Made available in DSpace on 2016-04-04T18:31:39Z (GMT). No. of bitstreams: 1 LUIZ RODOLFO BARRETO DA SILVA.pdf: 1309393 bytes, checksum: c820374f746f8a21bb89acd6347d0907 (MD5) Previous issue date: 2014-02-07 / This work discusses the development of a method for estimating the distance of sensor nodes in Wireless Sensor Networks (WSN) in indoor environments, considering the need for adaptation of the method due to the presence of random factors that may influence the estimation of such distances. The estimation method presented is based on a signal strength indicator, RSSI (Received Signal Strength Indicator). / Este trabalho aborda a elabora??o de um m?todo para a estimativa de dist?ncia de n?s sensores em Redes de Sensores Sem Fio (RSSF) em ambientes internos fechados, considerando necessidade de adapta??o do m?todo devido ? presen?a de fatores aleat?rios que podem influenciar a estimativa dessas dist?ncias. O m?todo de estimativa apresentado ? baseado em um indicador de intensidade de sinal, o RSSI (Received Sinal Strength Indicator).

O presente trabalho teve como objetivo apresentar uma metodologia que permita encontrar o posicionamento e rastrear as diferentes localizações de um suíno em uma baia, utilizando o valor do Receiver Signal Strenght Indicator (RSSI), entre o dispositivo móvel (suíno) e três dispositivos fixos, e uma Rede Neural Artificial do tipo Perceptron Multicamadas (PMC), responsável por interpretar os sinais RSSI e transformá-los em valores conhecidos, como em um plano cartesiano, com coordenadas no eixo X e eixo Y. A região de teste foi dividida em 289 pontos, sendo 286 utilizados para coleta de dados e para o treinamento da rede PMC. Para cada ponto, foram armazenados a sua posição dentro da baia e o valor RSSI entre o dispositivo móvel e os três dispositivos fixos. O processo foi repetido para 8 pontos escolhidos aleatoriamente dentro do espaço de teste e inseridos como entradas na rede PMC. Após treinamentos e operações realizadas com diversas arquiteturas foi possível concluir que àquela dotada de 10 neurônios na camada intermediária consistiu na melhor alternativa, cujos resultados de monitoramento e rastreamento das posições do dispositivo móvel foram encontradas com valores aceitáveis de exatidão. / This paper aims to present a methodology to find the positioning and tracking of the different locations of a pig in a stall, using the value of the Receiver Signal Strength Indicator (RSSI), between the mobile device (pig) and three devices fixed, and an Artificial Neural Network Multilayer Perceptron (MLP), responsible for interpreting the RSSI signals and turning them into known values, such as on a Cartesian plane, with coordinates on X axis and Y axis. The test region was divided into 289 points, with 286 points used for data collection and training of PMC network, and for each point, it was stored its position inside the stall and its RSSI value between the mobile devices and the three fixed. The process was repeated for 8 points chosen randomly within the space of test and entered as inputs into the PMC network. After training and operations with various architectures it was concluded that the architecture with 10 neurons in the hidden layer was the best alternative, whose the results of monitoring and tracking the positions of mobile device were found with acceptable accuracy.

