Wireless LAN Standards

At the time this book was published, the IEEE had ratified four major WLAN standards:

802.11, 802.11a, 802.11b, and 802.11g. This section lists the basic details of each WLAN standard, along with information about a couple of other standards bodies. This section also briefly mentions the emerging 802.1n standard, which the IEEE had not yet ratified by the time this Post was published.

Of the organizations listed in this table, the IEEE develops the specific standards for the different types of WLANs used today. Those standards must take into account the frequency choices made by the different worldwide regulatory agencies, such as the FCC in the U.S. and the ITU-R, which is ultimately controlled by the United Nations (UN).

The IEEE introduced WLAN standards with the creation of the 1997 ratification of the 802.11 standard. This original standard did not have a suffix letter, whereas later WLAN standards do. This naming logic, with no suffix letter in the first standard, followed by other standards with a suffix letter, is like the original IEEE Ethernet standard. That standard was 802.3, with later, more-advanced standards having a suffix, such as 802.3u for Fast Ethernet.

WAN Comparisons with Ethernet LANs

WLANs are similar to Ethernet LANs in many ways, the most important being that WLANs allow communications to occur between devices. The IEEE defines standards for both, using the IEEE 802.3 family for Ethernet LANs and the 802.11 family for WLANs.
Both standards define a frame format with a header and trailer, with the header including a source and destination MAC address field, each 6 bytes in length. Both define rules about how the devices should determine when they should send frames and when they should not.

The biggest difference between the two lies in the fact that WLANs use radiated energy waves, generally called radio waves, to transmit data, whereas Ethernet uses electrical signals flowing over a cable (or light on optical cabling). Radio waves pass through space, so technically there is no need for any physical transmission medium. In fact, the presence of matter—in particular, walls, metal objects, and other obstructions—gets in the way of the wireless radio signals.

Wireless LAN Concepts

Many people use WLANs on a regular basis today. PC sales continue to trend toward more laptop sales versus desktop computers, in part to support a more mobile workforce. PC users need to connect to whatever network they are near, whether at work, at home, in a hotel, or at a coffee shop or bookstore. The migration toward a work model in which you find working moments wherever you are, with a need to be connected to the Internet at any time, continues to push the growth of wireless LANs.

The wireless-capable customer laptops communicate with a WLAN device called an access point (AP). The AP uses wireless communications to send and receive frames with the WLAN clients (the laptops). The AP also connects to the same Ethernet LAN as the bookstore’s own devices, allowing both customers and employees to communicate with other sites.
This section begins the chapter by explaining the basics of WLANs, starting with a comparison of similarities between Ethernet LANs and WLANs. The rest of the section then explores some of the main differences.
A groan grasps the peanut near the offending anthology.