o access the Internet at initial speeds of 700Kbps from a vehicle moving at 60 mph (100 kph). South Korea licensed three firms to launch commercial WiBro services in 2006: SK Telecom (www.sktelecom.com/eng), KT Corp. (www.kt.co.kr/kthome/eng/index WMANs jsp), and Hanaro Telecom (www.hanaro.com/eng). (However, Hanaro has dropped out of the race at this point.) WiBro functions in the 2.3GHz spectrum band. Because two of the companies licensed to launch commercial WiBro, SK Telecom and KT, also own 3G networks, it is likely that the eventual implementation of WiBro will coexist with 3G. WiBro will affect Korea's growing number of Wi-Fi hotspots (KT alone has more than 25,000) because WiBro can cover the same areas as Wi-Fi but has higher speeds, offers QoS, and works in licensed spectrum, with few interference problems. WiMax and WiBro are both expected to conform to the final 802.16e (Mobile WiMax) standard. However, because even within a standard there can be mutually exclusive options, it remains uncertain how the two will eventually interoperate. There is currently a difference between the two in the PHY layer: While both Mobile WiMax and WiBro use SOFDMA, the channel bandwidths and the number of associated tones defined in the WiBro standard are not consistent with the WiMax Forum specifications. There is now a serious competitor to WiBro, a 3.5G technology called High- Speed Downlink Packet Access (HSDPA) that uses W-CDMA. SK Telecom asked Samsung Electronics and LG Electronics to build facilities worth US$100 million to support W-CDMA. (HSDPA is discussed in detail in Chapter 14, "Wireless WANs.") IEEE 802.20 (Mobile-Fi) IEEE 802.20, also referred to as Mobile-Fi, is optimized for IP and roaming in high-speed mobile environments. This standard is poised to fully mobilize IP, opening up major new data markets beyond the more circuit-centric 2.5G and 3G cellular standards. The Mobile Broadband Wireless Access (MBWA) Working Group was established as IEEE 802.20 in December 2002. Its main mission is to develop th