Article

Topology Management and TSCH Scheduling for Low-Latency Convergecast in In-Vehicle WSNs

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Abstract

Intra-vehicle Wireless Sensor Networks (WSNs) require reliable and real-time data delivery. The Time-Slotted Channel Hopping (TSCH) mode of the IEEE 802.15.4 standard provides a reliable solution for low-power networks through guaranteed medium access and channel diversity. However, satisfying the stringent requirements of dense in-vehicle networks demands for special consideration in network formation and TSCH scheduling. This paper targets convergecast in dense in-vehicle WSNs in which all nodes can potentially directly reach the sink node. A cross-layer Low-Latency Topology management and TSCH scheduling (LLTT) technique is proposed that provides a very high timeslot utilization for the TSCH schedule and minimizes communication latency. Two techniques, namely grouped retransmission and periodic aggregation, are also exploited to increase the performance of the TSCH communications. The experimental results show that LLTT reduces the end-to-end communication latency compared to other approaches, while keeping the communications reliable by using dedicated links and grouped retransmissions.

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... Farias et al. [10] proposed a queue-based algorithm for the path computation element to increase the reliability in industrial scenarios. The authors in [11] proposed a cross-layer low-latency topology management and TSCH scheduling technique that provides a very high timeslot utilization to minimize communication latency. The works in [10], [11] does not concern itself with throughput -a challenge we aim to handle in the paper. ...
... The authors in [11] proposed a cross-layer low-latency topology management and TSCH scheduling technique that provides a very high timeslot utilization to minimize communication latency. The works in [10], [11] does not concern itself with throughput -a challenge we aim to handle in the paper. Other centralized scheduling approaches in IIoT-TSCH networks worth mentioning are [12], which maximizes the energy efficiency, and [13] addressing latency issues. ...
... In the scheduling algorithms described above [10][11][12][13][14][15][16][17], the notion of fairness fails to exist. Several works in the literature have addressed fairness in the wireless networks domain [20][21][22]. ...
Article
Time-Slotted Channel Hopping (TSCH) mode in the IEEE 802.15.4-2015 standard provides ultra-high reliability and ultra-low power consumption to sensor devices. The key feature of TSCH is the scheduling of time slots and frequencies, which falls outside the current standards. In this paper, we focus on throughput maximizing and max-min fair scheduling problems in a centralized TSCH networks. At first, a polynomial time algorithm for the throughput maximizing scheduling problem is proposed. We proceed to investigate and deliberate on some instances of the problem with their combinatorial properties. Secondly, a novel auction based scheduling algorithm that uses a first-price sealed-bid auction mechanism is presented for the throughput maximizing problem. Simulation results show that the proposed algorithm obtains a close throughput performance to the optimal one obtained through CPLEX with a much lower complexity. Moreover, we propose a novel heuristic for the max-min fair scheduling problem and demonstrate its performance through extensive simulations in terms of the total throughput and fairness varying the number of nodes, frequencies and antennas. Simulation results indicate the effectiveness of the proposed algorithm and its close performance to the optimal solution.
... In [56], the authors study how to efficiently build a wireless network topology to gather data from onboard sensors in a car, where all nodes see each other, which permits a star topology. However, some links can be of poor quality. ...
... connexes sur l'utilisation de réseaux sans-fil à l'intérieur d'un pack batterie de véhicule électrique D'autres ont déjà commencé à étudier cette possibilité. Alonso et al.[76] ont évalué les performances de différentes antennes à l'intérieur d'une enceinte batterie, et recommandent d'utiliser des antennes PIFA dans la bande des 2,4GHz.La chaîne de traction, et en particulier le moteur du véhicule, émet des rayonnements électromagnétiques, mais qui se trouvent en dessous des 100kHz[75], et ne devraient donc pas interférer avec le réseau sans-fil.Dans[56], les auteurs étudient un réseau sans fil à bord d'un véhicule, où tous les noeuds sont à portée les uns des autres, et préconisent d'utiliser une topologie en arbre à 2 niveaux (en plus du noeud racine), afin d'utiliser les chemins les plus fiables. Ils suggèrent aussi d'utiliser un mécanisme d'agrégation des données aux noeuds intermédiaires.b.3 performance d'un réseau iot dans un pack batterie de véhicule électriqueAfin de connaître précisément la qualité moyenne des liens réseau avec la technologie choisie à l'intérieur d'un pack batterie, mais aussi de connaître l'impact de la position et des potentielles interférences avec d'autres utilisateurs de la bande des 2,4GHz, de nombreux tests ont été réalisés. ...
