Sharif Digital Repository

Wireless Sensor Networks (WSNs) consist of sensor nodes that are connected to each other and are widely used in many applications to acquire and process information. WSN nodes are battery powered, therefore energy management is a key factor for long live network. Node radio transceiver unit uses the most part of energy resource of the node and as a result limits the network lifetime. One way to prolong lifetime of network is to utilize routing protocols to manage energy consumption. To have an energy efficient protocol, we can apply cluster organization on the network, where sensor nodes are partitioned into groups called cluster. Then, the whole cluster data is sent through Cluster Head... 

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... 

Reducing energy consumption is one of the challenges facing wireless sensor networks with many solutions introduced for them with each having advantages and disadvantages. Some of the solutions introduced are based on using movable sinks. In this project, we attempt at proposing a place for the establishment of sinks using genetic algorithm that can reduce energy consumption in the net knots and increase the net life. This work should be done after reviewing the results of past researches and introduced methods. We will analyze the practicality of the proposed model using simulation and will show their advantages over the previous mentioned methods  

A large number of sensors are spread for monitoring of an area in a random manner. The aim is to have an efficient design for energy that can protect the coverage of the area. A number of sensor nodes that have high density and which are in the area have the duty of monitoring of the area. The aim of this process is to determine of maximum number of separate collections that they have a direct influence upon the life span of the network. The idea behind this approach is that the nodes in areas with low availability are less used as a data routing as well as nodes that have remaining energy. In order to reach this objective, the importance of each sensor node for its duty of protecting... 

Wireless Sensor Network (WSN) is a set of cheap wireless sensors that can collect, process and send environment’s data. WSN nodes are battery powered, therefore energy management is a key factor for long live network. One way to prolong lifetime of network is to utilize routing protocols to manage energy consumption. To have an energy efficient protocol, we can apply ZigBee protocols. ZiBgee standard is originated from IEEE802.15.4 standard that is defined for personal wireless networks with low bit rate. Now there are many different routing methods that are defined for ZigBee networks that have applications in different circumstances. These methods usually have been proposed in the network... 

Sensor networks is a set of sensors (nodes) which are communicating with each other, and gather information from different environments, and process them to give us valuable results. Sensors have a small energy source like a small battery which have to be used efficiently. Congestion detection and avoidance, together are of great importance in Wireless Sensor Networks (WSNs) in case of traffic load, data loss, and power consumption. In this work, we propose a new APS layer (application support sub-layer), which is another key standard component of Application layer, offering a well-defined interface and several control services. It functions as a bridge between the network layer and other... 

Node localization is an important issue in dynamic environments for location-dependent applications of Wireless Sensor Networks (WSNs). Geographical location information is necessary in many WSN applications. The goal of localization algorithm is to assign geographical coordinates to each unknown node position. Among different localization algorithms, DV-hop is one of the well- known algorithms. DV-hop algorithm is a range-free algorithm and has significant error in node location estimation. Since the node deployment is stochastic, minimizing this error has a critical role in location estimation accuracy of the algorithm. Increasing communication radius and number of anchors, to the certain... 

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 network (WSN) is a wireless network composed of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions data such as temperature, pressure, humidity, and so on[1-4]. In recently years, WSN has been applied to widely various areas. Since sensors are equipped with small batteries, which are costly if not impossible to recharge or replace, sensor network operations must be energy efficient in order to maximize the network lifetime. Given the power constraints in sensors, investigations into routing protocols in order to extend the... 

Wireless Sensor Networks (WSNs) are comprised by number of sensor nodes, which collect data and transmit them to the sink node, the battery of sensor nodes is limited and this issue appeals the attention of researchers to attempt to improve the energy consuming of sensor nodes in order to prolong the lifetime of networks. Circumstance of routing affects the lifetime of network. Researches have proved the efficiency of Clustering in routing protocols in WSNs. It is notable that the importance of CH selection is undeniable. In this thesis we have worked on the CH election and CH rotation of hybrid method, which utilizes Compressive Sensing (CS) in inter-cluster transmission. We have proposed... 

Wireless Sensor Networks (WSNs) consist of few hundred to thousand sensor nodes that are usually deployedrandomly in a sensing field. The duty of sensor nodes is to sense the environment for data collection and sending these data to a sink node for future processes. Sensor nodes are equipped with a non-rechargeable battery. Hence, network lifetime is an important issue in WSNs. When a static sink node is used in a WSN, sensor nodes that are located in the neighborhood of the sink node willdrain out of energy faster than other sensor nodes which are farther away from the sink node, because traffic load is heavier on sensor nodes which are closer to the sink node. This problem is named “the... 

Wireless Sensor Networks (WSNs) are prone to faults due to battery depletion of nodes, where a node failure can disturb routing, as it plays a key role in transferring sensed data to the end users. A WSN may be partitioned into groups of nodes called clusters; for every cluster, there is a node, called Cluster Head (CH) that is responsible for collecting and transferring data from all nodes in that cluster. This means that the CH is a single point of failure; i.e., once a CH fails, the whole cluster will fail, which leads to inability of its members for transferring data outside the cluster. This thesis presents a Fault-Tolerant and Energy-Aware algorithm (FTEA), which prolongs the lifetime... 

Wireless sensor networks (WSNs) consume energy for their sensing, computation, and communication. To extend the lifetime of the network, sensor nodes are equipped with energy storage devices. Recharging their batteries is impossible in most applications. Therefore, energy consumption needs to be monitored and be limited to extend the high performance operation of the network. In this network, the communication module consumes the highest amount of energy. While several methods are proposed to reduce the energy consumption, data compression is one of the most effective ways for energy management by reducing the number of bits to be broadcast. To determine the energy efficiency of the... 

Nowadays Wireless Sensor Networks are used in different situations such as greenhouse, agriculture, military applications and etc. The problem of Wireless Sensor Network is that the sensor nodes have limited the energy source. Besides, the power source of sensor nodes is not rechargeable or replaceable. So, one of the main challenges in Wireless Sensor Networks is saving energy. Whereas, most power is consumed due to transmissions, recently a lot of activities have been accomplished in order to reduce transmission times. In this thesis we have focused on a network coding method which is called Sensecode. Sensecode is a technique for reducing communications between nodes. Actually network... 

Most of the current routing protocols in the WMSNs only consider the inter-path interference and not necessarily intra-path interference factor which is considered as one of the main causes of energy consumption in these networks. Among those protocols that consider this factor, none of them has ever come up with an algorithm capable of performing the routing without the need to use either the special hardware in the nodes (referred to as the GPS or directional antennas) or with the unrealistic assumption that the interference range is equal to the transmission range. The previously mentioned factors are critical in the sense that the former assumption results in more expensive sensor nodes... 

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... 

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... 

Most of current the MAC protocols for Wireless Sensor Networks (WSNs) concern about energy efficiency rather than low latency. The main source of energy consumption in the MAC layer is idle listening, and most of these protocols use duty cycling for reducing energy consumption. But duty cycling method increases packet delivery latency. This problem is very critical in real time applications where packets should meet their deadline. There are some solutions for this problem. For example a node forwards data packets multi hop away instead of one hop in a single cycle. In this research, an efficient cross layer MAC protocol for real time applications is proposed. In this protocol multi hop... 

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... 

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...