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[EN] The IEEE 802.15.4 standard is one of the widely adopted networking specification for realizing different applications of Internet of Things (IoT). It defines several physical layer options and medium access control (MAC) sublayer protocols for low-power devices supporting low-data rates. One such MAC protocol is the deterministic and synchronous multichannel extension (DSME), which addresses the limitation on the maximum number of guaranteed time slots (GTSs) in 802.15.4-2011 MAC, and provides channel diversity to increase network robustness. However, beacon scheduling in peer-to-peer networks suffers from beacon slot collisions when two or more coordinators simultaneously compete for the same vacant beacon slot. In addition, the standard does not explore DSME-GTS scheduling (DGS) across multiple channels. This article addresses the beacon slot collision problem by proposing a nonconflicting beacon scheduling mechanism using association order (AO). Furthermore, a distributed multichannel DSME-GTS schedule is proposed that optimally assigns DSME-GTSs across different channels. The objective is to minimize the number of times-lots used while maximizing the usage of available channels. Through simulations, the proposed mechanisms' performance is analyzed in terms of energy efficiency, transmission overhead, scheduling efficiency, throughput, and latency and is shown to outperform the other existing schemes.

More and more devices, such as Bluetooth and IEEE 802.15.4 devices forming Wireless Personal Area Networks (WPANs) and IEEE 802.11 devices constituting Wireless Local Area Networks (WLANs), share the 2.4 GHz Industrial, Scientific and Medical (ISM) band in the realm of the Internet of Things (IoT) and Smart Cities. However, the coexistence of these devices could pose a real challenge - co-channel interference that would severely compromise network performances. Although the coexistence issues has been partially discussed elsewhere in some articles, there is no single review that fully summarises and compares recent research outcomes and challenges of IEEE 802.15.4 networks, Bluetooth and WLANs together. In this work, we revisit and provide a comprehensive review on the coexistence and interference mitigation for those three types of networks. We summarize the strengths and weaknesses of the current methodologies, analysis and simulation models in terms of numerous important metrics such as the packet reception ratio, latency, scalability and energy efficiency. We discover that although Bluetooth and IEEE 802.15.4 networks are both WPANs, they show quite different performances in the presence of WLANs. IEEE 802.15.4 networks are adversely impacted by WLANs, whereas WLANs are interfered by Bluetooth. When IEEE 802.15.4 networks and Bluetooth co-locate, they are unlikely to harm each other. Finally, we also discuss the future research trends and challenges especially Deep-Learning and Reinforcement-Learning-based approaches to detecting and mitigating the co-channel interference caused by WPANs and WLANs.

Bluetooth Low Energy (BLE) and IEEE 802.15.4 Time-Slotted Channel Hopping (TSCH) are widely used low-power standard technologies developed for short-range communications in the internet-of-things. In many applications, BLE and TSCH networks may be deployed in the vicinity of one another, which may lead to Cross Technology Interference (CTI) influencing each other's performance. Both technologies utilize channel hopping to alleviate the impact of external interferences. However, having a model to quantitatively estimate the performance of coexisting TSCH and BLE networks and analyze the role of networks' configuration settings is still an open problem. To address this, we provide a probabilistic analysis of collision-free communication of coexisting BLE and TSCH networks. Moreover, a fast coexistence simulation model is developed that computes the ratio of collision-free transmissions. This model is used to investigate how the performance of the coexisting networks may deviate from the results of the probabilistic analysis. It gives the designers a proper estimation of the worst case performance degradation due to such coexistence. It is shown that severity of the impact of coexisting BLE-TSCH networks on one another depends on the setup configurations and the relative timing of the two networks. The results show that these two technologies can coexist well with collision-free ratios of more than 92.58% and 96.29% in the tested configurations for TSCH and BLE, respectively.

We propose a novel cross-layer scheme to reduce energy consumption in wireless sensor networks composed of IEEE 802.15.4 IoT devices with adjustable transmit power. Our approach is based on the IETF’s Routing Protocol for Low power and lossy networks (RPL). Nodes discover neighbors and keep fresh link statistics for each available transmit power level. Using the product of ETX and local transmit power level as a single metric, each node selects both the parent that minimizes the energy for packet transmission along the path to the root and the optimal local transmit power to be used. We have implemented our cross-layer scheme in NG-Contiki using the Z1 mote and two transmit power levels (55mW and 31mW). Simulations of a network of 15 motes show that (on average) 66% of nodes selected the low-power setting in a 25m $\times25\text{m}$ area. As a result, we obtained an average reduction of 25% of the energy spent on transmission and reception of packets compared to the standard RPL settings where all nodes use the same transmit power level. In large scenarios (e.g., 150m $\times150\text{m}$ and 40–100 motes), our approach provides better results in dense networks where reducing the transmit power of nodes does not translate into longer paths to the root nor degraded quality of service.

The IEEE 802.15.4-2015 TSCH (Time Slotted Channel Hopping) standard provides high-reliability, deterministic delay, and energy efficiency with the channel hopping and the TDMA. The standard does not specify the scheduling method, which is an essential part of the solution. One of the representative studies in TSCH scheduling is Orchestra. It is an autonomous scheduling method with minimal overhead that does not require a negotiation process between nodes. However, with high traffic load, performance of the Orchestra is greatly degraded because of its fixed schedule. If a node has children, continuous collisions occur in the slot of the node. We propose a novel algorithm called SRCA (Slot Reallocation for Collision Avoidance), as a solution for this problem. The SRCA autonomously updates the schedule. When a child requests a slot reallocation, the parent allocates a new slot with a low probability of collision. Another algorithm called SJCA (Slot reJection for Collision Avoidance) is further proposed in this work. It improves the SRCA to operate in an environment with interference where a sending node can disturb a transmission from a hidden node. In the SJCA, a node determines whether a collision due to interference will occur in the slot newly allocated by the parent. If so, it rejects the slot and requests again. We compare the performance of the SRCA and the SJCA against the Orchestra and e-TSCH-Orch through simulations. It is confirmed that the SJCA is robust to interference. In most cases, the SJCA shows better performance of PAR (Packet Acknowledgement Ratio), PLR (Packet Loss Rate), and latency than others. It is also verified that the SJCA provides high-reliability and low latency compared to existing technologies.

