TABLE OF CONTENTS Application-level measurements resonate well with end-users; they provide a sense that there is some correlation to the ultimate end-user experience, rather than being merely some abstract property of the infrastructure devices. In some situations, such as in the case of the WLAN industry of 2006 or before, the lack of more advanced test tools drives the manufacturers and vendors themselves to make application-level measurements, because such measurements can be made with little more than the actual applications themselves, or a simulacrum thereof. As a consequence, much of the WLAN industry today still relies on application-level metrics and measurements to indirectly determine the capabilities of the underlying WLAN hardware and software. This chapter covers some of the key application-level tests and setups used in current practice. The focus is on system-level testing for enterprise and multimedia applications.
Application-level measurements are also referred to as system-level measurements, because they attempt to characterize the performance of a system as a whole, rather than any piece or subset of it. Much more than simply wireless clients and access points (APs) are involved by necessity in transporting traffic from its source to its sink, particularly when dealing with real-time traffic such as voice and video. A packet voice circuit usually comprises, from start to finish: a microphone, an audio encoder (codec), a packetizer, a wireless client, an AP, a wired network infrastructure (switches and routers), a call server or Voice over IP (VoIP) gateway, another AP, another wireless client, a depacketizer, an...