Le suivi des petits animaux utilisés dans le cadre de tests de laboratoire et l'analyse de leur comportement à distance, à faible coût et en temps réel suscitent depuis longtemps l’intérêt des chercheurs. Ceux-ci peuvent se faire par l’implantation de capteurs sans fils miniatures qui nécessitent des composants vitaux dont le plus problématique est l’antenne. En effet, la principale difficulté dans la conception d'antennes pour les dispositifs de communication bio-implantables est de fournir une structure rayonnante efficace et ce, malgré les contraintes de volume et le fort impact des tissus biologiques qui l’entourent. Si de nombreuses études ont porté sur l’utilisation d'antennes implantées dans la bande MICS (Medical Implant Communications Service) (402-405 MHz), il faut noter qu’à ces fréquences, la taille des antennes peut être un inconvénient réel dans le cas de petits animaux, d’où une recherche de miniaturisation. Une alternative consiste en l’utilisation de la technologie RFID (Radio-Frequency Identification) dans la bande UHF à 868 MHz. En effet, elle présente deux avantages primordiaux : elle facilite l'implantation du tag et ne nécessite pas l’ajout d'une batterie pour alimenter le périphérique implanté. Ce travail de thèse fait suite à un projet collaboratif financé par l’ANR (Agence Nationale de la Recherche) dans le cadre du Labex UCN@Sophia et qui a pour objectif la conception d’un système sans fils incluant aussi bien les tags RFID implantables, les antennes du lecteur et le lecteur connecté à un ordinateur se chargeant de la gestion centralisée des informations sur un serveur pour le suivi et la collecte de données de souris de laboratoire. Ce mémoire présente la conception d’antennes implantées pour tags RFID dans un modèle homogène représentant le corps d’une souris. Après l’analyse d’un bilan de liaison permettant de calculer les performances minimales de l’antenne implantée à concevoir pour une communication fiable et efficace, des antennes tags RFID passifs en 2D et en 3D ont été optimisées par différentes techniques pour atteindre des structures finales implantables ou injectables au dos d’une souris. Une caractérisation des solutions proposées en termes d’impédance, de champs E et H et de DAS (Débit d'Absorption Spécifique) a ensuite été effectuée dans un fantôme homogène. Enfin, un système d’interrogation permettant d’estimer la position de l’animal via la récupération du RSSI (Received Signal Strength Indicator) est présenté. / The monitoring of small animals in laboratory tests and the remote analysis of their behavior, with low cost and in real time interest researchers for a long time. This can be done by implanting miniature wireless sensors requiring vital components among which the most challenging is the antenna. Indeed, the main difficulty in designing antennas for bio-implantable communication devices is to provide an effective radiating structure, despite the volume constraints and the high impact of the surrounding biological tissues. Although many studies have focused on the use of implanted antennas dedicated to the MICS band (402405 MHz), it should be noted that at these frequencies, the size of the antennas can be a real disadvantage in the case of small animals, requiring miniaturization structures. Another solution consists in the using RFID (Radio-Frequency Identification) technology in the UHF band at 868 MHz. Indeed, it has two major advantages: it facilitates the implementation of the tag and does not require the addition of a battery to power the implanted device. This thesis funded by the ANR (French National Research Agency) within the framework of the Labex UCN@Sophia aims at designing a wireless system, including implantable RFID tags, reader's antennas and the reader connected to a computer that is responsible for the centralized management of information on a server for monitoring and collecting the data of laboratory mice. This thesis presents the design of implanted antennas for RFID tags in a homogeneous model representing the body of a mouse. After an analysis of a link budget allowing to determine the minimum performance of the implanted antenna to be designed for a reliable and an efficient communication, two RFID passive tag antenna designs have been optimized to obtain final structures able to be implanted or injected in the back of a mouse. A characterization of the proposed solutions in terms of impedance, E and H fields and SAR (Specific Absorption Rate) was then performed in a homogeneous phantom. Finally, an interrogation system capable to estimate the position of several animals placed in a cage thanks to the RSSI (Received Signal Strength Indicator) levels is presented.

This diploma thesis focuses on possible utilization of LoRa (Long Range) technology for indoor localization purposes. In this thesis, the starter kit SK-iM282A is used to create a LoRa-based wireless link in the 2.4 GHz ISM band. Main attention is focused on the experimental localization using the RSSI method in the various transmission environments, including a description of the localization principle, the procedure of processing the measured data and the evaluation of localized coordinates. The rightness of the proposed measurement setup and methodology is verified by extensive measurements in various environments and compared with state-of-the-art article.

