Low-Power and Lossy Wireless Networks (LLWNs) operate under stringent energy, memory, and bandwidth constraints and rely on inherently unreliable multi-hop links. Despite substantial progress in IoT networking, updating deployed LLWNs often still requires bulky, full-image firmware upgrades, even for minor network stack changes. This practice incurs excessive overhead, complicates reliable delivery over lossy links, and can temporarily disrupt connectivity due to mandatory reboots. We introduce FINE-STACK, a flexible architecture that decomposes the network stack into lightweight virtual functions coordinated by a central orchestrator. By enabling fine-grained composition and semantics-aware management of protocol components, FINE-STACK supports fast and selective over-the-air updates at runtime. It further improves the programmability of the network stack by enabling hybrid deployments that combine local in-network control with optional global optimization. We implemented and evaluated FINE-STACK on a real-world testbed, comparing programmability and performance across conventional deployment models and the hybrid model enabled by our design. The results demonstrate that hybrid deployments provide improved programmability and superior operational performance, while fine-grained modularity of the network stack substantially reduces update size and update time without violating strict memory, power and overhead constraints. Overall, FINE-STACK advances LLWNs toward practical network programmability, narrowing the gap between flexibility and efficiency, and making semantic runtime reconfiguration feasible on highly constrained IoT devices.

Low-power Lossy Wireless Networks (LLWNs) are characterized by constraints in memory, processing, and power consumption, coupled with an inherently dynamic wireless environment. In this context, a suite of programmable communication protocols is essential to efficiently adapt to varying network conditions, optimize resource utilization, and maintain performance within the stringent limitations of LLWN devices. In this work, we review and compare state-of-the-art network programmability techniques to assess their suitability for LLWNs. Based on the findings, we propose a new network architecture for LLWNs, utilizing software-defined networking for control plane programmability and Femto Containers lightweight virtualization for data plane programmability, ensuring it respects the constraints of LLWN devices. We have conducted a proof-of-concept validation to demonstrate the feasibility of Femto Containers to implement the data plane in LLWN on the FIT IoT-LAB testbed. The results show that our architecture successfully achieves a substantial reduction in update size while adhering to memory and power consumption constraints of LLWN devices, although this comes at the cost of a slightly acceptable increased packet processing delay.

Wireless industrial networks represent a key enabler for Industry 4.0. Since wireless links are known to be lossy, most deployments rely on scheduled transmissions to avoid collisions. Software Defined Networking (SDN) is a famous architecture where a controller centralizes all the configuration. In a scheduled wireless network, the SDN paradigm has to be extended to allocate both paths and bandwidth. Unfortunately, most solutions address only the initial configuration, which becomes suboptimal when the link quality evolves, or the conditions change. We propose here the mechanisms for continuous optimization. We define how control packets can reconfigure the data plane while guaranteeing a globally consistent state, even when the control plane exploits unreliable links. No data packet is dropped because of inconsistent forwarding rules. To be energy efficient, we also propose a scheduling algorithm that minimizes the network reconfiguration to minimize the overhead. Our simulation results highlight the strength of our proposition to handle topology and link quality changes.

The Industrial Internet of Things (IIoT) has now emerged for many industrial applications. However, many critical applications require high reliability and bounded end-to-end latency. Fortunately, scheduled wireless networks such as IEEE 802.15.4-TSCH try to orchestrate finely the transmissions. In particular, the Software-Defined Networking (SDN) paradigm is promising to concentrate the intelligence of the network in a controller and to simplify the functions achieved by the motes. SDN controller relies on link quality information of wireless devices to construct the routing topology of the network and to provision adequate radio resources for each link. We propose here an accurate link quality estimation scheme based on the SDN-TSCH, as an SDN solution for IEEE 802.15.4-TSCH network. We exploit the centralized view of the SDN controller to transmit packets of link quality estimation in a collision-free manner. Moreover, we investigate the performance of the control plane of SDN-TSCH through different shared, dedicated, and hybrid (mix of shared and dedicated cells) approaches. We figured out that the dedicated control plane provides high reliability and fast convergence for wireless SDN networks.

