Sharif Digital Repository

Today Ethernet is the predominant technology for implementing Local Area Networks. Its privileges encourage service providers to extend Ethernet from Local Area Networks to Metropolitan Area Networks or even Wide Area Networks. Ethernet benefits such as low operational costs, well interoperability, plug-n-paly characteristic and rapid provisioning on demand make Ethernet ideal for Metropolitan Area Networks.But Ethernet by itself has some weakness like flat structure that makes it unfit for use in Metropolitan Area Networks. A suitable solution for taking advantages of Ethernet benefits in service provider network is using Ethernet in access network and applying multi-point to multi-point... 

Among businesses operating under the sharing economy model, ride-sharing platforms or Internet taxis have attracted a lot of attention and have been able to encourage millions of people to use them in a few years. Meanwhile, what has been the subject of numerous researches in recent years is the motivation of people to use this type of business. Understanding what motivates users to use these businesses is important to them because it helps them allocate their resources optimally by focusing on the benefits, shortcomings, and potential disadvantages of their product, And then by improving the provided service, have more advantages and attractiveness in the eyes of customers. Accordingly, in... 

Along with the emergence of the smart city concept and the increasing demand for a wide range of vehicles, the Internet of Vehicles (IoV) has attracted a lot of attention by providing numerous benefits including vehicle accident warning, reducing pollution levels and traffic congestion, as well as entertainment services. Furthermore, IoV offers various services combining Vehicular ad hoc networks (VANETs) and IoT in smart cities. However, these types of networks are exposed to a variety of security and privacy risks due to the wireless nature, because the sensitive message is transmitted through an insecure channel in the IoV-based smart city environment, therefore, it is necessary to... 

The use of IoT-based technologies is expanding in many areas today. The use of audio and video processing in IoT systems has been used as an alternative to human operators by increasing power and reducing processing costs. Due to the large volume of audio and video data and bandwidth limitations, complete data transfer to cloud processing servers is not cost-effective in terms of efficiency and energy consumption. As a result, the solution that has provided good results is to discharge these device tasks to the available clouds. In other words, the capacity of resources in the environment can be used to optimize the total latency of the system and energy consumption. In this dissertation, we... 

Due to the world's reliance on fossil fuels, the climate change situation has become more severe and has presented major challenges. One of the most promising growth avenues to address these issues in the medium to long term is widespread electrification based on renewable sources. However, this is only feasible if the energy infrastructure can support distributed and renewable energy sources without affecting the performance of the power grid. A grid is also necessary for energy systems in order to connect various technologies and guarantee proper integration of supply and demand for maximum efficiency. A novel idea called Energy Internet (EI) has been put forth to accomplish these goals,... 

Nowadays, the construction industry has undergone extensive changes, with the advent of new technologies, it has departed from the traditional project implementation methods. One of these technologies is Virtual Reality, which is becoming more widespread in various stages of the life cycle of a project from design to delivery. Providing an opportunity for people to see the details of the final construction before completing the project could be regarded as one of the capabilities of this technology. Also, evaluating the project’s features at the time of construction and having a close understanding of product’s reality are the other beneficial aspects of VR. Meanwhile, the emergence and... 

Active queue management (AQM) is a key factor in congestion control and should provide appropriate feedback for flow control in traffic sources to overcome the congestion problem. Beside providing congestion control, achieving predictable queuing delay, maximizing link utilization, simplicity and robustness are also the main objectives of an AQM controller. We propose in this thesis an improved queue dynamic model while incorporating the packet drop probability as well. The proposed model is evaluated using ns2 platform. By applying the improved model, a new compensated proportionalintegral- derivative (PID) AQM controller is developed for TCP network. The time-varying nature of the network... 

The internet of things is a network of interconnected things (people, electronic devices, mechanical machines, etc.) that are able to transfer data. The applications of internet of things in electronic health (eHealth) are becoming increasingly interested. Deployment of eHealth facilitates the access of users to healthcare services, and improves the quality of the services. Using cloud computing provides the accessibility of healthcare services, and enables a data owner to share his health data with doctors and healthcare service providers. Health data is considered sensitive. So, leakage of any information about it endangers data owner privacy. Attribute-based encryption is a cryptographic... 

Demands on wireless access networks are growing enormously, thanks to deploying new generations of wireless communication systems—such as LTE, 4G, and in the near future 5G—and especially promoting new technologies, like Internet-of-Things (IoT). With the help of visible light communication (VLC) systems, networks have been developed the capacities of which can go beyond some Mbps, but this is not satisfying enough. Therefore, a newer version of VLC systems has been investigated, called Light-Fidelity (LiFi), which is complement to WiFi (in radio frequency networks(. Two main purposes of LiFi networks are obtaining a high-capacity wireless access network and using them for illumination... 

One of the applications of Internet of things (IoT) is its usage in the eHealth area. Various types of sensors (e.g., sensor to measure heart health, blood sugar levels, and respiratory) exist that not only provide required information for patients, but also send the health information to hospital staff through the network. Leveraging this technology in various intensive care units of hospital facilitate nurses and medical staff in monitoring of patients. However, moving towards these environments leads to new security challenges. One of the most important challenges is controlling access to sensors’ data and preserving patients privacy so that doctor and nurses should access patients’... 