When using a wireless repeater in a network, an overlap zone between the repeater and the primary access point that holds the internet connection is created. The theoretical throughput for connections through the repeater is reduced by half since the repeater can’t send and receive data at the same time when using only one channel which was the case in this thesis. To solve the problem with the overlap zone, an algorithm that runs in the form of a bash script on two openWRT-based access points where one acts as a repeater and the other one is a gateway with an internet connection was developed. The script uses the signal strength value (RSSI) to decide whether a wireless device is located within the overlap zone by comparing the measured value against a set threshold where the gateway still delivers higher throughput than the repeater. Wireless devices in the overlap zone are blocked on the repeater and will then connect to the gateway instead. Wireless devices that are located outside the overlap zone will connect to the access point that yields the strongest signal strength. The throughput to the gateway was measured at several locations with different signal strengths to both the gateway and the repeater. Wireless devices within the overlap zone that were connected to the repeater before the script was run gained a higher throughput after the script was run and made it connect directly to the gateway instead. / Vid användning av en trådlös repeater i ett nätverk skapas en överlappningszon mellan repeatern och den primära anslutningspunkten som har uppkopplingen mot internet. Den möjliga datagenomströmningshastigheten för uppkopplingar via repeatern halveras eftersom repeatern inte kan sända och ta emot samtidigt på samma kanal. För detta examensarbete fanns inte möjligheten att använda fler kanaler. För att lösa problemet med överlappningszonen utvecklades en algoritm som körs i form av ett bash-skript på två openWRT-baserade anslutningspunkter där den ena agerar som repeater och den andra är en gateway med internetuppkoppling. Skriptet använder värdet på signalstyrka (RSSI) för att avgöra om en trådlös enhet befinner sig i överlappningszonen genom att kontrollera uppmätt värde mot ett tröskelvärde där gatewayen fortfarande ger högre datagenomströmningshastighet än repeatern. Trådlösa enheter i överlappningszonen blockeras på repeatern och kopplar då upp till gatewayen istället. Utanför överlappningszonen kopplas enheter upp till den anslutningspunkt som har starkast signalstyrka. Datagenomströmningen till gatewayen mättes på flera platser med olika signalstyrkor till både gatewayen och repeatern. Trådlösa enheter i överlappningszonen som var uppkopplade till repeatern innan skriptet kördes fick en högre datagenomströmningshastighet efter att skriptet kört och styrt om anslutningen direkt till gatewayen istället.

Blind and visually impaired (BVI) users desire an indoor navigation tool that is inexpensive, convenient, and reliable. The purpose of this thesis is to examine the feasibility of using a smartphone as a platform for such a navigation tool. A good navigation tool should have both a good positioning accuracy and a user-friendly interface. Thus, one focus of this thesis is to improve the performance of an indoor positioning systems running on smartphones, as compared to existing systems. Another focus is to customize this indoor positioning system specifically for BVI users.  The proposed indoor positioning system is based upon Bluetooth Low Energy (BLE). It consists of two parts: BLE beacons deployed in the user’s environment and an Android phone which calculates its position and provides navigation assistance by audio and vibration. Two versions of the positioning software were developed based on different algorithms. One version uses a hybrid technique combining triangulation and fingerprinting. This version achieves a positioning accuracy of 1.83 meter, and volunteers (blind-folded sighted people) took on average 91.7 seconds to complete a complex 12-meter route. The other version uses a proximity algorithm, thus it does not give as accurate positioning results. With this algorithm, a blind user was able to finish a route of 115 meters consisting of two different floors in a building including entering/exiting an elevator and multiple office doors in 4 minutes 48 seconds. The blind user found the product to be helpful and user-friendly. Finally, we draw the conclusion