Industrial wireless sensor networks (IWSNs) play a key role in the Industry 4.0 revolution. The network infrastructure is critical to interconnect sensors and actuators and needs to respect key performance indicators. IEEE 802.15.4-TSCH is a candidate technology for IWSN since it relies on scheduled transmissions and frequency hopping to make the network more reliable. However, distributed scheduling solutions fail to provide high-reliability and low-end-to-end latency. Software defined network (SDN) tends now to emerge in wireless networks as well, where a controller is in charge of the whole network configuration. But scheduled wireless networks require to go beyond usual SDN forwarding rules by including the radio resource allocation (dedicated time-frequency blocks). Moreover, radio links are known to be unreliable, and we need to adapt the control and data planes to make the network efficient. We propose SDN-TSCH to orchestrate a scheduled network adapting the SDN paradigm. More specifically, the controller is in charge of 1) selecting the time source; 2) maintaining a tree structure for the control plane, with scheduled resources dedicated to the control plane; and 3) installing a new data flow while guaranteeing flow isolation. We also propose a very efficient link quality estimation technique tailored for scheduled TSCH networks. Our simulations highlight that the SDN controller can allocate in SDN-TSCH just-enough resources to respect both latency and reliability constraints.

The Industrial Internet of Things (IIoT) applications need to rely on a wireless infrastructure able to provide low end-to-end latency, and high reliability. Software-Defined Networking (SDN) is promising to make the network more agile, pushing the decision process to a controller. However, radio links are unstable while the controller needs to construct an accurate view of the network to schedule the transmissions efficiently. We propose here SDN-TSCH to separate the data and control planes for a scheduled network. We construct a reliable control plane, maintaining a collision-free path to and from the controller. Besides, SDN-TSCH guarantees flow isolation: each flow can reserve dedicated resources so that end-to-end reliability and latency constraints can be respected per flow. Finally, we also dedicate resources for best-effort traffic, to accommodate various applications. Our Cooja simulations highlight the flow isolation characteristics of SDN-TSCH: we provide very high reliability even in presence of best-effort traffic.

Synchronized MAC protocols are now considered as the ultimate solution to access the medium in wireless sensor networks. They guarantee both high throughout and constant latency and achieve reasonable energy consumption performance. However, synchronization is achieved at the cost of a complex framework with low flexibility on its parameters that is not suitable for some network topologies or application requirements. By contrast, asynchronous MAC protocols are versatile by nature but suffer from the tradeoff between energy consumption and latency. However, the addition of Wake-up Radio (WuR) can reduce the energy consumption of such protocols while maintaining very low latency thanks to its always-on feature and ultra-low power consumption. In this article, we present WuR-based Multi-hop Multi-channel (W2M), an asynchronous MAC protocol for wireless sensor networks. We also provide a fair comparison with Time Synchronized Channel Hopping (TSCH) through an extensive simulation campaign based on Contiki-NG and Cooja. Our results show that in low traffic scenarios, W2M outperforms TSCH in reducing both the energy consumption and the latency (at least 68% of energy is saved), but at the cost of slightly lower reliability.

The devices of Internet of Things (IoT) networks can be deployed for extended period of time in inaccessible locations. After their deployment, new features, bug fixes, or changes in the client needs can require an update of the node's behavior, and this update has to be transmitted over the radio medium. Proposals have been made in the literature to apply the Software Defined Network (SDN) paradigm to wireless sensor networks but they focus on the packet forwarding layer of the stack. In this work, we propose to extend the programmability to the whole stack with a fully programmable device architecture able to handle the runtime programming of every protocol on any hardware. We detail the use of extended finite-state machines (XFSM) on which the architecture is based and their conversion to compact executable bytecode that can be sent over radio. Simulations demonstrate that this architecture can reproduce a protocol from the literature and enable interoperability between programmable nodes and legacy nodes.

The IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) builds a Destination-Oriented Directed Acyclic Graph (DODAG) rooted at one node. This node may act as a border router to provide Internet connectivity to the members of the DODAG but such a situation creates a single point of failure. Upon border router failure, all nodes connected to the DODAG are affected as all ongoing communications are instantly broken and no new communications can be initiated. Moreover, nodes close to the border router should forward traffic from farther nodes in addition to their own, which may cause congestion and energy depletion inequality. In this article we specify a full solution to enable border router redundancy in RPL networks. To achieve this, we propose a mechanism leveraging cooperation between colocated RPL networks. It enables failover to maintain Internet connectivity and load balancing to improve the overall energy consumption and bandwidth. Our contribution has been implemented in Contiki OS and was evaluated through experiments performed on the FIT IoT-LAB testbed.

Wake-Up Radios is an emerging technology, aiming at pushing forward the frontiers of energy efficiency without trading it off for latency nor reliability. Extending the lifetime of the nodes as much as possible is one of the main goals in Multi-hop Wireless Sensor Networks. The Routing Protocol for Low Power and Lossy Networks (RPL) is commonly used in these applications. However, there is still an open problem in its design when it comes to achieving both stability and efficient routing at the same time. In this article, we present Load Balancing Parent Selection (LoBaPS), an algorithm to select opportunistically the next hop, based on RPL. It capitalizes on the Wake-Up Radio and its always-on feature, as well as its Ultra-Low Power consumption. We compare the performance of LoBaPS with that of W-MAC, a reference protocol that uses Wake-Up Radio and supports RPL in its traditional way. The results are obtained through simulations in COOJA for a network of nodes running ContikiOS, and show that the lifetime can be improved up to 55%, while the Packet Delivery Ratio (PDR) can raise a maximum of 20%, keeping a reasonable level of latency. In addition, the network is more robust to node shutdowns and requires less control overhead.

