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FAN: Fast and Active Network formation in IEEE 802.15.4 TSCH networks
Abstract
The IEEE 802.15.4 TSCH standard is designed to improve the reliability, timeliness, and energy efficiency of short-range wireless communications in industrial applications. TSCH relies upon a network formation process to efficiently create and maintain a synchronized reliable mesh network. The standard adopts a purely passive scan mechanism enabling joining nodes to listen to periodic Enhanced Beacons (EBs) in order to locate a TSCH network and associate to it. Nevertheless, the standard defines neither the advertisement strategy nor the rate at which the EBs should be sent. Consequently, long (re)association times might be observed, which postpones the proper functioning of the network and might have devastating consequences on the industrial application. In this paper, we propose a Fast and Active Network formation scheme (FAN) that leans on active scan procedures and Trickled beacon advertising strategies to accelerate the (re)association process. To do so, FAN equips joiners with a collision avoidance mechanism and allows them to initiate EB requests, on free channels, to trigger EBs. FAN is implemented in Contiki and evaluated through extensive realistic simulations and public testbed experiments. Obtained results assert the robustness of FAN compared to state-of-the-art solutions in terms of association times and overhead.
... Finally, our recent work [31] proposes FAN a Fast and Active Network Formation in IEEE 802.15.4 TSCH Networks. This solution leans on active scan procedures and Trickled beacon advertising strategies to accelerate the association process. ...
... However, all the above-mentioned solutions still in essence based on trade-off when using passive-scan. Concerning the FAN solution [31], indeed, this solution is active scan-based and enhances the performance of the network during the formation process. However, it does not take into account energy considerations since the joining nodes remain always-on during the formation process. ...
... Hence, collisions with other TSCH packets will be avoided. Alternatively, we can consider the use of a collision avoidance mechanism that has been developed in our recent work [31] to not conflict with the running schedule and avoid potential collisions. This mechanism is designed in a way to perform a Clear Channel Assessment (CCA) before sending every single EBR and abort EBR transmissions if the channel is found to be busy. ...
The Time Slotted Channel Hopping (TSCH) mode of the IEEE 802.15.4 standard is expected to revolutionize the Industrial Internet of Things. Indeed, it can achieve high reliability and deterministic latency with a very low duty cycle. Nevertheless, forming a TSCH network with the standard approach might not be as efficient, constituting, thus, one of the TSCH’s major issues. Such a network formation process relies on nodes passively scanning for advertised Enhanced Beacon (EB) frames to join the network. Doing so, a node wishing to join a TSCH network may stay awake randomly scanning for EBs for a considerable period of time, leading to a lengthy formation process with excessive energy consumption. To deal with these issues, this paper presents a practical and effective Radio duty-cycled, Active-Scan based network formation process for TSCH networks (RAST). Our proposal leans on active-scan procedures combined with radio duty cycling mechanisms to shorten joining delays and reduce energy consumption. Obtained results from extensive and realistic simulations show that our solution is efficient and outperforms state-of-the-art solutions, regarding the association time and energy consumption by up to two orders of magnitude.
... At the beginning, researchers proposed different approaches such as transmission of more number of EB frames in a slotframe [22], efficient selection of the collision-free EB broadcasting slots [23]- [26] and active EB scanning [27]- [29] to reduce the initial channel scanning time of the pledges. However, their solutions are limited to TSCH synchronization and allow only one-hop communication, where only the transmission of EB frame is considered. ...
IEEE has standardized the 802.15.4e Time Slotted Channel Hopping (TSCH) mode to provide stringent latency, higher reliability, and low duty-cycle in various Internet of Things (IoT) applications. TSCH eliminates interference and multi-path fading on
channels, but its channel hopping feature severely affects the 6TiSCH (IPv6 over IEEE 802.15.4e TSCH mode) network formation. Further, 6TiSCH Minimal Configuration standard does not provide sufficient bandwidth (i.e., minimal cell) for quick transmission of control packets required by the new nodes (i.e., pledges) during their network association. Many works have been proposed on 6TiSCH network
formation as it has high impact on network performance and lifetime. However, the existing works either did not use all the available physical channels while allocating minimal cell(s) or are not stable with topology changes. Therefore, this work proposes a Time-Variant RGB (TRGB) model for minimal cell allocation and scheduling, which results in faster association of pledges and maintains network stability. We evaluate the TRGB using Markov Chain model and also on a real 60-node testbed in FIT IoT-LAB. Testbed results show that TRGB achieves 51% and 23% improvement over the state-of-the-art scheme in terms of joining time and energy consumption, respectively, while maintaining stability of the network.
