In this paper, we propose to optimize the LoRaWAN®Adaptive Data Rate algorithm in case an inter-packet error correction scheme is available. We adjust its parameters based on analysis of the LoRa channel, supported by real-world traffic traces. The resulting protocol provides high reliability even over low quality channels with comparable Time on Air and similar downlink usage as the LoRaWAN solution. Simulations and emulation fed by real-world channel traces corroborate the analysis.

We propose to optimize the LoRaWAN Adaptive Data Rate algorithm in case an inter-packet error correction scheme is available. We adjust its parameters based on the analysis of the LoRa channel with multiple reception gateways, supported by real-world traffic traces. The resulting protocol provides very high reliability even over low quality channels, with comparable Time on Air and similar downlink usage as the currently deployed mechanism. Simulations corroborate the analysis, both over a synthetic random wireless link and over replayed real-world packet transmission traces.

In this paper, we present the results of extensive experiments on a testbed in the The Things Network (TTN), a public LoRa network. We evaluate the transmission quality of LoRa links by measuring the Packet Reception Rate (PRR) as a function of the payload length. The results show that there is only a slight impact of the payload length on PRR, which means that the bit error rate does not strongly influence the probability of packet reception. Our measurements show that the LoRa channel behaves like a slow fading Rayleigh channel, which translates into probability Ps of being (or not) in a favorable condition for each frame reception: once the frame preamble is received, there is great chance that the whole frame is correctly received. Probability Ps depends on the Spreading Factor and the Signal to Noise Ratio, and often becomes a dominant factor of successful reception depending on the signal strength at a gateway.

Although LoRaWAN offers many advantages, one of its main limitation is the insufficient downlink capacity in large-scale scenarios. This makes reliable communication impractical as, in LoRaWAN, reliability is achieved through the acknowledgement of confirmed messages. The contribution of this paper is to provide a comprehensive description of the problems associated with the presence of downlink traffic and to propose solutions to enable the use of acknowledgments for low to medium downlink load. The proposed mechanisms build on a more adequate and flexible choice of the gateway for each downlink transmission by the network server. Thus, they are entirely compatible with existing LoRaWAN technologies and deployments. Our simulation results show that the proposed solutions enable the successful realization of a higher percentage of LoRaWAN confirmed messages. Thus, the common practice of strongly discouraging the use of confirmed messages could be reconsidered to allow applications that require reliable communication.

This paper investigates thermal covert channels in the context of the Internet-of-Things. More, precisely we demonstrate such a channel on BLE-enabled devices. We explain how the core design principles of BLE link-layer protocol, combined with well-timed intensive CPU calculations can be leveraged to mount a thermal covert channel between two devices.

In this paper, we propose IoTChain, a combination of the OSCAR architecture [1] and the ACE authorization framework [2] to provide an E2E solution for the secure authorized access to IoT resources. IoTChain consists of two components, an authorization blockchain based on the ACE framework and the OSCAR object security model, extended with a group key scheme. The blockchain provides a flexible and trustless way to handle authorization while OSCAR uses the public ledger to set up multicast groups for authorized clients. To evaluate the feasibility of our architecture, we have implemented the authorization blockchain on top of a private Ethereum network. We report on several experiments that assess the performance of different architecture components.

In the Internet of Things, Packet Delivery Ratio and Time on Air are two predominant characteristics for both applications and operators, especially while using transmissions over Low Power Wide Area Networks such as LoRaTM. Our channel coding approach aims to improve these Quality of Service characteristics for LoRaWANTMnetworks. Our CCARR protocol uses Reed-Solomon FEC and structures successive frames into segments. A completion acknowledgements dynamically controls the amount of FEC overload. We estimate the potential gain of CCARR with a probabilistic analysis. Simulation and of-the-shelves testbed experiments of the protocol corroborate analysis trends and show a large Packet Delivery Rate improvement over LoRaWANTMand the literature with a controlled Time on Air increase due to optimized FEC overload.

In this paper, we propose a fast predictive resynchronization scheme that allows nodes to rejoin a 802.15.4e TSCH network with which they were previously synchronized. The idea of the scheme comes from the investigation of the internal and external root causes of the clock drift between two nodes--we have identified the causes and proposed a means for its estimation. Based on the prediction of the drift between any pair of nodes, we are able to determine the instant at which a node needs to wake up after desynchronization, thus reducing its energy consumption and the rejoin latency. We compare the proposed scheme with other state-of-the-art proposals through experiments on different hardware platforms. The experimental results show that desynchronized nodes rejoin up to 34 times faster and consume less energy by a factor of 1000 compared to the other proposals.

