Sharif Digital Repository

By rapid growth of technology in recent years, many services are provided for disabled people. Using wireless devices such as mobile phones in healthcare is a new idea which is gained attracted by some developers in recent years. On the other hand, nowadays game consoles are not only for playing games, but also have more functions such as using for education. Considering the above mentioned facts, this paper proposes a method to aid speech-impaired children using Nintendo DS Game console. This method helps the speech-impaired children which are not capable of using sign language well to communicate with others until they learn sign language well. Because the Nintendo DS is the most popular... 

Nowadays development of cell phone network provides huge and ubiquitous data, with wide application in transportation science. One of the most important advantages of these kinds of data is enabling the process of collecting information without any active users' interference. A big data set consisting of 300,000 cell phone users' information in Shiraz are studied. This data set includes spatiotemporal information of travelers for every 5 minutes in a time span of 40 hours in two consecutive days. The spatial part of each user's information contains the position of the BTS (Base Transceiver Station) to which his cell phone is currently connected. Due to the existence of outliers, it is... 

In last 20 years, the Internet and mobile communication growth in parallel. There are many sites specially designed for mobile phones that users must enter username and password to enter them. In this paper we introduce a new method based on CAPTCHA which does not require entering any password. Instead of entering the password, an image of a number is shown to the user and he/she must type it. The user response is coded with his/her mobile phone IMEI and sent to the server. The server checks user's response according to user's IMEI and if it was correct, let the user to enter the site, so there is no need to enter any password. This method has been implemented in PHP and J2ME languages and... 

Voice activity detection is an important step in some speech processing systems, such as speech recognition, speech enhancement, noise estimation, speech compression ... etc. In this paper a new voice activity detection algorithm based on wavelet transform is proposed. In this algorithm we use the energy in each sub band, and by two methods we extract feature vector from these values. Experimental results demonstrate advantage over different VAD methods. ©2008 IEEE  

One of the arising issues in wireless sensor networks is running multiple applications to reduce deployment, administrative and management costs. In this paper we assume a sensor network in which nodes of a group have a set of same applications in their external flash memory that some of them are loaded and running. Occasionally, these applications should be updated for reasons that are manifold ranging from fixing software bugs to retasking. It is often that updates for a subset of applications happen at the same time, for example when a routing protocol shared among a subset of applications is changed. To bring the sensor nodes up to date with the new versions of the applications, existing... 

Considering the significant growth in mobile phone use by customers and its high accessibility, this device can be considered as the most suitable tool in payment category. To implement a mobile payment service, there are many actors involved such as: bank, operator and service provider. As an effective interaction role and in order to optimize efficient parameters for implementing a mobile payment solution, it is necessary to present a suitable business model. Therefore, five different business models have been surveyed in the field of mobile payment in this research; then they were compared with MCDM evaluation method applications. Since one of the most effective parameter to select an... 

Localization of sensor nodes has become a fundamental requirement for many applications over Wireless Sensor Networks (WSNs). In this paper, we propose a range-free approach based on the Received Signal Strength (RSS) changes. A discrete and probabilistic localization method is offered to localize a moving beacon relative to sensor nodes. In this method we came to a more reliable and accurate result without increasing the number of sectors. We achieved a considerable improvement in localization reliability by defining the primary and secondary sectors and utilizing a Kalman approach for making decisions. The decision making process is based on the allocated probabilities given to each of... 

This paper addresses the issue of finding and accessing desired items when a large amount of data items are concerned, by proposing some concepts based on Tree Search Structure -a hierarchical structure for information retrieval. The proposed concepts are applicable to several environments such as File Managers on PCs, help tree views, site maps, taxonomies, and cell phones. A software tool, FTS (File Tree Search), that is developed to utilize the proposed concepts is also presented  

Key predistribution in sensor networks refers to the problem of distributing secret keys among sensor nodes prior to deployment. Recently, many key predistribution schemes have been proposed for wireless sensor networks. To further improve these techniques, researchers have also proposed to use sensors' expected location information to help predistribution of keying materials. In this paper we propose a lightweight and scalable key establishment scheme for GPS-enabled wireless sensor networks. This scheme has little communication overhead and memory usage. Since communications and computations of key establishment schemes are done only once and when the network is begin initiated, actually... 

Security in mobile handsets of telecommunication standards such as GSM, Project 25 and TETRA is very important, especially when governments and military forces use handsets and telecommunication devices. Although telecommunication could be quite secure by using encryption, coding, tunneling and exclusive channel, attackers create new ways to bypass them without the knowledge of the legitimate user. In this paper we introduce a new, simple and economical circuit to warn the user in cases where the message is not encrypted because of manipulation by attackers or accidental damage. This circuit not only consumes very low power but also is created to sustain telecommunication devices in aspect... 

