SwePub - sökning: WFRF:(Duquennoy Simon)

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1.	Al Nahas, Beshr, 1985, et al. (författare) Concurrent Transmissions for Multi-hop Bluetooth 5 2019 Ingår i: International Conference on Embedded Wireless Systems and Networks. - 2562-2331. ; , s. 130-141 Konferensbidrag (refereegranskat)abstract Bluetooth is an omnipresent communication technology, available on billions of connected devices today. While it has been traditionally limited to peer-to-peer and star network topology, the recent Bluetooth 5 standard introduces new operating modes to allow for increased reliability and Bluetooth Mesh supports multi-hop networking based on message flooding. In this paper, we present BlueFlood. It adapts concurrent transmissions, as introduced by Glossy, to Bluetooth. The result is fast and efficient network-wide data dissemination in multi-hop Bluetooth networks. Moreover, we show that BlueFlood floods can be reliably received by off-the-shelf Bluetooth devices such as smart phones, opening new applications of concurrent transmissions and seamless integration with existing technologies. We present an in-depth experimental feasibility study of concurrent transmissions over Bluetooth PHY in a controlled environment. Further, we build a small-scale testbed where we evaluate BlueFlood in real-world settings of a residential environment. We show that BlueFlood achieves 99% end-to-end delivery ratio in multi-hop networks with a duty cycle of 0.13% for 1-second intervals.
2.	Al Nahas, Beshr, 1985, et al. (författare) Low-power listening goes multi-channel 2014 Ingår i: Proceedings - IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2014. ; , s. 2-9 Konferensbidrag (refereegranskat)abstract Exploiting multiple radio channels for communication has been long known as a practical way to mitigate interference in wireless settings. In Wireless Sensor Networks, however, multi-channel solutions have not reached their full potential: the MAC layers included in TinyOS or the Contiki OS for example are mostly single-channel. The literature offers a number of interesting solutions, but experimental results were often too few to build confidence. We propose a practical extension of low-power listening, MiCMAC, that performs channel hopping, operates in a distributed way, and is independent of upper layers of the protocol stack. The above properties make it easy to deploy in a variety of scenarios, without any extra configuration/scheduling/channel selection hassle. We implement our solution in Contiki and evaluate it in a 97-node~testbed while running a complete, out-of-the-box low-power IPv6 communication stack (UDP/RPL/6LoWPAN). Our experimental results demonstrate increased resilience to emulated WiFi interference (e.g., data yield kept above 90% when Contiki MAC drops in the 40% range). In noiseless environments, MiCMAC keeps the overhead low in comparison to Contiki MAC, achieving performance as high as 99% data yield along with sub-percent duty cycle and sub-second latency for a 1-minute inter-packet interval data collection. © 2014 IEEE.
3.	Al Nahas, Beshr, et al. (författare) Network Bootstrapping and Leader Election in Low-power Wireless Networks 2017 Ingår i: Proceedings of the International Conference on Embedded Networked Sensor Systems (ACM SenSys 2017), November 5-8, 2017, Delft, The Netherlands. - New York, NY, USA : ACM Press. Konferensbidrag (refereegranskat)abstract Many protocols in low-power wireless networks require a leader to bootstrap and maintain their operation. For example, Chaos and Glossy networks need an initiator to synchronize and initiate the communication rounds. Commonly, these protocols use a fixed, compile-time defined node as the leader. In this work, we tackle the challenge of dynamically bootstrapping the network and electing a leader in low-power wireless scenarios.
4.	Al Nahas, Beshr, 1985, et al. (författare) Network-wide Consensus Utilizing the Capture Effect in Low-power Wireless Networks 2017 Ingår i: Proceedings of the Conference on Embedded Networked Sensor Systems (ACM SenSys). - New York, NY, USA : ACM. - 9781450354592 ; 2017-January:2017 Konferensbidrag (refereegranskat)abstract In low-power wireless networking, new applications such as cooperative robots or industrial closed-loop control demand for network-wide agreement at low-latency and high reliability. Distributed consensus protocols is a mature field of research in a wired context, but has received little attention in low-power wireless settings. In this paper, we present A2: Agreement in the Air, a system that brings distributed consensus to low-power multi-hop networks. We introduce Synchrotron, a synchronous transmissions kernel that builds a robust mesh by exploiting the capture effect, frequency hopping with parallel channels, and link-layer security. We build A2 on top of this reliable base layer, and enable the two- and three-phase commit protocols, as well as network services such as joining, hopping sequence distribution and re-keying.We evaluate A2 on four public testbeds with different deployment densities and sizes. A2 requires only 475 ms to complete a two-phase commit over 180 nodes. The resulting duty cycle is 0.5 percent for 1-minute intervals. We show that A2 achieves zero losses end-to-end over long experiments, representing millions of data points.When further adding controlled failures, we show that two-phase commit ensures transaction consistency in A2 while three-phase commit provides liveness at the expense of inconsistency under specific failure scenarios.
5.	Al Nahas, Beshr, 1985, et al. (författare) Poster abstract : Network bootstrapping and leader election utilizing the capture effect in low-power wireless networks 2017 Ingår i: SenSys 2017 - Proceedings of the 15th ACM Conference on Embedded Networked Sensor Systems. - New York, NY, USA : Association for Computing Machinery, Inc. - 9781450354592 Konferensbidrag (refereegranskat)abstract Many protocols in low-power wireless networks require a leader to bootstrap and maintain their operation. For example, Chaos and Glossy networks need an initiator to synchronize and initiate the communication rounds. Commonly, these protocols use a fixed, compile-time defined node as the leader. In this work, we tackle the challenge of dynamically bootstrapping the network and electing a leader in low-power wireless scenarios.
