Not all wireless networking gear is equal. There are
Wi-Fi wasn’t always the only major player in the home wireless networking market. Around the same time that the IEEE introduced the 802.11b standard, another WLAN technology, HomeRF, also entered the
The HomeRF working group supported and developed the HomeRF standard. The HomeRF working
802.11b has been around since the late 1990s, and there is a lot of equipment available based on this standard. You can find bargains if you look for older 802.11x gear, but bargain hunting can backfire. Much of the older equipment isn’t upgradeable, so as the IEEE and manufacturers introduce improvements to the 802.11x protocols, you won’t be able to take advantage of them.
on many access points and adapters is upgradeable. The EPROM and EEPROM chips holding the programming code that operates these devices continue to hold their programming even when they have no power. Professionals call this firmware because it
Manufacturers use firmware upgrades to introduce improvements or new capabilities to a device. Most recently, manufacturers have released security upgrades based upon the 802.11i standard. (802.11i is the standard that describes improved security for Wi-Fi devices.) The Wi-Fi Alliance based the new Wi-Fi Protected Access (WPA) encryption standard on portions of 802.11i.
Being able to take advantage of firmware upgrades is an important thing to consider when you are purchasing new equipment. You can find out if a device has upgradeable firmware by checking the manufacturer’s Web site or, when possible, the device’s documentation.
In the past few
For wireless devices to operate on the same network, they must use compatible standards and
Wi-Fi devices operate only with compatible devices that use the same frequency band (such as 2.4 GHz or 5 GHz), but there are certified
First introduced in 1997, 802.11 consists of the family of wireless standards developed by the IEEE. Currently three primary physical layer standards exist within 802.11. Physical layer standards describe the network medium and the mode of transmission; in the case of Wi-Fi the physical standards describe the frequency band, and the transmission technology used to access and communicate on the network operating in that band.
The physical layer standards are 802.11a, 802.11b, and 802.11g. When you’re shopping for Wi-Fi gear, these are the standards that you’ll encounter. Other standards, like 802.11i, describe different aspects of wireless networking, and you don’t really need to know them unless you’re an IT professional.
802.11b was the first 802.11x protocol introduced, actually appearing prior to 802.11a (the IEEE didn’t release the standards in alphabetical order). Wi-Fi has risen to dominate the home wireless market, and because 802.11b has been around the longest, there is an
802.11b devices operate in the 2.4GHz radio band, with a maximum capacity of 11Mbps. Heavy traffic on the same channel can significantly reduce throughput, and speed can decrease the farther you get from an access point. 802.11b divides the 2.4GHz network into 11 channels, although devices in a network usually utilize three in order to limit the chance of access points interfering with one another.
Other consumer electronic devices, including cordless phones and microwave ovens, also use the 2.4GHz band. When operating, these devices may interfere with 802.11b WLAN functions. If you already own other 2.4GHz devices, you may want to consider this before deciding which wireless standard to use.
I discuss ways of dealing with radio frequency interference (RFI) in Chapter 8.
802.11a operates in the 5GHz band and has a maximum capacity of 54 Mbps, almost five times faster than the maximum capacity of 802.11b. Realistically, 802.11a must be close to an access point to achieve maximum throughput. Compared to 802.11b and Wireless-G, the range of an 802.11a access point is significantly shorter. Because of this, 802.11a isn’t the best choice for providing Wi-Fi access to a wide area, unless you are willing to invest in multiple access points so that the signal
802.11a devices aren’t compatible with 802.11b devices, because they operate on different frequencies and use different technologies. If you have an existing 802.11b network, you’ll have to purchase new equipment for every network client.
802.11g, or Wireless-G, is the newest 802.11x physical layer standard. 802.11g has the same maximum throughput as 802.11a, but operates in the 2.4GHz band along with 802.11b. Wireless-G is backward compatible with 802.11b, and devices for both standards can interoperate on the same wireless network. An 802.11g access point can communicate with 802.11b cards, so you can upgrade your clients incrementally; but to take advantage of full Wireless-G throughput, all of your clients and access points must be Wireless-G devices.
Although Wireless-G is backward compatible with 802.11b, you’ll notice slower WLAN throughput on a network with mixed clients and access points (Wireless-G and 802.11b) than in a homogeneous network built only with Wireless-G gear.
Wired Equivalent Privacy (WEP) is the original Wi-Fi encryption algorithm used to secure communication on 802.11x networks. Experts defeated WEP, making it useless (well almost, but not entirely). In response, the IEEE
Meanwhile, the Wi-Fi Alliance has developed and introduced Wi-Fi Protected Access (WPA) as a replacement for WEP. The Wi-Fi Alliance based WPA on a subset of the 802.11i standard, and WPA provides better security than WEP. If possible, you should upgrade your gear to use WPA.
Although WPA is a great improvement over WEP, it isn’t perfect. There are ways that an intruder can defeat WPA, but these are more the result of poor password and passphrase selection by users and not flaws in WPA itself. Refer to Chapter 10 for WPA best practices.
Because it offers throughput comparable to 802.11a and is backward compatible with 802.11b, Wireless-G can be a good alternative to 802.11a. Wireless-G has price and performance advantages over 802.11a,
IEEE has recognized the 802.11n working
Bluetooth is a wireless personal area network (WPAN) technology developed by the Bluetooth Special Interest Group, an industry organization founded by Nokia, Ericsson, IBM, Intel, and Toshiba. Developers named Bluetooth after a twelfth- century king, Harald Blatand (Bluetooth), who unified Denmark and Norway. The goal of Bluetooth technology is to enable users to connect many different devices simply and easily without cables.
Although Bluetooth operates in the 2.4 GHz band, it doesn’t
Bluetooth connects devices and peripherals without annoying cables. You can already purchase keyboards, mice, printers, digital
Bluetooth devices can connect and create small ad hoc networks called piconets . In each piconet, the device that first initiates the connection becomes the master device. Each master device in a piconet can manage up to seven slave devices. Figure 1-8 illustrates a master and six slaves, leaving room for one additional device.
Figure 1-8: A Bluetooth piconet
A device can be a member of multiple piconets at one time, but can only be a master in one. Scatternets are piconets connected by one or more devices (see Figure 1-9). A scatternet may contain 10 fully loaded piconets at any one time.
Bluetooth is a useful and complementary technology to Wi-Fi, and you will begin to see it integrated into more devices every year. You can upgrade your printers and some other peripherals to use Bluetooth by installing small Bluetooth adapters. These adapters are inexpensive, with some costing less than $20.