Wireless networks have long been hailed as easily deployed, low-cost solutions for providing broadband services to an increasingly mobile population. As with any emerging technology, however, it wasn't long before attackers were exploiting it.
The popular version of wireless networking, known as WiFi, revolutionized the ways that both small home-offices and larger facilities work, making it trivial to extend bandwidth into areas where it was impractical or too expensive to run Ethernet cable. For a while it seemed as if WiFi offered instantly deployable, easily configurable, and most importantly mobile communications to the masses.
Soon, however, over-the-air sniffers, such as kismet and airsnort, allowed attackers to capture and decode data transmitted via WiFi. Rogue access points -- often illicitly deployed by users seeking easier access -- opened security holes deep within companies' enterprises, allowing attackers to completely circumvent traditional protections, such as firewalls and IDS, and simply break in through a wide-open back door. These rogue access points also became a useful way for attackers to capture passwords, credit card numbers, and other sensitive information.
It didn't take long for information technology professionals to realize that the promised land of WiFi was rife with risks, vulnerabilities, and unforeseen dangers that still cause significant security challenges today.
In addition, WiFi has caused many technical headaches. Its effective coverage radius, also known as the "cell radius," is fairly small -- typically a few hundred feet when used with omnidirectional antennas like those in your typical laptop. WiFi also has pretty substantial bandwidth limitations that make it impractical for high-density user environments or as a last-mile transport-layer solution. Over the years these technical challenges, along with the security problems, have been addressed in large part by constantly evolving standards and bolting security controls on top of WiFi. Examples include Wired Equivalent Privacy (WEP) encryption, WiFi Protected Access (WAP) encryption, and 802.1x.
Yet, without using highly directional and large antennas, WiFi still wasn't the optimum solution for large metropolitan-scale or long-haul point-to-point links. This is the reason WiMax and similar standards were born.
| | WiFi | WiMax |
|---|---|---|
| Recommended Uses | Short-range, LAN-centric | Long-range, MAN-centric |
| Spectrum | Unlicensed spectrum 802.11b/g – 2.4 GHz 802.11n – 2.4 GHz, 5 GHz | Unlicensed or licensed spectrum between 2-66 GHz US: 2.4 GHz International: 2.3 GHz, 3.5 GHz |
| Quality of Service | Minimal - QoS is relative only between packets/flows | Guaranteed - QoS is assured using scheduling algorithms at MAC layer |
| Cell Footprint | < 300 meters maximum Most implementations about 30 meters | Up to 10 kilometers Most implementations about 3 km |
| Bandwidth | 802.11b: 11 Mbps max 802.11g: 54 Mbps max 802.11n: at least 100 MbpsAll bandwidth is at short range | Up to 70 Mbps theoretical max Up to 40 dedicated subscriber channels Expect 15 Mbps at 3 km range |
WiMax refers to a standard designed to provide high-bandwidth wireless services on a metropolitan area scale. It provides a much greater bandwidth in comparison to WiFi, allowing users to share up to 70 Mbps at short range -- although 10 Mbps at 10 km is more typical -- per channel in fixed implementations. Each channel can be split between up to 40 simultaneous users, providing symmetric download speeds that rival a traditional DSL connection.
While WiFi has moved into high-bandwidth solutions with the advent of the draft 802.11n specification, which provides theoretical bandwidth maximums up to 248 Mbps, the true advantage WiMax maintains is in cell radius. Even with 802.11n, WiFi is typically limited to ranges under 300 meters without specialized equipment. In contrast, WiMax provides a much larger cell radius -- up to 3 km in fixed applications -- without significantly degrading its available bandwidth. These key features are the reason the WiMax standard is considered one of the leading contenders for the future of wireless broadband, for use in metropolitan area networks (MAN) and as the underpinnings of 4G cellular networks.
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