6.	Boano, Carlo Alberto, et al. (författare) IoTBench: Towards a Benchmark for Low-power Wireless Networking 2018 Ingår i: Proceedings of the 1st International Workshop on Benchmarking Cyber-Physical Networks and Systems. Konferensbidrag (refereegranskat)
7.	Boano, Carlo Alberto, et al. (författare) IoTBench: Towards a Benchmark for Low-power Wireless Networking 2018 Ingår i: 2018 1ST IEEE WORKSHOP ON BENCHMARKING CYBER-PHYSICAL NETWORKS AND SYSTEMS (CPSBENCH 2018). - 9781538667422 ; , s. 36-41 Konferensbidrag (refereegranskat)abstract Unlike other fields of computing and communications, low-power wireless networking is plagued by one major issue: the absence of a well-defined, agreed-upon yardstick to compare the performance of systems, namely, a benchmark. We argue that this situation may eventually represent a hampering factor for a technology expected to be key in the Internet of Things (IoT) and Cyber-physical Systems (CPS). This paper describes a recent initiative to remedy this situation, seeking to enlarge the participation from the community.
8.	Dawans, Sébastien, et al. (författare) On Link Estimation in Dense RPL Deployments 2012. - 9 Konferensbidrag (refereegranskat)abstract The Internet of Things vision foresees billions of devices to connect the physical world to the digital world. Sensing applications such as structural health monitoring, surveillance or smart buildings employ multi-hop wireless networks with high density to attain sufficient area coverage. Such applications need networking stacks and routing protocols that can scale with network size and density while remaining energy-efficient and lightweight. To this end, the IETF RoLL working group has designed the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL). This paper discusses the problems of link quality estimation and neighbor management policies when it comes to handling high densities. We implement and evaluate different neighbor management policies and link probing techniques in Contiki’s RPL implementation. We report on our experience with a 100-node testbed with average 40-degree density. We show the sensitivity of high density routing with respect to cache sizes and routing metric initialization. Finally, we devise guidelines for design and implementation of density-scalable routing protocols.
9.	De Guglielmo, Domenico, et al. (författare) Analysis and Experimental Evaluation of IEEE 802.15.4e TSCH CSMA-CA Algorithm 2017 Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 66:2, s. 1573-1588 Tidskriftsartikel (refereegranskat)abstract Time-slotted channel hopping (TSCH) is one of the medium access control (MAC) behavior modes defined in the IEEE 802.15.4e standard. It combines time-slotted access and channel hopping, thus providing predictable latency, energy efficiency, communication reliability, and high network capacity. TSCH provides both dedicated and shared links. The latter is special slots assigned to more than one transmitter, whose concurrent access is regulated by a carrier-sense multiple access with collision avoidance (CSMA-CA) algorithm. In this paper, we develop an analytical model of the TSCH CSMA-CA algorithm to predict the performance experienced by nodes when using shared links. The model allows for deriving a number of metrics, such as delivery probability, packet latency, and energy consumption of nodes. Moreover, it considers the capture effect (CE) that typically occurs in real wireless networks. We validate the model through simulation experiments and measurements in a real testbed. Our results show that the model is very accurate. Furthermore, we found that the CE plays a fundamental role as it can significantly improve the performance experienced by nodes.
10.	Dron, Wilfried, et al. (författare) An Emulation-based Method for Lifetime Estimation of Wireless Sensor Networks 2014. - 9 Konferensbidrag (refereegranskat)abstract Lifetime estimation in Wireless Sensor Networks (WSN) is crucial to ensure that the network will last long enough (low maintenance cost) while not being over-dimensioned (low initial cost). Existing solutions have at least one of the two following limitations: (1) they are based on theoretical models or high-level protocol implementations, overlooking low-level (e.g., hardware, driver, etc.) constraints which we ﬁnd have a signiﬁcant impact on lifetime, and (2) they use an ideal battery model which over-estimates lifetime due to its constant voltage and its inability to model the non-linear properties of real batteries. We introduce a method for WSN lifetime estimation that operates on compiled ﬁrmware images and models the complex behavior of batteries. We use the MSPSim/Cooja node emulator and network simulator to run the application in a cycle-accurate manner and log all component states. We then feed the log into our lifetime estimation framework, which models the nodes and their batteries based on both technical and experimental speciﬁcations. In a case study of a Contiki RPL/6LoWPAN application, we identify and resolve several low-level implementation issues, thereby increasing the predicted network lifetime from 134 to 484 days. We compare our battery model to the ideal battery model and to the lifetime estimation based on the radio duty cycle, and ﬁnd that there is an average over-estimation of 36% and 76% respectively.
11.	Duquennoy, Simon, et al. (författare) Demo: Snap – Rapid Sensornet Deployment with a Sensornet Appstore 2011. - 12 Konferensbidrag (refereegranskat)abstract Despite ease of deployment being seen as a primary advantage of sensor networks, deployment remains difficult. We present Snap, a system for rapid sensornet deployment that allows sensor networks to be deployed, positioned, and reprogrammed through a sensornet appstore. Snap uses a smartphone interface that uses QR codes for node identification, a map interface for node positioning, and dynamic loading of applications on the nodes. Snap nodes run the Contiki operating system and its low-power IPv6 network stack that provides direct access from nodes to the smartphone application. We demonstrate rapid sensor node deployment, identification, positioning, and node reprogramming within seconds, over a multi-hop sensornet routing path with a WiFi-connected smartphone.
12.	Duquennoy, Simon, et al. (författare) Let the Tree Bloom : Scalable Opportunistic Routing with ORPL 2013 Konferensbidrag (refereegranskat)
13.	Duquennoy, Simon, et al. (författare) Let the Tree Bloom: Scalable Opportunistic Routing with ORPL 2013 Ingår i: SenSys '13: Proceedings of the 11th ACM Conference on Embedded Networked Sensor Systems. - New York, NY, USA : ACM. - 9781450320276 Konferensbidrag (refereegranskat)abstract Routing in battery-operated wireless networks is challenging, posing a tradeoff between energy and latency. Previous work has shown that opportunistic routing can achieve low-latency data collection in duty-cycled networks. However, applications are now considered where nodes are not only periodic data sources, but rather addressable end points generating traffic with arbitrary patterns.We present ORPL, an opportunistic routing protocol that supports any-to-any, on-demand traffic. ORPL builds upon RPL, the standard protocol for low-power IPv6 networks. By combining RPL's tree-like topology with opportunistic routing, ORPL forwards data to any destination based on the mere knowledge of the nodes' sub-tree. We use bitmaps and Bloom filters to represent and propagate this information in a space-efficient way, making ORPL scale to large networks of addressable nodes. Our results in a 135-node testbed show that ORPL outperforms a number of state-of-the-art solutions including RPL and CTP, conciliating a sub-second latency and a sub-percent duty cycle. ORPL also increases robustness and scalability, addressing the whole network reliably through a 64-byte Bloom filter, where RPL needs kilobytes of routing tables for the same task.