... This process is inherently prone to errors (e.g., beacon storms [19]), and it can be energy inefficient and time-consuming if the packet overhead is high. Not many alternative association proposals exist; however, a few proposals can be found made by authors in [20][21][22] and in more advanced MACs in [23][24][25]. The standard addresses directly this problem to some degree in its IEEE 802.15.4e-2012 [26] amendment and is part of the latest revision of the standard [27]. ...
The IEEE 802.15.4 is a popular standard used in wireless sensor networks (WSNs) and the Internet of Things (IoT) applications. In these networks, devices are organized into groups formally known as personal area networks (PAN) which require a bootstrap procedure to become operational. Bootstrap plays a key role in the initialization and maintenance of these networks. For this reason, this work presents our implementation and performance analysis for the ns-3 network simulator. Specifically, this bootstrap implementation includes the support of three types of scanning mechanisms (energy scan, passive scan, and active scan) and the complete classic association mechanism described by the standard. Both of these mechanisms can be used independently by higher layers protocols to support network initialization, network joining, and maintenance tasks. Performance evaluation is conducted in total network association time and packet overhead terms. Our source code is documented and publicly available in the latest ns-3 official release.
... In [27] a dynamic algorithm to allocate resources during network bootstrap is given to guarantee fast join to TSCH network and distribute routing information properly. In [28], it is declared that the TSCH standard defines neither the advertisement strategy nor the rate of the transmission of proper EBs, then a Fast and Active Network formation (FAN) is proposed to accelerate the (re)association process. A key operation of FAN is to allow joiners to send EB requests to trigger EBs. ...
In a real-time wireless sensor network (RT-WSN), an unpredictable time length of the synchronization (or connection) process between nodes is generally a pity, though the communication after the connection may be controllable. The purpose of this paper is to solve this kind of pity based on the
multiple-request-single
occasion (multiple slave nodes request to send data to a single master node simultaneously before getting synchronized using the frequency channel hopping technique). Suppose that the master sends the
synchronization packet
(or
beacon
) and the slaves scan for this packet with different channels for connection. A slave
getting synchronized
with the master means that both nodes have just selected an identical
frequency
channel during a
time
region and the slave has received the synchronization packet successfully in this region, which is called
frequency and time synchronization
, abbreviated as
FTS
. For many existing wireless protocols, if they are directly adopted in this situation, two deficiencies exist as for real-time performances: First, the time length required for a slave to join the network is often not deterministic if one or more channels are disturbed. Second, when multiple slaves do their scanning simultaneously, which slave can synchronize with the master first is unpredictable so that a slave with a lower priority may be serviced prior to others. In this paper, two FTS examples with poor real-time performances are provided first. Then, a synchronization method named 1/
$2n$
FTS is presented and proved. With this method, a slave scans for the synchronization packet of the master with
$n$
different available channels repeatedly until it gets the packet while the master transmits the packet
$2n$
times in
$2n$
continuous timeslots. The width of the scan widow of the salve takes twice the width of the slot. In this way, every slave has the opportunity to get synchronized with the master at the end of the
$2n$
slots even if one or more (not all) channels are disturbed. Then, the slaves can send their requests to the master in different slots so that the master can schedule subsequent communications according to their requests and priorities. Also, if the mater broadcasts the beacon periodically, the time length for a slave to join or rejoin the master is not difficult to predict. The theorems associated with the 1/
$2n$
FTS method are demonstrated in experiments with NORDIC Semiconductor chips.
... The approaches proposed in [20] and [34] are centralized and those proposed in [21] and [22] are distributed. The authors of [24,29,35] have studied the network association process. In [25], the authors have addressed the blind channel hopping problem. ...
