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  • The Inria's Research Teams produce an annual Activity Report presenting their activities and their results of the year. These reports include the team members, the scientific program, the software developed by the team and the new results of the year. The report also describes the grants, contracts and the activities of dissemination and teaching. Finally, the report gives the list of publications of the year.

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Section: Research Program

Fundaments

Our general goal is to develop distributed mechanisms for optimizing the operation of networks both at the mentioned logical and physical levels of the architecture. Taking an information- and human-centric perspective, we envision networks as means to convey relevant information to users, while adapting to customary practices (in terms of context, interests, or content demands) of such users.

We now detail further our agenda along two main specific axes, namely Human-Centric Networking and Internet of Things, bearing in mind that we will develop generic solutions relevant to several of these axes wherever possible.

Finally, at the end of this section, we also detail our activities related to standization and open experimental IoT Platforms.

Human-Centric Networking

Cellular and wireless data networks are increasingly relied upon to provide users with Internet access on devices such as smartphones, laptops or tablets. In particular, the proliferation of handheld devices equipped with multiple advanced capabilities (e.g., significant CPU and memory capacities, cameras, voice to text, text to voice, GPS, sensors, wireless communication) has catalyzed a fundamental change in the way people are connected, communicate, generate and exchange data. In this evolving network environment, users' social relations, opportunistic resource availability, and proximity between users' devices are significantly shaping the use and design of future networking protocols.

One consequence of these changes is that mobile data traffic has recently experienced a staggering growth in volume: Cisco has recently foreseen that the mobile data traffic will increase 18-fold within 2016, in front of a mere 9-fold increase in connection speeds. Hence, one can observe today that the inherently centralized and terminal-centric communication paradigm of currently deployed cellular networks cannot cope with the increased traffic demand generated by smartphone users. This mismatch is likely to last because (1) forecasted mobile data traffic demand outgrows the capabilities of planned cellular technological advances such as 4G or LTE, and (2) there is strong skepticism about possible further improvements brought by 5G technology.

Congestion at the Internet's edge is thus here to stay. Solutions to this problem are either to densify infrastructure, or to offload to alternate networks. Densifying infrastructure (with Femtocells for instance) is expensive. Carriers therefore consider other solutions, such as simultaneously leveraging Wi-Fi access points and hot spots. However, the projected increase of mobile data traffic demand pushes towards additional complementary offloading methods. Novel mechanisms are thus needed, which must fit both the new context that Internet users experience now, and their forecasted demands.

In this realm, we focus on new approaches leveraging ultra-distributed, user-centric approaches over IP. One approach that is considered in the research community is to leverage spontaneous wireless networks to offload infrastructure-based cellular networks. For example, the delay-tolerant nature of some of the data traffic can be used in conjunction with sequences of opportunistic encounters between users to deliver such data to its destination, without infrastructure access point relaying. However, the full capacity and the achievable information propagation speed in such networks are still barely understood, and in particular, there is a need to refine the characterization of user behaviour and social interaction. Our recent work on leveraging user mobility patterns, contact and inter-contact patterns, content demand patterns will constitute a starting point.

Internet of Things at the Edge

The IoT is indeed expected to massively use this networking paradigm to gradually connect billions of new devices to the Internet, and drastically increase communication without human source or destination – to the point where the amount of such communications will dwarf communications involving humans. Over the last decade, we are witnessing an increasing variety in IoT technologies starting from IoT communication technologies. The main reason for this is the growing diversity of strong requirements (i.e., in terms of bandwidth, latency, energy savings, etc) coming from new varieties of IoT use-cases, which now go far beyond the original wireless sensor networking domain. Besides, such variety of new IoT devices still inherits from the extremely limited capabilities of traditional embedded systems and sensor networks, such as requirements in terms of low power usage, low memory, with today a greater emphasis on interoperability needs.

Large scale user environment automation require communication protocols optimized to efficiently leverage the heterogeneous and unreliable wireless vicinity (the scope of which may vary according to the application). In fact, extreme constraints in terms of cost, CPU, battery and memory capacities are typically experienced on a substantial fraction of IoT devices. We expect that such constraints will not vanish any time soon for two reasons. On one hand the progress made over the last decade concerning the cost/performance ratio for such small devices is quite disappointing. On the other hand, the ultimate goal of the IoT is ubiquitous Internet connectivity between devices as tiny as dust particles. These constraints actually require to redesign not only the network protocol stack running on these devices, but also the software platform powering these machines.

