WiMAX has the potential to replace a number of existing telecommunications infrastructures. In a fixed wireless configuration it can replace the telephone company's copper wire networks, the cable TV's coaxial cable infrastructure while offering Internet Service Provider (ISP) services. In its mobile variant, WiMAX has the potential to replace cellular networks. How do we get there?

What is WiMAX or Worldwide Interoperability for Microwave Access? WiMAX is an Institute of Electrical and Electronics Engineers (IEEE, see http://www.ieee.org) standard designated 802.16-2004 (fixed wireless applications) and 802.16e-2005 (mobile wire-less). The industry trade group WiMAX ForumTM (http://www.wimaxforum.org ) has defined WiMAX as a "last mile" broadband wireless access (BWA) alternative to cable modem service, telephone company Digital Subscriber Line (DSL) or T1/E1 service.

Fixed WiMAX

Figure 2 Fixed WiMAX offers cost effective point to point and point to multi-point solutions

What makes WiMAX so exciting is the broad range of applications it makes possible but not limited to broadband internet access, T1/E1 substitute for businesses, voice over Internet protocol (VoIP) as telephone company substitute, Internet Protocol Television (IPTV) as cable TV substitute, backhaul for Wi-Fi hotspots and cell phone towers, mobile telephone service, mobile data TV, mobile emergency response services, wireless backhaul as substitute for fiber optic cable.

WiMAX provides fixed, portable or mobile non-line-of sight service from a base station to a subscriber station, also known as customer premise equipment (CPE). Some goals for WiMAX include a radius of service coverage of 6 miles from a WiMAX base station for point-to-multipoint, non-line-of-sight (see following pages for illustrations and definitions) service. This service should deliver approximately 40 megabits per second (Mbps) for fixed and portable access applications. That WiMAX cell site should offer enough bandwidth to support hundreds of businesses with T1 speeds and thousands of residential customers with the equivalent of DSL services from one base station.

Mobile WiMAX

Figure 3 Mobile WiMAX allows any telecommunications to go mobile

Mobile WiMAX takes the fixed wireless application a step further and enables cell phone-like applications on a much larger scale. For example, mobile WiMAX enables streaming video to be broadcast from a speeding police or other emergency vehicle at over 70 MPH. It potentially replaces cell phones and mobile data offerings from cell phone operators such as EvDo, EvDv and HSDPA. In addition to being the final leg in a quadruple play, it offers superior building penetration and improved security measures over fixed WiMAX. Mobile WiMAX will be very valuable for emerging services such as mobile TV and gaming.

WiMAX is not Wi-Fi

Figure 4 Where Wi-Fi covers an office or coffee shop, WiMAX covers a city

One of the most often heard descriptions of WiMAX in the press is that it is "Wi-Fi on steroids". In truth, it is considerably more than that. Not only does WiMAX offer exponentially greater range and throughput than Wi-Fi (technically speaking 802.11b, although new variants of 802.11 offer substantial improvements over the "b" variant of 802.11), it also offers carrier grade quality of service (QoS) and security. Wi-Fi has been notorious for its lack of security. The "b" variant of 802.11 offered no prioritization of traffic making it less than ideal for voice or video. The limited range and throughput of Wi-Fi means that a Wi-Fi service provider must deploy multiple access points in order to cover the same area and service the same number of customers as one WiMAX base station (note the differences in nomenclature). The IEEE 802.11 Working group has since approved upgrades for 802.11 security and QoS.

Converged voice and data easy as FM radio?

Figure 5 With WiMAX, converged voice and data can be as easy as FM radio

Visualize turning on an FM radio in your office. You receive information (news, weather, sports) from that service (the FM radio station) and hardware (the FM radio with attached antenna). WiMAX can be described as being somewhat similar. In place of a radio station there is a base station (radio and antenna) that transmits information (internet access, VoIP, IPTV) and the subscriber has a WiMAX CPE that receives the services. The major difference is that with WiMAX the service is two-way or interactive.

Figure 6 WiMAX indoor CPE goes near the window and attaches to the customer's network