A new book title came to my attention, "Wimax/Mobilefi". I hadnt heard of MobileFi before so i did a bit of digging up and here are the details.
MobileFi is also known as Mobile-Fi or Mobile Broadband Wireless Access (MBWA) and is better known as IEEE 802.20
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 the specification for an efficient packet-based air interface optimized for the transport of IP-based services. The goal is to enable global deployment of low-cost, ubiquitous, interoperable, and always-on multivendor mobile broadband wireless access networks. IEEE 802.20 has designed a new physical layer (Layer 1 protocol) and MAC/link layer (Layer 2 protocol) around IP packet Layer 3. It can operate in licensed bands below 3.5GHz, with cell ranges of 9 miles (15 km) or more. IEEE 802.20 can operate at speeds of up to 155 mph (250 kph).
Unlike WiMAX, which was incubated inside IEEE 802.16 family and evolved from earlier 802.16 technologies, 802.20  or Mobile-Fi was designed from ground up as a technology to support high-mobility services. It aims to support mobility as high as 250 km/h and a peak rate of up to 260 Mbps in the licensed spectrum below 3.5 GHz. Th e enabling technologies are also OFDM, MIMO, and beam-forming. The draft standard is still under the IEEE standardization process.
Both WiMAX and 802.20 use OFDM-MIMO, which is emerging as the main technology for future cellular packet data networks, including 3GPP long-term evolution and 3GPP2 air interface evolution as well.
While the data rate and range of Mobile-Fi are only half those of Mobile WiMax, Mobile-Fi is inherently more mobile. It has an astonishing latency of just 10 milliseconds (500 milliseconds is standard for 3G communications) and can maintain integrity at speeds as high as 155 mph (250 kph), compared to just 60 mph (100 kph) for WiMax. Because it uses more common spectrumlicensed bands up to 3.5GHzit also offers global mobility, handoff, and roaming support. Whereas Mobile WiMax is looking at the mobile user walking around with a PDA or laptop, Mobile-Fi addresses high-speed mobility issues. One key difference is the manner in which the two standards are deployed. One assumption is that the carriers are going to deploy Mobile WiMax in their existing (802.16a) footprint as opposed to deploying a more widespread footprint, like a cellular network. Because Mobile-Fi is aimed at more ubiquitous coverage, a larger footprint will be required.
Countries and companies often seek to control the market by developing standards they hope will dominate the global scene. The United States has led the way with IEEE standards, and the European Union's ETSI standards are their counterparts. The work of standards consensus is ongoing, uncertain, and difficult to predict. Mobile operators, who are generally friendly to Mobile WiMax, see Mobile-Fi as a competing standard that could make their 3G licenses worth rather less than they paid for them. The fact that Intel is behind WiMax is a strong force and will undoubtedly push the WiMax standards forward.
Mobile-Fi will have to overcome several hurdles. First among them is the fact that it can be used only in licensed bands below 3.5GHz. Another is that Mobile-Fi trails the Mobile WiMax standards process by a couple years. Another hurdle is whether there is indeed a large requirement for 155 mph (250 kph) handoff. In addition, we do not know what effect Mobile WiMax being nationalized in Korea will have. And, very importantly, cellular companies may not be willing to undercut their 3G service. Certainly, we can assume that the US$100 billion investment in 3G spectrum by the European mobile carriers alone might be weighed against a workable Mobile-Fi standard. With the possibility of proprietary systems (e.g., WiBro, Flash-OFDM) being in place a number of years before Mobile-Fi is standardized, the likelihood is that by then, Mobile WiMax will be backward compatible with WiMax fixed services. Licensed or unlicensed, Mobile-Fi will not be ubiquitous, and WiMax probably will.
Further Reading:* Book: Wimax/Mobilefi
* Official IEEE 802.20 website