Time Slotted Channel Hopping (TSCH) is one of the Medium Access Control methods proposed in the IEEE 802.15.4e standard to deal with the requirements of the industrial Wireless Sensor Networks (WSNs), especially in terms of high reliability and low latency. The key feature of the TSCH method is the combination between a time slotted access with a channel hopping, while considering both shared and dedicated links. The latter are essential for ensuring transmissions without loss and additional delays. Therefore, the objective we are seeking to reach in this paper is to demonstrate the benefit use of dedicated links on industrial WSNs-based 802.15.4e TSCH method. To this end, we propose an analytical model-based Markov chains for the TSCH method taking into account the dedicated links, and we estimate the transmission probability \(\tau \) of a data packet. The latter will be then used to develop others analytical models, in order to derive a number of performance metrics, namely the average access delay, the reliability, the throughput, and the energy consumption. Furthermore, to validate the analytical model, we perform extensive simulations-based Monte-Carlo. Finally, to give credibility to the obtained simulation results, we compute \(95\%\) confidence intervals. Numerical results show that increasing the number of dedicated links reduces significantly the retransmission probability offering best network performances in terms of average access delay, reliability and throughput.
IETF IPv6 over the TSCH mode of IEEE 802.15.4e (6TiSCH) is an open communication protocol stack designed specifically for low-power wireless networks and aimed at being a key enabler technology of Industrial Internet of Things. 6TiSCH combines Time Slotted Channel Hopping (TSCH) with IPv6 to form a well-tuned and complete networking solution. In this paper, we study the parameters that affect the process of 6TiSCH network formation, such as the Enhanced Beacon transmission period, the scan period, the slotframe size, etc. We carry out extensive simulations to examine the impact of these parameters on the time of TSCH synchronization and the time of the formation of RPL Destination Oriented Graph. Results reveal that most of the studied variables affect greatly the 6TiSCH network formation time. This study allowed us to gain insights into how 6TiSCH networks behave during the bootstrapping phase, and how it is affected by different parameters.KeywordsIIoT6TiSCHTSCHNetwork formationIEEE 802.15.4
The IPv6 over IEEE 802.15.4e TSCH mode (6TiSCH) network is intended to provide reliable and delay bounded communication in multi-hop and scalable Industrial Internet of Things (IIoT). The IEEE 802.15.4e Time Slotted Channel Hopping (TSCH) link layer protocol allows the nodes to change their physical channel after each transmission to eliminate interference and multi-path fading on the channels. However, due to this feature, new nodes (aka pledges) take more time to join the 6TiSCH network, resulting in signiicant energy consumption and ineicient data transmission, which makes the communication unreliable. Therefore, formation of 6TiSCH network has gained immense interest among the researchers. To date, numerous solutions have been ofered by various researchers in order to speed up the formation of 6TiSCH networks. This paper briely discusses about the 6TiSCH network and its formation process, followed by a detailed survey on the works that considered 6TiSCH network formation. We also perform theoretical analysis and real testbed experiments for a better understanding of the existing works related to 6TiSCH network formation. This article is concluded after summarizing the research challenges in 6TiSCH network formation and providing few open issues in this domain of work.
Network bootstrapping is one of the initial tasks executed in any wireless network such as Industrial Internet of Things (IIoT). Fast formation of IIoT network helps in resource conservation and efficient data collection. Our probabilistic analysis reveals that the performance of 6TiSCH based IIoT network formation degrades with time because of the following reasons: (i) IETF 6TiSCH Minimal Configuration (6TiSCH-MC) standard
considered that beacon frame has the highest priority over all other control packets, (ii) 6TiSCH-MC provides minimal routing information during network formation, and (iii) sometimes, joined node can not transmit control packets due to high congestion in shared slots. To deal with these problems, this article proposes two schemes—opportunistic priority alternation and rate control (OPR) and opportunistic channel access (OCA). OPR dynamically adjusts the priority of control packets and provides sufficient routing information during network bootstrapping, whereas OCA allows the nodes having urgent packet to transmit it in less time. Along with the theoretical analysis of the proposed schemes, we also provide comparison-based simulation and real testbed experiment results to validate the proposed schemes together. The received results show significant performance improvements in terms of joining time and energy consumption.