IEEE 802.15.4 protocol is intended to accomplish the characteristics of low power and low rate Wireless Sensor Network. It employs carrier sense multiple access with collision avoidance (CSMA/CA) protocol to access the network using either unslotted or slotted mode. This paper concentrates on the unslotted CSMA/CA where the node tends to wait for a very limited backoff exponent value, and cannot perform clear channel assessment until backoff procedure is completed. Therefore, the collision probability and the average delay are high. To enhance the unslotted CSMA/CA performance, this paper proposes a modified unslotted CSMA/CA that divides the backoff delay into Main Backoff and Secondary Backoff. The Markov model for the modified CSMA/CA is presented to assess a single hop IEEE 802.15.4 behavior, and derive expressions for average delay, energy consumption and reliability. An optimization problem is also presented to minimize the delay while guaranteeing energy consumption and reliability constraints for the modified CSMA/CA. OPNET simulation tool is applied to compare the modified to the standard unslotted CSMA, and to validate the Markov model proposed. The results demonstrate that the modified CSMA improves the reliability, while reducing the average delay significantly.

[EN] The IEEE 802.15.4 standard is one of the widely adopted networking specification for Internet of Things (IoT). It defines several physical layer (PHY) options and medium access control (MAC) sub-layer protocols for interconnection of constrained wireless devices. These devices are usually battery-powered and need to support requirements like low-power consumption and low-data rates. The standard has been revised twice to incorporate new PHY layers and improvements learned from implementations. Research in this direction has been primarily centered around improving the energy consumption of devices. Recently, to meet specific Quality-of-Service (QoS) requirements of different industrial applications, the IEEE 802.15.4e amendment was released that focuses on improving reliability, robustness and latency. In this paper, we carry out a performance-to-cost analysis of Deterministic and Synchronous Multi-channel Extension (DSME) and Time-slotted Channel Hopping (TSCH) MAC modes of IEEE 802.15.4e with 802.15.4 MAC protocol to analyze the trade-off of choosing a particular MAC mode over others. The parameters considered for performance are throughput and latency, and the cost is quantified in terms of energy. A Markov model has been developed for TSCH MAC mode to compare its energy costs with 802.15.4 MAC. Finally, we present the applicability of different MAC modes to different application scenarios., This work was supported in part by the SERB, DST, Government of India under Grant ECRA/2016/001651.

The TSCH (Time Slotted Channel Hopping) protocol from the IEEE 802.15.4-2015 standard is known to be suitable for highly reliable applications in low-power networks of severely constrained wireless embedded devices. Most of the research on TSCH has focused on the 2.4 GHz frequency band. The present work extends the TSCH protocol to low data rate applications using the sub-GHz frequency bands for an increased link budget. We introduce multiple improvements on top of the standard TSCH, namely, a special schedule for the network's root nodes and their direct neighbors, as well as the option to have multiple root nodes in a single TSCH network. Experimental results in a testbed and a real-world deployment show that after applying the improvements, the network meets application requirements and provides reliable and energy-efficient operation.

Time Slotted Channel Hopping (TSCH) is a link layer protocol defined in the IEEE 802.15.4 standard. Although it is designed to provide highly reliable and efficient service targeting industrial automation systems, scheduling TSCH transmissions in the time and frequency dimensions is left to the implementers. We evaluate the performance of existing autonomous scheduling approaches for TSCH on various traffic patterns and network configurations. We thoroughly investigate the pros and cons of each scheme; moreover, we propose the use of node based channel allocation to improve the performance of the best scheme, and demonstrate its practicality and reliability, with up to 6 percentage points better packet delivery ratio than the second best option while retaining a similar radio duty cycle. Finally, based on our extensive performance evaluation, we provide some guidelines on how to select a scheduler for a given network.

Establishing confidentiality between communicating peers is still an issue in contexts where solutions based on asymmetric keys are not viable, such as in dynamic Internet of Things (IoT) systems made up of heterogeneous and resource constrained devices. From the current literature, channel anonymity emerges as a promising methodology able to support key-establishment protocols. But, to the best of authors’ knowledge, no works already demonstrated its practical adoption over a concrete communication technology. To bridge this gap, we experimentally show that a lightweight key-establishment protocol based on channel anonymity is viable. The contributions of this work are mainfold. First, we introduce EXCHANge, a protocol that achieves key-establishment exploiting channel anonymity despite the presence of either a passive or active global-eavesdropper adversary. Second, we evaluate the performance of EXCHANge through an extensive experimental campaign involving real world IoT devices (OpenMote-CC2538). Our results demonstrate that the proposed solution introduces a limited overhead, thus being able to meet the requirements of resource constrained devices Finally, we experimentally demonstrate the security of the EXCHANge protocol against passive and active adversaries. Overall, this paper proves that channel anonymity can be a powerful tool in the IoT setting, to achieve a secure, effective, and efficient key-establishment.

In this paper, wireless feedback control of multiple machines over a beacon-enabled IEEE 802.15.4 network is considered. In the beacon-enabled IEEE 802.15.4 network, beacons periodically structure superframes on the time axis, and each superframe consists of a contention access period (CAP) and a contention free period (CFP). In the CAP, a carrier sense multiple access/collision avoidance (CSMA/CA) is used; in the CFP, a guaranteed time slot (GTS)-based time division multiple access is used. Because of collision and backoff periods of packet transmission, the probability of communication failure in the CAP is greater than that in the CFP; however, the number of available GTSs is limited to seven by the standard. In order to improve the control performance of wireless feedback control, the controller must effectively allocate GTSs to transmit control input and state feedback of controlled machines. We provide a simple but efficient idea that takes both the feedback control mechanism and packet transmission mechanism of the CAP and CFP into consideration to better allocate GTSs. We propose a superior GTS allocation method that fully conforms to the IEEE 802.15.4 standard and show that the proposed method can further improve control performance.

Future Internet of Things (IoT) will utilize IEEE 802.15.4 based low data rate communication for various applications. In the IEEE 802.15.4 standard, nodes send data to their Personal Area Network (PAN) coordinator using the Guaranteed Time Slot (GTS). The standard does not meet the adaptive data requirements of GTS requesting nodes in an efficient manner. If requesting GTSs in an active period are more or less than the available limit, either the requested nodes will not be entertained or GTSs remain underutilized. Consequently, it may cause unnecessary delay or poor GTS utilization. In this paper, an Optimal GTS allocation Mechanism for Adaptive Duty cycle (OGMAD) is proposed that adapts the active period of the superframe in accordance with the requested data. OGMAD also reduces GTS size to improve link utilization as well as accommodate more GTS requesting nodes. Simulation results verify that OGMAD improves link utilization, reduces network delay and offers more nodes to transmit their data as compared to the standard.

