Abstract-Recent developments in processor, memory and radio technology have enabled wireless sensor networks which are deployed to collect useful information from an area of interest. The sensed data must be gathered and transmitted to a base station where it is further processed for end-user queries. Since the network consists of low-cost nodes with limited battery power, power efficient methods must be employed for data gathering and aggregation in order to achieve long network lifetimes.In an environment where in a round of communication each of the sensor nodes has data to send to a base station, it is important to minimize the total energy consumed by the system in a round so that the system lifetime is maximized. With the use of data fusion and aggregation techniques, while minimizing the total energy per round, if power consumption per node can be balanced as well, a near optimal data gathering and routing scheme can be achieved in terms of network lifetime.So far, besides the conventional protocol of direct transmission, two elegant protocols called LEACH and PEGASIS have been proposed to maximize the lifetime of a sensor network. In this paper, we propose two new algorithms under name PEDAP (Power Efficient Data gathering and Aggregation Protocol), which are near optimal minimum spanning tree based routing schemes, where one of them is the power-aware version of the other. Our simulation results show that our algorithms perform well both in systems where base station is far away from and where it is in the center of the field. PEDAP achieves between 4x to 20x improvement in network lifetime compared with LEACH, and about three times improvement compared with PEGASIS.

Wireless sensor networks have a broad range of applications in the category of environmental monitoring. In this thesis, we consider the problem of forest fire detection and monitoring as a possible application area of wireless sensor networks. Forest fires are one of the main causes of environmental degradation nowadays. The current surveillance systems for forest fires lack in supporting real-time monitoring of every point of the region at all time and early detection of the fire threats. Solutions using wireless sensor networks, on the other hand, can gather temperature and humidity values from all points of field continuously, day and night, and, provide fresh and accurate data to the fire fighter center quickly. However, sensor networks and nodes face serious obstacles like limited energy resources and high vulnerability to harsh environmental conditions, that have to be considered carefully.In our study, we propose a comprehensive framework for the use of wireless sensor networks for forest fire detection and monitoring. Our framework includes proposals for the wireless sensor network architecture, clustering and communication protocols, and environment/season-aware activity-rate selection schemes to detect the fire threat as early as possible and yet consider the energy consumption of the sensor nodes and the physical conditions that may hinder the activity of the network. We also implemented a simulator to validate and evaluate our proposed framework, which is using an external fire simulator library. We did extensive simulation experiments and observed that our framework can provide fast reaction to forest fires while also consuming energy efficiently. Kablosuz duyarga agları kullanılarak dogal ortamların izlenmesiüzerine biŗ cok uygulama alanı geliştirilmiştir. Bu tezçalışmamızda, bizler de orman yangınlarının erken tespitinde ve yangının izlenmesi sürecinde kablosuz duyarga aglarını kullanarak bir sistem tasarladık. Orman yangınları dünyadaçevresel tahribata neden olan başlıca sebeplerden biridir. Şu anki yangın gözetleme ve takip sistemleri ormanları anlık olarak bütünüyle izleme ve olası bir yangın tehlikesiniönceden tespit etme konusunda başarısız olmaktadır.Öte yandan, kablosuz duyarga aglarını kullanarak geliştirilençözümler sıcaklık ve nem degerlerini, anlık olarak, sahanın farklı noktalarından, gece ve gündüz farketmeksizin sürekli olarak alabilmekte ve de merkezi birimlere taze ve güvenilir bilgi sunabilmektedir. Fakat, duyarga aglarında kullanılan duyarga dügümleri kısıtlı enerji kaynaklarına sahiptir ve zorlu dış koşullara karşı dayanıklı degillerdir. Geliştirilen uygulamalarda bu engellerin dikkatli birşekilde ele alınması gereklidir.Tezçalışmamızda kablosuz duyarga aglarını kullanarak orman yangınlarını erken tespit etmek ve izleyebilmek amacıyla geniş kapsamlı bir sistem geliştirdik. Sundugumuz sistem kablosuz duyarga aglarıyla ilgili bir ag altyapısı, dügümlerin ormana yerleştirilmesi ile ilgiliözel bir mekanizma ve dügümlerin küme içi ve kümeler arası iletişim protokollerini içermektedi...

This paper introduces an adaptive, energy-aware and distributed fault-tolerant topologycontrol algorithm, namely the Adaptive Disjoint Path Vector (ADPV) algorithm, for heterogeneous wireless sensor networks. In this heterogeneous model, we have resource-rich supernodes as well as ordinary sensor nodes that are supposed to be connected to the supernodes. Unlike the static alternative Disjoint Path Vector (DPV) algorithm, the focus of ADPV is to secure supernode connectivity in the presence of node failures, and ADPV achieves this goal by dynamically adjusting the sensor nodes' transmission powers. The ADPV algorithm involves two phases: a single initialization phase, which occurs at the beginning, and restoration phases, which are invoked each time the network's supernode connectivity is broken. Restoration phases utilize alternative routes that are computed at the initialization phase by the help of a novel optimization based on the well-known setpacking problem. Through extensive simulations, we demonstrate that ADPV is superior in preserving supernode connectivity. In particular, ADPV achieves this goal up to a failure of 95% of the sensor nodes; while the performance of DPV is limited to 5%. In turn, by our adaptive algorithm, we obtain a twofold increase in supernode-connected lifetimes compared to DPV algorithm.

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