articularly the faster Mathematically expressed, orthogonality is when the inner product of two functions within the signal is zero. An orthogonal signal is one in which the phase of the signal is arranged to ensure that, in theory at least, no interference is created into an adjacent signal. 4 LTE User equipment, network efficiency and value Published 1 September 2010 available as a free download from http://www.makingtelecomswork.com/resources.html An exabyte is a million terabytes. These forecasts including tariff trends are drawn from industry sources and modelling and forecasting undertaken by RTT and The Mobile World. Making Telecoms Work than expected uptake of smart phones, we have revised our 2015 figure to 144 exabytes (see graphs in Chapter 4). Irrespective of whether the final figure is 90 exabytes or 150 exabytes or some larger number, the projected efficiency savings from new technology such as LTE are insufficient to bridge the gap between volume growth and value growth. New solutions and/or new income streams are therefore required in order to enable the sustainable growth of the mobile broadband industry. This includes technology and engineering innovation and specifically for wireless, a combination of materials innovation, RF component innovation, algorithmic innovation and radio engineering innovation. Market innovation to date seems to have been focused on producing ever more impenetrable tariffs and selling smart-phone insurance that users may or may not need. 1.8 Radio versus Copper, Cable and Fibre - Comparative Economics Radio engineering is a fascinating discipline but is best analysed in a broader context in which technical and commercial viability is benchmarked against other delivery options, copper, cable and fibre. The comparative economics are complex and can yield idiosyncratic and counterintuitive results. For example, if a large file is not time sensitive then the most efficient delivery method, at least in terms of cost, may be to put the data on a memory stick and post it. In 