In Wireless Sensor Networks (WSN), duty-cycled Medium Access Control (MAC) protocols trade off latency for energy efficient operation. Over the past few years, Wake-Up Radio (WuR) has been presented as the ultimate solution for this tradeoff, allowing to reduce both at the same time. However, this might not be the general case regarding the large range of network configurations used in WSN. Several previous works have been done comparing WuR to traditional duty-cycled solutions, but no one has investigated before the limitations of this technology. In this article, we analyze the benefits and drawbacks of using WuR in multi-hop WSN. We also identify black spots in WuR that have not been investigated yet. Our study is based on evaluations using COOJA, a simulator for networks of ContikiOS nodes. A traditional duty-cycled MAC protocol is also included in our study for comparative purposes. From our study, we quantify the performances of WuR and provide some guidelines on how this technology can be efficiently used in multi-hop wireless sensor networks.

The last decade saw the emergence of the Internet of Things (IoT) paradigm, which aims to connect any object to the Internet. In this context, a new type of wireless communication network emerged known as Low-Power Wire-Area Network (LPWAN). By contrast to well-known short range and multi-hop wireless networks, LPWAN networks allow long range communications at a low bit rate. Furthermore, LPWAN networks are considered to be integrated into 5G. Among LPWAN networks, the LoRaWAN technology gains more and more interest from the research and industrial communities. In this article, we have led a thorough experimental performance evaluation of LoRaWAN in an indoor environment. From this study, we quantify the limits of this technology and expose the merits of using LoRaWAN for IoT communications in the context of 5G.

Wireless Sensor Networks (WSN) have become popular in the last years. Paths between sensors are computed by routing protocols, which are specifically designed to cope with the characteristics of WSN. Lately, the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) has been accepted as the Internet Engineering Task Force (IETF) standard for routing packets in WSN. However, this protocol does not pay particular attention to mobile nodes. Furthermore, mobility has been contemplated as a way to improve sensing coverage and connectivity in unattended WSN. In addition, WSN will account for an increasingly huge number of connections, from 1.9 billion devices today to 9 billion by 2018 among which most of them would be mobile (e.g. wearable devices). Using RPL to support the mobility of nodes is the main problem investigated in this article. We propose a new version of the trickle algorithm which allows mobile nodes to move seamlessly into a routing topology build by RPL together with limiting the signalling overhead. Our proposal is compared to two other schemes available in the literature. Results highlight that our proposal significantly reduces disconnection times and increases the packet delivery ratio while mitigating the extra control traffic.

Wireless sensor networks (WSN) require pertinent and reliable data collection schemes in order to provide information about their deployment area. This article aims at detailing our contribution for message loss avoidance along prone-to-failure paths that monitoring reports would follow from sensors to sink stations. While many researchers have tackled this issue by focusing on particular layers of the embedded communication stack (e.g. medium access control or routing protocol), we propose an original layer-independent scheme. The key aspect of our solution is to create fake data sources that have acted as storage nodes during the failure of links leading to the sink station. Few control messages are required during our gradual recovery phase, thus maintaining a negligible overhead in terms of message complexity and energy consumption, and also resulting in much improved data delivery ratio.

Although mobility management within a network of wireless sensors is a relatively new subject, we envision that a mobile sensor will move through different networks. However, it is very likely that the routing protocol supported in a visited network is different from the one supported by the mobile sensor. In a convergecast communication model, it would suffice for mobile sensors to broadcast its messages into the visited network to have them forwarded to the sink. Though, this can lead to duplication of messages and therefore increase the network traffic in the visited network. In this article, we propose Mobinet whose objective is to enable mobile sensors to detect surrounding sensors in the visited network through passive listening in order to select one of them to transmit messages. We particularly focus on the energy consumption of the mobile sensors and consequently introduce various listening processes to limit the extra energy consumption resulting from the detection of surrounding sensors. Mobinet has been evaluated by simulation. Simulation results show the benefits of Mobinet in terms of message delivery and a lower energy consumption through the listening processes. They also highlight guidelines for future research.

