Oliveira, Camila Helena Souza. Gerenciamento Autonômico de Energia em Redes de Sensores Sem Fio Através do Escalonamento de Atividade dos Nós. 2011. 103 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências, Departamento de Computação, Fortaleza-CE, 2011. / Submitted by guaracy araujo (guaraa3355@gmail.com) on 2016-06-07T17:01:05Z No. of bitstreams: 1 2011_dis_chsoliveira.htm: 516 bytes, checksum: 5f53d35c4f0938cf35fd9c5325cc0b3c (MD5) / Approved for entry into archive by guaracy araujo (guaraa3355@gmail.com) on 2016-06-07T17:01:23Z (GMT) No. of bitstreams: 1 2011_dis_chsoliveira.htm: 516 bytes, checksum: 5f53d35c4f0938cf35fd9c5325cc0b3c (MD5) / Made available in DSpace on 2016-06-07T17:01:23Z (GMT). No. of bitstreams: 1 2011_dis_chsoliveira.htm: 516 bytes, checksum: 5f53d35c4f0938cf35fd9c5325cc0b3c (MD5) Previous issue date: 2011 / he evolution and development of new devices, increasingly cheaper and more efficient, expanded the use of Wireless Sensor Networks (WSN) and encouraged the creation of new applications in the contemporary scenery of Ubiquitous and Pervasive Computing. However, energy limitation remains a challenge in the field of WSN. This situation is aggravated even more by the infeasibility of energy recharge since, in many cases, WSN are used in inaccessible enviroments. With cheapness devices used in WSN, became easier to employ dense and large-scale networks in environments that will be monitored. The use of dense networks, which have a high degree redundancy of nodes, allows the network remains functional even with the exhaustion of some nodes. In addition to provide fault tolerance, the use of very dense networks offer the opportunity of implementing scheduling mechanisms for redundant nodes, in a way that the network lifetime is even better optimized. Assuming a scenery with very dense networks, this dissertation describes the implementation of an autonomic scheduling mechanism, simple, robust and scalable, in order to further improve the results already presented by BiO4SeL, which is a routing protocol based on Ant Colony and designed to maximize the network lifetime. The results show that the new scheduling scheme effectively improves the WSN lifetime based on BiO4SeL in dense scenarios. / A evolução no desenvolvimento de novos dispositivos, cada vez mais baratos e eficientes, expandiu o uso das Redes Sensores Sem Fio (RSSF) e incentivou a criação de novas aplicações, no cenário contemporâneo da Computação Ubíqua e Pervasiva. No entanto, a limitação de energia continua sendo um desafio na área de RSSF. Essa situação é agravada ainda mais pela a inviabilidade de recarga de energia já que, em muitos casos, as RSSF são utilizadas em ambientes inacessíveis. Com o barateamento dos dispositivos utilizados nas RSSFs, ficou mais fácil empregar redes muito densas e de larga escala nos ambientes a serem monitorados. O emprego de redes densas, que apresentam alto grau de redundância dos nós, permite que a rede continue funcional mesmo com a exaustão de alguns nós. Além de oferecer tolerância a falhas, o uso de redes muito densas oferece a oportunidade da implementação de mecanismos de escalonamento dos nós redundantes, de forma que o tempo de vida da rede seja ainda melhor otimizado. Assumindo um cenário com rede muito densas, este trabalho descreve a implementação de um mecanismo de escalonamento autonômico, simples, robusto e escalável, com o objetivo de melhorar ainda mais os resultados já apresentados pelo BiO4SeL, um protocolo de roteamento baseado em Colônia de Formigas e desenvolvido para maximizar o tempo de vida da rede. Os resultados mostram que o novo esquema de escalonamento efetivamente melhora o tempo de vida de uma RSSF baseada no BiO4SeL em cenários densos.

Sensor nodes in a wireless sensor network (WSN) have a small, non-rechargeable power supply. Each message transmission or reception depletes a sensor node’s energy. Many WSN applications are ad-hoc deployments where a sensor node is only aware of its immediate neighbours. The lack of a predefined route path and the need to restrict the amount of communication that occurs within the application area impose constraints on WSNs not prevalent in other types of networks. An area of active research has been how to notify the central sink (or monitoring hub) about an event in real-time by utilising the minimum number of messages to route a message from a source node to the destination sink node. In this thesis, strategies to limit communication within a WSN application area, while ensuring that events are reported on and responded to in real-time, is presented. A solution based on modelling a WSN as a small world network and then transmitting an initialisation message (IM) on network start-up to create multiple route paths from any sensor node to one or more sinks is proposed. The reason for modelling a WSN as a small world network is to reduce the number of nodes required to re-transmit a message from a source sensor node to a sink. The purpose of sending an IM at network start-up is to ensure that communication within the WSN is minimised. When routing a message to a static sink, the nodes closest to the static sink receive a disproportionate number of messages, resulting in their energy being consumed earlier. The use of mobile sinks has been proposed but to our knowledge no studies have been undertaken on the paths these mobile sinks should follow. An algorithm to determine the optimum path for mobile sinks to follow in a WSN application area is described. The purpose of an optimum path is to allow more equitable usage of all nodes to transfer an event message to a mobile sink. The idea of using multiple static sinks placed at specific points in the small world model is broadened to include using multiple mobile sinks called actors to move within a WSN application area and respond to an event in real-time. Current coordination solutions to determine which actor(s) must respond to the event result in excessive message communication and limit the real-time response to an event. An info gap decision theory (IGDT) model to coordinate which actor or set of actors should respond to the event is described. A comparison of the small world routing (SWR) model against routing using flooding and gossiping shows that the SWR model significantly reduces the number of messages transmitted within the network. An analysis of the number of IMs transmitted and received at individual node level shows that prudent selection of the hop count (number of additional nodes required to route a message to sink) to a sink node will result in a reduced number of messages transmitted and received per node within the network. The use of the IGDT model results in a robust decision on the actor(s) chosen to respond to an event even when uncertainty about the location and available energy of other actor(s) exists. / Thesis (PhD(Eng))--University of Pretoria, 2012. / Electrical, Electronic and Computer Engineering / unrestricted