vances on the right. a disadvantage to a comparable wireline communication system. Why then are wireless communications SO prevalent? Each wireless deployment may have its own availability is also increasing, due to investment in fixed design rationale, but two fundamental reasons cover infrastructure, as well as reduced device cost and size. most cases. First, wireless systems provide flexibility in Figure 1.0-3 categorizes select wireless technologies, deployment. Whether connecting a laptop PC in a con- graphed by system throughput and user mobility. Several ference room or a pipeline monitor in the Arctic, the groupings are identified for convenience. On the left are setup of a radio connection may be orders of magnitude Fixed Location systems, such as point-to-point micro- faster than a wireline connection, due to the fact that no wave and stationary satellite systems, which generally physical connecting media is required. Second, wireless operate at high rates (over one Mbps) on line-of-sight systems can provide the option of mobility. Communi- channels. Near the fixed systems, providing limited cating on the move is very useful, if not critical, to many mobility over shorter transmission paths but still applications, and this is just not well supported through supporting Mbps data rates, are Local Area systems, such a wired medium. as wireless local area networks (802.11) and personal Note that some of these "weaknesses" can cleverly be area networks (Bluetooth). Finally, Wide Area Mobile turned to the user's advantage. For example, attenuation Introduction CHAPTER 1.0 United States Telecom User Growth Homes w/ Telephones Cellular Subscribers Internet Users Figure 1.0-2 United States Telecom User Growth. With voice line penetration in saturation, wireless and Internet users continue to grow. Wireless data usage will follow. (Internet users include the United States and Canada.) and blocking may be leveraged to limit signal propagation over long-range line-of-sight paths. Several classes of and opportunitie