Comparative Study on Priority Based QOS Aware Mac Protocols for WSN

n Wireless Sensor Network (WSN), QoS (Quality of S\ud ervice) in sensor application plays a very importan\ud t\ud role. QoS based routing is required to ensure the b\ud est use of nodes in WSN. In this paper, a comparati\ud ve\ud study of QoS based routing in Media Access Control\ud (MAC) protocols are presented based on the traits t\ud o\ud solve problems like prioritization, timeliness, rel\ud iability etc. The study mainly focuses on some prio\ud rity\ud based QoS protocols used in WSN and a comparison am\ud ong them. The study reveals that among the five\ud mentioned protocols; QMAC, PRIMA, DB-MAC, RAP, GTS;\ud PRIMA shows the best performance in the\ud category of Packet Prioritization, Scheduling Schem\ud e, Queue Type, Energy Awareness and Qo

Improving the IEEE 802.15.4 Slotted CSMA/CA MAC for time-critical events in wireless sensor networks

In beacon-enabled mode, IEEE 802.15.4 is ruled by the slotted CSMA/CA Medium Access Control (MAC) protocol. The standard slotted CSMA/CA mechanism does not provide any means of differentiated services to improve the quality of service for timecritical events (such as alarms, time slot reservation, PAN management messages etc.). In this paper, we present and discuss practical service differentiation mechanisms to improve the performance of slotted CSMA/CA for time-critical events, with only minor add-ons to the protocol. The contribution of our proposal is more practical than theoretical since our initial requirement is to leave the original algorithm of the slotted CSMA/CA unchanged, but rather tuning its parameters adequately according to the criticality of the messages. We present a simulation study based on an accurate model of the IEEE 802.15.4 MAC protocol, to evaluate the differentiated service strategies. Four scenarios with different settings of the slotted CSMA/CA parameters are defined. Each scenario is evaluated for FIFO and Priority Queuing. The impact of the hiddennode problem is also analyzed, and a solution to mitigate it is proposed

A Novel Method for Service Differentiation in IEEE 802.15.4 : Priority Jamming

IEEE 802.15.4 employs carrier sense multiple access with collision avoidance (CSMA/CA), which is known to have difficulty for supporting quality of service (QoS). In this paper, a new priority scheme called priority jamming (PJ) is proposed for service differentiation for IEEE 802.15.4. The main idea of the proposed scheme is deferring the low priority packet transmission for the high priority packet. Clear channel assessment of IEEE 802.15.4 is modified to support the proposed PJ. The efficiency of the proposed scheme is validated by comparing the delay, throughput, and energy-per-bit with those of standard CSMA/CA. Simulations results showed that PJ improves the delay and throughput simultaneously while maintaining marginal difference in energy efficiency

PFPS: Priority-First Packet Scheduler for IEEE 802.15.4 Heterogeneous Wireless Sensor Networks

This paper presents priority-first packet scheduling approach for heterogeneous traffic flows in low data rate heterogeneous wireless sensor networks (HWSNs). A delay sensitive or emergency event occurrence demands the data delivery on the priority basis over regular monitoring sensing applications. In addition, handling sudden multi-event data and achieving their reliability requirements distinctly becomes the challenge and necessity in the critical situations. To address this problem, this paper presents distributed approach of managing data transmission for simultaneous traffic flows over multi-hop topology, which reduces the load of a sink node; and helps to make a life of the network prolong. For this reason, heterogeneous traffic flows algorithm (CHTF) algorithm classifies the each incoming packets either from source nodes or downstream hop node based on the packet priority and stores them into the respective queues. The PFPS-EDF and PFPS-FCFS algorithms present scheduling for each data packets using priority weight. Furthermore, reporting rate is timely updated based on the queue level considering their fairness index and processing rate. The reported work in this paper is validated in ns2 (ns2.32 allinone) simulator by putting the network into each distinct cases for validation of presented work and real time TestBed. The protocol evaluation presents that the distributed queue-based PFPS scheduling mechanism works efficiently using CSMA/CA MAC protocol of the IEEE 802.15.4 sensor networks

