ct. Self-evidently if a band per year had been added we would have twenty-band user devices by now, the average has been a new band every three years or SO yet here we have the international regulatory community assuming a transition from a five-band phone to a phone supporting ten bands or more within two to three years at the outside. This could only be done if a significant performance loss and significant increase in product cost was considered acceptable. Note that one operator's ten band phone will not be the same as another operator, further diluting available RF design and development capability. The US 700-MHz band plan is particularly challenging for RF design engineers both in terms of user-device design and base-station design. We revisit this topic in Chapter 12, Staying with user-device design considerations, Figure 5.8 illustrates the complexity introduced even when a relatively small subset of 3GPP bands is supported. Table 5.4 shows the core bands supported and the additional bands and band (either combination options. Note the separate MIMO front-end module (FEM) to support the diversity receive path. 21 http://www.stericsson.com/home/home.jsp Making Telecoms Work Table 5.4 Core band combination with international roaming support Core band combination band 1 plus other bands for international roaming support Band 1 3G WCDMA/LTE 1900/2100 MHz Band 2 US PCS 1900 1800/1900 MHz Band 4 US AWS 1700 1700/2100 MHz Band 5 and 6 US 850 band (plus Asia and Japan) 824/840 869/894 Band 8 Europe and Asia 900 MHz 880/915 925/960 Additional bands Band 3 1800 MHz Europe and Asia 1710/1785 1805/1880 Band 7 2.6 GHz band Band 11 1.5 GHz for Japan Bands 12 and 14 US 700 MHz Band 20 or European 800 MHz Band 40 2.3 GHz for China To support progress to or beyond requires substantial RF component innovation. Although most of these components have already been introduced in Chapter 3 we now need to revisit present and future performance benchmarks and how these devices may potentially resolve the multiple band allocation