14.	Duquennoy, Simon, et al. (författare) Leveraging IP for Sensor Network Deployment 2011. - 12 Konferensbidrag (refereegranskat)
15.	Duquennoy, Simon, et al. (författare) Lossy Links, Low Power, High Throughput 2011. - 11 Konferensbidrag (refereegranskat)abstract As sensor networks move towards general-purpose low-power wireless networks, there is a need to support both traditional low-data rate traffic and high-throughput transfer. To attain high throughput, existing protocols monopolize the network resources and keep the radio on for all nodes involved in the transfer, leading to poor energy efficiency. This becomes progressively problematic in networks with packet loss, which inevitably occur in any real-world deployment. We present burst forwarding, a generic packet forwarding technique that combines low power consumption with high throughput for multi-purpose wireless networks. Burst forwarding uses radio duty cycling to maintain a low power consumption, recovers efficiently from interference, and inherently supports both single streams and cross-traffic. We experimentally evaluate our mechanism under heavy interference and compare it to PIP, a state-of-the-art sensornet bulk transfer protocol. Burst forwarding gracefully adapts radio duty cycle both to the level of interference and to traffic load, keeping a low and nearly constant energy cost per byte when carrying TCP traffic.
16.	Duquennoy, Simon, et al. (författare) Orchestra : Robust mesh networks through autonomously scheduled TSCH 2015 Ingår i: SenSys 2015 - Proceedings of the 13th ACM Conference on Embedded Networked Sensor Systems. - New York, NY, USA : Association for Computing Machinery, Inc. - 9781450336314 ; , s. 337-350 Konferensbidrag (refereegranskat)abstract Time slotted operation is a well-proven approach to achieve highly-reliable low-power networking through scheduling and channel hopping. It is, however, difficult to apply time slotting to dynamic networks as envisioned in the Internet of Things. Commonly, these applications do not have predefined periodic traffic patterns and nodes can be added or removed dynamically. This paper addresses the challenge of bringing TSCH (Time Slotted Channel Hopping MAC) to such dynamic networks. We focus on low-power IPv6 and RPL networks, and introduce Orchestra. In Orchestra, nodes autonomously compute their own, local schedules. They maintain multiple schedules, each allocated to a particular traffic plane (application, routing, MAC), and updated automatically as the topology evolves. Orchestra (re)computes local schedules without signaling overhead, and does not require any central or distributed scheduler. Instead, it relies on the existing network stack information to maintain the schedules. This scheme allows Orchestra to build non-deterministic networks while exploiting the robustness of TSCH. We demonstrate the practicality of Orchestra and quantify its benefits through extensive evaluation in two testbeds, on two hardware platforms. Orchestra reduces, or even eliminates, network contention. In long running experiments of up to 72 h we show that Orchestra achieves end-to-end delivery ratios of over 99.99%. Compared to RPL in asynchronous low-power listening networks, Orchestra improves reliability by two orders of magnitude, while achieving a similar latency-energy balance.
17.	Duquennoy, Simon, et al. (författare) Poster Abstract: A benchmark for low-power wireless networking 2016 Ingår i: Proceedings of the 14th ACM Conference on Embedded Networked Sensor Systems. - New York, NY, USA : ACM. - 9781450342636 ; 14 November 2016, s. 332-333 Konferensbidrag (refereegranskat)abstract Experimental research in low-power wireless networking lacks a reference benchmark. While other communities such as databases or machine learning have standardized bench-marks, our community still uses ad-hoc setups for its exper-iments and struggles to provide a fair comparison between communication protocols. Reasons for this include the di-versity of network scenarios and the stochastic nature of wireless experiments. Leveraging on the excellent testbeds and tools that have been built to support experimental val-idation, we make the case for a reference benchmark to pro-mote a fair comparison and reproducibility of results. This abstract describes early design elements and a benchmark-ing methodology with the goal to gather feedback from the community rather than propose a definite solution.
18.	Duquennoy, Simon, et al. (författare) Poster Abstract: Opportunistic RPL 2013 Ingår i: EWSN'13: Proceedings of the 10th European Conference on Wireless Sensor Networks. Konferensbidrag (refereegranskat)abstract Sensor nodes constituting Wireless Sensor Networks (WSN) are often battery-operated and have limited resources. To save energy, nodes sleep most of the time, and wake up periodically to handle communication. Such radio duty cycling poses a basic trade-off between energy and latency. In previous work, we have shown that opportunistic routing is an efficient way to achieve low-latency yet energy efficient data collection in WSN. In this paper, we extend this approach to the context of low-power IP networks, where nodes need to be addressed individually and where traffic patterns are irregular. We present ORPL, an opportunistic extension of RPL, the standard, state-of-the-art routing protocol for low-power IP networks. We discuss our preliminary results obtained with Contiki in a 137-node testbed.
19.	Duquennoy, Simon, et al. (författare) TSCH and 6TiSCH for contiki : Challenges, design and evaluation 2018 Ingår i: Proceedings - 2017 13th International Conference on Distributed Computing in Sensor Systems, DCOSS 2017. - : IEEE. - 9781538639917 ; , s. 11-18 Konferensbidrag (refereegranskat)abstract Synchronized communication has recently emerged as a prime option for low-power critical applications. Solutions such as Glossy or Time Slotted Channel Hopping (TSCH) have demonstrated end-to-end reliability upwards of 99.99%. In this context, the IETF Working Group 6TiSCH is currently standardizing the mechanisms to use TSCH in low-power IPv6 scenarios. This paper identifies a number of challenges when it comes to implementing the 6TiSCH stack. It shows how these challenges can be addressed with practical solutions for locking, queuing, scheduling and other aspects. With this implementation as an enabler, we present an experimental validation and comparison with state-of-the-art MAC protocols. We conduct fine-grained energy profiling, showing the impact of link-layer security on packet transmission. We evaluate distributed time synchronization in a 340-node testbed, and demonstrate that tight synchronization (hundreds of microseconds) can be achieved at very low cost (0.3% duty cycle, 0.008% channel utilization). We finally compare TSCH against traditional MAC layers: Low-power listening (LPL) and CSMA, in terms of reliability, latency and energy. We show that with proper scheduling, TSCH achieves by far the highest reliability, and outperforms LPL in both energy and latency.
