Search

Introduces articles and research papers of the January 2003 issue of the journal "Wireless Networks."

The article presents an introduction to the book "Fixed Broadband Wireless."

Chapter 18 surveys routing algorithms in communication networks, where nodes are aware of the geographic position of themselves and their neighboring nodes. Guaranteed delivery is a salient property of the algorithms, assuming destination location is accurate, all nodes have the same transmission radius, and there are no obstacles. [ABSTRACT FROM PUBLISHER]

The article gives information about a chapter of the book "Telecommunications Optimization: Heuristic and Adaptive Techniques," edited by David W. Corne, Martin J. Oates and George D. Smith. In the last two decades, wireless communication systems such as cordless phones, paging systems, wireless data networks, satellite-based and cellular mobile systems have been steadily increasing in both popular importance and technological sophistication. The twin goals of this chapter are to familiarize mobile communication engineers with global search techniques and their potential, and to provide those interested in these techniques with an idea of the nature and scope of their application to mobile communications.

Smart antennas constitute a promising hut still emerging technology. Space-time processing algorithms provide powerful tools to enhance the overall performance of wireless cellular networks. Improvements, typically by a factor of two in cell coverage or capacity, are shown to be possible according to results from field deployments using simple beamforming. Greater improvements can be obtained from some of the more advanced space-time processing solutions described in this paper. The successful integration of space- time processing techniques will however also require a substantial evolution of the current air interfaces. Also, the design of space-tune algorithms must also he application- and environment-specific. [ABSTRACT FROM AUTHOR]

The article presents information on wireless communications. The field of mobile wireless communications is currently one of the fastest growing segments of the telecommunications industry. Wireless devices have nowadays found extensive use and have become an indispensable tool on the everyday life of many people. both the professionally and personally. To gain insight into the momentum of the growth of the wireless industry, it is sufficient to state the tremendous growth in the number of worldwide subscribers of wireless systems. This figure has risen from only one mobile subscriber per 100 inhabitants worldwide in 1990 to 26 subscribers per 100 inhabitants in 1999 and the growth continues. This increasing number of subscribers is obviously reflected in monetary terms as well.

The article discusses simulation of wireless network systems. Simulation is a general term that is used in many disciplines including performance evaluation of computer and telecommunications systems. A model is a description of a system by symbolic language or theory to be seen as a system with which the world of objects can be expressed. The article also reviews the main characteristics of the commonly used stochastic distributions used for the simulation of wireless networks. The article concludes with cases studies on the simulation of some wireless network systems.

Discusses wireless data networks. Concept of internetworking; Functions of the Open System Interconnection (OSI) reference model; Purposes of each layers of the OSI model.

The article focuses on fixed wireless access systems. The goal of this chapter is to review the main techniques used for Wireless Local Loop (WLL) including the Multichannel Multipoint Distribution Service, and the Local Multipoint Distribution Service. It is expected that the global WLL market will exceed 202 million subscribers by the year 2005. Much of this growth will be in the developing countries where over half the world's population lacks Plain Old Telephone Service. WLL systems have a number of advantages over wired systems to subscriber local loop support.

The article focuses on Personal Area Networks (PANs). The concept of a PAN differs from that of other types of data networks in terms of size, performance and cost. PANs are the next step down from LANs and target applications that demand short-range communications inside the Personal Operating Space (POS) of a person or device. There exist a number of different communication mediums to choose for implementing a PAN, such as electric and magnetic fields, radio and optical signal transmission. Finally, as in the case of all wireless networks human safety issues are of great concern. A PAN device will typically be very close to the user for long periods of time and therefore even small dangers could potentially have some impact on the user over time.

The article focuses on third generation (3G) cellular systems. The goal of 3G wireless networks is to provide efficient support for both voice and high hit-rate data services. Third generation mobile and wireless networks aim to fulfill the demands of future services. 3G systems will offer global mobile multimedia communication capabilities in a seamless and efficient manner. Regardless of their location, users will be able to use a single device in order to enjoy a wide variety of applications. The term 3G is usually accompanied by some vagueness, as sometimes different people mean different things when they refer to it. 3G was originally defined to characterize any mobile standard that offered performance 3G systems will provide at least 144 kbps for full mobility applications in all cases, 384 kbps for limited mobility applications in macro and microcellular environments and 2 Mbps for low mobility applications particularly in the micro and picocellular environments.

