Demand For High-speed Services Research Articles

Adaptive modulation and coding techniques for OFDMA systems

The demand for high-speed services and multimedia applications anywhere and anytime has led to the rise of wireless communications. In particular, WiMAX technology is nowadays considered one of the most prominent solutions capable to provide a Broadband Wireless Access (BWA) in metropolitan areas with a simpler installation and lower cost than traditional wired alternatives. This paper deals with the proposal of efficient adaptive modulation and coding techniques to be used in WiMAX based wireless networks, that allow to improve network performance in the case of Non Line-of-Sight communications, which are typical in urban environments. Through these techniques it is possible to switch the modulation order and coding rate in order to better match the channel conditions, and, hence, obtaining better performance both in terms of error probability and data throughput.

Pathways for telecommunications: a European outlook

The factors driving the transformation of telecommunication systems are used as the basis for describing major trends in network architecture and access structures, intelligent networks (INs), mobile and personal communications, and management functions. The factors include network digitization, the widespread use of optical fibers, and the increase in the range and demand for high-speed services. The interplay between technologies, markets, and standards is analyzed, and the need to identify consistent and harmonized patterns of development for network architectures and services is considered. In particular, telecommunications products, services, and regulations in Europe are discussed. >

An open environment for ATM broadband multimedia applications

Advances in trasmission and switching technologies promise a flexible and efficient Broadband ISDN (B-ISDN), based on Asynchronous Transfer Mode (ATM), able to meet the increasing demand of high speed services. Multimedia applications are in particular expected to play a key role in B-ISDN success. The paper wants to outline the architecture of an open environment based on a multimedia workstation for ATM developed in the framework of the Italian Information Technology project called Piano Finalizzato Telecomunicazioni (PFT). Design guidelines, interfaces and capabilities are described. After introducing the basic workstation architecture, some aspects of relevant multimedia applications and of the user interface are discussed.