Sharif Digital Repository

In this paper, we propose a new anonymous channel protocol for authentication in GSM mobile communication networks. The protocol is the result of incorporating our anonymity scheme to an efficient GSM authentication protocol proposed by Chang et al. As a result, our protocol has all the features of their scheme including anonymity. Compared with the most recent protocols in this area, such as those by Peinado and Hwang et al., we show that our scheme generally is more secure and more efficient. © 2008, Inderscience Publishers  

The use of Spread-Time CDMA for ultrawideband (UWB) wireless communication is proposed and its capability for supporting many high data rate users is investigated. Furthermore we will study a hybrid technique, namely, Spread-Time/Time-Hopping to increase the capacity of the above mentioned technique and simultaneously minimizing the effect of near-far in a typical CDMA system  

This paper considers the problem of digital data transmission through the Global System for Mobile communications (GSM). A data modem is presented that utilizes codebooks of Speech-Like (SL) symbols to transmit data through the GSM Adaptive Multi Rate (AMR) voice codec. Using this codebook of finite alphabet, the continuous vocoder channel is modeled by a Discrete Memory less Channel (DMC). A heuristic optimization algorithm is proposed to select codebook symbols from a database of observed human speech such that the capacity of DMC is maximized. Simulation results show that the proposed data modem achieves higher data rates and lower symbol error rates compared to previously reported... 

The swift growth of cellular mobile networks in recent years has made voice channels almost accessible everywhere. Besides, data hiding has recently attracted significant attention due to its ability to imperceptibly embed side information that can be used for signal enhancement, security improvement, and two-way authentication purposes. In this regard, we aim at proposing efficient schemes for hiding data in the widespread voice channel of cellular networks. To this aim, our first contribution is to model the channel accurately by considering a linear filter plus a nonlinear scaling function. This model is validated through experiments with true speech signals. Then we leverage on this... 

During the last years, researchers have proposed solutions to help smartphones improve execution time and reduce energy consumption by offloading heavy tasks to remote entities. Lately, inspired by the promising results of message forwarding in opportunistic networks, many researchers have proposed strategies for task offloading towards nearby mobile devices, giving birth to the Device-to-Device offloading paradigm. None of these strategies, though, offers any mechanism that considers selfish users and, most importantly, that motivates and defrays the participating devices who spend their resources. In this paper, we address these problems and propose the design of a framework that... 

In this paper, we develop a phase inverting technique to improve the received power of an antenna array, with an emphasis on the simplicity of the receiver hardware and reducing the power consumption. The goal is to propose a simple array architecture to develop intelligent algorithms to enhance the received power of the array. A test set-up with 8-element switched array antenna at 28 GHz has been developed to implement the proposed algorithms. The measured results reveal that in a high scattering environment, the phase inverting technique provides about 13 dB enhancement in the received power compared to a fixed array. This significant enhancement plays a major role in establishing a robust... 

In this paper we address the electromagnetic (EM) wave scattering from human body in millimeter-wave (MMW) band and 5G networks, where human body can be considered as an electrically large object. The complicated geometry of human body is accurately modeled using non-uniform rational B-spline (NURBS) surfaces as a thin dielectric slab with permittivity of human skin. Physical optics (PO) approximation is used to formulate the scattering problem. To solve highly oscillatory PO integrals, triangular boundary-rectangular mesh (TBRM) algorithm is exploited. This algorithm provides frequency-independent solution for PO integrals and allows frequency-independent meshing of the human body surface.... 

This paper considers the problem of secure data communication through the Global System for Mobile communications (GSM). The algebraic codebook method for data transmission through the Adaptive Multi Rate 12.2Kbps voice channel is investigated and its maximum achievable data rate is calculated. Based on the vocoder channel properties, the method's Bit Error Rate (BER) performance is improved by repetition coding and classification methods. Simulation results show that by simultaneous application of repetition coding and clustering methods, the decoder's performance improves about 6.5% compared to the case of no clustering for 1Kbps data communication in AMR 4.75 voice codec  

A5/1 is a stream cipher used in GSM to provide over-the-air communication privacy. Biham and Dunkelman proposed an attack on A5/1 with time complexity of 2∧(39.91) and data complexity of 2∧(21.1) known bits and memory complexity of 32 GB. In this paper, we propose an improvement on their attack. Our improvement is identification and elimination of useless states from the precomputed table. Furthermore, we propose another way for use of table in online phase of attack that causes decreasing in the time complexity to 2∧(37.89) and memory complexity decreases to half  

With the evolution and significant growth in wireless technology and the development of mobile commerce, businesses can achieve superior performance through the implementation of platforms for mobile payment. However, there are several platforms for mobile payment to choose from which makes the selection of an appropriate platform for specific applications a challenging task. In response to this challenge, the most common mobile payment platforms recorded in the literature have been reviewed. This paper presents the result of this review describing the advantages and disadvantages of each system and offers ranking of the technologies considered. MCDM method is used for assessing and... 

