Bandwidth and Energy Consumption Tradeoff for IEEE 802.15.4 in Multihop Topologies

IEEE 802.15.4, Multi-hop,ZigBee,WSNwe analyze IEEE 802.15.4 mechanisms including node organization, MAC mechanisms, energy conservation, topology construction and node association. We detail how we should modify IEEE 802.15.4 to cope efficiently with multihop topologies, scheduling the transmissions. We quantify the impact of the cluster-tree algorithm on the network performances. We expose how the overall throughput can be improved with a novel cluster-tree construction algorithm defined formally as a Mixed Integer Linear Programming formulation. We quantify the impact of each parameter on the performances of IEEE 802.15.4. In particular, we present a self-configuration algorithm to dynamically adjust the Backoff Exponent so that the protocol always operates in optimal conditions

Dynamic cluster scheduling for cluster-tree WSNs

While Cluster-Tree network topologies look promising for WSN applications with timeliness and energy-efficiency requirements, we are yet to witness its adoption in commercial and academic solutions. One of the arguments that hinder the use of these topologies concerns the lack of flexibility in adapting to changes in the network, such as in traffic flows. This paper presents a solution to enable these networks with the ability to self-adapt their clusters’ duty-cycle and scheduling, to provide increased quality of service to multiple traffic flows. Importantly, our approach enables a network to change its cluster scheduling without requiring long inaccessibility times or the re-association of the nodes. We show how to apply our methodology to the case of IEEE 802.15.4/ZigBee cluster-tree WSNs without significant changes to the protocol. Finally, we analyze and demonstrate the validity of our methodology through a comprehensive simulation and experimental validation using commercially available technology on a Structural Health Monitoring application scenario

Dimensioning and worst-case analysis of cluster-tree sensor networks

Modeling the fundamental performance limits of Wireless Sensor Networks (WSNs) is of paramount importance to understand their behavior under the worst-case conditions and to make the appropriate design choices. This is particular relevant for time-sensitive WSN applications, where the timing behavior of the network protocols (message transmission must respect deadlines) impacts on the correct operation of these applications. In that direction this paper contributes with a methodology based on Network Calculus, which enables quick and efficient worst-case dimensioning of static or even dynamically changing cluster-tree WSNs where the data sink can either be static or mobile. We propose closed-form recurrent expressions for computing the worst-case end-to-end delays, buffering and bandwidth requirements across any source-destination path in a cluster-tree WSN. We show how to apply our methodology to the case of IEEE 802.15.4/ZigBee cluster-tree WSNs. Finally, we demonstrate the validity and analyze the accuracy of our methodology through a comprehensive experimental study using commercially available technology, namely TelosB motes running TinyOS

IEEE 802.15.4e: a Survey

Several studies have highlighted that the IEEE 802.15.4 standard presents a number of limitations such as low reliability, unbounded packet delays and no protection against interference/fading, that prevent its adoption in applications with stringent requirements in terms of reliability and latency. Recently, the IEEE has released the 802.15.4e amendment that introduces a number of enhancements/modifications to the MAC layer of the original standard in order to overcome such limitations. In this paper we provide a clear and structured overview of all the new 802.15.4e mechanisms. After a general introduction to the 802.15.4e standard, we describe the details of the main 802.15.4e MAC behavior modes, namely Time Slotted Channel Hopping (TSCH), Deterministic and Synchronous Multi-channel Extension (DSME), and Low Latency Deterministic Network (LLDN). For each of them, we provide a detailed description and highlight the main features and possible application domains. Also, we survey the current literature and summarize open research issues

A Study of Delay and Data Traffic of IEEE 802.15.4 ZigBee-Based WSN in a Smart Home

Wireless sensor networks (WSN) play a key role in modern applications, for instance, in smart homes as will be demonstrated in this paper. ZigBee technology provides better support when compared with WiFi, Bluetooth and Ultra Wide Band (UWB) standards regarding transmission range. This paper deals with the use of ZigBee WSN in a domestic application, namely smart home control. This model comprises a smart home with multiple rooms, designed in such a way that each room has sensors comprise for a varied environment. The sensor nodes will be presented by ZigBee end device which transmits the traffic to a master node in the form of a ZigBee coordinator. An OPNET modeler V14.5 was used in this simulation study. This paper presents seven models related to delay and data traffic received to improve WSN performance. Seven different WSN designs variations were utilized according to the number of rooms, sensors, coordinators, and routers. The outcomes demonstrate that one coordinator model causes more delay when compared with multiple coordinator models. Conversely, the presence of a router causes additional delay. This model should help electrical engineers when designing smart homes that utilize WSNs

