385 research outputs found
Beacon scheduling in cluster-tree IEEE 802.15.4/ZigBee wireless sensor networks
The recently standardized IEEE 802.15.4/Zigbee protocol stack offers great potentials for ubiquitous and
pervasive computing, namely for Wireless Sensor Networks (WSNs). However, there are still some open and
ambiguous issues that turn its practical use a challenging task. One of those issues is how to build a
synchronized multi-hop cluster-tree network, which is quite suitable for QoS support in WSNs. In fact, the
current IEEE 802.15.4/Zigbee specifications restrict the synchronization in the beacon-enabled mode (by the
generation of periodic beacon frames) to star-based networks, while it supports multi-hop networking using
the peer-to-peer mesh topology, but with no synchronization. Even though both specifications mention the
possible use of cluster-tree topologies, which combine multi-hop and synchronization features, the
description on how to effectively construct such a network topology is missing. This report tackles this
problem, unveils the ambiguities regarding the use of the cluster-tree topology and proposes two collisionfree
beacon frame scheduling schemes
On the use of IEEE 802.15.4/ZigBee as federating communication protocols for Wireless Sensor Networks
Tese de mestrado. Redes e Serviços de Comunicação. Faculdade de Engenharia. Universidade do Porto, Instituto Superior de Engenharia. 200
Collision-free beacon scheduling mechanisms for IEEE 802.15.4/Zigbee cluster-tree wireless sensor networks
The recently standardized IEEE 802.15.4/Zigbee
protocol stack offers great potentials for ubiquitous and pervasive
computing, namely for Wireless Sensor Networks (WSNs).
However, there are still some open and ambiguous issues that turn
its practical use a challenging task. One of those issues is how to
build a synchronized multi-hop cluster-tree network, which is
quite suitable for QoS support in WSNs. In fact, the current IEEE
802.15.4/Zigbee specifications restrict the synchronization in the
beacon-enabled mode (by the generation of periodic beacon
frames) to star-based networks, while it supports multi-hop
networking using the peer-to-peer mesh topology, but with no
synchronization. Even though both specifications mention the
possible use of cluster-tree topologies, which combine multi-hop
and synchronization features, the description on how to effectively
construct such a network topology is missing. This paper tackles
this problem, unveils the ambiguities regarding the use of the
cluster-tree topology and proposes two collision-free beacon
frame scheduling schemes. We strongly believe that the results
provided in this paper trigger a significant step towards the
practical and efficient use of IEEE 802.15.4/Zigbee cluster-tree
networks
Wireless industrial monitoring and control networks: the journey so far and the road ahead
While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of today’s industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks
Energy efficient scheduling for cluster-tree wireless sensor networks with time-bounded data flows: application to IEEE 802.15.4/ZigBee
Cluster scheduling and collision avoidance are crucial issues in large-scale cluster-tree Wireless Sensor Networks
(WSNs). The paper presents a methodology that provides a Time Division Cluster Scheduling (TDCS) mechanism
based on the cyclic extension of RCPS/TC (Resource Constrained Project Scheduling with Temporal Constraints)
problem for a cluster-tree WSN, assuming bounded communication errors. The objective is to meet all end-to-end
deadlines of a predefined set of time-bounded data flows while minimizing the energy consumption of the nodes by
setting the TDCS period as long as possible. Sinceeach cluster is active only once during the period, the end-to-end
delay of a given flow may span over several periods when there are the flows with opposite direction. The scheduling
tool enables system designers to efficiently configure all required parameters of the IEEE 802.15.4/ZigBee beaconenabled
cluster-tree WSNs in the network design time. The performance evaluation of thescheduling tool shows that the
problems with dozens of nodes can be solved while using optimal solvers
Implementation details of the time division beacon scheduling approach for ZigBee cluster-tree networks
This technical report describes the implementation details of the Time Division Beacon Scheduling Approach in IEEE
802.15.4/ZigBee Cluster-Tree Networks. In this technical report we describe the implementation details, focusing on
some aspects of the ZigBee Network Layer and the Time Division Beacon Scheduling mechanism. This report
demonstrates the feasibility of our approach based on the evaluation of the experimental results. We also present an
overview of the ZigBee address and tree-routing scheme
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
Zigbee over tinyos: Implementation and experimental challenges
The IEEE 802.15.4/Zigbee protocols are a promising technology for Wireless
Sensor Networks (WSNs). This paper shares our experience on the implementation and
use of these protocols and related technologies in WSNs. We present problems and
challenges we have been facing in implementing an IEEE 802.15.4/ZigBee stack for
TinyOS in a two-folded perspective: IEEE 802.15.4/ZigBee protocol standards
limitations (ambiguities and open issues) and technological limitations (hardware and
software). Concerning the former, we address challenges for building scalable and
synchronized multi-cluster ZigBee networks, providing a trade-off between timeliness
and energy-efficiency. On the latter issue, we highlight implementation problems in terms
of hardware, timer handling and operating system limitations. We also report on our
experience from experimental test-beds, namely on physical layer aspects such as
coexistence problems between IEEE 802.15.4 and 802.11 radio channels
On the use of the ZigBee protocol for wireless sensor networks
This project was developed within the ART-WiSe framework of the IPP-HURRAY group
(http://www.hurray.isep.ipp.pt), at the Polytechnic Institute of Porto (http://www.ipp.pt).
The ART-WiSe – Architecture for Real-Time communications in Wireless Sensor networks – framework
(http://www.hurray.isep.ipp.pt/art-wise) aims at providing new communication architectures and
mechanisms to improve the timing performance of Wireless Sensor Networks (WSNs). The architecture is
based on a two-tiered protocol structure, relying on existing standard communication protocols, namely
IEEE 802.15.4 (Physical and Data Link Layers) and ZigBee (Network and Application Layers) for Tier 1
and IEEE 802.11 for Tier 2, which serves as a high-speed backbone for Tier 1 without energy consumption
restrictions.
Within this trend, an application test-bed is being developed with the objectives of implementing, assessing
and validating the ART-WiSe architecture. Particularly for the ZigBee protocol case; even though there is a
strong commercial lobby from the ZigBee Alliance (http://www.zigbee.org), there is neither an open source
available to the community for this moment nor publications on its adequateness for larger-scale WSN
applications. This project aims at fulfilling these gaps by providing: a deep analysis of the ZigBee
Specification, mainly addressing the Network Layer and particularly its routing mechanisms; an
identification of the ambiguities and open issues existent in the ZigBee protocol standard; the proposal of
solutions to the previously referred problems; an implementation of a subset of the ZigBee Network Layer,
namely the association procedure and the tree routing on our technological platform (MICAz motes, TinyOS
operating system and nesC programming language) and an experimental evaluation of that routing
mechanism for WSNs
Proposition and validation of an original MAC layer with simultaneous medium accesses for low latency wireless control/command applications
Control/command processes require a transmission system with some
characteristics like high reliability, low latency and strong guarantees on
messages delivery. Concerning wire networks, field buses technologies like FIP
offer this kind of service (periodic tasks, real time constraints...).
Unfortunately, few wireless technologies can propose a communication system
which respects such constraints. Indeed, wireless transmissions must deal with
medium characteristics which make impossible the direct translation of
mechanisms used with wire networks. The purpose of this paper is to present an
original Medium Access Control (MAC) layer for a real time Low Power-Wireless
Personal Area Network (LP-WPAN). The proposed MAC-layer has been validated by
several complementary methods; in this paper, we focus on the specific
Simultaneous Guaranteed Time Slot (SGTS) part
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