20.	Elsts, Atis, et al. (författare) Competition : Adaptive Time-Slotted Channel Hopping 2017 Ingår i: Proceedings of the 2017 International Conference on Embedded Wireless Systems and Networks. - : ACM Press. ; , s. 274-275 Konferensbidrag (refereegranskat)abstract Time-Slotted Channel Hopping (TSCH) from the IEEE 802.15.4-2015 standard uses channel hopping to combat interference and frequency-selective fading. It has attracted large attention from the research community due to its properties: high reliability in terms of packet delivery rates, and increased predictability in terms of energy consumption and latency, as compared to commonly used low-power CSMA MAC protocols.This work makes use of the Contiki OS implementation of the TSCH protocol. We extend the standardized TSCH protocol with adaptive channel selection, adaptive time synchronization, and adaptive guard time selection to improve its energy efficiency and reliability properties.
21.	Elsts, Atis, et al. (författare) Microsecond-Accuracy Time Synchronization Using the IEEE 802.15.4 TSCH Protocol 2017 Ingår i: 2016 IEEE 41st Conference on Local Computer Networks Workshops (LCN Workshops). - : IEEE Computer Society. - 9781509023479 ; , s. 156-164 Konferensbidrag (refereegranskat)abstract Time-Slotted Channel Hopping from the IEEE 802.15.4-2015 standard requires that network nodes are tightly time-synchronized. Existing implementations of TSCH on embedded hardware are characterized by tens-of-microseconds large synchronization errors; higher synchronization accuracy would enable reduction of idle listening time on receivers, in this way decreasing the energy required to run TSCH. For some applications, it would also allow to replace dedicated time synchronization mechanisms with TSCH. We show that time synchronization errors in the existing TSCH implementations on embedded hardware are caused primarily by imprecise clock drift estimations, rather than by real unpredictable drift variance. By estimating clock drift more precisely and by applying adaptive time compensation on each node in the network, we achieve microsecond accuracy time synchronization on point-to-point links and a < 2 μs end-to-end error in a 7-node line topology. Our solution is implemented in the Contiki operating system and tested on Texas Instruments CC2650-based nodes, equipped with common off-the-shelf hardware clock sources (±20 ppm drift). Our implementation uses only standard TSCH control messages and is able to keep radio duty cycle below 1 %.
22.	Elsts, Atis, et al. (författare) Temperature-resilient time synchronization for the internet of things 2018 Ingår i: IEEE Transactions on Industrial Informatics. - 1551-3203 .- 1941-0050. ; 14:5, s. 2241-2250 Tidskriftsartikel (refereegranskat)abstract Networks deployed in real-world conditions have to cope with dynamic, unpredictable environmental temperature changes. These changes affect the clock rate on network nodes, and can cause faster clock de-synchronization compared to situations where devices are operating under stable temperature conditions. Wireless network protocols, such as time-slotted channel hopping (TSCH) from the IEEE 802.15.4-2015 standard, are affected by this problem, since they require tight clock synchronization among all nodes for the network to remain operational. This paper proposes a method for autonomously compensating temperature-dependent clock rate changes. After a calibration stage, nodes continuously perform temperature measurements to compensate for clock drifts at runtime. The method is implemented on low-power Internet of Things (IoT) nodes and evaluated through experiments in a temperature chamber, indoor and outdoor environments, as well as with numerical simulations. The results show that applying the method reduces the maximum synchronization error more than ten times. In this way, the method allows reduction in the total energy spent for time synchronization, which is practically relevant concern for low data rate, low energy budget TSCH networks, especially those exposed to environments with changing temperature.
23.	Eriksson, Joakim, et al. (författare) Scaling RPL to Dense and Large Networks with Constrained Memory 2018 Ingår i: Proceedings of the 2018 International Conference on Embedded Wireless Systems and Networks. ; , s. 126-134 Konferensbidrag (refereegranskat)abstract The Internet of Things poses new requirements for reliable, bi-directional communication in low-power and lossy networks, but these requirements are hard to fulfill since most existing protocols have been designed for data collection. In this paper, we propose standard-compliant mechanisms that make RPL meet these requirements while still scaling to large networks of IoT devices under significant resource constraints. Our aim is to scale far beyond what can be stored in RAM on the nodes of the network. The only node that needs to have storage for all the routing entries is the RPL root node. Based on experimentation with largescale commercial deployments, we suggest two mechanisms to make RPL scale under resource constraints: (1) end-to-end route registration with DAO and (2) a policy for managing the neighbor table. By employing these mechanisms, we show that the bi-directional packet reception rate of RPL networks increases significantly.
24.	Eriksson, Joakim, et al. (författare) Scaling RPL to Dense and Large Networks with Constrained Memory 2018 Konferensbidrag (refereegranskat)
25.	Ghadimi, Euhanna, et al. (författare) Opportunistic routing in low duty-cycle wireless sensor networks 2014 Ingår i: ACM transactions on sensor networks. - : Association for Computing Machinery (ACM). - 1550-4867 .- 1550-4859. ; 10:4, s. 67- Tidskriftsartikel (refereegranskat)abstract Opportunistic routing is widely known to have substantially better performance than unicast routing in wireless networks with lossy links. However, wireless sensor networks are usually duty cycled, that is, they frequently enter sleep states to ensure long network lifetime. This renders existing opportunistic routing schemes impractical, as they assume that nodes are always awake and can overhear other transmissions. In this article we introduce ORW, a practical opportunistic routing scheme for wireless sensor networks. ORW uses a novel opportunistic routing metric, EDC, that reflects the expected number of duty-cycled wakeups that are required to successfully deliver a packet from source to destination. We devise distributed algorithms that find the EDC-optimal forwarding and demonstrate using analytical performance models and simulations that EDC-based opportunistic routing results in significantly reduced delay and improved energy efficiency compared to traditional unicast routing. In addition, we evaluate the performance of ORW in both simulations and testbed-based experiments. Our results show that ORW reduces radio duty cycles on average by 50% (up to 90% on individual nodes) and delays by 30% to 90% when compared to the state-of-the-art.