In this context, we will aim at contributing to the design of novel network protocols and software platforms optimized to fit these constraints while remaining compatible with legacy Internet. Our recent work on large IoT testbeds such as FIT and on software platforms such as the RIOT operating system will serve as a starting point to design and conduct large scale experiments that are expected to provide both fruitful feedback to our theoretical analysis, and validation of the protocols we propose in the realm of our standardisation activities. A recent example of this methodology is the publication of RFC6997, the specification of a routing protocol for sensor networks we proposed, which was standardized a few months ago. An example of technique which we plan to explore in this field is the use of network coding. Network coding is ideally suited to such spontaneous wireless networks for increasing communication reliability (while minimizing the traffic load) ; exploiting it fully requires keeping track of the information flows, the central topic of this project proposal. In this domain, we will use as starting point our latest work on practical network coding broadcast.

Information centric networking paradigms emerge to decouple data name and location and organizes pervasive content caching and nearest replica routing, promising performance gains in terms of native multi-homing optimization, content access time and network load, at the price of more complex, more voluminous and volatile state management in routers. In this context, we investigate generic network protocols, that provide a significantly advantageous tradeoff between performance gains and required router state complexity increase on low-end IoT networks.

Open Experimental IoT Platforms

One necessity for research in the domain of IoT is to establish and improve IoT hardware platforms and testbeds, that integrate representative scenarios (such as Smart Energy, Home Automation etc.) and follow the evolution of technology, including radio technologies, and associated experimentation tools. For that, we plan to build upon the IoT-LAB federated testbeds, that we have participated in designing and deploying recently. We plan to further develop IoT-LAB with more heterogeneous, up-to-date IoT hardware and radios that will provide a usable and realistic experimentation environment. The goal is to provide a tool that enables testing a validation of upcoming software platforms and network stacks targeting concrete IoT deployments.

In parallel, on the software side, IoT hardware available so far made it uneasy for developers to build apps that run across heterogeneous hardware platforms. For instance Linux does not scale down to small, energy-constrained devices, while microcontroller-based OS alternatives were so far rudimentary and yield a steep learning curve and lengthy development life-cycles because they do not support standard programming and debugging tools. As a result, another necessity for research in this domain is to allow the emergence of it more powerful, unifying IOT software platforms, to bridge this gap. For that, we plan to build upon RIOT, a new open source software platform which provides a portable, Linux-like API for heterogeneous IoT hardware. We plan to continue to develop the systems and network stacks aspects of RIOT, within the open source developer community currently emerging around RIOT, which we co-founded together with Freie Universitaet Berlin. The key challenge is to improve usability and add functionalities, while maintaining architectural consistency and a small enough memory footprint. The goal is to provide an IoT software platform that can be used like Linux is used for less constrained machines, both (i) in the context of research and/or teaching, as well as (ii) in industrial contexts. Of course, we plan to use it ourselves for our own experimental research activities in the domain of IoT e.g., as an API to implement novel network protocols running on IoT hardware, to be tested and validated on IoT-LAB testbeds.

Standardization of Architectures and Efficient Protocols for Internet of Things

As described before, and by definition, the Internet of Things will integrate not only a massive number of homogeneous devices (e.g., networks of wireless sensors), but also heterogeneous devices using various communication technologies. Most devices will be very constrained resources (memory resources, computational resources, energy). Communicating with (and amongst) such devices is a key challenge that we will focus on. The ability to communicate efficiently, to communicate reliably, or even just to be able to communicate at all, is non-trivial in many IoT scenarios: in this respect, we intend to develop innovative protocols, while following and contributing to standardization in this area. We will focus and base most of our work on standards developed in the context of the IETF, in working groups such as 6lo, CORE, LWIG etc., as well as IRTF research groups such as NWCRG on network coding and ICNRG on Information Centric Networking. We note however that this task goes far beyond protocol design: recently, radical rearchitecturing of the networks with new paradigms such as Information Centric Networking, ICN, (or even in wired networks, software-defined networks), have opened exciting new avenues. One of our direction of research will be to explore these content-centric approaches, and other novel architectures, in the context of IoT.