 guide to some of the key online information sites and resources relating to wireless networking, a comprehensive listing of acronyms and a glossary covering the key technical terms used throughout the book. This page intentionally left blank WIRELESS NETWORK ARCHITECTURE Introduction In the next two chapters, the logical and physical architecture of wireless networks will be introduced. The logical architecture is introduced in terms of the 7 layers of the OSI network model and the protocols that operate within this structure, with an emphasis on the Network and Data Link aspects that are most relevant to wireless networking - IP addressing, routing, link control and media access. Physical layer technologies are introduced, as a precursor to the more detailed descriptions later in the book, and the physical architecture of wireless networks is described, focussing on wireless network topologies and hardware devices. At each stage, some of the key characteristics of wired networking technologies are also briefly described, as a preliminary to the introduction of wireless networking technologies, in order to provide a background to the specific challenges addressed by wireless technologies, such as media access control. After this introduction, Part II will describe the basic concepts and technologies of wireless communication - both radio frequency and infrared. This page intentionally left blank CHAPTER Wireless Network Logical Architecture The logical architecture of a network refers to the structure of standards and protocols that enable connections to be established between physical devices, or nodes, and which control the routing and flow of data between these nodes. Since logical connections operate over physical links, the logical and physical architectures rely on each other, but the two also have a high degree of independence, as the physical configuration of a network can be changed without changing its logical architecture, and the same physical network can in many cases support different sets of stand