dio frequency analysts would err towards starting at the top and working down on the basis that the application layer has the most direct impact on the customer experience and therefore should be regarded as the prime enabler. This assumes that we are working in an industry that is customer led rather than technology led, but this is at odds with historical evidence that suggests that the economics of telecommunications supply and demand are directly dependent on fundamental innovations and inventions at the physical-layer level. The innovations in the lower layers are generally, though not exclusively, hardware innovations, the innovations in the upper layers are generally, though not exclusively, software innovations. This functional separation determines the structure of this book, with Part 1 reviewing user equipment hardware, Part 2 reviewing user equipment software, Part 3 reviewing network equipment hardware and Part 4 reviewing network equipment software. In terms of analysis methodology we are firmly in the bottom-up brigade. Readers with long memories might recall that this is uncannily similar to the structure used in '3G Handset and Network Design' and we would point out that this is entirely deliberate. The business of technology forecasting should in practice be a relatively precise science, but even if imperfect can be used to calibrate future efforts. '3 G Handset and Network Design' still provides a perfectly adequate primer to many of today's technology trends but lacked an ambition to integrate the technology and engineering story with economic analysis. 1.10 Technology and Engineering Economics - Regional Shifts and Related Influence on the Design and Supply Chain, RF Component Suppliers and the Operator Community Which brings us back towards our start point in which we said that we aim to make the case that technology and engineering economics are separate disciplines that deserve separate analysis. In this context we will find that technology and engineering capacity is also determined by th