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)–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 Industrial Internet of Things (IIoT) is having an ever greater impact on industrial processes and the manufacturing sector, due the capabilities of massive data collection and interoperability with plant processes, key elements that are focused on the implementation of Industry 4.0. Wireless Sensor Networks (WSN) are one of the enabling technologies of the IIoT, due its self-configuration and self-repair capabilities to deploy ad-hoc networks. High levels of robustness and reliability, which are necessary in industrial environments, can be achieved by using the Time-Slotted Channel Hopping (TSCH) medium access the mechanism of the IEEE 802.15.4e protocol, penalizing other features, such as network connection and formation times, given that a new node does not know, a priori, the scheduling used by the network. This article proposes a new beacon advertising approach for a fast synchronization for networks under the TSCH-Medium Access Control (MAC) layer and Routing Protocol for Low-Power and Lossy Networks (RPL). This new method makes it possible to speed up the connection times of new nodes in an opportunistic way, while reducing the consumption and advertising traffic generated by the network.
Wireless Sensor Networks have become a key enabler for Industrial Internet of Things (IoT) applications; however, to adapt to the derived robust communication requirements, deterministic and scheduled medium access should be used, along with other features, such as channel hopping and frequency diversity. Implementing these mechanisms requires a correct synchronization of all devices in the network, a stage in deployment that can lead to non-operational networks. The present article presents an analysis of such situations and possible solutions, including the common current approaches and recommendations, and proposes a new beacon advertising method based on a specific Trickle Timer for the Medium Access Control (MAC) Time-Slotted Channel Hopping (TSCH) layer, decoupling from the timers in the network and routing layers. With this solution, improvements in connection success, time to join, and energy consumption can be obtained for the widely extended IEEE802.15.4e standard.
IEEE802.15.4-TSCH (Time-Slotted Channel Hopping) is an emerging MAC protocol for low-rate wireless personal area networks (LR-WPANs). It combines time-division multiple access with channel-hopping to provide high reliability and ultralow power consumption. The formation of an IEEE802.15.4-TSCH network relies on the periodic transmission of Enhanced Beacons (EBs). The transmission frequency of the EBs affects the joining time of nodes. An increase of this frequency reduces their joining time. In this paper, we present an Advertisement Timeslot Partitioning technique (ATP) which can be used to increase the EB rate without the need of allocating more timeslots. The key idea behind ATP is that it compacts multiple EBs in a single timeslot while it uses a different channel for each EB. Since a joining node listens to a random channel, increasing the number of frequencies per timeslot, we increase the probability of receiving an EB. Our evaluation shows that ATP improves the average joining time by up to 65 % in the tested scenarios.
Synchronized communication has recently emerged as a prime option for low-power critical applications. Solutions such as Glossy or Time Slotted Channel Hopping (TSCH) have demonstrated end-to-end reliability upwards of 99.99%. In this context, the IETF Working Group 6TiSCH is currently standardizing the mechanisms to use TSCH in low-power IPv6 scenarios. This paper identifies a number of challenges when it comes to implementing the 6TiSCH stack. It shows how these challenges can be addressed with practical solutions for locking, queuing, scheduling and other aspects. With this implementation as an enabler, we present an experimental validation and comparison with state-of-the-art MAC protocols. We conduct fine-grained energy profiling, showing
the impact of link-layer security on packet transmission. We evaluate distributed time synchronization in a 340-node testbed, and demonstrate that tight synchronization (hundreds of microseconds) can be achieved at very low cost (0.3% duty cycle, 0.008% channel utilization). We finally compare TSCH against traditional MAC layers: low-power listening (LPL) and CSMA, in terms of reliability, latency and energy. We show
that with proper scheduling, TSCH achieves by far the highest reliability, and outperforms LPL in both energy and latency.
The IEEE 802.15.4e standard is an amendment of the IEEE 802.15.4-2011 protocol by introducing time-slotted channel hopping access behavior mode. However, the IEEE 802.15.4e only defines time-slotted channel hopping link-layer mechanisms without an investigation of network formation and communication scheduling which are still open issues to the research community. This article investigates the network formation issue of the IEEE 802.15.4e time-slotted channel hopping networks. In time-slotted channel hopping networks, a joining node normally takes a long time period to join the network because the node has to wait until there is at least one enhanced beacon message advertised by synchronized nodes (synchronizers) in the network on its own synchronization channel. This leads to a long joining delay and high energy consumption during the network formation phase, especially so in highly dynamic networks in which nodes join or rejoin frequently. To enable a rapid time-slotted channel hopping network formation, this article proposes a new design for slotframe structure and a novel adaptive joining scheme based on fuzzy logic. Our proposed scheme enables a synchronizer to be able to adaptively determine an appropriate number of enhanced beacons it should advertise, based on the number of available synchronizers in the network, so that joining nodes can achieve a short joining time while energy consumption of enhanced beacon advertisement at the synchronizers is optimized. Through extensive mathematical analysis and experimental results, we show that the proposed scheme achieves a significant improvement in terms of joining delay compared to state-of-the-art studies.