Thesis
The traction battery of an electric vehicle is a key component. It is also a sensitive system for which the voltage and temperature of the cells it is made of must be kept in a given working range. This is the role of the Battery Management System (BMS). The BMS is made of subsystems, called Cells Sensor Units (CSU), which supervise the cells and report their state to a central component named Master Control Unit (MCU). Moreover, they are in charge of performing battery cells balancing, as cells do not have exactly equal capacity, and imbalance between them may appear with usage over time, when they are wired in series. In current BMS implementations, this periodic communication is performed through wires. In this work, we have studied the possibility to replace this wired communication with a wireless medium, by using standardized protocol stack of the Internet of Things (IoT).After evaluating different communication protocols, we have chosen to base our work on IEEE Std. 802.15.4-2015 Time Slotted Channel Hopping (TSCH). We first have tested this protocol within an battery pack environment, through experimentation, using actual wireless capable nodes. Thus, we were able to determine that the radio links quality is high, that the car's engine electromagnetic emissions should not interfere with the wireless communication, and that most of the problems would come from other users of the 2.4GHz band, and Wi-Fi in particular. We then have sought to determine what the most adapted topology and scheduling management strategies for such a scenario are. To this end, we have proposed two algorithms for centralized network management, based on the Linear Programming and Simple Descent techniques, in order to optimize the topology and slotframe. Considering that many parameters are involved in this optimization work, we have therefore evaluated our algorithms under various setups, and used the results to determine what the best values for these algorithms parameters are. Moreover, we have proposed a routing protocol, which makes use of these algorithms in an iterative way to compute the best possible topology and slotframe, and which allows to propagate the decisions of the centralized network manager to the nodes. This protocol, heavily inspired by the Routing Protocol for Low-Power and Lossy Networks (RPL), relies on periodic messages and asynchronous events to keep the wireless nodes up-to-date with the latest network manager decision. Finally, we have tested this solution with a network of objects in a vehicular environment.
... Due to its harmonious features with the native protocol, WCAN chances in succeeding and predominating the I2V communication are strong. Likewise, the compatibility between heterogeneous IVNCSs with wireless sensor networks is expected to reduce wiring [71]. ...
Article
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The in-vehicular networked control system is among the most critical embedded processes. The controller area network (CAN) has prevailed intra-vehicle communication for decades. Meanwhile, requirements of future transportation systems are expected to emphasise the in-vehicle communication complexity, which endangers the reliability/safety of the intelligent navigation. At first, this study reviews the recent solutions proposed to overcome the CAN expanding complexity. Challenges that tomorrow's intelligent vehicles may raise for CAN reliability are investigated. The comprehensive coverage of current research efforts to remove the impact of these challenges is presented. Further, the in-vehicle system reliability of future automated vehicles is also related to the fault diagnosis performances. Hence, different classes of system-level diagnosis strategies are compared relatively to the requirements of automotive embedded networks. Furthermore, to thoroughly cover CAN reliability engineering issues, focus is given to the automotive validation techniques. The hardware in the loop, real-time analysis and computer-aided-design tools intervene in various phases along the in-vehicular network life cycle. Parameters that stand behind the efficiency and accuracy of these techniques in validating the new generation of vehicles are analysed. The authors finally draw some deductive predictions about the future directions related to the reliability of the intelligent transportation system in-vehicular communication.
... Both AMUS and LaDiS take into account that children should be scheduled before their parents in order to benefit from packet aggregation. The authors of LLTT [18] acknowledge this as well, but propose a practical periodic aggregation at the network layer instead. They also use shared time slots in order to boost the performance of LLTT. ...
