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6

Wireless Local Area Network (WLAN)

In the mid‐1990s, the first Wireless Local Area Network (WLAN) devices appeared on
the market, but they did not get a lot of consumer attention. This changed rapidly 10
years later, when the hardware became affordable and WLAN quickly became the
standard technology for connecting computers, smartphones and tablets to the Internet.
This chapter takes a closer look at this system, which was standardized by the Institute
of Electrical and Electronics Engineers (IEEE) in the 802.11 specification [1].
The first part of this chapter describes the fundamentals of the technology, which have
changed little since the beginning. In the second part, the chapter describes the evolu-
tionary steps that were taken over time to increase transmission speeds. In the final part,
security features are described as well as a number of optional functionalities.

6.1 Wireless LAN Overview

Wireless LAN received its name from the fact that it is primarily based on existing LAN
standards. These standards were initially created by the IEEE for wired interconnection of
computers and can be found in the 802.X standards (e.g. 802.3 [2]). In general, these stand-
ards are known as ‘Ethernet’ standards. The wireless variant, which is generally known as
Wireless LAN, is specified in the 802.11 standard. As shown in Figure 6.1, its main applica-
tion today is to transport Internet Protocol (IP) packets over layer 3 of the ISO model.
Layer 2, the data link layer, has been adapted from the wired world with relatively few
changes. To address the wireless nature of the network, a number of management opera-
tions have been defined, which are described in Section 6.2. Only layer 1, the physical layer,
is a new development, as WLAN uses airwaves instead of cables to transport data frames.

6.2 Transmission Speeds and Standards

Since the creation of the 802.11 standard, various enhancements have followed. Therefore,
a number of different physical layers, abbreviated as ‘PHY’, exist today in the standard
documents. Each PHY has been defined in a different document and a letter has been put
at the end of the initial 802.11 document name to identify the different PHYs (Table 6.1).
The breakthrough for WLAN was the emergence of the 802.11b standard that offered
datarates from 1 to 11 Mbit/s. The maximum datarate that could be achieved in a real

From GSM to LTE-Advanced Pro and 5G: An Introduction to Mobile Networks and Mobile Broadband,
Third Edition. Martin Sauter.
© 2017 John Wiley & Sons Ltd. Published 2017 by John Wiley & Sons Ltd.