that a smartphone can be a good platform for a BVI navigation tool, under the condition that the algorithm is proximity based and navigation utilizes a priori information about the environment. Another insight we gained is that we should put beacons on braille signs so that blind people can find them by using the navigation app. / Blinda och synskadade (BVI) användare önskar sej ett inomhus navigeringsverktyg som är billigt, bekvämt och pålitligt. Syftet med detta examensarbete var att undersöka möjligheten att med en smartphone och utplacerade fyrar/beacons ge en bra plattform för en inomhus navigeringsmetod. Ett bra navigationsverktyg bör ha både en bra positioneringsnoggrannhet och ett användarvänligt gränssnitt. Således är ett fokus för detta arbete att förbättra prestanda för på ett inomhus positioneringssystem som körs på smartphones, jämfört med andra befintliga system. Ett annat fokus är att anpassa denna inomhus positioneringssystem för speciella BVI användare. Det vidare utvecklade inomhuspositionering systemet bygger på Bluetooth Low Energy (BLE). Den består av två delar: BLE fyrar/beacons utplacerade i kontorsmiljön och en smartphone som beräknar sin position och ger navigeringshjälp av ljud/röst och vibrationer. Vi utformade två versioner av positionerings programvaran med olika algoritmer. En version använder en hybridteknik med triangulering och en med fingerprints. Det uppnår en positioneringsnoggrannhet som är <1,83 meter och den testades på tolv seende personer med bindel för ögonen. Det tog vid testet 91.7 sekunder i genomsnitt att utföra en komplex 12 meter lång bana. Den andra versionen använder en närhets-algoritm som inte ger ett specifikt positioneringsresultat. Med denna algoritm kunde en blind användare avsluta en rutt 115 meter bestående av två olika våningar från ingång i golvplanet samt ta en hiss och gå in på ett kontor och genom hela kontoret på 4 minuter och 48 sekunder. Den blinda användaren ansåg att navigeringsverktyget var både användbart och användarvänligt. Slutligen, drar vi slutsatsen att en smartphone kan vara en bra plattform för ett BVI navigeringsverktyg och då under förutsättning att algoritmen tar med närhet/position och inomhusmiljöinformation för att ge bästa möjliga användbarthet. En annan insikt vi fått är att vi ska lägga fyrar på punktskrift tecken så att blinda kan hitta dem med hjälp av navigering app.

Dans cette thèse, on s'est intéressé à trois problématiques des réseaux de capteurs sans fil (WSN). Dans un premier temps nous avons analysé l'impact de la chute de tension dans la batterie du nœud sur la puissance du signal en réception. On propose alors une méthode pour compenser l'augmentation apparente de la distance calculée entre les nœuds due à la diminution de l'énergie de la batterie. Pour les nœuds passant par deux états principaux endormi et actif, on propose d'étudier, la relation entre la diminution de la tension de la batterie en fonction du temps passé par un nœud dans l'état actif. Ensuite, on calcule le rapport entre la RSS et la distance entre les nœuds connectés avec des batteries complètement chargées. Après on mesure la RSS en faisant varier la tension de la batterie du nœud émetteur et en gardant le nœud récepteur à une distance constante. Finalement, on propose une relation entre la RSS observée et la tension actuelle de la batterie du nœud émetteur. Cette fonction permet de calculer la valeur corrigée de la RSS qui correspond à la distance réelle entre les nœuds connectés. Ainsi l'efficacité des méthodes de la localisation basée sur la RSS se trouvent améliorées. Dans la deuxième partie de cette thèse on propose une méthode d'estimation des positions des nœuds dans un WSN. Dans l'algorithme de localisation proposé, on utilise des nœuds ancres comme des points de référence. On a utilisé une approche heuristique pour trouver la topologie relative avec l'aide de la matrice de distance. Le but de la matrice de distance est d'indiquer s'il existe une connexion entre une paire de nœuds donnée et en cas de connectivité, la distance estimée entre ces nœuds. En utilisant les informations de connectivité entre les nœuds et leurs distances, on obtient la topologie du réseau. La méthode proposée utilise la solution de l'intersection de deux cercles au lieu de la méthode classique de triangulation, où un système quadratique de trois équations avec deux variables est utilisé ce qui rend la complexité de calcul