So why isnt WiMax being used?
Unlike the 802.11 standards, which send transmissions over a narrow frequency range, WiMAX allows data transport over multiple broad frequency ranges. Because it can work in multiple ranges, the technology avoids interference and it can support more users from a single station. For example, a single 802.11g access point would find itself hard pressed to deliver sufficient bandwidth for more than 50 simultaneous users. A WiMAX base station, such as the Proxim Tsunami MP.16 3500 can deal with up to 250 users at a given moment. So, if WiMAX is so wonderful, why aren't you using it already? Because, WiMAX is still being rolled out.First, Mathias wrote, the telecoms want "to keep the number of base stations to a minimum because they're expensive, the nature of a given radio connection changes as the mobile end moves. Specifically, fading comes into play, and at times the signal may fade so much that a connection can't be maintained." Then, Mathias continued, there's the problem of "capacity as lots of users attempt to access the relatively limited number of channels available. The solution here is simple in one respect -just add more base stations. Cellular carriers have to deal with this problem on a daily basis, but, again, the expense involved is one of the reasons that cellular systems still feature dropped calls, occasional gaps in service and (often) slow data throughput." WiMAX as a new technology faces this problem in an acute form since telecoms must balance rolling out enough base-stations to meet demand with not blowing their budget. Mathias concluded that "comparisons with cellular are quite appropriate here, since the challenges faced by cellular and mobile WiMAX are almost identical. And therein lies the biggest challenge-can mobile WiMAX really compete with cellular? Cellular-based wireless broadband services like 1xEV-DO, available from Sprint and Verizon, and HSDPA (High-Speed Downlink Packet Access), available from Cingular (now AT&T), will eventually offer multimegabit data services-exactly the territory mobile WiMAX is targeting.
As Craig Mathias is a principal at Farpoint Group, an advisory firm specializing in wireless networking and mobile computing explained in a white paper, "A look at WiMAX, problems and pluses", WiMAX requires a great deal of infrastructure work, which hasn't been done yet.