Jamming attacks in wireless sensor networks (WSNs) scenarios are detrimental to the performance of these networks and affect the security and stability of the service perceived by users. Therefore, the evaluation of the effectiveness of smart environment platforms based on WSNs has to consider the system performance when data collection is executed under jamming attacks. In this work, we propose an experimental testbed to analyze the performance of a WSN using the IEEE 802.15.4 CSMA/CA unslotted mode under jamming attacks in terms of goodput, packet receive rate (PRR), and energy consumption to assess the risk for users and the network in the smart scenario. The experimental results show that constant and reactive jamming strategies severely impact the evaluated performance metrics and the variance’ of the received signal strength (RSS) for some signal-to-interference-plus-noise ratio (SINR) ranges. The measurements obtained using the experimental testbed were correlated with analytical models. The results show that in the presence of one interferer, for SINR values higher than 4.5 dB, the PRR is almost 0.99, and the goodput 3.05 Kbps, but the system performance is significantly degraded when the amount of interferers increases. Additionally, the energy efficiency associated with reactive strategies is superior to the constant attack strategy. Finally, based on the evaluated metrics and with the proposed experimental testbed, our findings offer a better understanding of jamming attacks on the sensor devices in real smart scenarios.

This paper proposes a Duty-Cycle (DC) control method in order to improve the Packet Delivery Ratio (PDR) for IEEE 802.15.4-compliant heterogeneous Wireless Sensor Networks (WSNs). The proposed method controls the DC so that the buffer occupancy of sensor nodes is less than 1 and assigns DC to each sub-network (sub-network means a network consisting of a router node and its subordinate nodes). In order to use the appropriate DC of each sub-network to obtain the high PDR, this paper gives analytical expressions of the buffer occupancy. The simulation results show that the proposed method achieves a reasonable delay and energy consumption while maintaining high PDR.

International audience; Named Data Networking (NDN) is a promising architecture that aims to natively satisfy emerging applications such as the Internet of Things (IoT). Therefore, enabling NDN in realworld IoT deployments is becoming essential in order to benefit from Information Centric Networking (ICN) features. To design realistic NDN-based communication solutions for IoT, revisiting mainstream technologies such as low-power wireless standards may be the key. In this paper, we explore NDN forwarding over IEEE 802.15.4 following two steps. First, we mathematically model a broadcast-based forwarding strategy for NDN over constrained networks with the IEEE 802.15.4 technology in mind. The model estimates the number of frames transmitted and the mean round-trip time per request, under content popularity considerations. Second, based on mathematical and experimental observations of the broadcast-based forwarding at network level, we elaborate Named-Data Carrier-Sense Multiple Access (ND-CSMA), an adaptation of the Carrier-Sense Multiple Access (CSMA) algorithm used in IEEE 802.15.4. Results show that adaptations such as ND-CSMA may be reasonably envisioned to improve NDN efficiency with current IoT technologies.

En el presente trabajo se analiza el impacto en el rendimiento de IEEE 802.15.6 cuando es interferido por IEEE 802.15.4 o IEEE 802.11, pretendiendo dar una medida del grado de confiabilidad del primero, que es un protocolo creado para transmisión en baja potencia de parámetros vitales de pacientes humanos, cuando comparte la banda de frecuencias ISM con otros protocolos ampliamente difundidos como son los dos últimos. Las ISM son bandas de radiofrecuencia electromagnética no licenciadas, comprendidas (entre otras) desde los 2,4 a 2,5GHz1, reservadas internacionalmente para uso no comercial en áreas industrial, científica y médica. Se ha popularizado su uso en comunicaciones WiFi (distintas versiones de IEEE 802.11), Bluethoot, IEEE 802.15.6, IEEE 802.15.4, etc; pudiendo unos comportarse como ruido electromagnético de otros, especialmente en áreas densamente pobladas. A la fecha de redacción de la presente tesis, no se han encontrado trabajos donde se estudie el impacto en el rendimiento de IEEE 802.15.6 interferido por IEEE 802.15.4 o 802.11. Trabajos como el de R. Natarajan, P. Zand y M. Nabi [4] han realizado un estudio teórico y experimental de la degradación del rendimiento de IEEE 802.15.4 interferido por BLE (y viceversa) o por IEEE 802.11, pero no han considerado a IEEE 802.15.6. Otros como el de M.M Alam y E.B. Hamida compara las estrategias de coexistencia propuestas por IEEE 802.15.6 con interferencia intra-BAN, inter-BAN y degradación del canal debido al movimiento dinámico del cuerpo, pero no considera el caso en que el protocolo comparta canales con otros estándares. El presente trabajo analiza de forma teórica, repitiendo el escenario y método de R. Nataraja et al, el impacto en el rendimiento de IEEE 802.15.6 cuando es interferido por IEEE 802.11 o 802.15.4, Facultad de Informática

[EN] The IEEE 802.15.4 standard is one of the widely adopted specifications for realizing different applications of the Internet of Things. It defines several physical layer options and Medium Access Control (MAC) sublayer for devices with low-power operating at low data rates. As devices implementing this standard are primarily battery-powered, minimizing their power consumption is a significant concern. Duty-cycling is one such power conserving mechanism that allows a device to schedule its active and inactive radio periods effectively, thus preventing energy drain due to idle listening. The standard specifies two parameters, beacon order and superframe order, which define the active and inactive period of a device. However, it does not specify a duty-cycling scheme to adapt these parameters for varying network conditions. Existing works in this direction are either based on superframe occupation ratio or buffer/queue length of devices. In this article, the particular limitations of both the approaches mentioned above are presented. Later, a novel duty-cycling mechanism based on MAC parameters is proposed. Also, we analyze the role of synchronization schemes in achieving efficient duty-cycles in synchronized cluster-tree network topologies. A Markov model has also been developed for the MAC protocol to estimate the delay and energy consumption during frame transmission., This work is supported by Science and Engineering Research Board, Department of Science and Technology, Government of India under ECR 2016, Grant No. 2016/001651. This work has been partially supported by the "Ministerio de Economia y Competitividad" in the "Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia," "Subprograma Estatal de Generacion de Conocimiento," within the project under Grant No. TIN2017-84802-C2-1-P. This work has also been partially supported by European Union through the ERANETMED (Euromediterranean Cooperation through ERANET joint activities and beyond) Project ERANETMED3-227 SMARTWATIR.

Nowadays, several wireless communication solutions targeted at low-power devices (e.g. sensors, actuators) compete for market dominance. As a consequence, the deployment of the Internet of Things is slowed by fragmentation. However, Cross-Technology Communication (CTC) has appeared as a solution capable of bridging the compatibility gap between non-interoperable devices. In this way, we propose using Wake-up Radio (WuR) to achieve high rate bidirectional CTC, introducing WuR assisted CTC (WuR-CTC). Although WuR was originally proposed to reduce radio power consumption, it provides a secondary communications channel that can be used for high-speed and bidirectional CTC. With WuR-CTC, we demonstrate that WuR can lead to interoperability between non-compatible wireless devices, therefore, providing a compelling reason for the harmonization of the nascent WuR specifications. This article presents a WuR-CTC solution implemented on an heterogeneous testbed with IEEE 802.11 and IEEE 802.15.4 devices. The resulting testbed achieves reliable CTC with an effective throughput of 26.7 kbps. Moreover, the addition of WuR to the testbed devices provides energy savings, and, in a clear advantage over traditional duty-cycled solutions, allows devices to asynchronously maintain communications.

