The evolution of wireless communication and circuit technology has enabled the development of an infrastructure consists of sensing, computation and communication units that makes administrator capable to observe and react to a phenomena in a particular environment. The building block of such an infrastructure is comprised of hundreds or thousands of small, low cost, multifunctional devices which have the ability to sense compute and communicate using short range transceivers known as sensor nodes. The interconnection of these nodes forming a network called wireless sensor network (WSN). The low cost, ease of deployment, ad hoc and multifunctional nature has exposed WSNs an attractive choice for numerous applications. The application domain of WSNs varies from environmental monitoring, to health care applications, to military operation, to transportation, to security applications, to weather forecasting, to real time tracking, to fire detection and so on. By considering its application areas WSN can be argue as a traditional wired or wireless network. But in reality, these networks are comprised of battery operated tiny nodes with limitations in their computation capabilities, memory, bandwidth, and hardware resulting in resource constrained WSN. The resource constrained nature of WSN impels various challenges in its design and operations degrading its performance. On the other hand, varying numbers of applications having different constraints in their nature makes it further challenging for such resources constrained networks to attain application expectations. These challenges can be seen at different layer of WSNs starting from physical layer up to application layer. At routing layer, routing protocols are mainly concerned with WSN operation. The presence of these challenges affects the performance of routing protocols resulting in overall WSN performance degradation. The aim of this study is to identify the performance challenges of WSN and analyze their impact on the performance of routing protocols. For this purpose a thorough literature study is performed to identify the issues affecting the routing protocols performance. Then to validate the impact of identified challenges from literature, an empirical study has been conducted by simulating different routing protocols, taking into consideration these challenges and results are shown. On the basis of achieved results from empirical study and literature review recommendations are made for better selection of protocol regarding to application nature in the presence of considered challenges.

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In the wireless sensor network, the WLAN interference, multi-path fading andattenuation are the main reason for packets’ corruption. Forward errorcorrection is one of the methods for error mitigation. Many coding methods aredesigned to improve the reliability of wireless channel. However, none of thesecoding methods could handle the burst errors that widely exist in wirelesschannel and are mainly responsible for packet corruption. Interleaving isintroduced to robust these coding methods and make those corrupted packetsavailable to be corrected by spreading the burst errors. The Reed-Solomon(15,7) block code is used as the forwarding error correction in theseexperiments. In this paper, seven different symbol interleaving will be firstlysimulated in the Matlab platform under four different channels to evaluate theirpacket error rate performances. Then, two of the seven interleaving with betterperformance and the simplest interleaving algorithm, general block interleavingwill be implemented in the TinyOS platform, and they will be compared witheach other from packet error rate, interleaving time and memory consumptionaspects. Experiments show that, for theoretical channel, interleaving plays animportant role to enhance the capability to correct the corrupted packets exceptfor Rayleigh channel, in which the impact of interleaving is generally slight.Meanwhile for the channel under IEEE 802.11b/g interference, interleavingenhance more than 10% PER in the receiver. However for MFA channel, theenhancement is slight, only 1.85%. Convolutional interleaving has the best PERperformance in AWGN channel and the channel with deterministic SER, whilematrix interleaving has the lowest PER in WLAN affected channel. In thelatency and memory consumption aspect, For the same packet length, generalblock interleaving has the shortest interleaving time while matrix interleavinghas the longest. In the same interleaving algorithm, the execution time becomeslonger with growth of packet size. Within the same interleaving method, thelonger the packet size is, the more memory that would be consumed. Under thesame interleaving length, general block interleaving consumes least memoryand convolutional interleaving has the largest memory consumption.

In wireless sensor networks, communications are usually destroyed by signal attenuation, multipath fading and different kinds of interferences like WLAN and microwave oven interference. In order to build a stable wireless communication system, reactions like retransmission mechanisms are necessary. Since the way we must react to interference is different from the way we react to multipathfading and attenuation, the retransmission mechanism should be adjusted in different ways under those different cicumstances. Under this condition, channel diagnostics for discriminating the causes that corrupt the packets between multipath fading and attenuation (MFA) and WLAN interference are imperative. This paper presents a frame bit error rate (F-BER) regulated algorithm based on a joint RSSI-LQI classifier that may correctly diagnose the channel status. This discriminator is implemented on MicaZ sensor devices equipped with CC2420 transceivers. This discriminator is able to improve the accuracy to 91%. Although we need to wait for 2 or 3 necessary packets to make a decision, higher stability and reliability are presented when operating this discriminator.

In recent times, there has been a significant amount of research regarding the physical layer of wireless communications . The part of the physical layer, which cannot be ignored, is channel propagation. Different environments have different channels. Path loss, slow fading, fast fading and multipath fading are all involved in decisions regarding the condition of the channel . Based on related research, a number of empirical channel models are put forward to simulate a real environment with regards to communication and there are some simulation softwares that are able to implement those different channels. These include Matlab which is regarded as the best simulation software for the physical layer in wireless communication. OPNET is another network modeling simulation software, which could implement the entire process of the network communication, which Matlab is not able to complete . The network layer of OPNET is very mature and has the ability to implement different routing protocols. However, the description of the physical layer in OPNET is poor and there is only simple path loss model in pipeline modeling in OPNET. Thus, the objective of this thesis is to implement different channel models in OPNET and to make it capable to simulate in as close a manner as possible to a real environment.

