Sharif Digital Repository

Purpose: The purpose of this paper is to explore the process and competitive factors of entrepreneurship in digital space in Iran. Design/methodology/approach: In the last decades, the development and advancement of information and communication technologies (ICTs) and the business innovations related to them have defined a new economy which is known as "digital economy". Establishing and running businesses in this digital space means carrying out a kind of electronic commerce by exploiting the internet and other electronic networks. The new digital economy provides exceptional opportunities for many entrepreneurs to create new ventures in different business areas according to electronic... 

With the emergence of social networks and improvements in the internet speed, the video data has become an ever-increasing portion of the global internet traffic. Besides the content, the quality of a video sequence is an important issue at the user end which is often affected by various factors such as compression. Therefore, monitoring the quality is crucial for the video content and service providers. A simple monitoring approach is to compare the raw video content (uncompressed) with the received data at the receiver. In most practical scenarios, however, the reference video sequence is not available. Consequently, it is desirable to have a general reference-less method for assessing the... 

With IoT devices becoming abundant and WSN applications becoming evermore present, the once dream of ubiquitous connectivity is closer to realization than ever before. but this realization is hindered by many technical problems and lengthy time to markets. Currently, our best practice of feasibility analysis relies in the same simulators used to model and develop the network applications. Because of their broad range and immense usability challenges, these jack-of-all-trades simulators tend to be computation-intensive and hard to work with.Here, we propose a relatively light-weight simulator based on the analytical models of different parts of the network to aid in rapid development and ease... 

The Internet of Things (IoT) is an emerging phenomenon in the field of communication, in which smart objects communicate with each other and respond to user requests. The IoT provides an integrated framework providing interoperability across various platforms. One of the most essential and necessary components of IoT is wireless sensor networks. Sensor networks play a vital role in the lowest level of IoT. Sensors in sensor networks use batteries which are not replaceable, and hence, energy consumption becomes of great importance. For this reason, many algorithms have been recently proposed to reduce energy consumption. In this paper, a meta-heuristic method called whale optimization... 

The Internet of Things is a new concept in the world of information and communication technology, in which for each being (whether it be a human, an animal or an object), the possibility of sending and receiving data through communication networks such as the Internet or Intranet is provided. Wireless sensors have limited energy resources due to their use of batteries in supplying energy, and since battery replacement in these sensors is not usually feasible, the longevity of wireless sensor networks is limited. Therefore, reducing the energy consumption of the used sensors in IoT networks to increase the network lifetime is one of the crucial challenges and parameters in such networks. In... 

In the internet telephony, loss of IP packets causes instantaneous discontinuities in the received speech. In this paper, we have focused on finding an error resilient method for this problem. Our proposed method creates artificial correlation between speech samples that pre-distorts the speech signal. The receiver uses this correlation to reconstruct the lost speech packets. An appropriate speech enhancement technique is designed for the reduction of the processing error in the recovered speech caused by the speech codecs. The SegSNR results show the superiority of our proposed speech enhancement method over a recently proposed one. © 2007 IEEE  

Geo-distributed data-centers in cloud computing are becoming increasingly popular due to their lower end-user perceived latency and increased reliability in distributed applications. The important challenge of resource allocation in cloud management is more pronounced in geo-distributed data-centers compared to traditional data-centers. A geo-distributed cloud manager faces applications whose virtual machines (VMs) are far apart and need to interact with end users, access distributed data and communicate with each other. In such applications, the service level agreement is not met if the communication latency is not bounded. In this paper, we focus on the problem of finding data-centers for... 

Today P2P networks are responsible for a large amount of traffic on the Internet, as many Internet users employ such networks for content distribution. At the same time, P2P networks are vulnerable to security threats such as Internet worms and facilitate their propagation. Internet worms and more generally malware are a major concern to the network security community. There are many different type of worms in the wild, mostly categorized based on how they find and infect their new victims (i.e. active, passive, etc.). In this paper, we investigate a new approach for detecting passive worms and malware in P2P networks based on the popularity of files in the network. As part of our... 

The Internet of Things (IoT) technology enables numerous things with different processing power and storage capacity to communicate and share data with each other. Considering the constrained devices of the IoT network in terms of processing and storage, designing a lightweight authentication scheme is quite important. So in this paper, we propose a lightweight authentication scheme based on Chebyshev Chaotic Maps. In the proposed scheme we apply a hierarchical structure to define different access controls for various entities. We then provide a formal analysis via the BAN logic to show the security of our scheme. Moreover, we compare our proposed scheme with previous ones in terms of... 

By the advances in location-aware applications over the Internet, the need for information such as the geographical position of routers and hosts and also the Euclidian distance of nodes is more important than ever. These kinds of information can also provide a valuable insight for network administrators, analysts, and many others. In this paper, we propose an algorithm, called GPE, to estimate the geographical position of nodes across the Internet. In the proposed approach, Internet topology is modeled by a weighted graph. Each node of the graph may have a corresponding estimation of its position. Weight of each edge, in this graph, indicates the estimated length of corresponding link in... 

In this paper, we introduce novel mechanisms for measuring and evaluating the performance of a network and its devices, configured especially for Voice over IP (VoIP). We study the effects of different configurations on final voice quality by enabling or changing the related equipment features. In our study we quantify quality changes based on different router configurations and discuss precisely to what extent and how much this quality is improved versus features or special configurations of network devices. These results can be used for two purposes: compare and benchmark different routers in order to know which one is proper for a typical VoIP network, and select the best configurations.... 

An operator-assisted user-provided network (UPN) has the potential to achieve a low cost ubiquitous Internet connectivity, without significantly increasing the network infrastructure investment. In this paper, we consider such a network where the network operator encourages some of her subscribers to operate as mobile Wi-Fi hotspots (hosts), providing Internet connectivity for other subscribers (clients). We formulate the interaction between the operator and mobile users as a two-stage game. In Stage I, the operator determines the usage-based pricing and quota-based incentive mechanism for the data usage. In Stage II, the mobile users make their decisions about whether to be a host, or a... 

Today, peer-to-peer networks are become more popular among internet users and more than millions peers share high volume of data from anywhere. Sending and receiving these data increase the network traffics terribly. By improving the performance of these networks not only the efficiency of these networks increase but also the overall performance of the internet augments. To achieve high performance and resilience to failures, a peer can make connections with those other peers that are geographically closer to it. There are many solutions that are suggested for locality problem. In this paper, we suggest a Cube Connected Cycle as an overlay network to improve locality with higher performance