Sharif Digital Repository

Data aggregation is an efficient method to conserve energy by reducing packet transmissions in Wireless Sensor Networks. However, providing end-to-end data reliability is a major challenge when the network uses data aggregation. In this case a packet loss can miss a complete subtree of values, so greatly affect final results. Data transmission in multiple paths can tolerate this problem, but it may incur some computational error for duplicate-sensitive aggregates when aggregating individual sensor values multiple times. In this thesis, we have proposed a reliable data Aggregation protocol which uses the available path redundancy to deliver a correct aggregate result to the sink with a high... 

Due to the advances in wireless communications and electronics over the last few years, the development of networks of low-cost, low-power, and multifunctional sensors has received increasing attention. Most important constraints of this network are energy and bandwidth. Data aggregation is one of the effective approaches for reducing energy consumption in wireless sensor networks. Recent research on data collection reveals that, rather than reporting data through long, multi-hop and error-prone routes to a static sink using tree or cluster network structure, allowing and leveraging sink mobility is more promising for energy efficient data gathering. In this work we proposed an effective... 

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... 

Implement of smart grid has three mail reasons: Energy crisis caused by lake of traditional fuels, climate changes that can bring a lot of difficulties for human and great potentials of renewable energies. There are many diverse concepts in smart grid. Increase power quality, decrease power cuts, increase active consumer participations, effective way r of using distribution generation units are most important advantages of smart grid.I I;.Emerging new technologies are forced smart grid operators using this new technologies. Wireless Sensor Networks are one of these new technologies that can be used in smart gird. In this thesis we are going to study the rule of wireless sensor networks in... 

Wireless sensor networks (WSNs) have recently achieved a great deal of attention due to its numerous attractive applications in many different fields. Sensors and WSNs possesses a number of special characteristics that make them very promising in many applications, but also put on them lots of constraints that make issues in sensor network particularly difficult. These issues may include topology control, routing, coverage, security, and data management. In this thesis, we focus our attention on the coverage problem. Firstly, we study the best current solutions in the literature. We choose one of them as the basis of our work and study it thoroughly as the core model of our coverage model.... 

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... 

In this thesis, our aim was to assess the resource allocation problem in wireless sensor netowroks and to optimize network utility and lifetime. To achieve these aims, it is nesseccary to solve resource allocation problem through optimization methods. Since the central methods need a central node to manage resource allocation, they can not be implemented in sensor networks because the nodes neighbors to this central node drain energy very quickly. Also, since central methods require transmission of all information about network topology to this central node, every change in network topology result in transmission of new network topology informations and therefore, overload for frequent... 

We present a home energy management system that is able to manage home energy demand and resources to achieve minimum household payment in electricity dynamic pricing.Communication is used to collect needed data from the home energy system members and users in order toimprove demand and resources management. Some of the needed data comes from appliances and solar panels by wireless sensor network and some other is received from home users by a user interface.
Two algorithms are proposed that the first algorithm goal is to minimizing household payment and the second algorithm goals are flexible implementiation and decreasing household payment. To decrease household payment, these... 

Wireless networks with the shared media require Medium Access Control (MAC) protocol that provides contention resolution mechanism. The design of MAC protocol is a challenging issue because of limited energy source and high propagation delay in UnderWater Acoustic Sensor Networks (UWASNs). The most important goal of the MAC design for underwater sensor networks is to resolve data packet collision efficiently with respect to energy consumption. So, selection of MAC protocol is an important task because it has significant impact on the system efficiency. A suitable MAC protocol must consider some factors such as fairness, energy consumption, latency and throughput based on various... 

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... 

Due to their specific characteristics such as huge data loads, heavy processes, various quality of service requirements (delay, jitter and reliability), multimedia streams have different necessities in comparison with normal data streams. The challenges of wireless sensor networks (process power, storage capacity and power limitations) add up to the challenges faced in WMSNs. In order to improve the quality of service in wireless multimedia sensor networks, attention must be paid to all the network layers. In this study improvement of quality of service is sought through the design of a protocol for the network layer of the wireless multimedia sensor network.
This protocol tries to... 

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... 

One of the main challenges in the design of wireless sensor networks (WSNs) is minimizing the energy consumption while simultaneously maximizing the performance of sensors. In this thesis, we have considered WSNs based on beacon enabled IEEE 802.15.4/Zigbee Standards with low rate applications like temperature, humidity and light sensing, which mainly have been used in a smart home environment, and proposed a cross-layer design to overcome this challenge. The design involves an optimizer module that captures the application layer and MAC sub layer behaviors. Based on these behaviors, the optimizer dynamically changes the rate of node’s traffic at the application layer and the priority of... 

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... 

Prolonging the lifetime of wireless sensor networks (WSN) is one of the most important goals in the sensor network research. A lot of work has been done to achieve this goal. Since sensor nodes normally have limited resources in terms of energy, bandwidth and computation capability, efficiency is a key design goal in sensor network research. Data aggregation is a very important method to conserve energy by eliminating the inherent redundancy of raw data in dense WSNs. Previous research on data aggregation has demonstrated its effectiveness in reducing traffic, easing congestion and decreasing the energy consumption. However, few are actually designed for a real world application and... 

Energy harvesters are used in today’s Wireless Sensor Networks (WSNs) to harvest the energy from the environment. One of the important advantages of the energy harvesting sensor networks over battery-operated sensor networks is that the use of the energy harvester prolongs the life time of the nodes, while a battery-operated node becomes useless once its energy runs out. Although an energy harvester can provide a supply source with a lifetime much greater than a battery, the amount of available energy for an energy harvesting system is a random variable and is not as predictable as the energy of a battery. This unpredictability may cause reliability problems. In order to solve the existing... 

Recent advances in WSN have led to next generation of it for multimedia transmission which is WMSN. WMSN has several applications like environmental monitoring, advance health care delivery and etc. However, providing QoS requirements of transmitting video data like delay, bandwidth and packet loss with minimum distortion at perceived video quality over WMSN with resource constraints is a challenging problem. Using multipath routing protocol for video communication can increase bandwidth and decrease delay over WMSN. Moreover, all video packets have not the same effect on video distortion. We propose a scheduling mechanism which classifies packets according to their types and contents and... 

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... 

Wireless Sensor Networks (WSN) are wildly utilized in surveillance and controling applications, and because of their remote and standalone operation, lifetime and reliability of a typical WSN are two main concerns in these networks. One of the reliability threatening issues in a WSN is residual accessible energy for each node. Nowadays, energy harvesting systems are used in WSN nodes to catch environmental energy, and reduce the energy limitation. However, because of inherent uncertainty of energy harvesting systems, the networks that operate using environmental energy have new reliability issues. Different rate of energy harvesting, according to environmental conditions, is one of the most... 

WSNs have been gained much attention in both industrial and educational communities, as they are expected to bring interaction between humans, environment, and machines into a new level. Due to the differences between Wireless Sensor Networks and other wireless networks, new network architectures have been developed and many new routing protocols have been proposed for these architectures. To solve routing problems in WSNs by Swarm Algorithm (SA) is an active, interesting research area and this thesis tries to bring up a new SA towards this mater. Using artificial intelligence (AI) techniques in this environment is a promising task which is challenging at the same time. In this thesis we...