Wireless local area networks (WLANs) have traditionally been used to transport only data, but are now being used to carry voice traffic as well as provided new combined voice and data services. Voice over WLANs also offers more flexibility than wired networks (changes to a WLAN dont require changes to installed wiring) and greater capacity than wired networks. This book provides a solid overview of voice over WLANs/VoIP (voice over internet protocol) technology, including voice coding, packet loss, delay and jitter, and echo control. It shows how to combine both WLAN and VoIP technology to create effective voice over WLAN systems.

* Gives complete details on integrating voice and data services on WLANs, including wide area networks

* Explores quality of service (QoS) and security issues

* Step-by-step descriptions of how to plan and implement voice over WLAN networks

Nearly twenty years ago I was introduced to a fascinating new technology that has now become part of our everyday activity. At the time, I thought it was extremely cool to log into a distant server and read stuff. At the time, that stuff came at a hefty price—Internet time was over $2.00 per hour, connection speeds were measured in bauds, and to read the cool stuff required differentiating the Unix code from the content and following lines of text written in yellow as they wrapped against a particularly ugly green background. But it was extremely cool.

The coolness is still there, although it has certainly changed. It has been a pleasure to participate and experience the changes, from the yellow/green to the black text on gray backgrounds in the first Netscape browsers, to using images. And now we have the ability to interact with full-featured web-based applications like Google Docs & Spreadsheets, or downloadable tools that connect with Google servers for further functionality, such as Picasa and Google Earth.

Wasn’t the Web supposed to make everything easier? Oh sure, the maturation of companies doing business on the Web has made things more reliable and more secure, but easier? If you’ve been using the Web for a while (5+ years), you’ve noticed the evolution from static web pages to dynamic content. AJAX and other technologies provide an even greater level of interactivity giving end-users a richer Web experience. Google has pioneered the simple-interface approach. There are web sites devoted to every conceivable human activity and subject imaginable. (Don’t believe me? Point your browser to http://www.kli.org/tlh/newwords.html.)

Yes, all of these things make us more productive, more interested in the world around us, more connected to people and places we might never have a chance of knowing about. But is it easier? You should be able to do everything by yourself by now: fix your car, pick up girls (or guys), start your own company. Yet there is still a deep thirst for knowledge. Part of this has to do with customer expectations, and by customer, I mean anyone who visits your site. Customers demand more and more information. There is an almost insatiable desire for knowledge. At what point does the sheer volume of information make it impossible to present information to a user in a meaningful way? At what point do the scales tip and users become less interested in what information is presented to them and more interested in how it is presented to them?

I believe we’ve reached that point. Don’t get me wrong; users are still interested in the content of what they’re looking for, but more and more people, overwhelmed by the quantity of information available, are either turning to sites or products that summarize and organize content, using the first thing Google returns to them, or giving up altogether. Even inside a company or organization (where the choices of where to gather information are much more limited), users (employees) will choose what they are comfortable with, whether it’s an Oracle Portal system, a set of binders, or just walking over to a colleague’s desk to ask about the information they need. As a developer, your challenge is not only to present the data your customers want but present it in a meaningful way. In short, modern web development should be just as concerned with how information is presented as with what is presented.

The study of human motion dates back more than 2000 years. With the event of information technology, new areas have been added to this field. Research using computer vision and computer graphics contributes to a transformation of biomechanics into a discipline that now applies computing technology throughout; on the other hand, computer vision and computer graphics also benefit from defining goals aimed at solving problems in biomechanics. Besides interactions, all three areas also developed their own inherent research dynamics towards studying human motion.

Researchers from all three of these areas have contributed to this book to promote the establishment of human motion research as a multi-facetted discipline and to improve the exchange of ideas and concepts between these three areas. Some chapters review the state of the art whilst others report on leading edge research results, with applications in medicine, sport science, cinematography and robotics.

Automatic Program Development is a tribute to Robert Paige (1947-1999), our accomplished and respected colleague, and moreover our good friend, whose untimely passing was a loss to our academic and research community. We have collected the revised, updated versions of the papers published in his honor in the Higher-Order and Symbolic Computation Journal in the years 2003 and 2005.

Among them there are two papers by Bob: (i) a retrospective view of his research lines, and (ii) a proposal for future studies in the area of the automatic program derivation. The book also includes some papers by members of the IFIP Working Group 2.1 of which Bob was an active member. All papers are related to some of the research interests of Bob and, in particular, to the transformational development of programs and their algorithmic derivation from formal specifications. Automatic Program Development offers a renewed stimulus for continuing and deepening Bob's research visions.

A familiar touch is given to the book by some pictures kindly provided to us by his wife Nieba, the personal recollections of his brother Gary and some of his colleagues and friends.

About the Author

Prof. Olivier Danvy is editor in chief of the Higher Order for Symbolic Computation journal, and is also editor for two books in the LNCS series.

This book is written for Dr. Robert (Bob) Paige. Bob Paige, a professor of computer science and a leading researcher in the area of programming languages and transformational programming. Dr. Paige was the author of many research papers, covering related topics in programming languages, compilers, algorithms, and database design. An invited speaker at conferences and university seminars around the world, he also served regularly as a reviewer of research projects for major government agencies. He was a devoted mentor of PhD students who today hold research positions at leading universities and research centers.

Space, with its manifold layers of structure, has been an inexhaustible source of intellectual fascination since Antiquity. The science that began with the empirical discoveries of the Egyptian ‘rope-stretchers’, and that has inspired many of the greatest developments in mathematics over the centuries, now comprises such topics as spatial databases, automated geometrical reasoning and digital image processing. In this long intellectual history, however, one relatively recent, yet crucial, event stands out: the rise of the logical stance in geometry. Fundamental to this development is the analysis of geometrical structures in relation to the formal languages used to describe them, and the recognition of the special mathematical challenges—and opportunities—which such an analysis presents. The interplay between logic and geometry is the subject of this book.

By a spatial logic, we mean any formal language for describing geometrical entities and configurations, where ‘geometrical’ is understood in a broad sense. Unlike their well-studied temporal counterparts, spatial logics have been curiously neglected in the literature on mathematical logic, despite some early pioneering work by Tarski and others on the foundations of geometry and topology in the middle years of the previous century. Only in the last decade have spatial logics attracted renewed attention from logicians, partly as a response to work in such diverse fields as artificial intelligence, database theory, physics and philosophy.