In this paper, the problem of content caching in 5G cellular networks relying on social-aware device-to-device (D2D) communications is investigated. Our focus is on how to efficiently select important users (IUs) and how to allocate content files to the storage of these selected IUs to form a distributed caching system. We aim at proposing a novel approach for minimizing the downloading latency and maximizing the social welfare simultaneously. In particular, we first model the problem of maximizing the social welfare as a many-to-one matching game based on the social property of mobile users. We study this game by exploiting users’ social properties to generate the utility functions of the... 

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... 

With the advance of multimedia systems and wireless mobile communications, there has been a growing need to support multimedia services (such as mobile teleconferencing, mobile TV, telemedicine, and distance learning) using mobile multimedia technologies. Despite the research done in the field of mobile multimedia, delivery of real-time interactive video over noisy wireless channels is still a challenge for researchers. This paper presents a method for prioritising data partitioned MPEG-4 video in a way suitable for transmission over a mobile network. The effectiveness of the technique is demonstrated by examing its performance when the transport of the prioritized video streams can be... 

One of the most prominent features of code division multiple-access (CDMA) cellular networks is their ability for applying soft-handoff. This type of handoff results in a better supporting of seamless communication services, capacity enhancement, QoS improvement, etc. Because of existence of more parameters and flexibilities compared to hard-handoff, an optimum solution for soft-handoff management and admission control for new and handoff calls is necessary. In this paper we propose a new algorithm with two thresholds for admission of new and handoff calls, and with two decision boundaries for controlling of handoff traffic. We compare this algorithm with a simpler one with only one decision... 

To cope with the unprecedented growth of mobile data traffic, we investigate the performance gains obtained from unifying coverage-centric 4G mobile networks and capacity-centric fiber-wireless (FiWi) broadband access networks based on data-centric Ethernet technologies with resulting fiber backhaul sharing and WiFi offloading capabilities. Despite recent progress on backhaul-aware 4G studies with capacity-limited backhaul links, the performance-limiting impact of backhaul latency and reliability has not been examined in sufficient detail previously. In this paper, we evaluate the maximum aggregate throughput, offloading efficiency, and in particular, the delay performance of FiWi enhanced... 

Machine to machine (M2M) communication, which is also known as machine type communication (MTC), is one of the most fascinating parts of mobile communication technology and also an important practical application of the Internet of Things. The main objective of this type of communication, is handling massive heterogeneous devices with low network overheads and high security guarantees. Hence, various protocols and schemes were proposed to achieve security requirements in M2M communication and reduce computational and communication costs. In this paper, we propose the group-based secure lightweight handover authentication (GSLHA) protocol for M2M communication in LTE and future 5G networks.... 

In this paper, the problem of content caching in 5G cellular networks relying on social-aware device-to-device communications (DTD) is investigated. Our focus is on how to efficiently select important users (IUs) and how to allocate content files to the storage of these selected IUs to form a distributed caching system. We aim at proposing a novel approach for minimizing the downloading latency and maximizing the social welfare simultaneously. In particular, we first model the problem of maximizing the social welfare as a many-to-one matching game based on the social property of mobile users. We study this game by exploiting users' social properties to generate the utility functions of the... 

The main purpose of this paper is to present a novel procedure for accelerating a multi-objective optimization method of designing a 5G antenna. The optimization method was chosen after comparing four learning optimization algorithms. The Kriging algorithm was found to be superior to the Artificial Neural Network (ANN), Support Vector Machine (SVM), and Rational algorithms. Our methodology is creatively correlated to exploit some cost functions of height, the Dielectric constant of the substrate, and meta-material design variables, with a view to reducing the return loss and increasing the gain in learning from the Kriging model builder techniques. This was fully achieved in the present... 

Global System for Mobile communications (GSM) is a widely spread, reliable and P2P channel through all over the world. These characteristics make GSM a channel suitable for a variety of applications in different domains especially security applications such as secure voice communication. Performance and usage of GSM applications extremely depends on the transmission data rate. Hence, transmitting data over GSM is still an attractive topic for research. This paper considers the problem of digital data transmission through the GSM voice channel. A lower capacity bound for data transmission through the GSM Adaptive Multi Rate (AMR) voice codec is presented. The GSM channel is modeled in a...