augmentée. Lorsque deux nœuds connectés ont un autre nœud en commun, puis en utilisant les informations de distances entre ces nœuds interconnectés, nous pouvons calculer deux positions possibles pour le troisième nœud. La présence ou l'absence d'un lien entre le troisième nœud et un quatrième nœud, permet de trouver la position précise. Ce processus est réitéré jusqu'à ce que toutes les positions des nœuds aient été obtenues. Une fois la topologie relative calculée, il faut trouver la symétrie, l'orientation et la position de cette topologie dans le plan. C'est à ce moment que la connaissance des positions des trois nœuds entre en action. La topologie donne les coordonnées temporaires des nœuds. En ayant une comparaison de certaines caractéristiques entre les coordonnées temporaires et les coordonnées exactes, on trouve d'abord la symétrie de la topologie relative qui correspondrait à la topologie originale. En d'autres termes on vérifie si oui ou non la topologie relative est une image miroir de la topologie originale. Des opérateurs géométriques sont alors utilisés pour corriger la topologie relative par rapport à la topologie réelle. Ainsi, on localise tous les nœuds dans un WSN en utilisant exactement trois ancres. Dans la dernière partie de cette thèse, on propose une méthode pour la détection de défauts dans un WSN. Il y a toujours une possibilité qu'un capteur d'un nœud ne donne pas toujours des mesures précises. On utilise des systèmes récurrents et non récurrents pour la modélisation et on prend comme variable d'entrée, en plus des variables du nœud en question, les informations des capteurs voisins. La différence entre la valeur estimée et celle mesurée est utilisée pour déterminer la possibilité de défaillance d'un nœud / In this thesis three themes related to wireless sensor networks (WSNs) are covered. The first one concerns the power loss in a node signal due to voltage droop in the battery of the node. In the first part of the thesis a method is proposed to compensate for the apparent increase in the calculated distance between the related nodes due to decrease in the energy of the signal sending node battery. A function is proposed whose arguments are the apparently observed RSS and the current voltage of the emitter node battery. The return of the function is the corrected RSS that corresponds to the actual distance amongst the connected nodes. Hence increasing the efficiency of the RSS based localization methods in WSNs. In the second part of the thesis a position estimation method for localization of nodes in a WSN is proposed. In the proposed localization algorithm anchor nodes are used as landmark points. The localization method proposed here does not require any constraint on the placement of the anchors; rather any three randomly chosen nodes can serve as anchors. A heuristic approach is used to find the relative topology with the help of distance matrix. The purpose of the distance matrix is to indicate whether or not a pair of nodes has a connection between them and in case of connectivity it gives the estimated distance between the nodes. By using the information of connectivity between the nodes and their respective distances the topology of the nodes is calculated. This method is heuristic because it uses the point solution from the intersection of two circles instead of conventional triangulation method, where a system of three quadratic equations in two variables is used whereby the computational complexity of the position estimation method is increased. When two connected nodes have another node in common, then by using the information of distances between these interconnected nodes, two possible positions are calculated for the third node. The presence or absence of a connection between the third node and a fourth node helps in finding the accurate possibility out of the two. This process is iterated till all the nodes have been relatively placed. Once the relative topology has been calculated, we need to find the exact symmetry, orientation, and position of this topology in the plane. It is at this moment the knowledge of three nodes positions comes into action. From the relative topology we know the temporary coordinates of the nodes. By having a comparison of certain characteristics between the temporary coordinates and the exact coordinates; first the symmetry of relative topology is obtained that would correspond to the original topology. In other words