Wireless sensor networks are penetrating our daily lives, and they are starting to be deployed even in an industrial environment. The research on such industrial wireless sensor networks (IWSNs) considers more stringent requirements of robustness, reliability, and timeliness in each network layer. This Special Issue presents the recent research result on industrial wireless sensor networks. Each paper in the special issue has unique contributions in the advancements of industrial wireless sensor network research and we expect each paper to promote the relevant research and the deployment of IWSNs.

While IEEE 802.15.4 and its Time Slotted Channel Hopping (TSCH) medium access mode were developed as a wireless substitute for reliable process monitoring in industrial environments, most deployments use a single/static physical layer (PHY) configuration. Instead of limiting all links to the throughput and reliability of a single Modulation and Coding Scheme (MCS), you can dynamically re-configure the PHY of link endpoints according to the context. However, such modulation diversity causes links to coincide in time/frequency space, resulting in poor reliability if left unchecked. Nonetheless, to some level, intentional spatial overlap improves resource efficiency while partially preserving the benefits of modulation diversity. Hence, we measured the mutual interference robustness of certain Smart Utility Network (SUN) Orthogonal Frequency Division Multiplexing (OFDM) configurations, as a first step towards combining spatial re-use and modulation diversity. This paper discusses the packet reception performance of those PHY configurations in terms of Signal to Interference Ratio (SIR) and time-overlap percentage between interference and targeted parts of useful transmissions. In summary, we found SUN-OFDM O3 MCS1 and O4 MCS2 performed best. Consequently, one should consider them when developing TSCH scheduling mechanisms in the search for resource efficient ubiquitous connectivity through modulation diversity and spatial re-use.

Low-power Wireless Sensor Networks (WSNs) play a key role in realization of the Internet-of-Things (IoT). Among others, Time Slotted Channel Hopping (TSCH) is a Medium Access Control (MAC) operational mode of the IEEE 802.15.4 standard developed for communications in short range IoT networks. TSCH provides high level reliability and predictability by its channel hopping mechanism and time division channel access nature. In many applications, a number of TSCH networks may coexist in the same neighborhood. Several vehicles close to one another, each including a TSCH network for its in-vehicle communications, serve as an example. Since such networks are running independent of one another, they are not expected to be synchronized in time, and they are not scheduled to operate in exclusive frequency channels. This may lead to inter-TSCH interferences deteriorating the reliability of the networks, which is an important requirement for many IoT applications. This paper analyzes the impact of multiple asynchronous TSCH networks on one another. An analytical model is developed that estimates the chance of such interferences, and the expectation of the number of affected TSCH channels when a number of them are in the vicinity of one another. The developed model is verified using extensive simulations and real-world experiments. Also, a scalable and fast multi-TSCH coexistence simulator is developed that is used to get insight about coexistence behaviors of any number of TSCH networks with various configurations.

The next generation of the Internet of Things (IoT) networks is expected to handle a massive scale of sensor deployment with radically heterogeneous traffic applications, which leads to a congested network, calling for new mechanisms to improve network efficiency. Existing protocols are based on simple heuristics mechanisms, whereas the probability of collision is still one of the significant challenges of future IoT networks. The medium access control layer of IEEE 802.15.4 uses a distributed coordination function to determine the efficiency of accessing wireless channels in IoT networks. Similarly, the network layer uses a ranking mechanism to route the packets. The objective of this study was to intelligently utilize the cooperation of multiple communication layers in an IoT network. Recently, Q-learning (QL), a machine learning algorithm, has emerged to solve learning problems in energy and computational-constrained sensor devices. Therefore, we present a QL-based intelligent collision probability inference algorithm to optimize the performance of sensor nodes by utilizing channel collision probability and network layer ranking states with the help of an accumulated reward function. The simulation results showed that the proposed scheme achieved a higher packet reception ratio, produces significantly lower control overheads, and consumed less energy compared to current state-of-the-art mechanisms.

Wireless sensor network (WSN) research and development is producing viable solutions for various innovative applications, including critical areas such as the Internet of Things (IoT), which is becoming a significant feature of modern technology. WSNs form an integral component of the IoT infrastructure by, frequently, implementing the communication links between sensors and the access point or central coordinator. This design and use in IoT applications intensifies the incentive to attack WSNs as sensitive data is available and transmitted in wireless links, which inherently contain security vulnerabilities, especially from external malicious interference. To ensure satisfactory performance, safety and privacy, communication links and WSN devices must be secure. Hence, penetration testing to identify security vulnerabilities and responses to external intrusions is a prerequisite to forming secure connections and an overall secure network. Derived from a prior study, this paper explores the benefits of using software-defined radios (SDRs) for WSN/IoT data analysis and penetration testing by concentrating on implementing various intrusions using signal processing block based software like Simulink or GNU Radio. A comparison with traditional WSN packet sniffing/debugging tools is provided and the main security vulnerabilities of existing WSNs are surveyed by adopting the ZigBee protocol. An extension to WSN security analysis and testing is established by utilizing low-cost SDRs and specifying the ease of implementing various analysis techniques even when certain equipment, such as anechoic chambers, are unavailable. Stemming from previous simulations, the benefits of obtaining the in-phase and quadrature-phase samples, both with and without external interference, is also discussed.

4th International Symposium on Multidisciplinary Studies and Innovative Technologies, ISMSIT 2020 -- 22 October 2020 through 24 October 2020 -- -- 165025 2-s2.0-85097673514 The model of modern technology called the Internet of Things (IoT), is a global network of machines and devices that are able to work and interact with one another. The Internet of Things is known as the innovation of things to come and is increasing wide concentration and enthusiasm for a wide scope of fields and studies. The idea of IPv6 over Low Energy Wireless Personal Area Network (6LoWPAN) was considered to research and study the combination of programmable organization innovations and Low Energy Internet of Things (IoT) gadgets. Open-source programming just as equipment stages are utilized with the testing base executed to build the organization's versatility later on. The proposed engineering gives start to finish availability by means of a 6LoWPAN passage to include IPv6 has and power-restricted gadgets the same number of remote sensor networks utilize the IEEE 802.15.4-2015 standard that keeps up low force utilization and Internet capacities. Time allotment Channel Hopping (TSCH) is in actualicty a component or alteration of the Medium Access Control Protocol characterized by the IEEE 802.15.4 norm. Besides, the Internet Engineering Task Force (IETF) has incorporated with IPv6 by putting a TSCH in IEEE 802.15.4 (6TiSCH) to get explicit properties on remote sensor organizations. TSCH can exploit the booked time span to accomplish low-power activity with frequency jumping to decrease outer impedance and multi-way blurring. In spite of the fact that the TSCH standard gives a period and frequency division jumping system. In this research, we propose an improved version of TSCH in which the higher quality, lower noise channel is taken in the data transmission, and the technique of measuring clock drift between adjacent nodes, thus reducing the effective drift rate rather than resynchronizing. This greatly improves the reliability of the channel pattern for interference from wireless sensor networks. © 2020 IEEE.

