Sharif Digital Repository

Sensor Networks are set of devices which are distributed throughout an environment and are connected to each other, usually wirelessly, to collect environmental information including temperature, aire pressure, moist, pollution and physiological functions of the human body. Each device consists of a microprocessor, converter and power supply, transmitter and a receiver. In this study we intend to investigate such setup and the measured signals assuming they are sparse. A sparse signal is a discrete time signal most of indices of which are equal to zero. With this assumption at hand, we will be able to reduce the sampling rate and take advantage of sparse signal processing techniques. This... 

This study aims to identify the structural damage using deep learning. Damage to structures reduces their lifespan. Therefore, continuous monitoring of structures is necessary to detect any possible damages that occurred due to various causes. Structural health monitoring systems that use wired sensors to measure signals are costly and time-consuming to install. Whereas, wireless sensor-based damage detection systems are relatively cost-effective. However, one of the most important problems in using them is the loss or non-recording of some data, which severely affects the accuracy of a structural damage detection system. On the other hand, health monitoring using machine learning-based... 

Wireless sensor networks (WSN) is a new technology, foreseen to be used increasingly in the near future, and security is an important issue for it. However because of nodes resource limitations, other schemes proposed for securing general ad hoc networks, are not appropriate for WSNs. Usually some nodes act maliciously and they are able to do different kinds of DoS attacks. In order to make the network more secure, malicious nodes should be isolated from the network. In this thesis, we model the interaction of nodes in WSN and intrusion detection system (IDS) as a Bayesian game formulation and use this idea to make a secure routing protocol. By this approach nodes are motivated to act... 

One of the basic characteristics of Wireless Sensor Networks is their resource limitations. As a result, it is essential to try to decrease costs in such networks. These limitations are more critical in transmitting multimedia data with larger data units. In addition, when transmitting real-time multimedia data, delay is an important factor to consider. According to these limitations, Wireless Multimedia Sensor Networks are congestion prone. In this thesis, a transport layer protocol has been proposed. This protocol consists of three three steps in handling congestion. First, it detects congestion according to the queue length in the node. If the lsength is greater than a minimum threshold,... 

Wireless sensor networks (WSNs) can be used in a variety of applications. The prime shortcoming of these networks is their energy constraint. The main energy consumer in a sensor node is its radio transmitter. Therefore data prediction is one of the most effective methods to reduce the data transmission rate. By data prediction, a large amount of energy is saved; which results in the longevity of the network life. Environmental variations almost have similar effects on different sensor sources in a sensor device. So, considering the correlation between different sources reduces the noise impact and increases data prediction accuracy. In this thesis, we use temporal and multisource... 

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... 

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 networks (WSNs) use many tiny sensors to monitor phenomena such as temperature, humidity, brightness and traffic, and then transmit this information to a base station using wireless channels. WSNs find applications in military, ecological, urban and health related areas. Hierarchical wireless sensor networks are kind of sensor networks that use communication entities with different capabilities in terms of energy, processing power, bandwidth, communication range and etc. In this thesis, an introduction to WSNs and their applications, characteristics and designing factors is expressed. It continues on studying the infrastructures and the role of cryptography in enhancing... 

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 (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... 

Today with growth of wireless communications and progress of small and cheap sensors which have capability of communication and calculation, wireless sensor networks are important and useful topic. But due to energy restrictions, efficient use of resources and increasing network lifetime, have been considered as key factors in network design. In this regard, using efficient multicast routing in energy consumption, for an efficient data transmission to specific number of nodes instead of all nodes code updates, information requests, task assignments and etc., is necessary.On the other hand these networks use unlicensed spectrum and suffer from collision due to congestion caused by other... 

Nowadays Wireless Sensor Networks (WSNs) are found in a variety of applications such as environmental monitoring, military surveillance and medical systems. These applications interface with the real world environments and the delivery of data is subject to certain timing constraints. Most of the protocols being used in the WSNs do not satisfy real-time requirements and only deliver data in a best-effort fashion. However, real-time support in the WSNs remains an open research topic. This dissertation first studies real-time application and then real-time approaches in WSNs. Real-time applications are applications that require bounded service time. Normally in WSNs, communication delays are... 

With improving of technology, using of Wireless Sensor Networks (WSN) is rapidly increasing. In some application, wireless sensor network do need to supply realtimeness. In the other hand, in many cases, sensor networks are in risky environments distributed. Therefore, security is a key factor in sensor networks to performing their works properly optimized and maximum. Hence, both security and realtimeness features are important features of sensor networks. But because of common resource use, increasing efficiency of a feature will result in decreasing efficiency of other feature. In this thesis, we indicated to study mutual effect of security and realtimeness in Wireless Sensor Networks in... 

Recently, advances in the fabrication and integration of sensing, communication technologies and economical deployment of large scale sensor networks which are capable of large scale target tracking, become possible.therfore, the wireless sensor networks are a fast growing and marvelous research area that has attracted considerable research attention in the recent past. The creation of large-scale sensor networks interconnencting several hundered to a few thousand sensor nodes opens-up several wide range of application and technical challenges. Sensor nodes have been deployed to play significant roles in battlefield, disaster-prone area, traffic control, habitat monitoring and intruder... 

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... 

Nowadays wireless technology is widespread all over the world, because of extensive and successful application of low cost, low power, multifunctional tiny sensor nodes that can be grouped to make up of a wireless sensor network (WSN). Some of Wireless sensor network technologies include Zigbee, EnOcean, Personal area network, Ultra-Wideband and Bluetooth which this thesis focuses on the last one. Scalability, mobility, reliability and energy efficiency are some of the requirements and challenges of WSNs, which among them reliability and reducing energy consumption are two important objectives in wireless sensor networks. Since each sensor node has limited energy to consume, overcoming the...