DADC: A Novel Duty-cycling Scheme for IEEE 802.15.4 Cluster-tree-based IoT Applications

[EN] The IEEE 802.15.4 standard is one of the widely adopted specifications for realizing different applications of the Internet of Things. It defines several physical layer options and Medium Access Control (MAC) sublayer for devices with low-power operating at low data rates. As devices implementing this standard are primarily battery-powered, minimizing their power consumption is a significant concern. Duty-cycling is one such power conserving mechanism that allows a device to schedule its active and inactive radio periods effectively, thus preventing energy drain due to idle listening. The standard specifies two parameters, beacon order and superframe order, which define the active and inactive period of a device. However, it does not specify a duty-cycling scheme to adapt these parameters for varying network conditions. Existing works in this direction are either based on superframe occupation ratio or buffer/queue length of devices. In this article, the particular limitations of both the approaches mentioned above are presented. Later, a novel duty-cycling mechanism based on MAC parameters is proposed. Also, we analyze the role of synchronization schemes in achieving efficient duty-cycles in synchronized cluster-tree network topologies. A Markov model has also been developed for the MAC protocol to estimate the delay and energy consumption during frame transmission.This work is supported by Science and Engineering Research Board, Department of Science and Technology, Government of India under ECR 2016, Grant No. 2016/001651. This work has been partially supported by the "Ministerio de Economia y Competitividad" in the "Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia," "Subprograma Estatal de Generacion de Conocimiento," within the project under Grant No. TIN2017-84802-C2-1-P. This work has also been partially supported by European Union through the ERANETMED (Euromediterranean Cooperation through ERANET joint activities and beyond) Project ERANETMED3-227 SMARTWATIR.Choudhury, N.; Matam, R.; Mukherjee, M.; Lloret, J. (2021). DADC: A Novel Duty-cycling Scheme for IEEE 802.15.4 Cluster-tree-based IoT Applications. ACM Transactions on Internet Technology. 22(2). https://doi.org/10.1145/3409487S22

A Performance-to-Cost Analysis of IEEE 802.15.4 MAC With 802.15.4e MAC Modes

[EN] The IEEE 802.15.4 standard is one of the widely adopted networking specification for Internet of Things (IoT). It defines several physical layer (PHY) options and medium access control (MAC) sub-layer protocols for interconnection of constrained wireless devices. These devices are usually battery-powered and need to support requirements like low-power consumption and low-data rates. The standard has been revised twice to incorporate new PHY layers and improvements learned from implementations. Research in this direction has been primarily centered around improving the energy consumption of devices. Recently, to meet specific Quality-of-Service (QoS) requirements of different industrial applications, the IEEE 802.15.4e amendment was released that focuses on improving reliability, robustness and latency. In this paper, we carry out a performance-to-cost analysis of Deterministic and Synchronous Multi-channel Extension (DSME) and Time-slotted Channel Hopping (TSCH) MAC modes of IEEE 802.15.4e with 802.15.4 MAC protocol to analyze the trade-off of choosing a particular MAC mode over others. The parameters considered for performance are throughput and latency, and the cost is quantified in terms of energy. A Markov model has been developed for TSCH MAC mode to compare its energy costs with 802.15.4 MAC. Finally, we present the applicability of different MAC modes to different application scenarios.This work was supported in part by the SERB, DST, Government of India under Grant ECRA/2016/001651.Choudhury, N.; Matam, R.; Mukherjee, M.; Lloret, J. (2020). A Performance-to-Cost Analysis of IEEE 802.15.4 MAC With 802.15.4e MAC Modes. IEEE Access. 8:41936-41950. https://doi.org/10.1109/ACCESS.2020.2976654S4193641950

LBS: A Beacon Synchronization Scheme With Higher Schedulability for IEEE 802.15. 4 Cluster-Tree-Based IoT Applications