Internet of Things is a promising paradigm consensus of different technologies. It has gained increasing popularity during recent years. However it is still in its infancy phase. Heterogeneous and constrained devices, resource discovery, identification, scalability, mobility, difficulty of application development and deployment, and security requirements are some of the most important concerns that must be resolved in order to achieve more maturity. To address these challenges, several IoT platforms have been proposed. In some recent of them, a concept called virtual object(vo) has been introduced. A virtual object is a virtual representation of a physical device. Using this concept, many... 

Managing health data and providing remote treatment services to patients has always faced security and privacy challenges. Because of the importance and sensitivity of this data, the use of centralized networks such as cloud space and trustin a cloud server can be dangerous, due to the lack of complete trust in the cloud server. To prevent the threats of centralized systems, we provide a decentralized blockchain-based system in which miners, in addition to authenticating physicians and patients, are also responsible for searching encrypted data and all user activities can be tracked in the distributed ledger. The proposed scheme preserves data privacy, and there is no need to trust a server.... 

Widespread use of the interconnected devices has caused an increase in the number of online services and the Internet of Things applications. Some of the protocols used in networking equipment does not have the ability to manage the high volume of traffic, scalability and mobility. Existing networks with traditional protocols are rigid and the process of policy-making on network is slow. Manging the huge number of data flows is a complex and time-consuming task. To respond to such problems, in this study a Software defined architecture is proposed as an alternative to traditional network architecture. In this type of networks, administrators have overview on network controllers and network... 

With the easy access to internet and connected devices ubiquities, Today more than 50 million people use online education platforms to improve their skills and broaden their knowledge. In this research we tend to answer two questions based on data from Iranian students from top domestic universities.First question is which factors would these users consider in choosing their online education platform. This would be especially interesting to know in context of Iran’s cultural and job market situations.Second question we are interested in the same context is what are the factors that make users of these platforms to stop using them. This is very important since stoppage rate of online... 

Internet of Things means making the all of things smart to access them anytime, anywhere through the Internet. Existing of IoT as a novel way of networking, opens up new issues round the communication and network world. One of them is how to establish the security in such a diffuse network. Because the members of this network are not smart phones, computers or any other usual networking technologies, but they are the normal things and appliances in our daily lives, such as refrigerators. Smart things are mostly resource-constrained and power-limited so the former ways of securing networks cannot be applicable in IoT. Thus, Security bootstrapping has is introduced a solution for establishing... 

With the advent of the Internet of Things (IoT), e-health has become one of the main topics of research. Due to the sensitivity of patient information, patient privacy seems challenging. Nowadays, patient data is usually stored in the cloud in healthcare programs, making it difficult for users to have enough control over their data. The recent increment in announced cases of security and surveillance breaches compromising patients' privacy call into question the conventional model, in which third-parties gather and control immense amounts of patients' Healthcare data. In this work, we try to resolve the issues mentioned above by using blockchain technology. We propose a blockchain-based... 

Today’s biggest IoT companies are built on the extraction of insight from data of sensors, and data processing has become crucial in IoT businesses. Nevertheless, the size of data which should be processed is growing significantly fast. The pace of the data growing has changed the nature of data processing in IoT. Today, IoT industries demand highly scalable and fault tolerant data processing architectures which can handle the massive amount of data. In this research, we presented a distributed architecture for scalable and resilient data processing based on the Liquid which is a nearline and offline big data architecture. We used the Reactive Manifesto to design the architecture highly... 

In real-time packet-based communication systems one major problem is misrouted or delayed packets which result in degraded perceived voice quality. If some speech packets are not available on time, the packet is known as lost packet. The easiest task of a network terminal receiver is to replace silence for the duration of lost speech segments. In a high quality communication system in order to avoid quality reduction due to packet loss a suitable method and/or algorithm is needed to replace the missing segments of speech.There are several methods which have been proposed to reduce the effect of packet loss such as Waveform Substitution, High Order Autoregressive, Linear Prediction (LP),... 

This study analyzes determinants of customers’ switching intentions. The context of this study is service area and we have studied customers’ behavior of internet service providers. In this research we focus both on transactional and relational variables. We have tried to clarify the role of consumers’ commitment on their intentions to switch. Drawing from literature and based on previous service switching research we have developed a switching model. This includes two component of customer commitment and the antecedents of commitment. We have developed our hypothesis according to this model and the literature review. The survey was administered to ADSL internet home users. A sample of 130... 

Building Information Model (BIM) is a process supported by various tools, technologies, and contracts, including the production and management of a digital display of the physical and functional characteristics of sites. The BIM has been affected highly by the state of the art in digital design techniques and is focused as one of the mainstays of the 4th industrial revolution era. Integration of BIM in the processes related to the design, construction, and operation of buildings is practically made according to the aspects of environmental sustainability. Considering the Internet of Things (IoT) paradigm in Industry 4.0, it seems that the BIM concept can be more effectively and efficiently...