CPU-based many-core processors present an alternative to multicore CPU and GPU processors. In particular, the 93-Petaflops Sunway supercomputer, built from clustered many-core processors, has opened a new era for high performance computing that does not rely on GPU acceleration. However, memory bandwidth remains the main challenge for these architectures. This motivates our endeavor for optimizing one of the most data-intensive kind of stencil computations, namely the three-dimensional applications of the lattice Boltzmann method (LBM). We propose optimizations on many-cores processors by using local memory and asynchronous software-prefetching on a representative 3D LBM solver as an example. We achieve 33 % performance gain on the Kalray MPPA-256 many-core processor by actively streaming data from/to local memory, compared to the “passive” OpenCL programming model.

Embedded devices of the Internet of Things form the so-called low-power and lossy networks. In these networks, nodes are constrained in terms of energy, memory, and processing. Links are lossy and exhibit a transient behavior. From the point of view of energy expenditure, governing control overhead emission is crucial and is the role of the Trickle algorithm. We address Trickle's fairness problem to evenly distribute the transmission load across the network, while keeping the total message count low. First, we analytically analyze two underlying causes of unfairness in Trickle networks: 1) desynchronization among nodes and 2) nonuniform topologies. Based on our analysis, we propose a first algorithm whose performance and parameters we study in an emulated environment. From this feedback, we design a second algorithm Trickle-D that adapts the redundancy parameter to achieve high fairness while keeping the transmission load low. We validate Trickle-D in real-life conditions using a large scale experimental testbed. Trickle-D requires minimal changes to Trickle, zero user input, emits 17.7% less messages than state-of-the-art and 37.2% less messages than state-of-practice, while guaranteeing high fairness across the network.

This paper focuses on the performance of wireless sensor networks characterized by a hybrid topology composed of mobile and static sensor nodes. The Routing Protocol for Low power and lossy networks (RPL), which is standardized as an IPv6 routing protocol for low power and lossy networks, uses the trickle timer algorithm to handle changes in the network topology. However, this algorithm is not well adapted to dynamic environments. This paper enhances the trickle timer in order to fit with mobility requirements. Most of previous works have improved this algorithm without considering the random movement of nodes. In this work, the proposed timer algorithm takes into consideration the random trajectory of mobile nodes, pause time and node's velocity. It is also dynamically adjusted to prevent from node disconnections. The performance of the modified protocol is evaluated and compared with native RPL, MERPL and RPL with reverse Trickle. The results show that our protocol optimization offers better performance.

This paper focuses on wireless sensor networks (WSNs) for healthcare and medical applications which aim to look after patients by monitoring vital signs, diagnostics and drug administrations. WSNs in such applications are usually composed of different types of small-size battery powered sensors. In fact, wearable sensors are used to collect information about the signs of a person that needs a medical care. Static sensors, deployed inside the hospital or the home building, are used to collect information about indoor environment. The collected data is then transmitted towards the sink. Since some patients can move, WSN topology is hybrid and composed of mobile and static nodes. Routing Protocol for Low Power and Lossy Networks (RPL), an IPv6 distance vector routing protocol designed for static wireless sensor network, can be adapted to our need. So in this paper, we propose to modify RPL in order to fit with an hybrid topology. The performance of the modified protocol is evaluated and compared with the existing RPL protocol. The results show that our protocol optimization for healthcare application offers better performance.

Wireless sensor network protocols very often use the Trickle algorithm to govern information dissemination. For example, the widely used IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) uses Trickle to emit control packets. We derive an analytical model of Trickle to take into account multiple redundancy constants and the common lack of synchronization among nodes. Moreover, we demonstrate message count unfairness when Trickle uses a unique global redundancy constant because nodes with less neighbors transmit more often. Consequently, we propose a heuristic algorithm that calculates a redundancy constant for each node as a function of its number of neighbors. Our calculated redundancy constants reduce unfairness among nodes by distributing more equally the number of transmitted messages in the network. Our analytical model is validated by emulations of constrained devices running the Contiki Operating System and its IPv6 networking stack. Furthermore, results very well corroborate the heuristic algorithm improvements.

