Networking Bible

Chapter 14. Wi-Fi Networks

IN THIS CHAPTER

• Wi-Fi and how it works

• 802.11 standards

• Build wireless links and networks

• Available wireless devices

The IEEE 802.11x wireless networking standards known as Wi-Fi have sparked a revolution in computer networking over the last decade. In this chapter you will learn about the different standards, their performance characteristics, and how you can create networks or network links with this technology. Wireless networks support two different types of architectures: ad hoc and infrastructure modes.

The commonly used standards are all radio frequency communication links over public bands in the 2.4 GHz or 5 GHz frequency range. Wi-Fi separates the bandwidth into channels and then uses a form of spread spectrum transmission that either creates a direct sequence of overlapping transmissions or transmits using a frequency-hopping scheme. This chapter presents both Direct-Sequence Spread Spectrum (DSSS) and Frequency-Hopping Spread Spectrum (FHSS) in detail. Signals are encoded onto the carrier waves that DSSS and FHSS create using a number of different modulation technologies that you learn about in this chapter. In particular, Phase Shift Keying methods are popular.

The 802.11x frames are similar to Ethernet frames and are described here. The main method for sending frames uses Carrier Sense Multiple Access with Collision Avoidance. Methods for handshaking, traffic control, and connection management are described.

Access points, gateways, and routers are ...