eanwhile, the rollout of the 4G mobile telecommunications systems and standardi- sation of the new TDD technology called TD-LTE has meant that most TD-SCDMA investment is being reconsidered. Both TD-CDMA and TD-SCDMA have failed to gain much traction in the market place. Despite strong support from governments and major companies, the worldwide mobile telecommunications industry is converging to one main set of standards, and it is uneconomical to roll out technologies which do not gain a worldwide following [11, 12]. Case Study Questions How is TDD superior to FDD in power control? How is an uplink synchronous system valuable? Why do you think the focus of TD-SCDMA was voice communications? How did the government influence the choice of mobile telecommunications tech- nology in China and why? How do you see the importance of Chinese government support in the emergence of the TD-LTE standard? W-CDMA Release 5 - Introduction of HSDPA The first version of Release 5 of the W-CDMA standard was published in 2002. Release 5 introduced a new downlink data transmission scheme called High Speed Downlink Packet Access (HSDPA). HSDPA enabled increased data transmission speeds, from the base station to the mobile device, to a speed of several megabits per second. This meant that it became practical for mobile devices to perform functions such as downloading large files or streaming video, for example by using YouTube. If channel conditions are good (e.g. if the SINR is high) then according to Shannon's the- orem the channel capacity is high. This means that higher transmission rates may be supported within the same bandwidth. The mechanism used to realise higher transmission rates is the application of higher order modulation techniques, such as 64-QAM (quadrature amplitude modulation) or 16-QAM instead of quadrature phase shift keying (QPSK). As discussed in Chapter 7, higher order modulation techniques can enable more bits per signal constellation point/symbol. Release 5 of the W-CDMA standard incorporated 16-QAM, which en