This paper presents a centralized fault detection algorithm for wireless sensor networks. Faulty sensor nodes are identified based on comparisons between neighboring nodes and own central node and dissemination of the decision made at each node. RNS system is used to tolerate transient faults in sensing and communication. In this system, arithmetic operations act on residues - reminder of dividing original number in several definite modules - in parallel. Consequently computations on these residues which are smaller than the original number are performed, so speed up arithmetic and decreased power consumption is achieved. ©2009 IEEE  

Sudoku puzzle is a logical game which has recently got very popular. Every day various mass media print these puzzles. As a result these puzzles are a suitable alternative for hidden data transfer. SMS (short message service) is one of the popular mobile-phone services. In this service people can write short messages and send it to each other through mobile phones. In this paper a method has been presented for Steganography (hiding data) in Sudoku puzzles and through SMS. In this method after hiding data in a Sudoku puzzle, the puzzle is sent in a way that it does not attract any attention. Steganography algorithm is based on order of place of numbers 1 through 9 in one of the specified row... 

Today sending spams has turned to be a major problem in the Internet. In last 20 years, the Internet and mobile communication growth in parallel. So the spams are also born on the mobile phones as the form of SMS (Short Message Service) spams. In this paper a new method is proposed for filtering SMS spams using CAPTCHA (Completely Automatic Public Turing Test to Tell Computer and Human Apart) systems. CAPTCHA systems are used to distinguish between human users and computer programs automatically. In this method, the picture of an object is sent as an SMS picture message. Also name of that object and name of three other objects are written in the SMS as a multiple-choose question. The user... 

Lifetime is the most important concern in wireless sensor networks due to limited battery power of sensor nodes. In this paper, we focus on designing an energy-efficient and energy-aware routing algorithm, LLR, to increase the operational lifetime of multi-hop wireless sensor networks in the presence of unreliable communication links. Our proposed protocol utilizes a parameter, Broadcasting Delay, in each node associated with the hop parameters passed by a route request packet to select long lifetime paths in the network. The key point in Broadcasting Delay formulation is that it includes both node and link specific parameters. We use two different scenarios: either the link layer... 

Wireless sensor networking remains one of the most exciting and challenging research domains of our time. Sensor nodes are arranged in the clusters and relay nodes could have been used as cluster head with more power, but this method has a Low Speed for networks with many sensors. In another method Storage and forwarding nodes are used to transfer the data from sensors to the base station. In this method, the data might have been failed due to the damage of the storage node. In this article, a hybrid method has been used to improve the network quality, which in that network, in addition to the forwarding and storage nodes, there is also cluster head. The purpose of this article is to solve... 

Power and bandwidth constraints are two major challenges in wireless sensor networks. Since a considerable amount of energy in sensor networks is consumed for data transmission, compression techniques may prolong the life of such networks. Moreover, with fewer bits to transmit, the network can cope better with the problem of inadequate bandwidth. In this paper, we consider an image sensor network and propose a paradigm based on the principles of Distributed Source Coding (DSC) for efficient compression. Our method relies on high correlation between the sensor nodes. The algorithm consists of two phases: the Training Phase and the Main Phase. In the Training Phase an aggregation node or a... 

In this work, an optimum frequency is found for the operation of single cavity photonic switches. At this optimum point, the transmission contrast of ON and OFF states takes its highest value, while keeping the device power threshold relatively low and the device speed acceptably high. Then, the dynamic behavior of a typical single cavity all optical switch is investigated in the optimum operation point through temporal Coupled Mode Theory. Switching speed and power are discussed, and the device is shown to be applicable for telecommunication and data processing applications. The analysis is quite general, and can be used for resonant structures, such as photonic crystals and microring... 

The IP Multimedia Subsystem is a basis for a significant new architecture which offers network operators the opportunity to expand their services, integrating voice and multimedia communications and delivering them into new environments with new purposes. The IMS is an overlay network on top of IP that uses SIP as the primary signaling mechanism. Using IMS bears several new security challenges. In this paper we provide an overview of IMS and its architecture. Then we represent a secure model to overcome some of IMS security challenges. ©2009 IEEE  

In this paper, we propose an approach for routing in SPEED protocol considering residual energy in routing decisions. Due to the limited energy of a sensor node, energyefficient routing is a very important issue in sensor networks. This approach finds energy-efficient paths for delayconstrained data in real-time traffic. The SPEED protocol does not consider any energy metric in its routing. In our approach, routing is based on a weight function, which is a combination of the three factors: Delay, Energy & Speed. Here, the node with the greatest value in the weight function is to be selected as the next hop forwarding. We increase the network lifetime by considering energy metric in routing... 

Motivated by applications of sensor networks, there has been growing interest in monitoring large scale distributed systems. In these applications, we usually wish to monitor a global system condition defined as a function of local network elements parameters. In this paper, we study Reactive Monitoring in sensor networks, which has the benefit of operating in a decentralized manner. Our primary concern in adopting such a monitoring paradigm is reducing the communication cost which is the dominant factor of energy drain in wireless sensor networks. In this study, we address the reactive aggregate monitoring problem by casting the underlying threshold assignment as an optimization problem....