Internet of Things (IoT)-based devices consist of wireless sensor nodes that are battery-powered, thus, energy efficiency is a major issue. IEEE 802.15.4-compliant IoT devices operate in the unlicensed Industrial, Scientific, and Medical (ISM) band of 2.4 GHz and are subject to interference caused by high-powered IEEE 802.11-compliant Wireless Local Area Network (WLAN) users. This interference causes frequent packet drop and energy loss for IoT users. In this work, we propose a WLAN Aware Cognitive Medium Access Control (WAC-MAC) protocol for IoT users that uses techniques, such as energy detection based sensing, adaptive wake-up scheduling, and adaptive backoff, to reduce interference with the WSN and improve network lifetime of the IoT users. Results show that the proposed WAC-MAC achieves a higher packet reception rate and reduces the energy consumption of IoT nodes.

IEEE 802.15.4, Low data Rate low power Wireless Personal Area Network (LR-WPAN) standard uses fixed duty cycle of the superframe operation. Fixed duty cycle operation of the stated standard suffers from several network issues like Personal Area Network (PAN) tedious initialization interval, nodes association duration, number of associated nodes, average network delay, throughput and nodes energy etc. Low duty cycle control operation with lower energy consumption of the network is one of the attractive feature of IEEE 802.15.4. Two superframe parameters Beacon Order (BO) and Superframe Order (SO) decide the beacon interval and duty cycle of the standard and has a strong impact on the performance of other network parameters. In this paper we analyze the IEEE 802.15.4 MAC with brief simulations by varying the two superframe parameters BO and SO to accomplish the finest performance of the WBAN network.

Smart building is an effective solution to address the issue of energy consumption in today’s cyber-physical systems (CPSs) connected world. As an important tool to collect information from a fleet of electric appliance that installed in the building scope, a wireless sensor network is widely employed for this purpose. In this paper, we propose to incorporate forward error correction into the media access control layer of IEEE 802.15.4 standard for packets transmission, as the originally used automatic repeat request mechanism is a timing and energy consumed process that should be avoided in a noisy wireless channel of a smart building environment. Based on the developed CPS simulation platform, the bits error rate and packets error rate of convolutional codes (CCs), Reed-Solomon (RS) codes, and their concatenated codes are intensively investigated, on condition of been applied to different packet length and code rates. We show that the CCs are superior to other codes in most cases. However, the RS and CCs concatenated codes are good candidates, and the RS codes with larger symbol length are preferred for a longer packet. In this regard, future research will concentrated on non-line-of-sight wireless channel, and take the pulse interference from other devices into account.

The development of Medium Access Control (MAC) protocols for Internet of Things should consider various aspects such as energy saving, scalability for a wide number of nodes, and grouping awareness. Although numerous protocols consider these aspects in the limited view of handling the medium access, the proposed Grouping MAC (GMAC) exploits prior knowledge of geographic node distribution in the environment and their priority levels. Such awareness enables GMAC to significantly reduce the number of collisions and prolong the network lifetime. GMAC is developed on the basis of five cycles that manage data transmission between sensors and cluster head and between cluster head and sink. These two stages of communication increase the efficiency of energy consumption for transmitting packets. In addition, GMAC contains slot decomposition and assignment based on node priority, and, therefore, is a grouping-aware protocol. Compared with standard benchmarks IEEE 802.15.4 and industrial automation standard 100.11a and user-defined grouping, GMAC protocols generate a Packet Delivery Ratio (PDR) higher than 90%, whereas the PDR of benchmark is as low as 75% in some scenarios and 30% in others. In addition, the GMAC accomplishes lower end-to-end (e2e) delay than the least e2e delay of IEEE with a difference of 3 s. Regarding energy consumption, the consumed energy is 28.1 W/h for GMAC-IEEE Energy Aware (EA) and GMAC-IEEE, which is less than that for IEEE 802.15.4 (578 W/h) in certain scenarios.

In this paper we provide a model for analyzing the saturation throughput of the ieee 802.15.4 mac protocol, which is the de-facto standard for wireless sensor networks, ensuring fair access to the channel. To this end, we introduce the concept of a natural layer, which reflects the time that a sensor node typically has to wait prior to sending a packet. The model is simple and provides new insight how the throughput depends on the protocol parameters and the number of nodes in the network. Validation experiments with simulations demonstrate that the model is highly accurate for a wide range of parameter settings of the mac protocol, and applicable to both large and small networks. As a byproduct, we discuss fundamental differences in the protocol stack and corresponding throughput models of the popular 802.11 standard.

Recently, Flying Ad-hoc Networks (FANETs), enabling ad-hoc networking between Unmanned Aerial Vehicles (UAVs) is gaining importance in several military and civilian applications. The sensitivity of the applications requires adaptive; efficient; delay bounded and scalable communication network among UAVs for data transmission. Due to communication protocol complexity; rigidity; cost of commercial-off-the-shelf (COT) components; limited radio bandwidth; high mobility and computational resources; maintaining the desired level of Quality of Service (QoS) becomes a daunting task. For the first time in this research we propose multicluster FANETs for efficient network management; the proposed scheme considerably reduces communication cost and optimizes network performance as well as exploit low power; less complex and low cost IEEE 802.15.4 (MAC) protocol for intercluster and intracluster communication. In this research both beacon enabled mode and beaconless modes have been investigated with Guaranteed Time Slots (GTS) and virtual Time Division Multiple Access (TDMA) respectively. The methodology plays a key role towards reserving bandwidth for latency critical applications; eliminate collisions and medium access delays. Moreover analysis ad-hoc routing protocols including two proactive (OLSR, DSDV) and one reactive (AODV) is also presented. The results shows that the proposed scheme guarantees high packet delivery ratios while maintaining acceptable levels of latency requirements comparable with more complex and dedicatedly designed protocols in literature.