Les réseaux de capteurs sans fil (RCSFs) ont suscité un grand intérêt scientifique durant cette dernière décennie. Un des grands défis des RCSFs est d'assurer une communication avec la Qualité de Service (QoS) exigée par l'application tout en prenant en considération les contraintes intrinsèques des capteurs. Un autre défi est relatif à la génération des trafics hétérogènes avec des priorités diverses, ce qui impose des contraintes supplémentaires aux différents protocoles de communication. Dans cette thèse, nous nous intéressons aux protocoles de routage dédiés aux RCSFs. Dans un premier temps, nous proposons des améliorations de deux protocoles appartenant à deux catégories différentes de routage. L'objectif est de surmonter les contraintes liées aux caractéristiques des capteurs sans fil et d'assurer de meilleure performance. Dans un deuxième temps, nous proposons une solution pour remédier à la vulnérabilité de la technique des chemins multiples aussi bien dans le cas d'une seule source ou que dans le cas de plusieurs sources. Ainsi, nous avons proposé un protocole de routage à chemins multiples, capable de créer des chemins tout en évitant l'effet du rayon de détection de porteuse. Ce protocole nommé « Carrier Sense Aware Multipath Geographic Routing (CSA-MGR) », satisfait la QoS exigée par les RCSFs. Comme application directe de notre solution, nous avons étudié un scénario d'irrigation par goutte-à-goutte en utilisant les RCSFs. Principalement, nous nous sommes intéressés au cas d'un dysfonctionnement de système, tel que la rupture des tuyaux d'irrigation ou bien le blocage des émetteurs. Ainsi, nous distinguons deux niveaux de priorité pour les informations transmises par le réseau, et en utilisant le protocole CSA-MGR, nous concevons un routage selon la priorité exigée. Notre travail a été validé avec NS2 et TOSSIM ainsi par une implémentation réelle sur des noeuds capteurs TelosB. Les résultats des simulations numériques et des tests expérimentaux montrent l'apport de nos contributions par rapport aux solutions existantes. / Wireless Sensor Networks (WSNs) have aroused great scientific interest during the last decade. One of the greatest challenge of WSNs is to ensure communication with the Quality of Service (QoS) required by the application while taking into account the inherent constraints of the sensor nodes. Another challenge is related to the generation of heterogeneous traffic with different priorities, which imposes additional constraints on different communication protocols. In this thesis, we are interested specifically to routing protocols dedicated to WSNs. First, we propose improvements of protocols based on combinatorial optimization techniques and those based on nodes geographic positions to overcome the related constraints of WSNs. Secondly, we propose a solution to address the vulnerability of the multiple paths technique, whether for the case of a single source or several sources in the network. Thus, our main contribution is to provide a multi-path routing protocol, able to creating paths while avoiding the carrier sense range effect. This protocol denoted "Carrier Sense Aware Multipath Geographic Routing (CSA-MGR)" meets the QoS required by WSNs. As direct application of our solution, we studied a drip irrigation scenario using WSNs. Mainly, we studied the case where a system dysfunctioning occurs, such as irrigation pipe rupture or the emitters blocking. Also, we distinguish two priority levels for the data transmitted over the network, and based on the CSA-MGR, we design routing according to the required priority. Our work in this thesis has been validated through NS2 and TOSSIM simulators and also through a real implementation over the TelosB motes. The results of numerical simulations and experimental results show the advantage of our contributions compared to existing solutions.

In this thesis, an investigation of the performance of multipath routing in Wireless Sensor Networks (WSN) is performed. The communication in the network under study is to take place from individual nodes to the sink node. The investigation involved multipath finding methods in WSN. Also, it involves investigating the weight assignment, traffic splitting and route selection methods for the different paths discovered by each node in the WSN. Also, a comparison between Hybrid Routing Protocol, Source Routing Protocol and Diffusion Routing Protocol is performed. A simple traffic routing algorithm for each routing protocol has been developed to conceptualize how the network traffic is routed on a set of active paths. The investigation of the Hybrid, Source and Diffusion Routing Protocol involved using multiple paths simultaneously to transmit messages that belong to the same flow by using a weight assigned to each path and transmit each message as a whole. Finally, the power consumption and the QoS in terms of message delays for a WSN were investigated and compared between different protocols.