Preprint
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The Industrial Internet of Things (IoT) has gained a lot of momentum thanks to the introduction of Time Slotted Channel Hopping (TSCH) in IEEE 802.15.4. At last, we can enjoy collision-free, low-latency wireless communication in challenging environments. Nevertheless, the fixed size of time slots in TSCH provides an opportunity for further enhancements. In this paper, we propose an enhanced centralized TSCH scheduling (ECTS) algorithm with simple packet aggregation while collecting data over a tree topology. Having in mind that the payload of a sensor node is rather short, we attempt to put more than one payload in one packet. Thus, we occupy just one cell to forward them. We investigated the schedule compactness of ECTS in Matlab, and we evaluated its operation, after implementing it in Contiki-NG, using Cooja. Our results show that ECTS with packet aggregation outperforms TASA in terms of slotframe duration and imposes fairness among the nodes in terms of latency. A validation exercise using real motes confirms its successful operation in real deployments.
... In the literature, a number of applications of 6TiSCH are present. However, most of them only consider monitoring applications [9] [10] [11]. How to use the 6TiSCH networks in control applications remains an unresolved issue. ...
Conference Paper
IETF 6TiSCH is emerging as a promised open-standard for industrial internet of things (IIoT). With employing Time Slotted Channel Hopping (TSCH) mode, 6TiSCH can meet critical requirements in the industrial sector such as reliability, determinism and real time. 6TiSCH is currently focusing on monitoring applications. This paper considers its applicability in industrial control, in which sensor and actuator are coexistent in the network. We first investigate applicable wireless sensor-actuator models based on 6TiSCH. Then, an efficient data transmission scheme between sensor and actuator is proposed. Through simulation results, we show that our solution achieves a significant improvement in terms of end-to-end latency and energy consumption compared to the bursty transmission in the 6TiSCH networks.
... Although these approaches provide theoretically optimal scheduling, in practice, they suffer significant control overhead to update network information for the root node and slow schedule adjustment when topology is changed. For this reason, centralized scheduling methods are more suitable for a static environment where routing topology rarely changes [32]. ...
Conference Paper
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Although low-power lossy network (LLN), at its early stage, commonly used asynchronous link layer protocols for simple operation on resource-constrained nodes, development of embedded hardware and time synchronization technologies made Time-Slotted Channel Hopping (TSCH) viable in LLN (now part of IEEE 802.15.4e standard). TSCH has the potential to be a link layer solution for LLN due to its resilience to wireless interference (e.g., WiFi) and multi-path fading. However, its slotted operation incurs non-trivial cell scheduling overhead: two nodes should wake up at a time-frequency cell together to exchange a packet. Efficient cell scheduling in dynamic multihop topology in wireless environments has been an open issue, preventing TSCH's wide adoption in practice. This work introduces ALICE, a novel autonomous link-based cell scheduling scheme which allocates a unique cell for each directional link (a pair of nodes and traffic direction) by closely interacting with the routing layer and using only local information, without any additional communication overhead. We implement ALICE on Contiki and evaluate its effectiveness on the IoT-LAB public testbed with 68 nodes. ALICE generally outperforms Orchestra (the state-of-the-art method) and even more so under heavy traffic and high node density, increasing throughput by 2 times with 98.3% reliability and reducing latency by 70%, route changes by 95%, and radio duty cycle by 35%. ALICE can serve as an autonomous scheduling framework, which paves the way for TSCH-based LLN to go on.
... To minimize communication delays and make full use of time slots in In-Vehicle WSNs, the authors of [18] proposed a cross-layer low-latency topology management method that adapts an optimized graph isomorphism strategy, then, the schedule generator provides low delivery latency by adopting the selected topology. The work in [19] presented a new network model that considered a multidimensional scheduling space as flow-link-channel-slot tuples. ...