IEEE 802.15.4: a Federating Communication Protocol for Time-Sensitive Wireless Sensor Networks

Wireless Sensor Networks (WSNs) have been attracting increasing interests for developing a new generation of embedded systems with great potential for many applications such as surveillance, environment monitoring, emergency medical response and home automation. However, the communication paradigms in WSNs differ from the ones attributed to traditional wireless networks, triggering the need for new communication protocols. In this context, the recently standardised IEEE 802.15.4 protocol presents some potentially interesting features for deployment in wireless sensor network applications, such as power-efficiency, timeliness guarantees and scalability. Nevertheless, when addressing WSN applications with (soft/hard) timing requirements some inherent paradoxes emerge, such as power-efficiency versus timeliness, triggering the need of engineering solutions for an efficient deployment of IEEE 802.15.4 in WSNs. In this technical report, we will explore the most relevant characteristics of the IEEE 802.15.4 protocol for wireless sensor networks and present the most important challenges regarding time-sensitive WSN applications. We also provide some timing performance and analysis of the IEEE 802.15.4 that unveil some directions for resolving the previously mentioned paradoxes

Feedback based real-time MAC (RT-MAC) protocol for data packet streaming in wireless sensor networks

Wireless sensor networks (WSNs) are generally used for event driven monitoring or periodic reporting. Once a triggering event happens, it needs to be reported in real-time as a continuous stream for some duration. In order to address such communication requirements, this thesis introduces a soft Real-Time MAC (RT-MAC) protocol for real-time data packet streaming in wireless sensor networks. RT-MAC eliminates contention for a wireless medium by introducing a feedback control packet, called Clear Channel (CC). As a result, RT-MAC has a consistent and predictable data transmission pattern that provides end-to-end delay guarantees. Additionally, RT-MAC has a lower end-to-end delay than other real-time WSN MAC protocols for two reasons: (1) it maximizes spatial channel reuse by avoiding the false blocking problem caused by request-to-send (RTS) and clear-to-send (CTS) exchanges in wireless MAC protocols (2) it reduces contention duration of control packets to facilitate faster data packet transfer. Thus, RT-MAC facilitates periodic data packet deliveries as well as alarming event reporting. RT-MAC operates both with and without duty cycle mode (sleep/wakeup schedule for sensor nodes). Duty cycle mode of RT-MAC is useful in situations where energy conservation is one of the goals along with real-time requirements. RT-MAC is well suited for multi-hop communication with a large number of hops. RT-MAC protocol supports single-stream communication between a randomly selected source and sink node pair as well as multi-stream communication among different source and sink node pairs. This thesis provides the lower and upper end-to-end delay bounds for data packets transfer in normal mode of operation of RT-MAC protocol. We used state diagram analysis to show the in-depth functioning of RT-MAC protocol. This thesis also presents Markov analysis of RT-MAC that shows the behavior of the protocol in fault scenarios. Extensive simulation results are also presented in this thesis. These results show significant improvement in delay, packet throughput performance, and uniformity in packet transmission pattern at a cost of a very small increase in energy consumption as compared to other real-time MAC protocols such as VTS and general purpose MAC protocols such as S-MAC and T-MAC

La gestion de la qualité de service temps-réel dans les réseaux de capteurs sans fil