The article focuses on wireless communications. Wireless networks, as the name suggests, utilize wireless transmission for exchange of information. The exact form of wireless transmission can vary. For example, most people are accustomed to using remote control devices that employ infrared transmission. However, the dominant form of wireless transmission is radio-based transmission. Radio technology is not new, it has a history of over a century and its basic principles remain the same with those in its early stage of development. As spectrum is a scarce resource, it needs to be licensed in order to ensure interference-free operation. Furthermore, the characteristics of signal propagation in street microcells and inside buildings are examined and a scheme used for modeling packet losses in wireless systems is presented. Analog transmissions have been typically been employed in older generations of wireless systems while the newer generations employ the more efficient digital transmission. An overview of techniques that increase the performance of wireless systems by combating the deficiencies of the wireless medium are presented. These include antenna diversity, multi-antenna transmission, coding, equalization, power control and multi-carrier modulation. An introductory overview of the basic techniques and interactions at the different network layers is made with the help of the OSI reference model.

Presents the table of contents, foreword, preface, and acknowledgements portion of the journal "Wireless Data Technologies."

Focuses on the history of wireless technologies. Concept of the operational wireless telegraph apparatus developed by Guglielmo Marconi; Timeline on the evolution of wireless technologies; Functions of packet radio.

The article focuses on electronic wave propagation. Wireless communication from one point to another requires a transmitter and an antenna electromagnetic waves. When the wave is not in free space or encounters objects, it can change amplitude, phase, and direction and may no longer be a uniform plane. In short, the plane wave characterization is just a temporary description of the wave at a given time and at a given location. Free-space transmission is a primary consideration in essentially all fixed broadband wireless communication systems.

The article focuses on multiple-access techniques. While global spectrum partitioning is the mechanism for multiple access to the entire spectrum, for wireless systems operating in a particular geographic area in the same frequency band, multiple access means the simultaneous access to the same frequencies or channels within the same area by multiple users. While the multiple-access quality of service delivered to the user is a function of the service type and acceptable service delay, the radio channel performance criteria for all multiple-access schemes can be reduced to the fundamental consideration of interference between systems and within systems.

The article focuses on propagation environment models. Except for a vacuum such as outer space, wireless system wave propagation is affected by the elements and characteristics of the real environment in which the networks are deployed. Topographic maps are the fundamental source of information of terrain elevations. The map contains many types of information, including lines of constant elevation, or contours, that undulate across the map. The contour lines are usually drawn at regular elevation spacing so that relative line density is an indicator of how steep or how shallow the terrain slope is.

The article focuses on Point-to-multipoint (PMP) network architecture. PMP network architecture is the most widely used approach for electronic communication with a large number of destinations or nodes. It is used for wired telephone systems in which twisted wire pairs from each phone terminal are routed to a central office where calls are placed on shared trunk circuits for onward routing. The wired PMP networks provide service to discrete locations, whereas the wireless systems listed are designed to provide service to an area where the specific locations of the service users are usually unknown.

The article focuses on propagation models that are fundamental tools for designing any fixed broadband wireless communication system. A propagation model basically predicts what will happen to the transmitted signal while in transit to the receiver. Modern communication systems achieve higher capacity by using a wider band of frequencies. For such systems, narrowband prediction of signal levels and fading alone does not provide enough information to predict system performance. As a consequence, the concept of a propagation model has been broadened to include models of the entire transfer function of the channel.

The article focuses on interference suppression and Code Division Multiple Access system (CDMA). If the interfering signal correlation function is specified, the closed-form solution for the SNR improvement factor can be obtained. This will be illustrated in this section by modeling the interference as a narrowband first-order autoregressive process. Solving the filter coefficients from the given system of equations is conceptually straightforward, but rather cumbersome and tedious work. For the analysis of the mutual influence of CDMA and narrowband communications network, the interfering signal to occupy a multiple frequency band has been assumed.