CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [428]
You can increase range in a couple of ways. You can install multiple WAPs to permit “roaming” between one WAP’s coverage area and another’s—an EBSS, described earlier in this chapter. Or you can install a replacement that increases a single WAP’s signal strength, thus increasing its range. If that is still not enough, signal boosters are available that can give you even more power.
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EXAM TIP Look for basic troubleshooting questions on the CompTIA A+ certification exams dealing with factors that affect wireless connectivity, range, and speed.
Wireless Networking Standards
To help you gain a better understanding of wireless network technology, here is a brief look at the standards they use.
IEEE 802.11-Based Wireless Networking
The IEEE 802.11 wireless Ethernet standard, more commonly known as Wi-Fi, defines methods by which devices may communicate by using spread-spectrum radio waves. Spread-spectrum broadcasts data in small, discrete chunks over the frequencies available within a certain frequency range.
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NOTE In the early days of wireless networking, many techs and marketing people assumed Wi-Fi stood for Wireless Fidelity, a sort of play on the common sound signal of high fidelity. It might have at one time, but the Wi-Fi Alliance, the governing standards body for 802.11-based networking, just uses the term Wi-Fi today.
The 802.11-based wireless technologies broadcast and receive on one of two licensefree industrial, scientific and industrial radio bands: 2.4 GHz and 5.8 GHz. Even though the ISM band is 5.8 GHz, we just say “5 GHz” for reasons I can’t answer. Over the years, the original 802.11 standard has been extended to 802.11a, 802.11b, 802.11g, and 802.11n variations used in Wi-Fi wireless networks. Each of these versions of 802.11 uses one of the two ISM bands, with the exception of 802.11n, which uses one but may use both. Don’t worry; I’ll break this down for you in a moment.
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NOTE Wi-Fi is by far the most widely adopted wireless networking type today. Not only do millions of private businesses and homes have wireless networks, but many public places such as coffee shops and libraries also offer Internet access through wireless networks.
Newer wireless devices can communicate with older wireless devices, so if you are using an 802.11n WAP, all of your 802.11g devices can use it. The exception to this is 802.11a, which requires that all of the equipment directly support it. The following paragraphs describe the important specifications of each of the popular 802.11-based wireless networking standards.
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NOTE Devices that use the original 802.11 (with no letter) standard are obsolete these days. You’re likeliest to find them in service on some brave early wireless adopter’s network—or in a museum. The original 802.11 standard was hampered by both slow speeds (2 Mbps maximum) and limited range (about 150 feet). The 802.11 standard employed some of the same features that are in use in the current wireless standards; 802.11 uses the 2.4-GHz broadcast range.
802.11a Despite the “a” designation for this extension to the 802.11 standard, 802.11a was actually on the market after 802.11b. The 802.11a standard differs from the other 802.11-based standards in significant ways. Foremost is that it operates in the 5-Ghz frequency range. This means that devices that use this standard are less prone to interference from other devices that use the same frequency range. 802.11a also offers considerably greater throughput than 802.11 and 802.11b at speeds up to 54 Mbps, though its actual throughput is no more than 25 Mbps in normal traffic conditions. Although its theoretical range tops out at about 150 feet, its maximum range will be lower in a typical office environment. Despite the superior