Article
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As a key characteristic for industrial wireless sensor networks, deterministic scheduling aims to ensure that real-time data flows arrive at destination devices under deadline constraints by allocating necessary communication resources, such as time slots and channels. Current research on deterministic scheduling mainly focuses on how to obtain a feasible scheduling solution. However, optimizing average transmission delays under deterministic flow deadlines is rarely considered when multiple scheduling solutions exist. To address this issue, in this paper we propose two scheduling algorithms: branch and bound based on link conflict classification, and least conflict degree first. The prior algorithm obtains optimal schedulable ratio by constructing a search tree and adopting necessary conditions of scheduling. The latter algorithm dynamically adjusts the scheduling order of flows to distribute channels in a heuristic manner, and achieves approximate optimal schedulable ratio in a short time with low complexity. Simulation results show that both of the proposed algorithms effectively reduce the average transmission delays of real-time data flows while guaranteeing that all flows are delivered before their deadlines.
... According to the above analysis and related literatures [12][13][14], some empirical values can be given. In order to minimize the time average power consumption of the system, we can describe the problem as the following optimization problem: ...
Article
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In the Industrial Internet of Things (IIoT), it is an urgent task to reduce power loss and enhance energy efficient through reasonable allocation of resources. Inspired by time slot channel frequency hopping, this paper puts forward a dynamic allocation model for time and power resources. Based on the proposed model, a dynamic resource allocation algorithm was designed to reduce energy consumption. In addition, a power and time allocation algorithm was developed to maximize the energy efficiency of the system. The workflows of the two algorithms were introduced in details. Simulation results show that both dynamic resource allocation algorithm could reduce the energy loss of the communication system, while ensuring the stability of the data queue. The research findings help to promote the performance of communication systems in different scenarios of the IIoT.
... A motivating example is wireless in-vehicle networks. Since TSCH is designed for reliable industrial applications, it is considered as a promising option for communication of various devices (sensors, actuators, and microprocessors) within a vehicle [2]. However, there are many cases (e.g., behind traffic lights or in the parking lots) in which several vehicles are very close to one another in a period of time. ...
Article
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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 realworld 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.
... A tangible advantage of these solutions is the ability to cover larger areas, at the price of an increased communication latency. Multi-hop WSNs often rely on a multi-level tree topology that stems from a root node [45]. As a matter of fact, mesh topologies also exist where routes between nodes are (somehow) arbitrary, but they are less common in practice and will not be analyzed in this work. ...
Article
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Reliability, power consumption, and latency are the three main performance indicators of wireless sensor networks. Time slotted channel hopping (TSCH) is a promising technique introduced in the IEEE 802.15.4 standard that performs some steps ahead in the direction of the final dream to meet all the previous requirements at the same time. In this article, a simple and effective mathematical model is presented for TSCH that, starting from measurements performed on a real testbed, permits to characterize both the network and the surrounding environment. To better characterize power consumption, an experimental measurement campaign was purposely performed on OpenMote B devices. The model, which was checked against a real 6TiSCH implementation, can be employed to predict network behaviour when configuration parameters are varied, in such a way to satisfy different application contexts. Results show that, when one of the three above indices is privileged, unavoidably there is a worsening of the others.
... Although the solutions proposed in these studies can optimize the latency and channels in the convergecast operation, the system performance is still degraded remarkably by interference, such as noise or other devices that affect the connectivity and induce low reliability on the ISM channels. Some techniques have been directly applied to improve the convergecast reliability, such as allowing retransmissions [20], [21] or constructing multiple routing choices [22]. Nevertheless, these methods might only enhance the convergecast reliability to some extent but generally can not maximize the reliability under stringent latency constraints. ...
Article
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The performance of data aggregation in industrial wireless communications can be degraded by environmental interference on Industrial Scientific Medical (ISM) channels. In this paper, the opportunistic spectrum access capability of cognitive radio (CR) was applied to enable devices to share primary channels with the aim of enhancing the transmission performance of the WirelessHART network. We considered a linear convergecast network, where the packets generated at each device were routed to the gateway (GW) through the aid of neighboring devices. The solar-powered cognitive access points (CAPs) were deployed to improve the successful transmission probability of the packets among field devices by opportunistically allocating the primary channels to the devices for data transmissions. In this paper, we formulate the scheduling problem of long-term throughput maximization as a framework of a Markov decision process by considering the constraints of the minimum delay, the number of required ISM channels, and the harvested energy at the CAPs. Then, we propose a deep reinforcement learning-based scheduling scheme to optimally assign multiple ISM and primary channels to the field devices in each superframe to maximize the received packets at the GW. The simulation results confirmed the superiority of the proposed scheme compared to existing methods.
