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If you want broadband Internet connectivity, chances are you use a DSL, or cable-modem-based landline connection at home or a T1, T3 or frame-relay at the office.
WiMAX technology promises to replace that last mile connection with a point-to-multipoint wireless connection in the same way that 802.11 Wi-Fi has replaced the wired LAN.
WiMAX, the commercial name for a variety of technologies that use the IEEE 802.16 standard, promises an open wireless standard that can deliver, in theory, up to 70M bps data throughput at ranges of up to 31 miles. As the IEEE is quick to point out though, those kinds of WiMAX ranges and speeds are myths. A more practical line of sight range might be 10M bps at 10 miles. In a city environment, realistically you’ll be glad to see 10M bps at a mile range.
However, to get away from the line of sight requirements, when vendors today, such as the recent alliance of Sprint and Clearwire, talk about WiMAX, what they’re actually thinking about deploying is Mobile WiMAX.
Mobile WiMAX is based on the IEEE 802.16e-2005 standard. This technology, in practice, should deliver 1 to 5M bps throughput at a range of about a mile. Higher, burst rate speeds, up to its maximum of 40M bps, may also be possible.
There’s nothing new about point-to-multipoint microwave networks. Companies such as Alcatel-Lucent and Siemens have offered it for years, but their products relied on various proprietary technologies. The end result is that these wireless long-haul technologies have tended to only be used in vertical markets. WiMAX, on the other hand, with its standardized technology, offers the possibility of low-cost, standards-compliant components from multiple, competing suppliers.
WiMAX also lends itself to multiple uses. For example, 802.16 divides its MAC (media access control) layer into sub-layers. These sub-layers can support different transport protocols, such as IPv4; IPv6; ATM (asynchronous transfer mode) and voice. With MPLS (Multiprotocol Label Switching), vendors can allocate their WiMAX broadband capabilities dynamically. For a telecomm, this means that they can use WiMAX to offer customers an all-in-one wireless Internet, mobile voice, fixed voice, and multimedia package.
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.
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.
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.