[EN] The IEEE 802.15.4 standard is one of the most widely used link layer technology for building Internet of Things (IoT). It specifies several physical layer options and MAC layer for meeting low-power and low-rate requirements of devices deployed in a network of IoT. The standard also specifies a synchronization scheme for devices connected in a star topology, operating in beacon-enabled (BE) mode using periodic beacons. The BE mode facilitates synchronization among devices for data transmission and is suitable for large networks to establish low duty-cycles. Absence of a such a scheme for a cluster-tree network has confined its application only to nonbeacon mode. The challenge here is to schedule beacon frame transmissions of multiple devices in a nonoverlapping manner to avoid beacon collisions. This paper tackles the problem of synchronization by proposing localized beacon synchronization (LBS) scheme, a distributed technique for beacon scheduling in cluster-tree network topologies. LBS uses 2-hop information and association order to compute beacon transmission offsets that better utilize the available time slots, incur fewer transmissions, and is highly scalable. Further, we analytically show that the schedulability of the proposed scheme is higher compared to other related schemes. In addition, we also address the important issue of resynchronization that has been ignored in all of the prior works. The proposed resynchronization mechanisms consider the interdependencies between synchronization and duty-cycling schemes and are shown to significantly lower the synchronization overhead when synchronization among devices is lost.This work was supported by the Science and Engineering Research Board, Department of Science and Technology, Govt. of India, under Grant ECR/2016/001651.Choudhury, N.; Matam, R.; Mukherjee, M.; Lloret, J. (2019). LBS: A Beacon Synchronization Scheme With Higher Schedulability for IEEE 802.15. 4 Cluster-Tree-Based IoT Applications. IEEE Internet of Things. 6(5):8883-8896. https://doi.org/10.1109/JIOT.2019.2924317888388966

A Beacon and GTS Scheduling Scheme for IEEE 802.15.4 DSME Networks

[EN] The IEEE 802.15.4 standard is one of the widely adopted networking specification for realizing different applications of Internet of Things (IoT). It defines several physical layer options and medium access control (MAC) sublayer protocols for low-power devices supporting low-data rates. One such MAC protocol is the deterministic and synchronous multichannel extension (DSME), which addresses the limitation on the maximum number of guaranteed time slots (GTSs) in 802.15.4-2011 MAC, and provides channel diversity to increase network robustness. However, beacon scheduling in peer-to-peer networks suffers from beacon slot collisions when two or more coordinators simultaneously compete for the same vacant beacon slot. In addition, the standard does not explore DSME-GTS scheduling (DGS) across multiple channels. This article addresses the beacon slot collision problem by proposing a nonconflicting beacon scheduling mechanism using association order (AO). Furthermore, a distributed multichannel DSME-GTS schedule is proposed that optimally assigns DSME-GTSs across different channels. The objective is to minimize the number of times-lots used while maximizing the usage of available channels. Through simulations, the proposed mechanisms' performance is analyzed in terms of energy efficiency, transmission overhead, scheduling efficiency, throughput, and latency and is shown to outperform the other existing schemes.Choudhury, N.; Matam, R.; Mukherjee, M.; Lloret, J. (2022). A Beacon and GTS Scheduling Scheme for IEEE 802.15.4 DSME Networks. IEEE Internet of Things. 9(7):5162-5172. https://doi.org/10.1109/JIOT.2021.3110866516251729

NCHR: A Nonthreshold-Based Cluster-Head Rotation Scheme for IEEE 802.15.4 Cluster-Tree Networks

[EN] The IEEE 802.15.4 standard specifies two network topologies: 1) star and 2) cluster tree. A cluster-tree network comprises of multiple clusters that allow the network to scale by connecting devices over multiple wireless hops. The role of a cluster head (CH) is to aggregate data from all devices in the cluster and then transmit it to the overall personal area network (PAN) coordinator. This specific role of CH needs to be rotated among multiple coordinators in the cluster to prevent it from energy drain out. Prior works on CH rotation are either based on threshold energy levels or rely on periodic rotation. Both approaches have their respective limitations and, at times, result in unnecessary CH rotations or nonoptimal selection of CH. To address this, we propose a nonthreshold CH rotation scheme (NCHR), which incurs minimal rotation overhead. It supports topological changes, node heterogeneity, and can also handle CH failures. Through simulations and hardware implementation, the performance of the proposed NCHR scheme is analyzed in terms of network lifetime, CH rotation overhead, and the number of CH rotations. It is shown that the proposed scheme boosts network lifetime, incurs less rotation overhead, and needs fewer CH rotations compared to other related schemes.This work was supported in part by the Science and Engineering Research Board, Department of Science and Technology, Government of India through ECR, 2016 under Grant 2016/001651; in part by the "Ministerio de Economia y Competitividad" in the "Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia, Subprograma Estatal de Generacion de Conocimiento" within the Project under Grant TIN2017-84802-C2-1-P; and in part by the European Union through the ERANETMED (Euromediterranean Cooperation through ERANET Joint Activities and Beyond) Project ERANETMED3-227 SMARTWATIR.Choudhury, N.; Matam, R.; Mukherjee, M.; Lloret, J.; Kalaimannan, E. (2021). NCHR: A Nonthreshold-Based Cluster-Head Rotation Scheme for IEEE 802.15.4 Cluster-Tree Networks. IEEE Internet of Things. 8(1):168-178. https://doi.org/10.1109/JIOT.2020.30033201681788