it tells whether or not the relative topology is a mirror image of the original topology. Some geometrical operators are used to correct the topology position and orientation. Thus, all the nodes in the WSN are localized using exactly three anchors. The last part of the thesis focuses on the detection of faults in a WSN. There is always a possibility that a sensor of a node is not giving accurate measurements all of the time. Therefore, it is necessary to find if a node has developed a faulty sensor. With the precise information about the sensor health, one can determine the extent of reliance on its sensor measurement. To equip a node with multiple sensors is not an economical solution. Thus the sensor measurements of a node are modeled with the help of the fuzzy inference system (FIS). For each node, both recurrent and non-recurrent systems are used to model its sensor measurement. An FIS for a particular node is trained with input variables as the actual sensor measurements of the neighbor nodes and with output variable as the real sensor measurements of that node. The difference between the FIS approximated value and the actual measurement of the sensor is used as an indication for whether or not to declare a node as faulty

Made available in DSpace on 2016-04-04T18:31:41Z (GMT). No. of bitstreams: 1 Daniel Braga Barros.pdf: 1635481 bytes, checksum: ec710a6205eb45d3f4d04f3be0f51c33 (MD5) Previous issue date: 2014-12-12 / This paper presents a study of the radio frequency signals variations influencing people in order to identify relevant relationships between the occupancy rate of a closed environment and the RSSI (Received Signal StrengthIndicator) inside of it. The achievement of spatial occupation noninvasively enables increased service quality in several areas. In this paper are shown experimental tests that enabled the verification of a second order model that provides the number of people within an environment, and the variance and the average signal intensity as a parameter are presented. From the installation of a wireless IEEE 802.15.4 sensor wire in a classroom network data power variation of communication signals positioned between the line of sight inside the room sensors were collected. The results show an increasing trend of the variance of RSSI and a decrease of the average of the same index, both increase in proportion to the number of people in the environment.The model obtained in this work enables the achievement of spatial occupation, defined by the number of students present, with less than two people error. After the results it was observed that the use of the RSSI reading sensor networks can serve as a type of omnidirectional sensor capable of performing the volumetric reading of the environment in terms of occupation. This study can to base future applications for Wi-Fi devices; this is a fairly widespread technology. / Este trabalho apresenta um estudo das varia??es de sinais de r?dio frequ?ncia na influ?ncia das pessoas, objetivando identificar rela??es relevantes entre a taxa de ocupa??o de um ambiente fechado e a RSSI (Received Signal StrengthIndicator) no interior do mesmo. A obten??o do n?vel de ocupa??o espacial de maneira n?o invasiva possibilita o aumento da qualidade de servi?o em diversas ?reas. Nesse trabalho s?o apresentados testes experimentais que possibilitaram a verifica??o de um modelo de segunda ordem que fornece o n?mero de pessoas dentro de um ambiente, tendo a vari?ncia e a m?dia da intensidade de sinal como par?metro. A partir da instala??o de uma rede sensor sem fio padr?o IEEE 802.15.4 em uma sala de aula, foram coletados dados da varia??o de pot?ncia dos sinais de comunica??o entre os sensores posicionados em linha de visada no interior da sala. Os resultados obtidos apresentaram uma tend?ncia de crescimento da vari?ncia do RSSI e, um decrescimento da m?dia deste mesmo indicador, ambos proporcionais ao aumento do n?mero de pessoas no ambiente. O modelo obtido neste trabalho possibilitou a obten??o da ocupa??o espacial, definida pelo n?mero de alunos presentes, com um erro menor que duas pessoas. A partir dos resultados observou-se que a utiliza??o da leitura da RSSI em redes de sensores, pode servir como um tipo de sensor omnidirecional capaz de realizar a leitura volum?trica do ambiente, em termos de ocupa??o. Este estudo pode embasar futuras aplica??es para os dispositivos Wi-Fi, sendo esta uma tecnologia bastante disseminada.

