l-estate cost that is a composite of the site or right of access negotiation and acquisition cost and ongoing site or right of access administration costs. Present fibre to the home (ftth) deployments, for example, imply significant street-level engineering and financial-resource allocation that has to be justified in terms of bidirectional data throughput value amortised against relatively ambitious return on investment expectations. In cellular and mobile broadband networks, similar ROI criteria have to be applied to realise a return from spectral investment, site acquisition and ongoing site-management costs. Cellular and mobile broadband networks are, of course, in practice, a composite of radio access, copper and fibre. Wireless costs are reducing but whether they are reducing faster than other delivery options remains open to debate. 21.18.3 The Interrelationship of RF Access Efficiency and Network Cost The escalation of spectral and site values has highlighted a perceived need for cellular and mobile broadband technologies to provide incremental but rapid improvements in capacity, the number of users per MHz of allocated or auctioned spectrum multiplied by typical user per data throughput requirements, and coverage (range). New technologies are therefore justified on the basis of their 'efficiency' in terms of user/data throughput per MHz, which we will call, for lack of a better term, 'RF access efficiency'. In practice, new technologies need to offer useful performance gains, lower real costs and increased margins for vendors. Future Trends, Forecasting, the Age of Adaptation and More Transformative Transforms 21.18.4 The Engineering Effort Needed To Realise Efficiency Gains However, new technologies, particularly new radio technologies, generally deliver initially disappointing performance gains. This is because the potential gains implicit in the technology can only be realised through the application of significant engineering effort. 21.18.5 The Impact of Standards and Spectral Policy on RF Network E