TABLE OF CONTENTS Measurements and test methods applicable to the WLAN Physical (PHY) layer, principally 802.11a/b/g PHYs, are dealt with in this chapter. (The emerging area of MIMO PHYs (i.e., 802.11n) is covered in Chapter 10.) Also, manufacturing test, which involves a large number of PHY layer measurements, is dealt with in Chapter 7.
PHY layer measurements are performed for various reasons:
functional tests done during design and development of wireless LAN (WLAN) equipment and chips;
performance tests, which try to quantify how well the RF and baseband portions of the equipment works;
characterization tests used to determine how the equipment or chipset performs under various conditions;
compliance measurements, done to ascertain whether the equipment conforms to government-mandated emissions requirements, or to specifications in the 802.11 PHY standard.
This chapter will focus on the tests and measurements that are performed on completed devices or systems. Measurements on chipsets are carried out on a reference implementation, such as the chipset vendor'sreference design or evaluation board. Measurements on boxlevel products are done using prototypes, or even the final production version. It is extremely unusual to make PHY layer measurements at the large-system level (i.e., involving more than one Access Point (AP) or client at a time).
A variety of PHY layer measurements are performed by engineers during the design and development of WLAN equipment (or chipsets). By far the widest range of RF test instruments is used here: network analyzers, spectrum analyzers, oscilloscopes, signal generators,...