The Datagram Transport Layer Security (DTLS) protocol is the IETF standard for securing the Internet of Things. The Constrained Application Protocol, ZigBee IP, and Lightweight Machine-to-Machine (LWM2M) mandate its use for securing application traffic. There has been much debate in both the standardization and research communities on the applicability of DTLS to constrained environments. The main concerns are the communication overhead and latency of the DTLS handshake, and the memory footprint of a DTLS implementation. This paper provides a thorough performance evaluation of DTLS in different duty-cycled networks through real-world experimentation, emulation and analysis. In particular, we measure the duration of the DTLS handshake when using three duty cycling link-layer protocols: preamble-sampling, the IEEE 802.15.4 beacon-enabled mode and the IEEE 802.15.4e Time Slotted Channel Hopping mode. The reported results demonstrate surprisingly poor performance of DTLS in radio duty-cycled networks. Because a DTLS client and a server exchange more than 10 signaling packets, the DTLS handshake takes between a handful of seconds and several tens of seconds, with similar results for different duty cycling protocols. Moreover, because of their limited memory, typical constrained nodes can only maintain 3–5 simultaneous DTLS sessions, which highlights the need for using DTLS parsimoniously.

In this paper, we propose a new scheme that allows coupling beacon-enabled IEEE 802.15.4 with the RPL routing protocol while keeping full compliance with both standards. We provide a means for RPL to pass the routing information to Layer 2 before the 802.15.4 topology is created by encapsulating RPL DIO messages in beacon frames. The scheme takes advantage of 802.15.4 command frames to solicit RPL DIO messages. The effect of the command frames is to reset the Trickle timer that governs sending DIO messages. We provide a detailed analysis of the overhead incurred by the proposed scheme to understand topology construction costs. We have evaluated the scheme using Contiki and the instruction-level Cooja simulator and compared our results against the most common scheme used for dissemination of the upper-layer information in beacon-enabled PANs. The results show energy savings during the topology construction phase and in the steady state.

Network lifetime improvement of multi-hop wireless sensor networks is a challenging problem. In fact, the network lifetime can be extended by energy saving techniques such as energy-efficient protocols. However, one of the most promising research directions to overcome the network lifetime problem is the compression. Indeed, compression consists in minimizing the size of packets transmitted by the sensors. Nevertheless, compression deals only with data while addresses compression is not considered. In this work, Slepian-Wolf source coding and address allocation are used jointly in multi-hop wireless sensor networks to reduce the size of the transmitted addresses. Our simulation findings demonstrate significant gains in network lifetime, while keeping energy dissipation at very satisfactory levels even in multi-hop networks.

Billions of smart, but constrained objects wirelessly connected to the global network require novel paradigms in network design. New protocol standards, tailored to constrained devices, have been designed taking into account requirements such as asynchronous application traffic, need for caching, and group communication. The existing connection-oriented security architecture is not able to keep up-first, in terms of the supported features, but also in terms of the scale and resulting latency on small constrained devices. In this paper, we propose an architecture that leverages the security concepts both from content-centric and traditional connection-oriented approaches. We rely on secure channels established by means of (D)TLS for key exchange, but we get rid of the notion of the “state” among communicating entities. We provide a mechanism to protect from replay attacks by coupling our scheme with the CoAP application protocol. Our object-based security architecture (OSCAR) intrinsically supports caching and multicast, and does not affect the radio duty-cycling operation of constrained objects. We evaluate OSCAR in two cases: 802.15.4 Low Power and Lossy Networks (LLN) and Machine-to-Machine (M2M) communication for two different hardware platforms and MAC layers on a real testbed and using the Cooja emulator. We show significant energy savings at constrained servers and reasonable delays. We also discuss the applicability of OSCAR to Smart City deployments.

RPL, the routing protocol proposed by IETF for IPv6/6LoWPAN Low Power and Lossy Networks has significant complexity. Another protocol called LOADng, a lightweight variant of AODV, emerges as an alternative solution. In this paper, we compare the performance of the two protocols in a Home Automation scenario with heterogenous traffic patterns including a mix of multipoint-to-point and point-to-multipoint routes in realistic dense non-uniform network topologies. We use Contiki OS and Cooja simulator to evaluate the behavior of the ContikiRPL implementation and a basic non-optimized implementation of LOADng. Unlike previous studies, our results show that RPL provides shorter delays, less control overhead, and requires less memory than LOADng. Nevertheless, enhancing LOADng with more efficient flooding and a better route storage algorithm may improve its performance.

Improving the network lifetime is an important design criterion for wireless sensor networks. To achieve this goal, we propose in this paper a novel approach which applies source-coding on addresses in heterogeneous IPv6 Cluster-based wireless sensor network. We formulate the problem of maximizing the network lifetime when Slepian-wolf coding is applied on addresses in network composed of line-powered and battery-powered sensors. This problem optimizes the placement of line-powered sensors to enable the battery-powered ones to exploit the addresses correlation and reduce the size of their emitted packets and thus improve the network lifetime. The numerical results show that a significant network lifetime improvement can be achieved (about 25% in typical scenario).