Centralized graph based TSCH scheduling for IoT network applications

The current specification of the IEEE 802.15.4 standard supports several application specific Quality of Service (QoS) requirements for Internet of Things (IoT) network applications. Specifically, the Time Slotted Channel Hopping (TSCH) MAC mode provides effective latency and throughput performance through the use of dedicated timeslots between two communicating devices. Despite the impact TSCH MAC can facilitate in low-power lossy networks (LLNs), the standard does not explore either the building or maintaining of a schedule. The challenge is to build an energy-efficient TSCH schedule that repeats periodically over several channels. To address this problem, we propose a centralized cluster-level TSCH scheduling mechanism from the energy-efficiency perspective. The proposed mechanism derives a collision graph for each of the clusters in the network topology to schedule non-overlapping timeslots. The Bron–Kerbosch algorithm is used as a sub-procedure for finding the complete sub-graphs of a graph. In addition, we analytically compute the transmission and energy overhead with the help of a Markov Model for TSCH

Edge ML Technique for Smart Traffic Management in Intelligent Transportation Systems

In urban traffic, a Dynamic Traffic Light System (DTLS) is an important aspect of automatic driving. DTLS estimates the time of the light signal from images of dynamically changing road traffic. In conventional traffic light systems, light signals are enabled at predefined or fixed time intervals without having information on the current traffic density on the road. This static behavior of the traffic light system increases unnecessary waiting time on the road, eventually creating traffic jams, environmental pollution, and other health emergencies. The smart traffic light system addresses these issues with self-learning algorithms and dynamically allows traffic to pass by learning current traffic density. In this paper, a vision-based DTLS is proposed using the YOLO (You Only Look Once) object detection algorithm that detects and counts the total number of vehicles on the roads of a traffic signal junction. The traffic signals are tuned based on the computed traffic to minimize the overall delay at that junction. Moreover, the traffic junctions are facilitated to communicate with the adjacent junctions to transmit the cumulative traffic delay observed. This delay is used to prioritize traffic passing through salient blocks like schools, offices, hospitals, etc. The paper aims to minimize the overhead incurred in both computations of traffic (using approximate computing) and in communication networks (using low-power technologies of IEEE 802.15.4 standard, specifically DSME MAC and/or LoRaWAN). The proposed system accomplishes its objective of smart city infrastructure by optimizing the traffic flow. Further, the paper provides a mechanism for green traffic corridors for emergency vehicles

An Efficient Multilevel Probabilistic Model for Abnormal Traffic Detection in Wireless Sensor Networks

Wireless sensor networks (WSNs) are low-cost, special-purpose networks introduced to resolve various daily life domestic, industrial, and strategic problems. These networks are deployed in such places where the repairments, in most cases, become difficult. The nodes in WSNs, due to their vulnerable nature, are always prone to various potential threats. The deployed environment of WSNs is noncentral, unattended, and administrativeless; therefore, malicious attacks such as distributed denial of service (DDoS) attacks can easily be commenced by the attackers. Most of the DDoS detection systems rely on the analysis of the flow of traffic, ultimately with a conclusion that high traffic may be due to the DDoS attack. On the other hand, legitimate users may produce a larger amount of traffic known, as the flash crowd (FC). Both DDOS and FC are considered abnormal traffic in communication networks. The detection of such abnormal traffic and then separation of DDoS attacks from FC is also a focused challenge. This paper introduces a novel mechanism based on a Bayesian model to detect abnormal data traffic and discriminate DDoS attacks from FC in it. The simulation results prove the effectiveness of the proposed mechanism, compared with the existing systems

A Survey on the Noncooperative Environment in Smart Nodes-Based Ad Hoc Networks: Motivations and Solutions

In ad hoc networks, the communication is usually made through multiple hops by establishing an environment of cooperation and coordination among self-operated nodes. Such nodes typically operate with a set of finite and scarce energy, processing, bandwidth, and storage resources. Due to the cooperative environment in such networks, nodes may consume additional resources by giving relaying services to other nodes. This aspect in such networks coined the situation of noncooperative behavior by some or all the nodes. Moreover, nodes sometimes do not cooperate with others due to their social likeness or their mobility. Noncooperative or selfish nodes can last for a longer time by preserving their resources for their own operations. However, such nodes can degrade the network's overall performance in terms of lower data gathering and information exchange rates, unbalanced work distribution, and higher end-to-end delays. This work surveys the main roots for motivating nodes to adapt selfish behavior and the solutions for handling such nodes. Different schemes are introduced to handle selfish nodes in wireless ad hoc networks. Various types of routing techniques have been introduced to target different types of ad hoc networks having support for keeping misbehaving or selfish nodes. The major solutions for such scenarios can be trust-, punishment-, and stimulation-based mechanisms. Some key protocols are simulated and analyzed for getting their performance metrics to compare their effectiveness