[EN] The IEEE 802.15.4 standard is one of the most widely used link layer technology for building Internet of Things (IoT). It specifies several physical layer options and MAC layer for meeting low-power and low-rate requirements of devices deployed in a network of IoT. The standard also specifies a synchronization scheme for devices connected in a star topology, operating in beacon-enabled (BE) mode using periodic beacons. The BE mode facilitates synchronization among devices for data transmission and is suitable for large networks to establish low duty-cycles. Absence of a such a scheme for a cluster-tree network has confined its application only to nonbeacon mode. The challenge here is to schedule beacon frame transmissions of multiple devices in a nonoverlapping manner to avoid beacon collisions. This paper tackles the problem of synchronization by proposing localized beacon synchronization (LBS) scheme, a distributed technique for beacon scheduling in cluster-tree network topologies. LBS uses 2-hop information and association order to compute beacon transmission offsets that better utilize the available time slots, incur fewer transmissions, and is highly scalable. Further, we analytically show that the schedulability of the proposed scheme is higher compared to other related schemes. In addition, we also address the important issue of resynchronization that has been ignored in all of the prior works. The proposed resynchronization mechanisms consider the interdependencies between synchronization and duty-cycling schemes and are shown to significantly lower the synchronization overhead when synchronization among devices is lost., This work was supported by the Science and Engineering Research Board, Department of Science and Technology, Govt. of India, under Grant ECR/2016/001651.

One of the main features of future factories envisaged by Industry 4.0 is the integration of humans, machinery and sensors, which will be able to exchange information, trigger actions and collaborate while on the move. The management of Industrial Wireless Sensor Networks (IWSNs) including mobile nodes is a challenging target, as mobility support has a significant impact on the network complexity and management.Recently, Software Defined Networking (SDN) has been proposed as a paradigm for controlling IWSN, with the purpose of providing a smart management of mobile nodes in industrial scenarios. However, resource management, that is, slot and frequency assignment, needs ad hoc clustering strategies to avoid the waste of resources that would impair IWSN scalability. Network scalability is a crucial requisite for the successful development of both IWSN and the Industry 4.0 vision as a whole. For this reason, clustering policies are today a cutting-edge research topic.This paper exploits the SDN approach to manage IWSN and proposes a platform for the evaluation of clustering strategies which can be profitably applied to scalable IWSN that support mobility.

In a wireless body area network (WBAN), wireless biomedical sensors are placed around, on, or inside the human body. Given specific requirements, WBANs can significantly improve healthcare, diagnostic monitoring, and other medical services. However, the existing standards such as IEEE 802.11 and IEEE 802.15.4 have some limitations to meet all the requirements of WBANs. Many medium access control (MAC) protocols have been studied so far, most of which are derived from the IEEE 802.15.4 superframe structure with some improvements and adjustments. However, the MAC protocols do not provide the required quality of service (QoS) for various types of traffic in a WBAN. In this paper, a traffic-aware MAC (TA-MAC) protocol for WBANs is proposed, in which time slots are dynamically allocated on the basis of traffic priority, providing the required QoS. According to the performance evaluation results, the proposed TA-MAC is better than IEEE 802.15.4 MAC and the conventional priority-based MAC in terms of transmission time, system throughput, energy efficiency, and collision ratio.

Part 2: Security and Network Management; International audience; Several Internet of Things (IoT) applications have strict performance requirements, in terms of reliability and power consumption. IEEE 802.15.4 Time Slotted Channel Hopping (TSCH) is a recently stan-dardised Medium Access Control (MAC) protocol that supports these requirements by keeping the nodes time-synchronised. In order to ensure successful communication between a sender and a receiver, the latter starts listening shortly before the expected frame's arrival. This time offset is called guard time and it aims to reduce the probability of missed frames due to clock drift. This paper investigates the impact of the guard time on the energy consumption and proposes a scheme for the decen-tralised adaptation of the guard time in each node depending on its hop-distance from the sink. Simulations and test-bed experiments demonstrate that guard time adaptation can reduce the energy consumption by up to 50%, without compromising the reliability of the network.

International audience; The convergence of operational and information technologies in the industry requires a new generation of IP-compliant communication protocols that can meet the industrial performance requirements while facilitating the integration with novel web-based supervisory control and data acquisition (SCADA) systems. For more than a decade, the industry has relied on time-slotted channel hopping (TSCH) communication technology to meet these performance requirements through standards such as WirelessHART and ISA100.11a. TSCH-based networks have proven to yield over 99.999% end-to-end reliability, supporting flow isolation and QoS management while ensuring over a decade of battery lifetime. However, these technologies were designed to address the factory use cases of a decade ago, not considering IP compliance or standardized network management and resource orchestration as a must. The Internet Engineering Task Force (IETF) and the 6TiSCH working group (WG) have been actively working on this challenge by designing protocols to bridge the performance of industrial solutions with IP-compliant networks. The effort has resulted in 6TiSCH, a set of specifications that define the IPv6 control plane to manage and orchestrate a TSCH network. 6TiSCH provides the missing elements for zero-configuration TSCH network bootstrap, efficient network access authentication, and distributed and modular scheduling mechanisms. As a cross-layer effort, 6TiSCH leverages and integrates other IETF specifications and the WG has also driven the definition of novel specifications in other IETF WGs. An ultimate goal of this effort is the definition of a fully functional architecture where a combination of IETF protocols enables the envisioned convergence on top of the IEEE industrial standard. This paper introduces the work done by the 6TiSCH WG at IETF, evaluates the performance of the reference implementation, and discusses the 6TiSCH software ecosystem.

The paper aims at providing the technical investigation on implementation options for the key retrieval security procedures and consequent security subsystem architecture in the IEEE 802.15.4 compatible devices. Since the security procedures typically consume most processing capacity of IEEE 802.15.4 device, an efficient implementation of the security subsystem is essential. A brief functional overview of the key retrieval procedures has been provided. General investigations on key retrieval procedures implementation have been performed. Three general approaches for implementation of key retrieval procedures in the security subsystem have been considered: a) software implementation; b) hardware implementation; and c) hardware-software implementation. The aim is to determine optimum implementation approach corresponding to low-cost and low-power consumption requirements. An expediency of hardware and software implementation of the key retrieval procedures has been estimated.

15th International Conference on Distributed Computing in Sensor Systems (DCOSS) 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. This work has been partially funded by the H2020 collaborative Europe/Taiwan research project 5G-CORAL (grant num. 761586).

The Internet of Things (IoT) will bring together billions of devices, denoted as Smart Objects (SOs), in an Internet-like architecture. Typically, SOs are embedded devices with severe constraints in terms of processing capabilities, available memory (RAM/ROM), and energy consumption. SOs tend to be deployed in environments in which the human intervention is not suitable or needs to be minimized (e.g., smart city maintenance). They must adapt to the surrounding environment by self-configuring: to this end, several mechanisms have been proposed (e.g., UPnP, ZeroConf, etc.). In this paper, we focus on IEEE 802.15.4 networks with IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) adaptation layer, where IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) is the routing protocol of choice. In this context, we propose a lightweight RPL-based mechanism to Resource Discovery (RD) and Service Discovery (SD), denoted as DiRPL. In particular, DiRPL exploits the RPL handshake to detect new nodes in the network, resources are then simply discovered with a Constrained Application Protocol (CoAP) request and can thus be published in a local resource directory. A very attractive feature of the proposed DiRPL approach is that it builds on well-defined and well-known standard protocols. The performance of the proposed system is investigated with WisMote nodes deployed inside the Cooja simulator, running the Contiki operating system. Practical application scenarios to large-scale smart city monitoring, such as smart lighting and large-scale water consumption monitoring, are investigated.

