Eight-Oh-Two-Dot-Eleventy Something? (Or, Understanding Wireless Standards)
The most popular standards for wireless networks are the IEEE 802.11 standards. These essential wireless Ethernet standards use many of the same networking techniques that the cabled Ethernet standards (in other words, 802.3) use. Most notably, 802.11 networks use the same CSMA/CD technique as cabled Ethernet to recover from network collisions.
The 802.11 standards address the bottom two layers of the IEEE seven-layer model: the Physical layer and the Media Access Control (MAC) layer. Note that TCP/IP protocols apply to higher layers of the model. As a result, TCP/IP runs just fine on 802.11 networks.
The original 802.11 standard was adopted in 1997. Two additions to the standard, 802.11a and 802.11b, were adopted in 1999. The latest and greatest version is 802.11g.
Table 9-2 summarizes the basic characteristics of the three variants of 802.11.
| Standard | Speeds | Frequency | Typical Range (Indoors) |
|---|---|---|---|
| 802.11a | Up to 54 Mbps | 5 GHz | 150 feet |
| 802.11b | Up to 11 Mbps | 2.4 GHz | 300 feet |
| 802.11g | Up to 54 Mbps | 2.4 GHz | 300 feet |
Open table as spreadsheet Most wireless networks are now based on the 802.11b standard. Although 802.11a is faster than 802.11b, it's considerably more expensive and has less range. In addition, 802.11a and 802.11b aren't compatible with each other because 802.11a transmits at 5 GHz and 802.11b transmits at 2.4 GHz. As a result, 802.11a and 802.11b devices can't receive each other's signals.
The new standard, 802.11g, solves this problem by enabling high-speed connections at 2.4 GHz. As a result, 802.11g devices are compatible with existing 802.11b networks.
| Warning | 802.11b networks operate on the same radio frequency as many cordless phones: 2.4 GHz. If you set up an 802.11b network in your home and you also have a 2.4 GHz cordless phone, the network and phone may occasionally interfere with each other. The only way to completely avoid the interference is to switch to a 900 MHz phone or use more-expensive 802.11a network components, which transmit at 5 GHz rather than at 2.4 GHz. |
