s, VSAT services, and in some areas fixed multi- North American consumers still have to choose be- point systems, are available. tween three or four incompatible second generation digital technologies, though the evolution path points toward two technologies in the coming generation (3G). Where we are going Within the last year, cellular carriers have deployed their first serious large-scale data offerings, with medium rate The advances of the recent decades show no sign of (~50 kbps) packet data overlaid on their voice channels. slowing. Despite the current (2003) telecom slump, For the first time, wide area consumer data services are wireless research and development continues apace. In- available at moderate data rates and low costs. It is yet to cremental improvements in all facets of wireless com- be seen exactly how this offering will be used, or how munications should continue for the foreseeable future. widely it will be accepted. Additionally, there are certain ongoing research areas that could potentially provide quantum advances across the Applications wireless landscape. We just discussed the current wireless landscape from a Software radio technological viewpoint. We can also consider wireless In conventional radios, we see open system interconnect products in terms of the supported applications, such (OSI) Layer 1 (physical) implemented in (mostly analog) as voice, messaging, private data, and Internet access. hardware, with filters and amplifiers, for example, Introduction CHAPTER 1 .0 designed for operation at specific frequencies consistent Cost-using today's technologies, digital logic gates with the radio's intended usage. Layer 2 (data link) are inherently less expensive than analog components. may be implemented in custom digital hardware or a Power consumption-there is potentially more oppor- general-purpose digital signal processor; higher layers are tunity to optimize for lower power consumption usually executed by software/firmware in general- (and therefore longer battery life) for a sof