Time slotted operation is a well-proven approach to achieve highly reliable low-power networking through scheduling and channel hopping. It is, however, difficult to apply time slotting to dynamic networks as envisioned in the Internet of Things. Commonly, these applications do not have pre-defined periodic traffic patterns and nodes can be added or removed dynamically.
This paper addresses the challenge of bringing TSCH (Time Slotted Channel Hopping MAC) to such dynamic networks. We focus on low-power IPv6 and RPL networks, and introduce Orchestra. In Orchestra, nodes autonomously compute their own, local schedules. They maintain multiple schedules, each allocated to a particular traffic plane (application, routing, MAC), and updated automatically as the topology evolves. Orchestra (re)computes local schedules without signaling overhead, and does not require any central or distributed scheduler. Instead, it relies on the existing network stack information to maintain the schedules. This scheme allows Orchestra to build non-deterministic networks while exploiting the robustness of TSCH.
We demonstrate the practicality of Orchestra and quantify its benefits through extensive evaluation in two testbeds, on two hardware platforms. Orchestra reduces, or even eliminates, network contention. In long running experiments of up to 72~h we show that Orchestra achieves end-to-end delivery ratios of over 99.99%. Compared to RPL in asynchronous low-power listening networks, Orchestra improves reliability by two orders of magnitude, while achieving a similar latency-energy balance.
The Time Slotted Channel Hopping (TSCH) Medium Access Control (MAC) has been introduced in the recent IEEE 802.15.4e amendment to improve energy efficiency and reliability of short range wireless communications in industrial applications. However the joining phase can take very long time due to the operation of TSCH and beside being a problem in the deployment phase it may become a relevant source of energy consumption. To overcome this issue the present contribution investigates the problem of acquiring the first synchronization in a TSCH network from several points of view: (i) two novel mechanisms are proposed and implemented in real motes to speed up joining operations; (ii) for each of them, the average joining time is analytically modeled with closed form expressions as a function of node density, communication reliability, and beacon transmission frequency; (iii) the effectiveness of these novel algorithms and the accuracy of their models are experimentally validated in different scenarios. Keywords—Synchronization, IEEE 802.15.4, Time Slotted Channel Hopping, Industrial Internet of Things.
The Time Slotted Channel Hopping (TSCH) mode of the standard IEEE 802.15.4 provides Medium Access Control (MAC) for most Low power and Lossy Network (LLN) applications in the Internet of Things (IoT). TSCH uses a synchronized schedule with frequency diversity to allow flexible, reliable and resilient communication. The standard defines an association algorithm to allow nodes to autonomously form the network. The time required to create the network can be long, which consumes valuable energy given that nodes keep their radios on when trying to associate. In this paper, we propose a theoretical model to estimate the time required for a node to associate to one single synchronizer. This model extends and complements earlier mathematical models. Its results comply with outcomes from extensive simulation studies. This makes the proposed model a valuable tool to further investigate the time needed to form TSCH-based LLN networks.
Industrial applications of Internet of Things (IoT) demand high reliability, deterministic latency, and high scalability with energy efficiency to the communication and networking protocols. 6TiSCH is a Time Slotted Channel Hopping (TSCH) medium access control (MAC) protocol running under the IPv6 enabled higher layer protocols for Industrial IoT (IIoT). In this paper, we theoretically analyze the network formation protocol in 6TiSCH network. Analysis reveals that the performance of the 6TiSCH network degrades when a pledge (new node) joins as it increases channel congestion by allowing to transmit beacon message. On the other hand, beacon transmission is essential to expand or reorganize the present network topology. To overcome this performance tradeoff, a channel condition based dynamic beacon interval (C2DBI) scheme is proposed in which beacon transmission interval varies with channel congestion status during network formation. Channel congestion status is estimated by each joined node in distributed manner, and subsequently changes its beacon generation interval to best fit with present condition. Finally the performance of C2DBI is compared with the minimal configuration standard and few other benchmark protocols. Analytical, simulation and real testbed results show that the proposed scheme outperforms the state of the art protocols in terms of joining time and energy consumption during network formation.