Abstract In the past few years, the concept of pervasive connectivity has become of crucial importance. New protocols have therefore been standardized to enable IPv6 mobility, such as the Network Mobility Basic Support (NEMO BS) protocol. This protocol is particularly suited for providing a global IPv6 connectivity in intelligent transportation systems. Yet, despite its popularity and maturity, it still suffers from various limitations which prevent its adoption in large‐scale commercial deployments. Among these are operator specific issues such as the lack of practical and efficient bootstrapping procedure. Also, a global connectivity enables the provision of value‐added services whose attractiveness mainly depends on their ease of configuration. In this paper, we focus on solutions to address both the bootstrapping of NEMO BS and service discovery in a mobile environment. By investigating various bootstrapping proposals, we advocate the use of a standardized solution extended with the missing pieces to operate in a NEMO BS environment. We also expose how operator services could be exported and announced in the mobile subnet. Authentication and authorization to access these services are also investigated. Experiments on a prototype show that our proposal brings the missing blocks towards the deployment of network mobility service in intelligent transportation systems. Copyright © 2009 John Wiley & Sons, Ltd.

In this paper, we briefly describe an interactive roulette game enabled over a wireless sensor network platform. It basically consists in a train speeding in one way (the spinning roulette) and in a message hopping along some deployed sensors in the other way (the wheeling ball). This demonstration aims at illustrating in an interactive manner the high radio channel randomness in dense wireless sensor networks, as well as its impact on the communication protocols.

The Network Mobility Basic Support (NEMO BS) protocol is the IETF standard to manage the mobility of entire IPv6 networks. One of the typical applications of this protocol is to deploy NEMO BS in transportations such as train or bus. As a result, passengers can benefit from global and permanent IPv6 connectivity with legacy IPv6 terminals equipped with a common wireless technology such as Wi-Fi. However, a mobile network is generally managed by a single mobile router which carries out all operations related to mobility and packet forwarding. In this article, we present a new proposal which enables the cooperation of multiple mobile routers to improve the bandwidth, network coverage and reliability of a mobile network. In addition, a dynamic load sharing mechanism between all available mobile routers is supported. This solution mainly relies on Neighbor Discovery and has been experimented on a real testbed.

The mobile IPv6 protocol is becoming one of the most common ways to support IPv6 mobility. Yet, despite its popularity the protocol still suffers various limitations which prevent it from being adopted in large scale commercial deployments. Among these is the protocol's poor support (or lack thereof) for rapid and seamless handovers. When moving from one subnet to another, a mobile node may experience connection and/or packet loss which may introduce noise and cuts in real-time media streams delivered to the user. Many different solutions to this problem have been presented and evaluated in various papers during the last few years but none of them have so far been selected as the standard mobile IPv6 handover optimization. In this article an experimental analysis of two optimization schemes were presented and compared their performance to that of a standard mobile IPv6 implementation. One of them, the fast handovers mobile IPv6 protocol (FMIPv6) is being strongly supported by IETF working groups and is probably the one that, among all other handover optimization schemes, has most approached standardization. The GPS handovers solution, on the other hand seems to be one of the few that have the maturity and completeness of the FMIPv6 protocol, and in the same time resolves problems that seem to be unaddressed by FMIPv6. All analysis in this paper is based upon experimentation which the authors believed is superior to simulation or emulation when dealing with a subject that is so heavily influenced by the implementation specifics of the accompanying technologies. Mobile nodes in all experiments are communicating via the IEEE 802.11 WLAN technology. All experiments are conducted with unmodified versions of popular conferencing and streaming applications Gnomemeeting and VLC.

IEEE 802.11 networks are now very common and are present in various locations. While roaming through access points, a mobile node is often required to perform a link layer handover. This mechanism causes user-interceptable connection loss and breaks in time-sensitive communication, especially if a network layer handover follows the link layer handover. Many solutions attempting to improve this process have been proposed but only a few use geolocation systems in the management of the handover. In this article, we present a new method to enhance both link layer and network layer handovers using geolocation information provided by a GPS system. The idea behind our algorithm is to predict the next mobile node point of attachment and the associated sub-network using the position of the mobile nodes. This method has been implemented using the new Mobile IP daemon for GNU/Linux operating system and evaluated through two scenarios

Given the relatively limited coverage area of 802.11 access points, stations moving inside WLAN are often required to perform a handover. The time needed for a STA to switch from one AP to another is too long for real-time applications to continue operating seamlessly, even if no layer 3 handover is to occur ulteriorly. Many solutions have been proposed for improving the layer 2 handover latency, but we have observed a lack of performance analysis and comparison of the different algorithms. In this article we present two new schemes that aim to enhance L2 handover mechanisms. The main characteristic of these new methods is to reduce the discovery time. We then provide an evaluation of four algorithms in order to analyse and compare solutions in six different scenarios