Enhancement of The IEEE 802.15.4 Standard By Energy Efficient Cluster Scheduling

The IEEE 802.15.4 network is gaining popularity due to its wide range of application in Industries and day to day life. Energy Conservation in IEEE 802.15.4 nodes is always a concern for the designers as the life time of a network depends mainly on minimizing the energy consumption in the nodes. In ZigBee cluster-tree network, the existing literature does not provide combined solution for co-channel interference and power efficient scheduling. In addition, the technique that prevents network collision has not been provided. Delay and reliability issues are not addressed in the QoS-aware routing. Congestion is one of the major challenges in IEEE 802.15.4 Network. This network also has issues in admitting real time flows. The aim of the present research is to overcome the issues mentioned above by designing Energy Efficient Cluster Scheduling and Interference Mitigation, QoS Aware Inter-Cluster Routing Protocol and Adaptive Data Rate Control for Clustered Architecture for IEEE 802.15.4 Networks. To overcome the issue of Energy efficiency and network collision energy efficient cluster scheduling and interference mitigation for IEEE 802.15.4 Network is proposed. It uses a time division cluster scheduling technique that offers energy efficiency in the cluster-tree network. In addition, an interference mitigation technique is demonstrated which detects and mitigates the channel interference based on packet-error detection and repeated channel-handoff command transmission. For the issues of delay and reliability in cluster network, QoS aware intercluster routing protocol for IEEE 802.15.4 Networks is proposed. It consists of some modules like reliability module, packet classifier, hello protocol module, routing service module. Using the Packet classifier, the packets are classified into the data and hello packets. The data packets are classified based on the priority. Neighbour table is constructed to maintain the information of neighbour nodes reliabilities by Hello protocol module. Moreover, routing table is built using the routing service module. The delay in the route is controlled by delay metrics, which is a sum of queuing delay and transmission delay. For the issues of congestion and admit real-time flows an Adaptive data rate control for clustered architecture in IEEE 802.15.4 Networks is proposed. A network device is designed to regulate its data rate adaptively using the feedback message i.e. Congestion Notification Field (CNF) in beacon frame received from the receiver side. The network device controls or changes its data rate based on CNF value. Along with this scalability is considered by modifying encoding parameters using Particle Swarm Optimization (PSO) to balance the target output rate for supporting high data rate. Simulation results show that the proposed techniques significantly reduce the energy consumption by 17% and the network collision, enhance the performance, mitigate the effect of congestion, and admit real-time flows

Enhanced collision avoidance mechanisms for wireless sensor networks through high accuracy collision modeling

Wireless channel and multi-hop communications cause a significant number of packet collisions in Wireless Sensor Networks (WSNs). Although a collision may cause packet loss and reduce network performance, low-power wireless transceivers allow packet reception in the presence of collisions if at least one signal can provide a sufficiently high power compared with other signals. Therefore, with respect to the large number of nodes used in WSNs, which necessitates the use of simulation for protocol development, collisions should be addressed at two layers: First, collisions should be modeled at the physical layer through a high-accuracy packet reception algorithm that decides about packet reception in the presence of collisions. Second, collision avoidance mechanisms should be employed at the Medium Access Control (MAC) layer to reduce packet losses caused by collisions. Unfortunately, the existing packet reception algorithms exhibit low accuracy and impede the development of efficient collision avoidance mechanisms. From the collision avoidance perspective, existing contention-based MAC protocols do not provide reliable packet broadcasting, thereby affecting the initialization performance of WSNs. In addition, despite the benefits of schedule-based MAC protocols during the data-gathering phase, the existing mechanisms rely on unrealistic assumptions. The first major contribution of this work is CApture Modeling Algorithm (CAMA), which enables collision modeling with high accuracy and efficiency at the physical layer. The higher accuracy of CAMA against existing approaches is validated through extensive comparisons with empirical experiments. The second major contribution includes mechanisms that improve the reliability of packet broadcasting. In particular, adaptive contention window adjustment mechanisms and the Geowindow algorithm are proposed for collision avoidance during the initialization phases. These mechanisms considerably improve the accuracy of the initialization phases, without violating duration and energy efficiency requirements. As the third major contribution, a distributed and concurrent link-scheduling algorithm (called DICSA) is proposed for collision avoidance during the data-gathering phase. DICSA provides faster slot assignment, higher spatial reuse and lower energy consumption, compared with existing algorithms. Furthermore, evaluating DICSA within a MAC protocol confirms its higher throughput, higher delivery ratio, and lower end-to-end delay

Industrial Wireless Sensor Networks

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