26.	Hazra, Saptarshi, et al. (författare) Handling inherent delays in virtual IoT gateways 2019 Ingår i: Proceedings - 15th Annual International Conference on Distributed Computing in Sensor Systems, DCOSS 2019. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728105703 - 9781728105710 ; , s. 58-65 Konferensbidrag (refereegranskat)abstract Massive deployment of diverse ultra-low power wireless devices in different application areas has given rise to a plethora of heterogeneous architectures and communication protocols. It is challenging to provide convergent access to these miscellaneous collections of communicating devices. In this paper, we propose VGATE, an edge-based virtualized IoT gateway for bringing these devices together in a single framework using SDRs as technology agnostic radioheads. SDR platforms, however, suffer from large unpredictable delays. We design a GNU Radio-based IEEE 802.15.4 experimental setup using LimeSDR, where the data path is time-stamped at various points of interest to get a comprehensive understanding of the characteristics of the delays. Our analysis shows that GNU Radio processing and LimeSDR buffering delays are the major delays. We decrease the LimeSDR buffering delay by decreasing the USB transfer size but show that this comes at the cost of increased processing overhead. We modify the USB transfer packet size to investigate which USB transfer size provides the best balance between buffering delay and processing overhead across two different host computers. Our experiments show that for the best measured configuration the mean and jitter of latency decreases by 37% and 40% respectively for the host computer with higher processing resources. We also show that the throughput is not affected by these modifications.
27.	Hewage, Kasun, et al. (författare) Enabling TCP in Mobile Cyber-physical Systems 2015. - 7 Ingår i: 2015 IEEE 12th International Conference on Mobile Ad Hoc and Sensor Systems. - : IEEE Computer Society. - 9781467391016 ; , s. 289-297 Konferensbidrag (refereegranskat)abstract Cyber-physical systems consist of several wirelessly connected components such as sensors that monitor physical phenomena, computational entities that make decisions based on sensed information and actuators that interact with physical processes. Connecting cyber-physical systems to the Internet using IP protocols increases interoperability by avoiding the need for protocol translation gateways. Unfortunately, in this context TCP has been disregarded since it is known to perform poorly in wireless scenarios as it treats packet loss as an indicator for network congestion rather than poor link quality. In this paper, we use the Low-power Wireless Bus (LWB) as a link layer for TCP/IP, taking advantage of its reliability and its routing-free communication. We design a system that integrates LWB with a low-power IP stack and includes TCP-aware schedulers for LWB. We evaluate our system with experiments on real hardware using uIP, a popular embedded Internet protocol stack. Our results demonstrate high TCP throughput in mobile and static scenarios and, furthermore, show that mobility does not decrease TCP performance.
28.	Hithnawi, Anwar, et al. (författare) CrossZig: Combating Cross-Technology Interference in Low-power Wireless Networks 2016 Ingår i: 2016 15th ACM/IEEE International Conference on Information Processing in Sensor Networks, IPSN 2016 - Proceedings. - : IEEE. - 9781509008025 Konferensbidrag (refereegranskat)abstract Low-power wireless devices suffer notoriously from Cross- Technology Interference (CTI). To enable co-existence, researchers have proposed a variety of interference mitigation strategies. Existing solutions, however, are designed to work with the limitations of currently available radio chips. In this paper, we investigate how to exploit physical layer properties of 802.15.4 signals to better address CTI. We present CrossZig, a cross-layer solution that takes advantage of physical layer information and processing to improve low-power communication under CTI. To this end, CrossZig utilizes physical layer information to detect presence of CTI in a corrupted packet and to apply an adaptive packet recovery which incorporates a novel cross-layer based packet merging and an adaptive FEC coding. We implement a prototype of CrossZig for the low-power IEEE 802.15.4 in a software-defined radio platform. We show the adaptability and the performance gain of CrossZig through experimental evaluation considering both micro-benchmarking and system performance under various interference patterns. Our results demonstrate that CrossZig can achieve a high accuracy in error localization (94.3% accuracy) and interference type identification (less than 5% error rate for SINR ranges below 3 dB). Moreover, our system shows consistent performance improvements under interference from various interfering technologies.
29.	Hithnawi, A., et al. (författare) Poster abstract : Cross-layer optimization for low-power wireless coexistence 2015 Ingår i: SenSys 2015 - Proceedings of the 13th ACM Conference on Embedded Networked Sensor Systems. - New York, NY, USA : ACM Digital Library. - 9781450336314 ; , s. 443-444 Konferensbidrag (refereegranskat)abstract We present a system that leverages physical layer features to combat Cross-Technology Interference (CTI) in low-power wireless networks. Our system incorporates: (i) a lightweight interference detection mechanism for low-power radios that recognizes the type of interference in the received signal, (ii) a lightweight error detection mechanism to estimate and characterize error patterns within interfered packets, and (iii) a CTI-aware protocol that dynamically adapts transmission and recovery mode to the current interference patterns. We implement a prototype of our system for the lowpower IEEE 802.15.4 in software defined radios (SDR). Our early results of the system components demonstrate that we can achieve a high accuracy in error detection and interference type identification. Moreover, we observed a significant performance improvement compared to the standard 802.15.4 systems without interference-awareness.
30.	Hithnawi, Anwar, et al. (författare) Poster Abstract: Low-Power Wireless Channel Quality Estimation in the Presence of RF Smog 2014. - 7 Konferensbidrag (refereegranskat)abstract Low-power wireless networks deployed in indoor environments inevitably encounter high-power Cross Technology Interference (CTI) from a wide range of wireless devices operating in the shared RF spectrum bands. This severely reduces the performance of such networks and possibly causes loss of connectivity, which affects their availability and drains their resources. In this work, to address the channel uncertainty, a consequence of CTI, we propose a novel channel metric that (i) harnesses the local knowledge of a node about the wireless channel to discern the presence of persistent high-power interferers, and (ii) assists the node in inferring its proximity to the dominant interference sources in the physical space. In order to motivate and validate the necessity of such a metric, we empirically characterize the impact of the interaction between high/low-power cross technology interferers and IEEE 802.15.4.
