Hossam Afifi

Bio: Hossam Afifi is an academic researcher from Telecom SudParis. The author has contributed to research in topics: Wireless network & The Internet. The author has an hindex of 22, co-authored 176 publications receiving 1793 citations. Previous affiliations of Hossam Afifi include French Institute for Research in Computer Science and Automation & École Normale Supérieure.

Wi-Fi, Bluetooth, Zigbee and WiMax

Abstract: The book provides a complete and detailed description of the recent wireless technologies including Wi-Fi, Bluetooth, ZigBee and WiMAX. These technologies are considered to be important topics in the telecommunication industry in the next decade. Some critical subjects are particularly developed such as security, quality of service, roaming and power conservation. The book also includes some chapters on practical aspects.

Integrating networks measurements and speech quality subjective scores for control purposes

Abstract: Traditionally, QoS has been addressed by using network measurements (e.g., loss rates and delays), and little attention has been paid to the quality perceived by end-users of the applications running over the network. Here, we address the issue of integrating speech quality subjective scores and network parameters measurements, for designing control algorithms that would yield the best QoS that could be delivered under a given communications network situation. First, we build a neural network based automaton to measure speech quality in real time, at the style of a group of human subjects when participating in an MOS test. We consider the effects of changes in network parameters (e.g., packetization interval, packet loss rate and their pattern distribution) and encoding on speech signals transmitted over the network. Our database includes transmitted speech signals in different languages. Then, we outline a control mechanism which, based on the application performance within a session (i.e., MOS speech quality scores generated by the neural networks), dynamically adjusts parameters (codec and packetization interval). Finally, we analyze preliminary results to show two main benefits: first, a better use of bandwidth, and second, delivery of the best possible speech quality given the network current situation.

Methods for IPv4-IPv6 transition

Abstract: The future Internet networks are expected to use IPv6 version rather than the IPv4 one. This is mainly due to the limitations of IPv4 in terms of addresses, routing and security QoS issues developed by the Internet community are also tailored for both versions and will be easily deployed in both sides. Since a huge amount of sub-networks are already installed for the v4 version, it is difficult to imagine ISPs starting deploying the v6 version without some assurance that old legacy networks will still be able to connect to the Internet. In this paper we present some mechanisms that have been proposed to ease this transition especially for v4 users that still want to communicate with their old applications. We present also an IPv6 tunneling mechanism that has some advantages over the other models. We show how one could use such a mechanism to transparently establish hybrid communications between two worlds in both ways and discuss some important issues like scalability and performance.

Improving mobile authentication with new AAA protocols

Abstract: The rapid growth of wireless technology and the increasing use of such technologies in coordination with the Internet demand a very careful look at issues related to security. As more and more users attempt to utilize such technologies in the context of providing security demanding services, it is essential to recognize the potential threats in wireless technologies. This paper focuses on authentication as part of the significant issues related to security and proposes a new authentication method combining the AAA framework and the UMTS security. As for that, this work presents results that show how the concepts of AAA and the USIM mechanism can be combined for the adaptability of mobile environment as well as for the efficient authentication. It also presents the specification and the implementation of the combination of diameter of the AAA protocols and USIM. In addition to the design implementation, this work reports on the performance results showing that this combination can be a good solution to authentication in a mobile environment.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

An Introduction to Game Theory

Abstract: This chapter is devoted to a more detailed examination of game theory. Game theory is an important tool for analyzing strategic behavior, is concerned with how individuals make decisions when they recognize that their actions affect, and are affected by, the actions of other individuals or groups. Strategic behavior recognizes that the decision-making process is frequently mutually interdependent. Game theory is the study of the strategic behavior involving the interaction of two or more individuals, teams, or firms, usually referred to as players. Two game theoretic scenarios were examined in this chapter: Simultaneous-move and multi-stage games. In simultaneous-move games the players effectively move at the same time. A normal-form game summarizes the players, possible strategies and payoffs from alternative strategies in a simultaneous-move game. Simultaneous-move games may be either noncooperative or cooperative. In contrast to noncooperative games, players of cooperative games engage in collusive behavior. A Nash equilibrium, which is a solution to a problem in game theory, occurs when the players’ payoffs cannot be improved by changing strategies. Simultaneous-move games may be either one-shot or repeated games. One-shot games are played only once. Repeated games are games that are played more than once. Infinitely-repeated games are played over and over again without end. Finitely-repeated games are played a limited number of times. Finitely-repeated games have certain or uncertain ends.