Made available in DSpace on 2016-04-04T18:31:42Z (GMT). No. of bitstreams: 1 LUCAS AUGUSTO DE ARAUJO MARQUES LEAO.pdf: 1843994 bytes, checksum: 99d00d63745d6c077be1b0e0f8b0d518 (MD5) Previous issue date: 2015-05-12 / Wireless Sensor Networks (WNS) have been applied as monitoring solution for building management systems. The sensors are responsible for monitoring environment aspects such as temperature, lighting and energy consumption. However, the sensors are exposed to adverse conditions and frequent environment changes, which can dramatically affect communication and data flow. Thus, this work proposes a routing algorithm based on fuzzy logic to identify the best routes in an indoor wireless sensor network. The evaluated parameters are presented (RSSI, Standard Deviation and Packet Error Rate) along with the cost definition process for each route, the best route identification sequence and the results obtained in simulation and experimentation. The proposed solution mixes WSN routing techniques along with fuzzy logic to characterize and define the link cost. The developed algorithm was faced with a routing solution based on RSSI. The experiments demonstrate that the solution allows the selection of higher quality links, reducing the probability of packet loss in comparison to the algorithm based on RSSI. / As Redes de Sensores Sem Fio (RSSF) t?m sido uma solu??o amplamente utilizada no contexto de sistemas de gerenciamento de edifica??es. Os sensores s?o respons?veis por monitorar diversos aspectos do ambiente, como temperatura, ilumina??o e consumo de energia. Entretanto, os sensores est?o expostos a condi??es adversas e mudan?as constantes do ambiente, que podem afetar de maneira definitiva a comunica??o e flu?ncia dos dados. Neste sentido, este trabalho apresenta uma proposta de algoritmo de roteamento baseado em l?gica difusa para identifica??o dos melhores caminhos em uma rede de sensores sem fio indoor. S?o apresentados os par?metros utilizados (RSSI, Desvio Padr?o do RSSI e Taxa de Erro de Pacote) para a defini??o do custo de cada caminho, a sequ?ncia de identifica??o de melhor caminho e os resultados obtidos em simula??o e aplica??o pr?tica. A solu??o proposta agrega t?cnicas de roteamento em RSSF ? utiliza??o de l?gica difusa para caracteriza??o e defini??o dos custos dos enlaces entre os sensores. O algoritmo desenvolvido foi confrontado com uma solu??o de roteamento baseada em RSSI. Os experimentos demonstram que a solu??o permite a sele??o de enlaces de melhor qualidade, reduzindo a probabilidade de perda de pacote em compara??o ao algoritmo baseado apenas em RSSI.

[pt] As redes de sensores sem fio se constituem numa área que outorga grandes oportunidades para a oferta de uma série de aplicações inovadoras e com baixo custo. Os dispositivos destas redes são bastantes pequenos e sua fonte de alimentação são baterias. O tempo de vida destas é limitado, limitando assim o tempo da vida dos sensores e da rede como um todo. Por esta razão nos últimos anos o tema de eficiência energética tem atraído grande interesse de pesquisadores. O aumento do custo da energia e do consumo global da energia pelo setor de ICT (Information and Communications Technologies) têm crescido vertiginosamente devido ao aumento continuo do número de clientes e da demanda por aplicações de maior complexidade. Por tudo isso têm sido desenvolvidos distintos métodos e técnicas para economizar energia nas RSSF. Neste trabalho se implementam dois algoritmos que levam em conta critérios para economizar os custos de energia da rede e através de experimentos de simulação se avalia os mesmos. Nos resultados pode se observar as vantagens de trabalhar com sistemas que visam a eficiência energética. / [en] The WSNs (Wireless Sensor Networks) belong to an area that gives rise to great opportunities to spread innovative and low cost applications. These kinds of networks are composed of tiny devices with limited energy. The main source of power supply for WSNs are batteries, which are limited in cycle life, thus limiting the sensors lifetime and the network as a whole. Due to that fact, the energy efficiency network is becoming the main concern to be addressed by researchers. Rising energy prices and global energy consumption by the ICT (Information and Communications Technologies) sector have grown dramatically due to the continuous increase in customer number and the demand for more complex applications. For the reasons outlined above, different energy-saving techniques for WSNs have been developed. Two energy-saving algorithms for WSNs were implemented in this thesis, and they were tested by experimental evaluation using simulation. The results obtained from the simulations showed the advantages of working with systems aiming at energy efficiency.