31.	Hithnawi, Anwar, et al. (författare) TIIM : Technology-independent interference mitigation for low-power Wireless Networks 2015 Ingår i: IPSN 2015 - Proceedings of the 14th International Symposium on Information Processing in Sensor Networks (Part of CPS Week). - New York, NY, USA : Association for Computing Machinery, Inc. - 9781450334754 ; , s. 1-12 Konferensbidrag (refereegranskat)abstract The rise of heterogeneity in wireless technologies operating in the unlicensed bands has been shown to adversely affect the performance of low-power wireless networks. Cross-Technology Interference (CTI) is highly uncertain and raises the need for agile methods that assess the channel conditions and apply actions maximizing communication success. In this paper, we present TIIM, a lightweight Technology-Independent Interference Mitigation solution that detects, quantifies, and reacts to CTI in realtime. TIIM employs a lightweight machine learning classifier to (i) decide whether communication is viable over the interfered link, (ii) characterize the ambient conditions and apply the best coexistence mitigation strategy. We present an in-depth experimental characterization of the effect of CTI on 802.15.4 links, which motivated and influenced the design of TIIM. Our evaluation shows that TIIM, while exposed to extensive and heterogeneous interference, can achieve a total PRR improvement of 30% with an additional transmission overhead of 5.6%.
32.	Hithnawi, Anwar, et al. (författare) Understanding the Impact of Cross Technology Interference on IEEE 802.15.4 2014. - 7 Konferensbidrag (refereegranskat)abstract Over the last few decades, we witnessed notable progress in wireless communication. This has led to rapid emergence of heterogeneous wireless technologies that share the RF spectrum in an un-coordinated way. Such a coexistence introduces high uncertainty and complexity to the medium, affecting reliability and availability of wireless networks. This problem aggravates for technologies operating in the lightly regulated, yet crowded ISM bands. To address coexistence of different technologies in the scarce RF spectrum, provide proper interference-aware protocols, and mitigation schemes, we need to develop a good understanding of the interaction patterns of these technologies. In this paper, we provide a thorough study of the implications of Cross Technology Interference (CTI) on the particularly vulnerable low-power IEEE 802.15.4 wireless networks. We identify the underlying vulnerabilities that hamper 802.15.4 to withstand CTI. We show that the uncertainty that CTI induces on the wireless channel is not completely stochastic; CTI exhibits distinct patterns that can be exploited by interference-aware protocols.
33.	Kovatsch, Matthias, et al. (författare) A Low-Power CoAP for Contiki 2011. - 11 Konferensbidrag (refereegranskat)abstract Internet of Things devices will by and large be battery-operated, but existing application protocols have typically not been designed with power-efficiency in mind. In low-power wireless systems, power-efficiency is determined by the ability to maintain a low radio duty cycle: keeping the radio off as much as possible. We present an implementation of the IETF Constrained Application Protocol (CoAP) for the Contiki operating system that leverages the ContikiMAC low-power duty cycling mechanism to provide power efficiency. We experimentally evaluate our low-power CoAP, demonstrating that an existing application layer protocol can be made power-efficient through a generic radio duty cycling mechanism. To the best of our knowledge, our CoAP implementation is the first to provide power-efficient operation through radio duty cycling. Our results question the need for specialized low-power mechanisms at the application layer, instead providing low-power operation only at the radio duty cycling layer.
34.	Kovatsch, Matthias, et al. (författare) Actinium: A RESTful Runtime Container for Scriptable Internet of Things Applications 2012. - 9 Konferensbidrag (refereegranskat)abstract Programming Internet of Things (IoT) applications is challenging because developers have to be knowledgeable in various technical domains, from low-power networking, over embedded operating systems, to distributed algorithms. Hence, it will be challenging to ﬁnd enough experts to provide software for the vast number of expected devices, which must also be scalable and particularly safe due to the connection to the physical world. To remedy this situation, we propose an architecture that provides Web-like scripting for low-end devices through Cloud-based application servers and a consistent, RESTful programming model. Our novel runtime container Actinium (Ac) exposes scripts, their conﬁguration, and their lifecycle management through a fully RESTful programming interface using the Constrained Application Protocol (CoAP). We endow the JavaScript language with an API for direct interaction with mote-class IoT devices, the CoapRequest object, and means to export script data as Web resources. With Actinium, applications can be created by simply mashing up resources provided by CoAP servers on devices, other scripts, and classic Web services. We also discuss security considerations and show the suitability of this architecture in terms of performance with our publicly available implementation.
35.	Kuo, Ping Heng, et al. (författare) An integrated edge and Fog system for future communication networks 2018 Ingår i: 2018 IEEE Wireless Communications and Networking Conference Workshops (WCNCW). ; , s. 338-343 Konferensbidrag (refereegranskat)abstract Put together, the edge and fog form a large diverse pool of computing and networking resources from different owners that can be leveraged towards low latency applications as well as for alleviating high traffic volume in future networks including 5G and beyond. This paper sets out a framework for the integration of edge and fog computing and networking leveraging on ongoing specifications by ETSI MEC ISG and the OpenFog Consortium. It also presents the technological gaps that need to be addressed before such an integrated solution can be developed. These noticeably include challenges relating to the volatility of resources, heterogeneity of underlying technologies, virtualization of devices, and security issues. The framework presented is a Launchpad for a complete solution under development by the 5G-CORAL consortium.
36.	Landsiedel, Olaf, 1979, et al. (författare) Low power, low delay: Opportunistic routing meets duty cycling 2012 Ingår i: IPSN'12 - ACM/IEEE Proceedings of the 11th International Conference on Information Processing in Sensor Networks, (Beijing;16 - 20 April 2012). - New York, NY, USA : ACM. - 9781450312271 ; , s. 185-196 Konferensbidrag (refereegranskat)abstract Traditionally, routing in wireless sensor networks consists of two steps: First, the routing protocol selects a next hop, and, second, the MAC protocol waits for the intended destination to wake up and receive the data. This design makes it difficult to adapt to link dynamics and introduces delays while waiting for the next hop to wake up. In this paper we introduce ORW, a practical opportunistic routing scheme for wireless sensor networks. In a dutycycled setting, packets are addressed to sets of potential receivers and forwarded by the neighbor that wakes up first and successfully receives the packet. This reduces delay and energy consumption by utilizing all neighbors as potential forwarders. Furthermore, this increases resilience to wireless link dynamics by exploiting spatial diversity. Our results show that ORW reduces radio duty-cycles on average by 50% (up to 90% on individual nodes) and delays by 30% to 90% when compared to the state of the art.