Technology evolution have made possible to connect all kind of devices to IP network. This becomes an evident objective for sensors networks research. The IETF 6LoWPAN RFC proposal was developed in that sense to use the benefit of IPV6 over wirelessly connected sensors (WSN). The IEEE 802.15.4 MAC layer stack being popular in the domain of wireless sensors within constrained resources, a few 6LoWPAN adaptations already exist. In this paper, we investigate the possibility of using IPv6 for sensor networks connected through powerline communication (PLC) non-wireless mediums and demonstrate possible interoperability. This document propose the first adaptation of the IEEE 802.15.4 commons standard on PLC medium. Following this standard interface, we demonstrate the possibility to carry out data on PLC with great reliability, and low power energy requirement using our WPC™ physical layer (called Watt Pulse Communication (WPC)). This allows to benefit from the development of WSN research for PLC communication networks. Moreover, such a IEEE 802.15.4/6LoWPAN communication stack provides a generic communication standard for heterogeneous sensors networks. Thus, we finally demonstrate interoperability with tests between powerline and wireless sensor networks running IEEE 802.15.4/6LoWPAN stacks.

Cluster computing has clearly shown the necessity of high performance communication systems. Several high performance network vendors are competing with different approaches: all-in- harware vs. programmable interfaces. Using the programmable Myrinet NICs we show that the performance limits of this approach are far better from the usual expectation when using optimized pipeline software design. Moreover, the ability to propose classical API like MPI with efficient protocols, partially embedded at the NIC level are very promising in terms of performances and communication/computation overlap.

L. Prylli and B. Tourancheau (1998) presented the BIP low level communication protocols for Myrinet programmable NICs. On one side BIP has proven that a very small latency and a very large throughput can be delivered that surpass other communication layers for Myrinet. On another side hardware implementations like Giganet or SCI show very good performance for medium size messages. Our aim in this paper is to study how the programmable NICs can compare with the hardware solutions for the medium size messages. We conducted a very precise model of the pipeline behavior directed by the NIC program in order to identify the bottlenecks. The results show that the pipeline quality is very important. We develop an adaptive strategy as described by K. Yocum et al. (1998). We then introduce it in BIP. Experiments show up to a twofold gain over the previous BIP and reach the performance above the hardware solutions.

Presents a scalable protocol for conducting periodic probes of network performance in a way that minimizes collisions between separate probes. The goal of the protocol is to enable active performance monitoring of large-scale distributed computational systems and networks. We use the protocol to generate time series of measurement data that are then exposed to numerical forecasting models when a prediction of network performance is required. We present the protocol and demonstrate its effectiveness using the Network Weather Service -a tool for dynamically predicting network, CPU, memory and storage performance.

Article Free Access Share on BIP-SMP: high performance message passing over a cluster of commodity SMPs Authors: Patrick Geoffray RHDAC, project CNRS-INRIA ReMap, LHPC (Matra Systèmes & Information) ISTIL UCB-Lyon 69622 VILLEURBANNE RHDAC, project CNRS-INRIA ReMap, LHPC (Matra Systèmes & Information) ISTIL UCB-Lyon 69622 VILLEURBANNEView Profile , Loïc Prylli LIP, project CNRS-INRIA ReMap, LHPC (ENS-Lyon), ENS-Lyon, 69634 LYON LIP, project CNRS-INRIA ReMap, LHPC (ENS-Lyon), ENS-Lyon, 69634 LYONView Profile , Bernard Tourancheau RHDAC, project CNRS-INRIA ReMap, LHPC (Matra Systèmes & Information) ISTIL UCB-Lyon 69622 VILLEURBANNE and LIP, project CNRS-INRIA ReMap, LHPC (ENS-Lyon), ENS-Lyon, 69634 LYON RHDAC, project CNRS-INRIA ReMap, LHPC (Matra Systèmes & Information) ISTIL UCB-Lyon 69622 VILLEURBANNE and LIP, project CNRS-INRIA ReMap, LHPC (ENS-Lyon), ENS-Lyon, 69634 LYONView Profile Authors Info & Claims SC '99: Proceedings of the 1999 ACM/IEEE conference on SupercomputingJanuary 1999 Pages 20–eshttps://doi.org/10.1145/331532.331552Published:01 January 1999Publication History 23citation404DownloadsMetricsTotal Citations23Total Downloads404Last 12 Months21Last 6 weeks5 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF