Self-organization for wireless multi-hop systems can be divided into two categories: proactive cluster-based solutions and reactive on-demand solutions. Whereas the former have been studied for ad-hoc networks, the latter seem more adapted to low-energy low-traffic wireless sensor networks. We show that, despite the relative high cost to build and maintain a topology, a cluster-based approach is particularly suited for Body Area Networks. We present AnyBody, a selforganization protocol in which sensors attached to a person are grouped into clusters.

No abstract

While security is generally perceived as an important constituent of communication systems, this paper offers a viable security-communication trade-off particularly tailored to smart grids. These systems, often composed of embedded nodes with highly constrained resources, require, e.g., metering data to be delivered efficiently while neither jeopardizing communication nor security. Data aggregation is a natural choice in such settings, where an additional challenge is to facilitate per-hop and end-to-end security as well as a mechanism to protect the valid nodes from exhaustion threats. The prime contribution of this paper is to include into the security design framework issues related to aggregation, wireless fading and shadowing channels, physical layer parameters (such as choice of modulation, packet length, channel coder), medium access control parameters (such as average number of transmissions), routing parameters (such as choice of route). Relying on analysis and corroborating simulations, unprecedented design guidelines are derived which determine the operational point beyond which aggregation is useful as well quantifying the superiority of our protocol enriched with a protection mechanism against nonintended packets (malicious or nonmalicious) w.r.t. nonaggregated and/or unsecured solutions.

Abstract-Whilst security is generally perceived as an important constituent of communication systems, this paper offers a viable security-communication-tradeoff particularly tailored to Advanced Metering Infrastructures (AMIs) in Smart Grid systems. These systems, often composed of embedded nodes with highly constrained resources, require e.g. metering data to be delivered efficiently whilst neither jeopardizing communication nor security. Data aggregation is a natural choice in such settings, where the challenge is to facilitate per-hop as well as end-toend security. The prime contribution of this paper is to propose a secure aggregation protocol that meets the requirements of Smart Grids, and to analyze its efficiency considering various system configurations as well as the impact of the wireless channel through packet error rates. Relying on analysis and corroborative simulations, unprecedented design guidelines are derived which determine the operational point beyond which aggregation is useful as well quantifying the superiority of our protocol w.r.t. non-aggregated solutions.

Low-power wireless applications require different trade-off points between latency, reliability, data rate and power consumption. Given such a set of constraints, which physical layer should I be using? We study this question in the context of 6TiSCH, a state-of-the-art recently standardized protocol stack developed for harsh industrial applications. Specifically, we augment OpenWSN, the reference 6TiSCH open-source implementation, to support one of three physical layers from the IEEE802.15.4g standard: FSK 868 MHz which offers long range, OFDM 868 MHz which offers high data rate, and O-QPSK 2.4 GHz which offers more balanced performance. We run the resulting firmware on the 42-mote OpenTestbed deployed in an office environment, once for each physical layer. Performance results show that, indeed, no physical layer outperforms the other for all metrics. This article argues for combining the physical layers, rather than choosing one, in a generalized 6TiSCH architecture in which technology-agile radio chips (of which there are now many) are driven by a protocol stack which chooses the most appropriate physical layer on a frame-by-frame basis.

No abstract

LPWANs have recently emerged as a promising solution for enabling industrial IoT applications. To fully exploit their potential, LPWANs need to be connected to the Internet. However, the severe capacity constraints of LPWAN technologies challenge IPv6 support, and even 6LoWPAN-based adaptations are not sufficient. In this paper, we present SCHC, an ultralightweight IPv6 adaptation layer designed for LPWANs, which is being standardized by the IETF.

Wireless networks traditionally use a single physical layer for communication: some use high bit-rate short-range radios, others low bit-rate long-range radios. This article introduces g6TiSCH, a generalization of the standards-based IETF 6TiSCH protocol stack. g6TiSCH allows nodes equipped with multiple radios to dynamically switch between them on a link-by-link basis, as a function of link-quality. This approach results in a dynamic trade-off between latency and power consumption. We evaluate the performance of the approach experimentally on an indoor office testbed of 36 OpenMote B boards. Each OpenMote B can communicate using FSK 868 MHz, O-QPSK 2.4 GHz or OFDM 868 MHz, a combination of long-range and short-range physical layers. We measure network formation time, end-to-end reliability, end-to-end latency, and battery lifetime. We compare the performance of g6TiSCH against that of a traditional 6TiSCH stack running on each of the three physical layers. Results show that g6TiSCH yields lower latency and network formation time than any of the individual PHYs, while maintaining a similar battery lifetime.INDEX TERMS Agile Networking, IoT, 6TiSCH, Industrial IoT.