During the last century, the significant increase in electricity demand, and its consequences, has appeared as a serious concern for the utility companies, but no essential change has been applied to the conventional power grid infrastructure till now. Recently, researchers have identified efficient control and power distribution mechanisms as the immediate challenges for conventional power grids. Hence, the next step for conventional power grid toward Smart Grid is to provide energy efficiency management along with higher reliability via smart services, in which the application of Information and Communication Technology (ICT) is inevitable. ICT introduces powerful tools to comply with the smart grid requirements. Among various ICT properties, the telecommunication network plays a key role for providing a secure infrastructure. The two-way digital communication system provides an interaction between energy suppliers and consumers for managing, controlling and optimizing energy distribution. We can also define the smart grid as a two-way flow of energy and control information, where the electricity consumers can generate energy using green energy resources. The main objective of this thesis is to select an effective communication infrastructure to support the smart grid services by considering wireless and optical communication technologies. Fiber-wireless (FiWi) networks are considered as a potential solution to provide a fast and reliable network backbone with the optical access network integration and the flexibility and mobility of the wireless network. Therefore, we adopt the integration of the wireless sensor network (WSN) to Ethernet Passive Optical Network (EPON) as a broadband access network to transmit smart meter data along with the Fiber To The Home/Building/Curb (FTTX) traffic through the shared fiber. Finally, we present and analyze the simulation results for the aforementioned infrastructure based on our adopted priority-based FTTX-WSN integration model.

Tillfredsställande inomhusmiljö är idag mycket viktigt eftersom människor spenderar majoriteten av sin tid inomhus. För att fastställa och reglera inomhusmiljön måste denna mätas. Detta sker med olika sensorer och de vanligaste är koldioxid-, kolmonoxid-, temperatur- och luftfuktighetssensorer. Mätsystem som idag mäter inomhusmiljö är dyra att köpa in och att installera. Dessutom varierar de i svårighetgrad att konfigurera. Med hjälp av billig elektronik och trådlösa sensornätverk kan den totala kostnaden, inte minst installationskostnader, reduceras eftersom radiolänkar utnyttjas istället för kabelbunden kommunikation. Trådlösa sensornätverk kan även underlätta konfigurering av mätsystemet om ändringar behöver göras. Denna studie beskriver design och konstruktion av ett trådlöst sensornätverk för mätning av infraljud, koldioxidhalt, temperatur och relativ luftfuktighet. Bristen på mätsystem som mäter inomhusmiljö där infraljud är en av mätparametrarna gör det önskvärt att mäta infraljud istället för en av de andra vanliga mätparametrarna. I studien konstrueras en sensornod, en gateway och PC programvara. Utvärdering och test av konstruerat system utförs och resultaten jämförs mot ett referenssystem. Resultaten visar att mätsystemet i jämförelse med ett referenssystem ger tillfredsställande resultat. Avvikelserna mellan systemen är liten. Resultat från infraljudsmätningarna visar att mätsystemet kan mäta infraljudnivå men behöver filtreras för att återge korrekta signalnivåer.

Wireless sensor networks (WSNs) allow us to instrument the physical world in novel ways, providing detailed insight that has not been possible hitherto. Since WSNs provide an interface to the physical world, each sensor node has a location in physical space, thereby enabling us to associate spatial properties with data. Since WSNs can perform periodic sensing tasks, we can also associate temporal markers with data. In the environmental sciences, in particular, WSNs are on the way to becoming an important tool for the modelling of spatially and temporally extended physical phenomena. However, support for high-level and expressive spatial-analytic tasks that can be executed inside WSNs is still incipient. By spatial analysis we mean the ability to explore relationships between spatially-referenced entities (e.g., a vineyard, or a weather front) and to derive representations grounded on such relationships (e.g., the geometrical extent of that part of a vineyard that is covered by mist as the intersection of the geometries that characterize the vineyard and the weather front, respectively). The motivation for this endeavour stems primarily from applications where important decisions hinge on the detection of an event of interest (e.g., the presence, and spatio-temporal progression, of mist over a cultivated field may trigger a particular action) that can be characterized by an event-defining predicate (e.g., humidity greater than 98 and temperature less than 10). At present, in-network spatial analysis in WSN is not catered for by a comprehensive, expressive, well-founded framework. While there has been work on WSN event boundary detection and, in particular, on detecting topological change of WSN-represented spatial entities, this work has tended to be comparatively narrow in scope and aims. The contributions made in this research are constrained to WSNs where every node is tethered to one location in physical space. The research contributions reported here include (a) the definition of a framework for representing geometries; (b) the detailed characterization of an algebra of spatial operators closely inspired, in its scope and structure, by the Schneider-Guting ROSE algebra (i.e., one that is based on a discrete underlying geometry) over the geometries representable by the framework above; (c) distributed in-network algorithms for the operations in the spatial algebra over the representable geometries, thereby enabling (i) new geometries to be derived from induced and asserted ones, and (ii)topological relationships between geometries to be identified; (d) an algorithmic strategy for the evaluation of complex algebraic expressions that is divided into logically-cohesive components; (e) the development of a task processing system that each node is equipped with, thereby with allowing users to evaluate tasks on nodes; and (f) an empirical performance study of the resulting system.