From Devices to Architectures

Energy-harvesting-powered computing offers intriguing and vast opportunities to dramatically transform the landscape of Internet of Things (IoT) devices and wireless sensor networks by utilizing ambient sources of light, thermal, kinetic, and electromagnetic energy to achieve battery-free computing. In order to operate within the restricted energy capacity and intermittency profile of battery-free operation, it is proposed to innovate Elastic Intermittent Computation (EIC) as a new duty-cycle-variable computing approach leveraging the non-volatility inherent in post-CMOS switching devices. The foundations of EIC will be advanced from the ground up by extending Spin Hall Effect Magnetic Tunnel Junction (SHE-MTJ) device models to realize SHE-MTJ-based Majority Gate (MG) and Polymorphic Gate (PG) logic approaches and libraries, that leverage intrinsic-non-volatility to realize middleware-coherent, intermittent computation without checkpointing, micro-tasking, or software bloat and energy overheads vital to IoT. Device-level EIC research concentrates on encapsulating SHE-MTJ behavior with a compact model to leverage the non-volatility of the device for intrinsic provision of intermittent computation and lifetime energy reduction. Based on this model, the circuit-level EIC contributions will entail the design, simulation, and analysis of PG-based spintronic logic which is adaptable at the gate-level to support variable duty cycle execution that is robust to brief and extended supply outages or unscheduled dropouts, and development of spin-based research synthesis and optimization routines compatible with existing commercial toolchains. These tools will be employed to design a hybrid post-CMOS processing unit utilizing pipelining and power-gating through state-holding properties within the datapath itself, thus eliminating checkpointing and data transfer operations

Internet of Things (IoT): Societal Challenges & Scientific Research Fields for IoT

International audienceJust as the Internet radically reshaped society, the Internet of Things (IoT) willhave an impact on all areas of human life: from our homes, vehicles, workplacesand factories, to our cities and towns, agriculture and healthcare systems. It willalso affect all levels of society (individuals, companies and state-level), from urbanto rural and the natural world beyond. This makes it essential to have a properunderstanding of IoT and the challenges which relate to it. The primary aims ofthis document are to (i) determine the scope of IoT, its origins, current developments and perspectives, and (ii) identify the main societal, technical and scientific challenges linked to IoT.It seems inevitable that IoT will become increasingly omnipresent. Indeed, itis set to penetrate every aspect of all of our lives, connecting everything (billionsof new heterogeneous machines communicating with each other) and measuringeverything: from the collective action we take at a global level, right down to oursmallest individual physiological signals, in real-time. This is a double-edged sword,in that it simultaneously gives people cause for hope (automation, ­optimisation,innovative new functionalities etc.) and cause for fear (surveillance, dependency,cyberattacks, etc.). Given the ever-evolving nature of the IoT, new challenges linked to privacy, transparency, security appear, while new civil and industrialresponsibilities are starting to emerge.IoT is centred around an increasingly complex set of interlinked concepts andembedded technologies. At an industrial level, this growing complexity is makingthe idea of having full control over all components of IoT increasingly difficult, oreven infeasible. However, as a society, we must get to grips with the technologicalfoundations of IoT. One challenge for education will therefore be to graduallyincrease awareness of IoT, both in order to protect individuals’ sovereignty andfree will, and to initiate the training of our future scientists and technicians. Apublic research institute such as Inria can contribute towards understandingand explaining the technological foundations of IoT, in addition to preservingsovereignty in Europe.IoT will inevitably increase dependency on certain types of embeddedt ­ echno­logy. It is hence necessary to identify the new risks that entail, and todevise new strategies in order to take full advantage of IoT, while minimising theserisks. Similarly to the situation in other domains where one must continually seekto preserve ethics without hindering innovation, creating a legal framework forIoT is both necessary and challenging. It nevertheless seems clear already thatthe best way of facing up to industrial giants or superpowers is to take action atthe EU level, as shown by recent examples such as GDPR. Furthermore, given thegrowing influence of technological standards on society, playing an active rolein the process of standardising IoT technology is essential. Open standards andopen source – conceived as a common public good – will be pivotal for IoT, justas they have been for the Internet. Last but not least, massive use of IoT can helpbetter capture and understand the environmental challenges we are ­currentlyfacing – it is also expected IoT will help to mitigate these challenges. The goals inthis context are not only to reduce the quantities of natural resources consumedby IoT (for production, deployment, maintenance and recycling). We must alsoaim to more accurately evaluate the overall net benefit of IoT on the environment,at a global level. This requires determining and subtracting IoT’s environmentalcosts from its (measured) benefits, which is currently a challenge. The growingimpact of IoT underscores the importance of remaining at the cutting edge whenit comes to scientific research and technological development. This documenttherefore aims to (i) highlight the wide range of research fields which are fundamental to IoT, and(ii) take stock of current and future research problems in each of these fields. A number of links are made throughout the document to contributionsmade by Inria. These contributions are, by their nature, diverse (basic and appliedresearch, open source software, startup incubation) and concern the majority ofresearch fields on which IoT is based

Failure Analysis in Next-Generation Critical Cellular Communication Infrastructures