The 6TiSCH protocol layer in Industrial Internet of Things (IIoT) fills the gap between the IETF low-power IPv6 communication stack and TSCH. Along with reliability, timed data delivery, and interoperability in IIoT network, 6TiSCH also deals with network bootstrapping. In this paper, the formation method of 6TiSCH network is assessed. It is observed that because of highest priority of beacon frames and unawareness of the requirement of routing information by a new node, performance of 6TiSCH network formation degrades. Therefore, we propose an opportunistic priority alternation scheme for urgent requirement of other control packets to form the 6TiSCH network quickly. We also opportunistically increase the transmission rate of packets carrying routing information. The proposed scheme is implemented on Cooja simulator and compare the simulation results with the benchmark protocol - Minimal Configuration Standard. Simulation results show that the proposed scheme converges faster than the benchmark protocol in network formation.
The IETF, concerned with the evolution of the Internet architecture, nowadays also looks into industrial automation processes. The contributions of a variety of IETF activities, initiated during the last ten years, enable now the replacement of proprietary standards by an open standardized protocol stack. This stack, denoted in the following as 6TiSCH-stack, is tailored for industrial internet of things (IIoTs). The suitability of 6TiSCH-stack for Industry 4.0 is yet to explore. In this paper, we identify four challenges that, in our opinion, may delay or hinder its adoption. As a prime example of that, we focus on the initial 6TiSCH-network formation, highlighting the shortcomings of the default procedure and introducing our current work for a fast and reliable formation of dense network.
One of the most recent and reliable MAC protocols for low-rate wireless personal area networks is the IEEE802.15.4-TSCH. The formation of an IEEE802.15.4-TSCH network depends on the periodic transmission of Enhanced Beacons (EBs), and, by extension, on the scheduling of EB transmissions. In this paper, we present and analyze a negative phenomenon that can occur in most of the autonomous EB scheduling methods proposed in the literature. This phenomenon, which we call full collision, takes place when all the neighboring EB transmissions of a joining node collide. As a consequence, a node may not be able to join the network fast, consuming a considerable amount of energy as well. In order to eliminate collisions during EB transmissions, and, thus, to avoid the occurrence of this phenomenon, we propose a novel autonomous collision-free EB scheduling policy. The results of our simulations demonstrate the superiority of our policy compared to two other recently proposed policies.
The Time-Slotted Channel Hopping (TSCH) mode of the standard IEEE~802.15.4 provides Medium Access Control (MAC) for most Low-power and Lossy Network (LLN) applications in the Internet of Things (IoT). 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 (RPL) 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.
Which wireless technology is able to meet the requirements of space launch vehicles in terms of latency, throughput and robustness? The IEEE 802.15.4e amendment has been designed to meet such requirements. More specifically, the Time Slotted Channel Hopping (TSCH) mode has been designed for industrial automation, process control and equipment monitoring. In this paper, we focus on the time needed by a joining node to detect beacons advertising the TSCH network. An Enhanced beacon is a TSCH frame that contains information on synchronization, channel hopping and timeslot used in the advertised network. However, the advertising policy is left unspecified by the IEEE 802.15.4e standard and is under the responsibility of a layer upper than the MAC one. Since beacons are broadcast, they are lost in case of collisions.The main problem is how to avoid such collisions? In this paper, we propose a Deterministic Beacon Advertising Algorithm, called DBA. The goal of DBA is to ensure that beacons are transmitted on all frequencies used by the TSCH network, regularly and without collision. With DBA, the exact value for the maximum time for a joining node to detect a beacon can be computed easily. We use the NS3 Simulator to evaluate this time as well as the number of message losses, considering different network topologies (star or multihop). We compare the performance of DBA with that of two algorithms existing in the state of the art.