37.	Mangano, Frederic, et al. (författare) Formal verification of a memory allocation module of Contiki with FRAMA-C : A case study 2017 Konferensbidrag (refereegranskat)abstract Formal verification is still rarely applied to the IoT (Internet of Things) software, whereas IoT applications tend to become increasingly popular and critical. This short paper promotes the usage of formal verification to ensure safety and security of software in this domain. We present a successful case study on deductive verification of a memory allocation module of Contiki, a popular open-source operating system for IoT. We present the target module, describe how the code has been specified and proven using Frama-C, a software analysis platform for C code, and discuss lessons learned.
38.	Martina, Brachmann, et al. (författare) IEEE 802.15. 4 TSCH in Sub-GHz : Design Considerations and Multi-band Support 2019 Ingår i: Proceedings of the IEEE LCN. - : IEEE COMPUTER SOC. - 9781728110288 ; , s. 42-50 Konferensbidrag (refereegranskat)abstract In this paper, we address the support of Time-Slotted Channel Hopping (TSCH) on multiple frequency bandswithin a single TSCH network. This allows to simultaneously runapplications with different requirements on link characteristicsand to increase resilience against interference. To this end, wefirst enable sub-GHz communication in TSCH, which has beenprimarily defined for the 2.4 GHz band. Thereafter, we proposetwo designs to support multiple physical layers in TSCH on thesame nodes. Our experimental evaluation shows that TSCH isapplicable in a wide range of data rates between 1.2 kbps and1000 kbps. We find that data rates of 50 kbps and below have along communication range and a nearly perfect link symmetry,but also have a 20x higher channel utilization compared to higherdata rates, increasing the risk of collisions. Using these findings,we show the advantages of the multi-band support on the exampleof synchronization accuracy when exchanging TSCH beaconswith a low data rate and application data at a high data rate.
39.	McNamara, Liam, et al. (författare) Demo Abstract: SicsthSense - Dispersing the Cloud 2014 Annan publikation (refereegranskat)
40.	McNamara, Liam, et al. (författare) Demo Abstract: SicsthSense - Dispersing the Cloud 2014 Ingår i: Proceedings of the European Conference on Wireless Sensor Networks (EWSN 2014). Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract This demo presents SicsthSense, our open cloudplatform for the Internet of Things. SicsthSense enables lowpower devices such as sensor nodes and smartphones to easilystore their generated data streams in the cloud. This allows thedata streams, and their history, to be made permanently availableto users for visualisation, processing and sharing. Moving sensordata computation and monitoring into the cloud is a promisingavenue to enable centralisation of control and redistribution ofcollected data.We showcase SicsthSense running with real sensor nodescollecting environmental data and posting it to our datastore.This live data is then visualised and made available for sharingbetween users of the platform. Our Android App will also bedistributed to enable participants to stream their phone sensorsinto the system, demonstrating how simple it can be to startmachine-to-machine interactions with SicsthSense.
41.	Michel, Mathieu, et al. (författare) Load-Balanced Data Collection through Opportunistic Routing 2015. - 9 Ingår i: 2015 International Conference on Distributed Computing in Sensor Systems. - 9781479988563 ; , s. 62-70 Konferensbidrag (refereegranskat)abstract Wireless Sensor Networks performing low-power data collection often suffer from uneven load distribution among nodes. Nodes close to the network root typically face a higher load, see their battery deplete first, and become prematurely unable to operate (both sensing and relaying other nodes' data). We argue that opportunistic routing, by making forwarding decision on a per-packet basis and at the receiver rather than the sender, has the potential to better balance the load across nodes. We extend ORPL, an opportunistic version of the standard routing protocol RPL, with support for load-balancing. In our protocol, ORPL-LB, nodes continuously adapt their wake-up interval in order to adjust their availability and attain a deployment-specific target duty cycle. We implement our protocol in Contikiand present our experimental validation in Indriya, a 93-nodestestbed. Our results show that ORPL-LB reduces significantly(by approximately 40%) the worst node's duty cycle, with little or no impact on packet delivery ratio and latency.
42.	Misra, Prasant, et al. (författare) Supporting Cyber-Physical Systems with Wireless Sensor Networks : An Outlook of Software and Services 2013. - 10 Ingår i: Journal of the Indian Institute of Science. - : Indian Institute of Science. - 0970-4140. ; 93:3, s. 463-486 Tidskriftsartikel (refereegranskat)abstract Sensing, communication, computation and control technologies are the essential building blocks of a cyber-physical system (CPS). Wireless sensor networks (WSNs) are a way to support CPS as they provide fine-grained spatial-temporal sensing, communication and computation at a low premium of cost and power. In this article, we explore the fundamental concepts guiding the design and implementation of WSNs. We report the latest developments in WSN software and services for meeting existing requirements and newer demands; particularly in the areas of: operating system, simulator and emulator, programming abstraction, virtualization, IP-based communication and security, time and location, and network monitoring and management. We also reflect on the ongoing efforts in providing dependable assurances for WSN-driven CPS. Finally, we report on its applicability with a case-study on smart buildings.