... Time-synchronized channel hopping (TSCH) is among the most popular standards in the scope of WSAN to support real-time data traffic. Salient features, such as time-division multiple-access (TDMA), centralized scheduling and frequency diversity, have gradually underpinned its adoption in a number of application domains, from factory automation and process control [9] to vehicles [16], paving the way for the Industrial Internet of Things (IIoT) and Industry 4.0 [15]. ...
Conference Paper
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With the scope of Industry 4.0 and the Industrial Internet of Things (IIoT), wireless technologies have gained momentum in the industrial realm. Wireless standards such as WirelessHART, ISA100.11a, IEEE 802.15.4e and 6TiSCH are among the most popular, given their suitability to support real-time data traffic in wireless sensor and actuator networks (WSAN). Theoretical and empirical studies have covered prioritized packet scheduling in extenso, but only little has been done concerning methods that enhance and/or guarantee real-time performance based on routing decisions. In this work, we propose a greedy heuristic to reduce overlap in shortest-path routing for WSANs with packet transmissions scheduled under the earliest-deadline-first (EDF) policy. We evaluated our approach under varying network configurations and observed remarkable dominance in terms of the number of overlaps, transmission conflicts, and schedulability, regardless of the network workload and connectivity. We further observe that well-known graph network parameters, e.g., vertex degree, density, betweenness centrality, etc., have a special influence on the path overlaps, and thus provide useful insights to improve the real-time performance of the network.
... In [17], a clustering algorithm based on Prim's minimum-spanning-tree was proposed, which is not suitable for crossroads in urban road environments. In [18], a periodic clustering method that uses effectively available bandwidth was proposed to reduce the delay caused by clustering. However, this method is only suitable for the cluster mechanism of static network nodes, not for dynamic vehicle networks [19]. ...
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The cellular vehicle-to-everything (C-V2X) networks support diverse kinds of services such as traffic management, road safety, and sharing data. However, the safety issues cannot be ignored in the process of information transmission. In this paper, a joint clustering and blockchain scheme is proposed for real-time information security transmission to prevent some vehicles from sending malicious messages to disrupt the traffic order at the crossroads in C-V2X networks. In this scheme, the dynamic stability of the cluster is maintained by updating the trust value of the vehicle nodes, which can improve the real-time and accuracy of the information transmission. The modified Webster algorithm is presented to divert the traffic flow so as to reduce the traffic jams at the crossroads. Meanwhile, the blockchain technology is utilized to establish a vehicle trust management mechanism in C-V2X, which can avoid malicious tampering of vehicle information during information sharing and ensure the safety of vehicle information communication. The simulation results of the Veins simulation platform are provided to demonstrate the effectiveness of the proposed algorithm and verify that the proposed scheme can guarantee the security of real-time information transmission.
... They make a central node schedule slotframes for all nodes according to global information on traffic load and conflict relation among nodes. LLTT [33] also builds a fixed TSCH network to reduce end-to-end latency. However, these schemes assume fixed routing topology and constant traffic load, which does not hold in the real world. ...
... Centralized and M. Angurala, M. Bala and Sukhvinder Singh Bamber Egyptian Informatics Journal xxx (xxxx) xxx distributed techniques consider conditions such as failures in the medium access, collisions in the wireless medium, traffic and many more. R. Tavakoli et al. [26] proposed Time-Slotted Channel Hopping (TSCH) and cross layer Low-Latency topology management to provide high timeslot utilization for the TSCH schedule with minimum latency. M. Vecchio et al. [27] proposed an integrated optimization framework by means of topology design to improve the convergence speed of a distributed consensus algorithm. ...