The advent of communication technologies marks a transformative phase in critical infrastructure construction, where the meticulous analysis of failures becomes paramount in achieving the fundamental objectives of continuity, security, and availability. This survey enriches the discourse on failures, failure analysis, and countermeasures in the context of the next-generation critical communication infrastructures. Through an exhaustive examination of existing literature, we discern and categorize prominent research orientations with focuses on, namely resource depletion, security vulnerabilities, and system availability concerns. We also analyze constructive countermeasures tailored to address identified failure scenarios and their prevention. Furthermore, the survey emphasizes the imperative for standardization in addressing failures related to Artificial Intelligence (AI) within the ambit of the sixth-generation (6G) networks, accounting for the forward-looking perspective for the envisioned intelligence of 6G network architecture. By identifying new challenges and delineating future research directions, this survey can help guide stakeholders toward unexplored territories, fostering innovation and resilience in critical communication infrastructure development and failure prevention

Sophisticated Batteryless Sensing

Wireless embedded sensing systems have revolutionized scientific, industrial, and consumer applications. Sensors have become a fixture in our daily lives, as well as the scientific and industrial communities by allowing continuous monitoring of people, wildlife, plants, buildings, roads and highways, pipelines, and countless other objects. Recently a new vision for sensing has emerged---known as the Internet-of-Things (IoT)---where trillions of devices invisibly sense, coordinate, and communicate to support our life and well being. However, the sheer scale of the IoT has presented serious problems for current sensing technologies---mainly, the unsustainable maintenance, ecological, and economic costs of recycling or disposing of trillions of batteries. This energy storage bottleneck has prevented massive deployments of tiny sensing devices at the edge of the IoT. This dissertation explores an alternative---leave the batteries behind, and harvest the energy required for sensing tasks from the environment the device is embedded in. These sensors can be made cheaper, smaller, and will last decades longer than their battery powered counterparts, making them a perfect fit for the requirements of the IoT. These sensors can be deployed where battery powered sensors cannot---embedded in concrete, shot into space, or even implanted in animals and people. However, these batteryless sensors may lose power at any point, with no warning, for unpredictable lengths of time. Programming, profiling, debugging, and building applications with these devices pose significant challenges. First, batteryless devices operate in unpredictable environments, where voltages vary and power failures can occur at any time---often devices are in failure for hours. Second, a device\u27s behavior effects the amount of energy they can harvest---meaning small changes in tasks can drastically change harvester efficiency. Third, the programming interfaces of batteryless devices are ill-defined and non- intuitive; most developers have trouble anticipating the problems inherent with an intermittent power supply. Finally, the lack of community, and a standard usable hardware platform have reduced the resources and prototyping ability of the developer. In this dissertation we present solutions to these challenges in the form of a tool for repeatable and realistic experimentation called Ekho, a reconfigurable hardware platform named Flicker, and a language and runtime for timely execution of intermittent programs called Mayfly

Energy-Sustainable IoT Connectivity: Vision, Technological Enablers, Challenges, and Future Directions

Technology solutions must effectively balance economic growth, social equity, and environmental integrity to achieve a sustainable society. Notably, although the Internet of Things (IoT) paradigm constitutes a key sustainability enabler, critical issues such as the increasing maintenance operations, energy consumption, and manufacturing/disposal of IoT devices have long-term negative economic, societal, and environmental impacts and must be efficiently addressed. This calls for self-sustainable IoT ecosystems requiring minimal external resources and intervention, effectively utilizing renewable energy sources, and recycling materials whenever possible, thus encompassing energy sustainability. In this work, we focus on energy-sustainable IoT during the operation phase, although our discussions sometimes extend to other sustainability aspects and IoT lifecycle phases. Specifically, we provide a fresh look at energy-sustainable IoT and identify energy provision, transfer, and energy efficiency as the three main energy-related processes whose harmonious coexistence pushes toward realizing self-sustainable IoT systems. Their main related technologies, recent advances, challenges, and research directions are also discussed. Moreover, we overview relevant performance metrics to assess the energy-sustainability potential of a certain technique, technology, device, or network and list some target values for the next generation of wireless systems. Overall, this paper offers insights that are valuable for advancing sustainability goals for present and future generations.Comment: 25 figures, 12 tables, submitted to IEEE Open Journal of the Communications Societ

Radio Resource Management for Unmanned Aerial Vehicle Assisted Wireless Communications and Networking

In recent years, employing unmanned aerial vehicles (UAVs) as aerial communication platforms or users is envisioned as a promising solution to enhance the performance of the existing wireless communication systems. However, applying UAVs for information technology applications also introduces many new challenges. This thesis focuses on the UAV-assisted wireless communication and networking, and aims to address the challenges through exploiting and designing efficient radio resource management methods. Specifically, four research topics are studied in this thesis. Firstly, to address the constraint of network heterogeneity and leverage the benefits of diversity of UAVs, a hierarchical air-ground heterogeneous network architecture enabled by software defined networking is proposed, which integrates both high and low altitude platforms into conventional terrestrial networks to provide additional capacity enhancement and expand the coverage of current network systems. Secondly, to address the constraint of link disconnection and guarantee the reliable communications among UAVs as aerial user equipment to perform sensing tasks, a robust resource allocation scheme is designed while taking into account the dynamic features and different requirements for different UAV transmission connections. Thirdly, to address the constraint of privacy and security threat and motivate the spectrum sharing between cellular and UAV operators, a blockchain-based secure spectrum trading framework is constructed where mobile network operators and UAV operators can share spectrum in a distributed and trusted environment based on blockchain technology to protect users' privacy and data security. Fourthly, to address the constraint of low endurance of UAV and prolong its flight time as an aerial base station for delivering communication coverage in a disaster area, an energy efficiency maximization problem jointly optimizing user association, UAV's transmission power and trajectory is studied in which laser charging is exploited to supply sustainable energy to enable the UAV to operate in the sky for a long time