In this paper, we focus first on the time needed by a node to join a Time Slotted Channel Hopping (TSCH) network, this time is called joining time. Second, we are also interested in the network building time. Since the data generated by a sensor node remain unavailable as long as this node has not yet joined the wireless sensor network, these times are of prime importance for applications having strong latency requirements on data gathering. The joining time depends on the beacon advertising policy that has been left unspecified by the standard. The contribution of this paper is triple. First, we propose an Enhanced Deterministic Beacon Advertising algorithm, called EDBA, that ensures a collision-free advertising of beacons and minimizes the average joining time. Second, we model the behavior of a joining node by a Markov chain, validated by NS3 simulations, and compute the average joining time. Third, we compare the performance of EDBA with this of MBS, considered as the best beacon advertising algorithm in the literature.
The industrial Internet of Things (IIoT) is expected to revolutionize the current industry. The capillary introduction of sensors and actuators for real-time monitoring and remote control and their seamless integration into existing information systems will represent a technological breakthrough. The definition of wireless communication standards will play a crucial role in reducing deployment costs and minimizing the time for installation. The new IPv6 over the TSCH mode of IEEE802.15.4e communication stack, 6TiSCH, represents the current leading standardization effort that aims at achieving both reliable and timed wireless communication and integration within IPv6 communication networks for industrial systems. In this paper, the network formation dynamics of 6TiSCH networks are assessed, considering the current guidelines for the so-called minimal configuration, a static initial configuration to guarantee control communication during network bootstrap. It is shown that the minimal configuration might lead to long network formation and suboptimal performance of the routing algorithm which may result into a disconnected network. In order to overcome this issue, a dynamic resource management algorithm to be executed during network bootstrap is proposed. Simulation and experimental results show that the proposed solution allows to minimize the network formation time and also helps in optimizing routing operations leading to the discovery of better routes.
Time Slotted Channel Hopping (TSCH) Medium Access Control (MAC) is a key feature of the IEEE 802.15.4 standard, aimed at accommodating the requirements of industrial Internet of Things systems. Time Division Multiple Access (TDMA) is a main pillar of TSCH, on top of which frequency hopping is added to increase the resilience of short range radio links. A tight synchronization among the network nodes is required in TSCH. Luckily, once a node joins the network, several lean techniques can be used to keep alive its synchronization. On contrary, the subtleties of the joining phase in TSCH still deserve investigations since they could hinder an effective usage of the TSCH MAC. To this end, the problem of acquiring the first synchronization in a TSCH network is investigated hereby, from several perspectives: (i) four novel mechanisms are proposed and implemented in real motes to speed up joining operations; (ii) their average joining time is analytically modeled with closed form expressions as a function of node density, communication reliability, and beacon transmission frequency; (iii) their effectiveness and the agreement between experimental and theoretical outcomes are evaluated in several scenarios.
Time Slotted Channel Hopping (TSCH) is one of main features of IEEE 802.15.4e standard designed for wireless sensor networks. It improves energy efficiency, network capacity and communication reliability in industrial applications. However, in the joining phase of TSCH network formation, sensor nodes have to remain awake status for a long time till they can reach synchronization. This is the reason which consumes a significant amount of energy. In this paper, we therefore propose a reliable lightweight joining scheme for TSCH network formation to speed up joining operation. The scheme is present in detail through analysis models as well as implementation result in real sensor nodes. Moreover, the comparison with other approaches is also mentioned to show the potential efficiency and better performance of our proposal.
Time Slotted Channel Hopping (TSCH) is one of the access behavior modes defined in the IEEE 802.15.4e standard. It combines time slotted access with multi-channel and channel hopping capabilities, providing predictable latency, energy efficiency, high network capacity, and high communication reliability. In this paper we focus on the formation process of TSCH networks, which relies on the regular advertisement of Enhanced Beacons (EBs). We consider a simple random-based advertisement algorithm, and evaluate its performance, through analysis and simulation, in terms of joining time (i.e., total time taken by a new node to join the network). We found that the joining time depends on a number of factors and, mainly, on the number of channels used for EB advertisement.
Low-Rate Wireless Personal Area Networks Amendment 1: MAC Sublayer
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Area Networks. Part 15.4: Low-Rate Wireless Personal Area Networks
Amendment 1: MAC Sublayer. IEEE Std., April 2012.
Ieee standard for low-rate wireless networks
IEEE, "Ieee standard for low-rate wireless networks," IEEE Std 802.15.4-2015, pp. 1-709, 2016.
The trickle algorithm
- P Levis
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