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In this contemporary era, recent developments have seen proliferation of methods on improving energy utilization for wireless sensor networks. Although the proposed methods can mitigate the problem of rapid battery depletion to some extent, the lifespan of sensor nodes is still a biggest constraint. Many studies conducted so far have shown continuous network functions with the help of external harvesting techniques. However, these provide low output because of the limitation on the energy capturing devices. Therefore, energy limitation strongly restricts the usage of wireless sensor nodes. This paper aims to provide high recharging rates and better energy efficiency by proposing a three-step mechanism, which is an extension of our existing proposed work J-ERLB (Joint Energy Replenishment and Load Balancing). In a three-step mechanism, topology selection followed by recharging and load balancing are combined together to prolong the lifetime of sensor nodes. Topology selection is performed by implementing J-ERLB on various topologies like ring, star, and cluster. Further, taking advantage of Unmanned Aerial vehicle (UAV) we focus on data collection and high-rate recharging. We have implemented System on Chip (SoC) integrated chip on UAV to achieve goal of perpetual network operations. Finally, the effectiveness of proposed mechanism is tested by comparing its numerical outcomes with existing J-ERLB and J-MERDG (Joint Mobile Energy Replenishment and Data Gathering) techniques. The overall throughput for 3SM is doubled in comparison with the existing techniques, whereas the average remaining energy shows 6 times better savings for the proposed solution in comparison to the existing J-ERLB and J-MERDG when varying data rates is applied.
... In [20], the authors study how to efficiently build a wireless network topology to gather data from onboard sensors in a car, where all nodes see each other, which permits star topology. However, some links can be of poor quality. ...
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The Battery Management System of an Electric Vehicle is a system designed to ensure safe operation of the battery pack, and report its state to other systems. It is a distributed system, and the communication between its sub-modules is performed through wired buses. In this article, we study the opportunity to use a wireless technology named IEEE Std 802.15.4 Time Slotted Channel Hopping, a standardized protocol for low power and lossy networks. We first describe the real-world experiments we did to measure the link quality, at Medium Access Control layer, for wireless nodes placed inside an EV battery pack. Then, we propose two topology management and scheduling strategies using techniques named Linear Programming and Simple Descent, based on the results obtained in the experiments. Their goal is to achieve efficient data transfer while complying to the battery management constraints.
... Many distributed TSCH scheduling algorithms are proposed based on the basic 6top random cell selection [20,21]. In essence, Karaagac et al. [22] presented an overview of how 6TiSCH architecture and an experimental study that represents the deterministic behavior in 6TiSCH networks. ...
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Chapter
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The IEEE 802.15.4 and ZigBee applications are widely used specifications for the design of Wireless Sensor Networks (WSNs), Among the different available network topologies, cluster-tree networks are pointed out as the most suitable to implement large-scale WSNs, becoming an attractive solution for monitoring applications. However, cluster-tree networks may suffer from high end-to-end communication delay and also from network congestion. Thus, the selection of efficient network formation schemes and the definition of adequate communication structures are relevant research issues. In this context, this paper proposes an efficient mechanism to improve convergecast traffic in large-scale cluster-tree wireless sensor networks. The main idea combines a network formation process driven by the data generation characteristics of individual nodes and an efficient allocation scheme of the active periods, in order to improve typical convergecast message streams generated by the sensor nodes. Simulation results show that efficient network configuration approaches can significantly reduce end-to-end communication delays and decrease the overall network congestion.