Proximity service (ProSe), using the geographic location and device information by considering the proximity of mobile devices, enriches the services we use to interact with people and things around us. ProSe has been used in mobile social networks in proximity and also in smart home and building automation (Google Home). To enable ProSe in smart home, reliable and stable network protocols and communication infrastructures are needed. Thread is a new wireless protocol aiming at smart home and building automation (BA), which supports mesh networks and native Internet protocol connectivity. The latency of Thread should be carefully studied when used in user-friendly and safety-critical ProSe in smart home and BA. In this paper, a system level model of latency in the Thread mesh network is presented. The accumulated latency consists of different kinds of delay from the application layer to the physical layer. A Markov chain model is used to derive the probability distribution of the medium access control service time. The system level model is experimentally validated in a multi-hop Thread mesh network. The outcomes show that the system model results match well with the experimental results. Finally, based on an analytical model, a software tool is developed to estimate the latency of the Thread mesh network, providing developers more network information to develop user-friendly and safety-critical ProSe in smart home and BA. Funding Agencies|Norwegian Research Council [262854/F20]

With the development of the Internet of Things (IoT), Low Data Rate-Personal Area Networks (LR-WPAN) have been deployed for different applications. Now comes the need to integrate these networks in search of greater connectivity, performances, and geographic coverage. This integration is facilitated by the recent deployment of low power wide area networks (LPWAN) in the licensed bands, especially narrowband IoT (NB-IoT) and long-term evolution for machine-type communications (LTE-M), which are standardized technologies that will continue evolving as part of the fifth generation (5G) specifications. This paper proposes a design methodology for combined networks using LR-WPAN and LPWAN technologies. These networks are combined at the device level using a cluster-tree topology. An example is shown here, where an existing IEEE 802.15.4 network is combined with NB-IoT. To this end, new dual nodes are incorporated, acting as cluster heads. The paper discusses the different aspects of formation and operation of the combined network. A dynamic link selection (DLS) algorithm is also proposed, based on which cluster headers dynamically determine the preferred link, depending on link quality and type of traffic. Extensive simulations show that the DLS algorithm significantly increases battery life on dual nodes, which are the nodes with the highest power demands.

Wireless Body Area Network (WBAN) has been a potential avenue for future digitized healthcare systems. WBAN has unique challenges and features compared to other wireless sensor networks. In addition to battery power consumption, the vulnerability and the unpredicted channel behaviour make channel access a serious problem. Time Division Multiple Access (TDMA) Medium Access Control (MAC) protocols can help in achieving a reliable and energy efficient WBAN. IEEE 802.15.4 provides TDMA based mechanisms to save energy consumption. However, both contention-free and inactive periods are static and do not consider channel status or nodes reliability requirements. Hence, this paper presents two IEEE 802.15.4 TDMA based techniques to improve WBAN reliability and energy efficiency. The first technique allows nodes to avoid channel deep fade by distributing adaptively their sleep period during their active period according to their channel status. Thereafter, in the second technique, nodes are dynamically allocated time slots according to their requirements, which depend on their link's status. The proposed techniques are evaluated within various traffic rates and their performances are compared with the legacy IEEE 802.15.4 MAC. Results reveal that the proposed techniques are able to promote the WBAN reliability and energy efficiency.

In this paper, we evaluate available bandwidth as a routing metric for IEEE 802.15.4-based ad-hoc networks. The available bandwidth on a data forwarding path is an approximation of the forwarding path’s residual data relaying capacity. High available bandwidth on a data forwarding path implies low data traffic load on the path, therefore data flows may experience low delay and high packet delivery ratio (PDR). Our aim is to evaluate available bandwidth as a routing metric. We present different available-bandwidth-based routing protocols for IEEE 802.15.40-based networks, namely: end-to-end available-bandwidth-based routing protocol (ABR), available bandwidth and contention-aware routing protocol (ABCR), and shortest hop-count and available-bandwidth-based opportunistic routing protocol (ABOR). Moreover, we also present variants of ABR and ABCR capable of distributing a flow’s data packets on multiple paths by maintaining the top K downstream nodes (the downstream nodes that advertised best data forwarding paths towards a sink node) corresponding to each sink node in a routing table. We focus on both single-sink and multi-sink networks. We performed extensive simulations, and the simulation results demonstrate that the available bandwidth routing metric shows better results when combined with a routing metric that helps to limit a data forwarding path’s length, i.e., shortest hop-count or intra-flow contention count. For multi-path data forwarding towards the same sink node, and at high traffic volumes, the available bandwidth metric demonstrates best performance when combined with the shortest hop-count routing metric.

Network sniffers are invaluable tools for designing, testing, commissioning and running distributed embedded systems. They become even more useful if these systems build on low-power wireless networks (LoWPAN), particularly when these scale in density and/or space and impose stringent quality-of-service requirements. This paper presents Z-Monitor, a low-cost and open-source network/protocol analyzer for LoWPANs. Z-Monitor is better than existing solutions since it combines the following features all-together: it covers the most widely used LoWPAN protocols, namely IEEE 802.15.4, 6LoWPAN, RPL and ZigBee; packet sniffing can be performed by any IEEE 802.15.4-compliant node, e.g., TelosB or MicaZ, requiring no extra hardware; the code is in Java (host PC), so it is OS-agnostic, and is freely available as open-source; Z-Monitor provides an user-friendly graphical user interface and a complete set of functionalities; nonetheless, Z-Monitor software architecture and programming approach are modular, so it is easily adaptable and extensible. We demonstrate and validate Z-Monitor in several LoWPAN network scenarios/settings and sites, ranging from a small-scale laboratory test-bed to a 400+ real-world deployment.

The Internet of Things (IoT) has been one of the main focus areas of the research community in recent years, the requirements of which help network administrators to design and ensure the functionalities and resources of each device. Generally, two types of devices&mdash, constrained and unconstrained devices&mdash, are typical in the IoT environment. Devices with limited resources&mdash, for example, sensors and actuators&mdash, are known as constrained devices. Unconstrained devices includes gateways or border routers. Such devices are challenging in terms of their deployment because of their connectivity, channel selection, multiple interfaces, local and global address assignment, address resolution, remote access, mobility, routing, border router scope and security. To deal with these services, the availability of the IoT system ensures that the desired network services are available even in the presence of denial-of-service attacks, and the use of the system has become a difficult but mandatory task for network designers. To this end, we present a novel design for wireless sensor networks (WSNs) to address these challenges by shifting mandatory functionalities from unreliable to reliable and stable domains. The main contribution of our work consists in addressing the core network requirements for IoT systems and pointing out several guidelines for the design of standard virtualized protocols and functions. In addition, we propose a novel architecture which improves IoT systems, lending them more resilience and robustness, together with highlighting and some important open research topics.