In the last years, Wireless Sensor Networks ‘WSN’ knew a tremendous evolution which attracted many applications. WSN has several characteristics that make it a unique research field, such as, WSN nodes’ constraints and the unreliable (lossy) wireless communication. The IEEE 802.15.4 standard is the first standard designed for this type of networks known as LR-WPANs ‘Low-Rate Wireless Personal Area Network’. The energy conservation mechanism proposed by the current standard is quite efficient and very flexible. This flexibility comes from the ability to configure different duty cycles to meet specific applications’ requirements. However, this mechanism has a considerable impact on the end-to-end delay. Our approach resolves the energy/delay trade-off by avoiding the storage of the real-time data in the coordinator during sleep time, more particularly in Multi-source Multi-sink networks. A new superframe structure is adopted and a deterministic reception scheduling is used. In this thesis, we also proposed a new WPAN model for the Network Simulator 3 ‘NS-3’.Le monde des réseaux de capteurs sans fil ‘RCSF’ a connu de grands progrès au cours de ces dernières années. Ainsi, les RCSF ont pu intégrer divers champs d’application (environnement, militaire, médecine, domotique ...) dont quelques-uns ayant des exigences en termes de qualité de service ‘QdS’. Cependant, la garantie de la QdS dans un RCSF pose des problèmes de recherche non triviaux, à cause de la nature peu fiable de la communication sans fil et des limitations des ressources des nœuds RCSF (processeur, mémoire, énergie ...). Dans le cadre de cette thèse, nous nous sommes focalisés sur les protocoles MAC afin d’améliorer le support de QdS dans les RCSF. Plus particulièrement, le standard IEEE 802.15.4. Les mécanismes de conservation d’énergie proposés par ce standard sont efficaces et présentent une flexibilité par rapport aux besoins des applications. Néanmoins, le temps de sommeil des nœuds affecte considérablement le délai de communication, donnant naissance à un compromis énergie/délai. Pour résoudre ce problème, nous avons amélioré ce standard pour un meilleur support des applications temps-réel. L’approche proposée permet de réduire le délai de communication de manière significative, même pour de faibles rapports cycliques, grâce au nouveau format de la supertrame. Les performances ont été validées par simulation et sur des plateformes de nœuds RCSF réelles. Nous avons proposé également un modèle de simulation pour le standard IEEE 802.15.4 sous le simulateur NS-3

Utilisation des réseaux de capteurs de canne pour les applications de surveillance de personnes

The world is undergoing profound demographic changes closely linked with the development of the field of public health. The increase in life expectancy is accompanied by an increase in the number of elderly people, in particular those with chronic diseases. Several existing research projects have as objective to ensure the maintenance to homes of the elderly, by a better follow-up by using new technologies. Among them, we find the proposed CANet who proposed the use of sugar cane as a tool for monitoring non-intrusive by the integration of a multitude of sensors. The cane used a wireless communication system, which allows him to exchange with a collection center or surveillance. This technological solution allows the respect of the private life of older persons, without limiting their freedom. Our thesis subject is inscribed in the framework of this project CANet. The work of this thesis is organized primarily around the design of an architecture protocol topology, and access methods for wireless networks, which allow monitoring of older persons through a network of sensors embedded in a cane. The main objective of the thesis is the study of architectures and protocols implemented at the level wireless communication to provide a reliable network infrastructure for various services for monitoring, measures, routing of data to a control center remote (medical office, members of the family, etc.). These proposals have been the subject of a theoretical study and analysis of performance by simulation.Le monde actuel connaît de profondes mutations démographiques étroitement liées au développement du domaine de la santé publique. L’accroissement de l’espérance de vie s’accompagne d’une augmentation du nombre des personnes âgées, en particulier celles atteintes de maladies chroniques. Plusieurs projets de recherche existants ont comme objectif d’assurer le maintien à domicile des personnes âgées, par un meilleur suivi en utilisant les nouvelles technologies. Parmi eux, nous trouvons le projet CANet qui propose l’utilisation de la canne comme un outil de surveillance non intrusif par l’intégration d’une multitude de capteurs. La canne utilise un système de communication sans fil qui lui permet d’échanger avec un centre de collecte ou de surveillance. Cette solution technologique permet le respect de la vie privée des personnes âgées, sans limiter leur liberté. Notre sujet de thèse s’inscrit dans le cadre de ce projet CANet. Les travaux de thèse sont principalement organisés autour de la conception d’une architecture topologique protocolaire, et des méthodes d’accès aux réseaux sans fil qui permettent la surveillance des personnes âgées à travers un réseau de capteurs embarqués dans une canne. L’objectif principal de la thèse est l’étude des architectures et des protocoles mis en œuvre au niveau communication sans fil pour offrir une infrastructure réseau fiable pour divers services de surveillance, de mesures, d'acheminement de données vers un centre de contrôle distant (cabinet médical, membres de la famille, etc.). Ces propositions ont fait l’objet d’une étude théorique et d’analyses de performances par simulation