As the wireless communications technologies evolve dramatically, the recent research focus has shifted to the development of fourth-generation (4G) mobile systems. Instead of developing a new uniform standard for all wireless communications systems, 4G communication networks strive to seamlessly integrate various existing wireless communication technologies. One of the major challenges in this ...

The maximal-ratio combining (MRC) scheme is investigated in detail. Other diversity combining schemes, such as selection combining (SC) and equal gain combining (EGC) are outperformed by MRC in the case of coherent communications. First, the case of M independent fading channels is considered. The output signal-tonoise ratio (SNR) expression is derived, and an expression for the bit error rate ...

The new generation of mobile communications, characterized by the ubiquity of the services and the heterogeneity of the technologies, has new needs: it shows the deficiencies of the present standards in several aspects and arise others that cover the new requirements. In this work, on the one hand, the deficiencies in security aspects of the current standards, and on the other hand, two new wor...

Anonymous communication techniques are vital for some types of ecommerce applications. There have been several different approaches developed for providing anonymous communication over the Internet. In this paper, we review key techniques for anonymous communication and describe an alternate anonymous networking approach based on agile agents intended to provide anonymous communication protecti...

The world of telecommunications, especially mobile communications, continues to evolve with innovative technologies and high-speed data services. In many economies, mobile phones have overtaken fixed lines. In this dynamic context, we have envisaged to study mobile communication diffusion in Germany and India, from a historical comparative perspective. The basic standard for comparison has been...

Technological advances have allowed all conferees to hold a mobile conference via wireless communication. When designing a conference scheme for mobile communications it should be taken into account that the mobile users are typically using portable devices with limited computing capability. Moreover, wireless communications are more susceptible to eavesdropping and unauthorized access than con...

The functionalities of the next generation Internet protocol, IPv6, have become increasingly interesting due to the current merging of the traditional cellular mobile communications and the traditional data-communications into the future wireless systems, as e.g., UMTS. IPv6 provides several enhanced functionalities requested for the future mobile systems. In this article the largest advantages...

Speech Coding at low and very low bit rate has become the paramount importance in accommodating the tremendous increase in the number of users in the presence of constraints of bandwidth and power in such areas as cellular radio, GSM or satellite links. The paper will cover important areas in Speech Coding. First part is concerned with an overview of the speech production model. The second part...

This article presents an overview of security issues for mobile and wireless communications. It describes the security requirements and architectural options for these networks. Subsequently three technologies are discussed in more detail: mobile phones (GSM and 3GSM), Wireless LAN (IEEE 802.11) and Personal Area Networks (Bluetooth). A critical evaluation is given of the strengths and weakness...