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In IEEE 802.15.4 standard for low-power low-range wireless communications, only one channel is employed for transmission which can result in increased energy consumption, high network delay and poor packet delivery ratio (PDR). In the subsequent IEEE 802.15.4-2015 standard, a Time-slotted Channel Hopping (TSCH) mechanism has been developed which allows for a periodic yet fixed frequency hopping pattern over 16 different channels. Unfortunately, however, most of these channels are susceptible to high-power coexisting Wi-Fi signal interference and to possibly some other ISM-band transmissions. This interference manifests itself in the form of the presence/absence of other devices with either or both static and dynamic channel selection policies. In order to isolate channels with undesirable conditions, blacklisting mechanisms are defined to adapt the channel hopping process. However, the existing solutions which form blacklists unrealistically assume that the statistical model of the external interference remains fixed, and do not vary over time. In this paper, we realistically assume that the impact of external interferes on 802.15.4 may generally follow a non-stationary pattern, and accordingly formulate the adaptive channel hopping problem as a Dynamic Multi-Armed Bernoulli Bandit (Dynamic MABB) process from the machine learning theory. We then propose an online learning algorithm with track-ability properties for computing an adaptive hopping policy. Simulations confirm that when the statistics of the external interference has a switching regime, the proposed solution outperforms the previous schemes in terms of both energy efficiency as well as two important KPIs for TSCH-based networks, i.e., PDR and latency.
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Load balancing and energy conservation techniques are one of the significant constraints in the design of in software defined wireless sensor network (SD-WSN). Usually, clustering method helps the network in the minimum utilization of energy that results in enhancing network lifetime. Moreover, various nodes in the multi-hop network that are near to the base station drain their battery very quickly thus lead to creating hot spot problem in a network. To overcome such constraints, this paper proposes a multilayer clustering architecture for selection of forwarding node, rotation of cluster head, and inter and intra-cluster routing communication. The proposed scheme efficiently tackle the rotation of forwarder node by incorporating routing table (table list) at each node. Moreover, the rotation is performed by the consideration of two threshold levels of the residual energy of a node. Also, the exploitation of decision maker node, forwarder node, backup forwarder node, and non-forwarder node enhancing the routing strategy in a network. The performance of the proposed scheme is tested and evaluated by C programming language. The results show that the proposed scheme successful achieve better results than TLPER and EADUC in energy consumption per node, end-to-end communication, hop count in cluster formation.
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Emerging Industrial Internet of Things applications, such as smart factories, require reliable communication and robustness against interference from colocated wireless systems. To address these challenges, frequency-hopping spread spectrum has been used by different protocols, including IEEE802.15.4-2015 TSCH. Frequency-hopping spread spectrum can be improved with the aid of blacklists to avoid bad frequencies. The quality of channels in most environments shows significant spatial-temporal variation, which limits the effectiveness of simple blacklisting schemes. In this article, we propose an enhanced blacklisting solution to improve the TSCH protocol. The proposed algorithms work in a distributed fashion, where each pair of receiver/transmitter nodes negotiates a local blacklist, based on the estimation of packet delivery ratio. We model the channel quality estimation as a multiarmed bandit problem and show that it is possible to create blacklists that provide results close to optimal without any separate learning phase. The proposed algorithms are implemented in OpenWSN and evaluated through simulations in 2 different scenarios with about 40 motes and experiments using an indoor testbed with 40 TelosB motes.
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Time-Slotted Channel Hopping (TSCH) is a part of an emerging IEEE 802.15.4e standard to enable deterministic low-power mesh networking. It promises to pave the way to the future Internet of (Important) things by offering high reliability and low latency for wireless industrial applications. Nonetheless, the standard only provides a framework but it does not mandate a specific scheduling mechanism. In this paper, we propose a centralized Adaptive MUlti-hop Scheduling method (AMUS) based on the latest TSCH MAC. AMUS first enables sequential multi-hop scheduling to provide low latency guarantee for time critical applications. Secondly, the novel tentative cell allocation method allocates additional resources to vulnerable links such that possible MAC retransmissions can be accommodated within the same slotframe, hence significantly reducing the delay caused by interference or collisions. Last but not least, the battery power of the node can be further conserved by adopting the proposed End-of-Q notification mechanism. Preliminary simulation results have confirmed that AMUS outperforms other popular scheduling algorithms in the literature.
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In this article we provide a comprehensive review of the existing literature on techniques and protocols for in-network aggregation in wireless sensor networks. We first define suitable criteria to classify existing solutions, and then describe them by separately addressing the different layers of the protocol stack while highlighting the role of a cross-layer design approach, which is likely to be needed for optimal performance. Throughout the article we identify and discuss open issues, and propose directions for future research in the area
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