43.	Misra, Prasant, et al. (författare) Supporting cyber-physical systems with wireless sensor networks : An outlook of software and services 2013 Ingår i: Journal of the Indian Institute of Science. - 0970-4140. ; 93:3, s. 463-486 Tidskriftsartikel (refereegranskat)
44.	Oikonomou, George, et al. (författare) The Contiki-NG open source operating system for next generation IoT devices 2022 Ingår i: SoftwareX. - : Elsevier B.V.. - 2352-7110. ; 18 Tidskriftsartikel (refereegranskat)abstract Contiki-NG (Next Generation) is an open source, cross-platform operating system for severely constrained wireless embedded devices. It focuses on dependable (reliable and secure) low-power communications and standardised protocols, such as 6LoWPAN, IPv6, 6TiSCH, RPL, and CoAP. Its primary aims are to (i) facilitate rapid prototyping and evaluation of Internet of Things research ideas, (ii) reduce time-to-market for Internet of Things applications, and (iii) provide an easy-to-use platform for teaching embedded systems-related courses in higher education. Contiki-NG started as a fork of the Contiki OS and retains many of its original features. In this paper, we discuss the motivation behind the creation of Contiki-NG, present the most recent version (v4.7), and highlight the impact of Contiki-NG through specific examples. © 2022 The Authors
45.	Peyrard, Alexandre, et al. (författare) Towards Formal Verification of Contiki : Analysis of the AES-CCM* Modules with Frama-C 2018 Ingår i: Proceedings of the 2018 International Conference on Embedded Wireless Systems and Networks. ; , s. 264-269 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract The number of IoT (Internet of Things) applications is rapidly increasing and allows embedded devices today to be massively connected to the Internet. This raises software security questions. This paper demonstrates the usage of formal verification to increase the security of Contiki OS, a popular open-source operating system for IoT. We present a case study on deductive verification of encryption-decryption modules of Contiki (namely, AES--CCM*) using Frama-C, a software analysis platform for C code.
46.	Peyrard, Alexandre, et al. (författare) Towards Formal Verification of Contiki OS : Analysis of the AES-CCM* Modules with Frama-C 2018 Ingår i: Proceedings of the Workshop on Recent advances in secure management of data and resources in the IoT (RED-IOT), February 14-16, 2018, Madrid, Spain. Konferensbidrag (refereegranskat)abstract The number of Internet of Things (IoT) applications israpidly increasing and allows embedded devices today tobe massively connected to the Internet. This raises softwaresecurity questions. This paper demonstrates the usageof formal verification to increase the security of Contiki,a popular open-source operating system for the IoT. Wepresent a case study on deductive verification of encryptiondecryptionmodules of Contiki (namely, AES–CCM*) usingFrama-C, a software analysis platform for C code.
47.	PrithviRaj, Narenda, et al. (författare) BLE and IEEE 802.15.4 in the IoT : Evaluation and Interoperability Considerations 2016 Ingår i: Internet Of Things. - Cham : Springer International Publishing. - 9783319470757 - 9783319470740 ; , s. 427-438 Konferensbidrag (refereegranskat)abstract As the Internet of Things is gaining momentum, low-power communication technologies proliferate. In this paper, we focus on Bluetooth Low Energy (BLE) and IEEE 802.15.4 (CSMA, Low-power listening, and TSCH), and advocate low-power IPv6 for interoperability between the two. We perform a thorough experimental comparison of their link-layer performance, both in idle radio environment and when facing heavy (controlled) external interference. Our results suggest that both technologies can achieve interesting and complementary latency-energy trade-offs. Based on our results, we discuss possible interoperability between BLE and IEEE 802.15.4 and present related open issues.
48.	Raza, Shahid, et al. (författare) Demo abstract : Securing communication in 6LoWPAN with compressed IPsec 2011 Ingår i: DCOSS. ; , s. 1-2 Konferensbidrag (refereegranskat)
49.	Raza, Shahid, et al. (författare) Demo Abstract: Securing Communication in 6LoWPAN with Compressed IPsec 2011. - 13 Konferensbidrag (refereegranskat)abstract With the inception of IPv6 it is possible to assign a unique ID to each device on planet. Recently, wireless sensor networks and traditional IP networks are more tightly integrated using IPv6 and 6LoWPAN. Real-world deployments of WSN demand secure communication. The receiver should be able to verify that sensor data is generated by trusted nodes and/or it may also be necessary to encrypt sensor data in transit. Available IPv6 protocol stacks can use IPsec to secure data exchanges. Thus, it is desirable to extend 6LoWPAN such that IPsec communication with IPv6 nodes is possible. It is beneficial to use IPsec because the existing end-points on the Internet do not need to be modified to communicate securely with the WSN. Moreover, using IPsec, true end-to-end security is implemented and the need for a trustworthy gateway is removed. In this demo we will show the usage of our implemented lightweight IPsec. We will show how IPsec ensures end-to-end security between an IP enabled sensor networks and the traditional Internet. This is the first compressed lightweight design, implementation, and evaluation of a 6LoWPAN extension for IPsec. This demo complements the full paper that will appear in the parent conference, DCOSS’11.
50.	Raza, Shahid, et al. (författare) Secure Communication for the Internet of Things : A Comparison of Link-Layer Security and IPsec for 6LoWPAN 2012. - 15 Ingår i: Security and Communication Networks. - : Wiley. - 1939-0114 .- 1939-0122. Tidskriftsartikel (refereegranskat)abstract The future Internet is an IPv6 network interconnecting traditional computers and a large number of smart objects. This Internet of Things (IoT) will be the foundation of many services and our daily life will depend on its availability and reliable operation. Therefore, among many other issues, the challenge of implementing secure communication in the IoT must be addressed. In the traditional Internet, IPsec is the established and tested way of securing networks. It is therefore reasonable to explore the option of using IPsec as a security mechanism for the IoT. Smart objects are generally added to the Internet using IPv6 over Low-power Wireless Personal Area Networks (6LoWPAN), which defines IP communication for resource-constrained networks. Thus, to provide security for the IoT based on the trusted and tested IPsec mechanism, it is necessary to define an IPsec extension of 6LoWPAN. In this paper, we present such a 6LoWPAN/IPsec extension and show the viability of this approach. We describe our 6LoWPAN/IPsec implementation, which we evaluate and compare with our implementation of IEEE 802.15.4 link-layer security. We also show that it is possible to reuse crypto hardware within existing IEEE 802.15.4 transceivers for 6LoWPAN/IPsec. The evaluation results show that IPsec is a feasible option for securing the IoT in terms of packet size, energy consumption, memory usage, and processing time. Furthermore, we demonstrate that in contrast to common belief, IPsec scales better than link-layer security as the data size and the number of hops grow, resulting in time and energy savings. Copyright © 2012 John Wiley & Sons, Ltd.

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