Sharif Digital Repository

Recent advances in Micro-Electro-Mechanical Systems (MEMS) technology, wireless communications,and digital electronics have enabled the development of low-cost, low-power,multifunctional sensor nodes that are small in size and communicate untethered in short distances.Wireless Sensor Network (WSN) including these sensors has been utilized in many applications, namely military and environmental applications. Due to unchangeable battery in most WSNs, Power consumption is an important challenge in such systems. A sensor node expends maximum energy in data communication. Control environmental parameter is among the most important applications of WSN. The actual physical environmental information... 

Recent advancements in wireless communications and also a tendency to use low cost, tiny, and autonomous high performance products have led to the emergence of wireless sensor networks (WSNs). As the main source of power in a sensor node is a limited and irreplaceable battery, energy is the main important issue. Data aggregation, as an in-network processing method, is a promised technique aiming to conserve energy by reducing the number of packet transmissions through the network. It is a key, yet time-consuming functionality in WSNS, where we hold packets in intermediate nodes to promote aggregation efficiency. However, the requirement of real-time communications is becoming more and more... 

To make Wireless Multimedia Sensor Networks (WMSNs) more practical, researchers have tried to meet its challenges in the last decade. Some factors of WMSNs, such as low bandwidth and channel errors, cause a decrease in the video quality that is declared as distortion. On the other hand, one important requirement in the context of multimedia streaming is its quality. In this thesis, we first introduce and use an adaptive cross-layer error control in the link layer, and then we implement a new cross-layer source rate control Mechanism for efficient and reliable real-time multimedia streaming in wireless sensor networks. Our main objective is to minimize distortion. Some of the used cross-layer... 

Nowadays, Wireless Sensor Networks (WSNs) play a role in the field of information technology for data gathering purposes. In general, each WSN contains many inexpensive wireless nodes, each capable of collecting, processing, and storing environmental information, and communicating with neighboring nodes. WSNs have been successfully used in different applications such as object tracking, emergency guiding, and environment monitoring. The popular WSN platforms in real-world applications are MICAz, Tmote , and Dust Network. Two standards, namely the ZigBee and IEEE 802.15.4 standards are projected to provide interoperability of different platforms, and to define physical, MAC, and network... 

Wireless Sensor Networks (WSNs) are rapidly emerging as an important area in mobile computing research. Applications of WSNs are numerous and growing, some of them are even highly critical, like military or safety applications. Security measures must be applied to protect the network from a variety of attacks. Since no intrusion prevention measure is perfect, intrusion detection becomes an important second wall to protect the network. WSNs have unique nature which is different from other kinds of networks. In this project, we examine the characteristics and vulnerabilities of WSNs and propose a new intrusion detection model to protect the network security. In this work we have not only... 

Congestion in Wireless Sensor Networks (WSNs) leads to both packet loss and excessive energy consumption. That is why congestion has to be controlled during the life of a WSN. One of the go well protocols that has tried to tackle congestion in WSNs is PCCP. PCCP utilizes a cross-layer optimization, imposes a hop-by-hop approach and achieves efficient congestion control; however it has got its own shortcomings. Here we have carried out a survey on congestion problem and have proposed a solution called Modified PCCP to elevate the performance of PCCP by making some changes in the scheduler which is designed in the cross layer. Using this model the congestion is controlled and the PCCP protocol... 

Wireless Sensor Networks (WSNs) have attracted much attention in recent years for their unique characteristics and wide use in many different applications. WSNs are composed of many tiny sensor nodes that have limitations on energy level, bandwidth, processing power and memory. Therefore, reducing energy consumption and the increased network lifetime and scalability are the main routing challenges in sensor networks. Many algorithms were presented for routing in sensor networks; a class of theses algorithms is hierarchical algorithms based on clustering. Their main goals are to reduce energy consumption, distribution energy consumption in the whole network and increasing scalability. There... 

Wireless Sensor Network (WSN) is a rapidly growing technology that is used to meet different requirements of a wide range of applications. Energy conservation is one of the main design challenges in WSNs due to limited energy resources. Routing plays a significant role for energy efficient communication in WSNs. Although there are many research studies that utilize energy efficient routing to conserve energy in WSNs, there are a few works that took advantage of machine learning techniques for saving energy through energy efficient routing.The main goal of this thesis is to indicate that machine learning is a functional approach to many problems in WSNs. To fulfill this goal we first... 

A Wireless Sensor Network is one of the attended research context that is used to meet different requirements of a wide range of applications. One of the usages of WSNs is in Animal Tracking. Many Animal Tracking methods have weaknesses that can be enhanced. By considering WSN properties and many different usages of Machine Learning techniques reported in a variety of fields and considering Animal Tracking methods characteristics, WSNs can be improved by applying Machine Learning techniques. The main goal of this thesis is to show that with help of Machine Learning techniques, performance of Animal Tracking by means of Wireless Sensor Networks increases. To fulfill this goal, we first... 

Wireless sensor networks consist of many small sensor nodes which suffer from some limitations like energy level, band width, processing ability and memory; therefore, decreasing energy consumption, increasing network lifetime and scalability are the main challenges in the area of routing in wireless sensor networks. In the field of routing in sensor networks, many algorithms have been suggested, one group of which is clusterbased hierarchical algorithms. The main goals of such algorithms are reducing energy consumption, distributing consumed energy within whole network and increasing scalability of algorithm. There are some problems in most of cluster-based routing algorithms which cause... 

Wireless sensor networks have a wide range of applications in the world. In most of the applications, collected data is not usable without the knowledge about the localization of events. There are two approaches to specifying the location of a sensor: using hardware solutions such as GPS, which is an expensive solution, and using the localization algorithm. Therefore, localization has an important role in sensor networks. Most of the current localization algorithms are non-adaptive and proposed for fixed wireless sensor networks. Recently, adaptive localization algorithms have been considered because of their simple implementation, fast result and low computation overhead for each node. In... 

Recent advances in miniaturization and low power design have led to a flurry of activity in wireless sensor networks (WSNs). Sensor networks have different constraints than traditional wired networks. A wireless sensor network is a special network with large numbers of nodes equipped with embedded processors, sensors, and radios. These nodes collaborate to accomplish a common task such as environment monitoring or asset tracking. Many of these applications interface with real world environments and delivery of data is subject to certain constraints. So It is often necessary for communication to meet real-time constraints. Most existing real-time protocols don’t use packet scheduling schemes... 

Recently there is a huge growth in industrial automation. Industrial automation is defined as trying to do some tasks automatically and without direct human intervention. Using industrial automation may help increasing efficiency, quality and safety. Industrial automation also could increase Competitiveness and flexibility of industries. In human life there is a large area of activities that automation could be used and different industries like oil and gas companies, electrical generation and distribution industries, medical companies, textile and other industries could use automation to increase their efficiency. But recently there is a growing demand for building automation and home...