The high level of robustness and reliability required in industrial environments can be achieved using time-slotted channel hopping (TSCH) medium access control (MAC) specified in institute of electrical and electronics engineers (IEEE) 802.15.4. Using frequency channel hopping in the existing TSCH network, a parallel rendezvous technique is used to exchange packets containing channel information before network synchronization, thereby facilitating fast network synchronization. In this study, we propose a distributed radio listening (DRL)&ndash, TSCH technique that uses a two-way transmission strategy based on the parallel rendezvous technique to divide the listening channel by sharing the channel information between nodes before synchronization. The performance evaluation was conducted using the OpenWSN stack, and the actual experiment was carried out by utilizing the OpenMote-cc2538 module. The time taken for synchronization and the number of rendezvous packets transmitted were measured in linear and mesh topologies, and the amount of energy used was evaluated. The performance results demonstrate a maximum average reduction in synchronization time of 67% and a reduction in energy consumption of 58% when compared to the performance results of other techniques.

The adoption of software defined networking (SDN) within traditional networks has provided operators the ability to manage diverse resources and easily reconfigure networks as requirements change. Recent research has extended this concept to IEEE 802.15.4 low-power wireless networks, which form a key component of the Internet of Things (IoT). However, the multiple traffic patterns necessary for SDN control makes it difficult to apply this approach to these highly challenging environments. This paper presents Atomic-SDN, a highly reliable and low-latency solution for SDN in low-power wireless. Atomic-SDN introduces a novel synchronous flooding (SF) architecture capable of dynamically configuring SF protocols to satisfy complex SDN control requirements, and draws from the authors’ previous experiences in the IEEE EWSN Dependability Competition: where SF solutions have consistently outperformed other entries. Using this approach, Atomic-SDN presents considerable performance gains over other SDN implementations for low-power IoT networks. We evaluate the Atomic-SDN through simulation and experimentation, and show how utilizing SF techniques provides latency and reliability guarantees to SDN control operations as the local mesh scales. We compare the Atomic-SDN against the other SDN implementations based on the IEEE 802.15.4 network stack, and establish that the Atomic-SDN improves SDN control by orders-of-magnitude across latency, reliability, and energy-efficiency metrics.

Providing Internet of Things (IoT) environments with service level guarantee is a challenging task for improving IoT application usage experience. We specify in this paper an IoT architecture enabling an IoT Service Level Agreement (iSLA) achievement between an IoT Service Provider (IoT-SP) and an IoT Client (IoT-C). In order to guarantee the IoT applications&rsquo, requirements, Quality of Service (QoS) mechanisms should be implemented within all the layers of the IoT architecture. Thus, we propose a specific mechanism for the lowest layer of our service level based IoT architecture (i.e., sensing layer). It is an adaptation of the IEEE 802.15.4 slotted CSMA/CA mechanism enabling to take into consideration the requirements of real-time IoT services. Our access method called QBAIoT (QoS based Access for IoT) extends IEEE 802.15.4 systems by creating a new contention access period for each specified traffic class in the iSLA. Furthermore, due to the huge number of IoT connected devices, self-configuring capability provisioning is necessary for limiting human intervention and total cost of ownership (TCO). Thus, we integrate a self-configuring capability to the QBAIoT access method by implementing the MAPE-K closed control loop within the IoT High Level Gateway (HL-Gw) of our proposed QoS based IoT architecture.

The time-slotted channel hopping (TSCH) mode of the standard IEEE 802.15.4 provides medium access control for most low-power and lossy network (LLN) applications in the Internet of Things. TSCH creates a synchronized mesh network capable of delivering data packets in a reliable and timely manner. The standard defines a scan mechanism to allow nodes to detect the presence of a TSCH network and to associate to it. However, the time required to do so can be long, which causes excessive energy consumption, as nodes that are trying to associate stay awake during this process. In this paper, we present a rendezvous-based algorithm for TSCH association called PRV-TSCH that significantly reduces the time required for going through this process. The algorithm uses the principle of parallel rendezvous to allow nodes to associate to a TSCH network in a very short time. The interaction between the IPv6 Routing Protocol for LLNs and the time to associate to the TSCH network is also studied. The results of extensive simulation experiments and a mathematical model demonstrate that PRV-TSCH outperforms the purely passive scan proposed by the standard in terms of the time and energy required to associate to a TSCH network.

Wireless industrial applications require high level of Quality of Service (QoS) such as low-delay and jitter performances, low-power operations as well as end-to-end reliability close to 100%. However, considering the large number of wireless networks operating in 2.4 GHz, the radio technologies are more prone to the external interference, which eventually may negatively affect the reliability, the delay and the goodput performance due to collisions and retransmissions. To tackle the previously detailed issues, Time-Slotted Channel Hopping (TSCH) Medium Access Control (MAC) protocol emerged with IEEE 802.15.4-2015 as an alternative to the industrial standards such as WirelessHART and ISA100.11a. TSCH is based on frequency hopping to avoid the interference, while the medium access is based on a scheduler (i.e., slotframe) that repeats periodically to avoid the collisions. Yet, the majority of the proposed TSCH schedulers are based on traditional collision detection and retransmission in the following slotframe, which essentially increases the end-to-end delay performance. In this poster, we consider allocating consecutive timeslots for a single data transmission, to allow thus, to retransmit the data packet within the slotframe in case of losses. We study the potential trade-offs, reliability and delay versus energy consumption, when considering the over-allocation approach.

International audience; The IEEE802.15.4 wireless technology is one of the enablers of the Internet of Things. It allows constrained devices to communicate with a satisfactory data rate, payload size and distance range, all with reduced energy consumption. To provide IoT devices with a global Internet identity, 6LoWPAN defines the IPv6 adaptation to communicate over IEEE802.15.4. However, this integration still needs additional protocols to support other IoT requirements, which makes the IP stack in IoT devices more complex and therefore shows the limitations of the IP model to support the needs of future Internet. Named Data Networking represents an alternative that can natively support IoT constraints including mobility, security and human readable data names. This paper is a synthesis of an ongoing work that investigates the integration of NDN with IEEE802.15.4 for constrained IoT devices. The proposed design has been implemented in a real-world smart agriculture scenario, and evaluated by simulation focusing on energy consumption and network overhead in comparison to IP-based protocols.