Our objectives in this chapter are to describe the basic building blocks in performance evaluation as we focus on identifying and understanding the effects of interference in wireless communications and its impact on system performance.

Since we set out to evaluate the effects of interference on performance, the first question we ask is what is interference? The term “interference” has been extensively used in the context of communication, in both wired and wireless systems. While an accurate definition may be dependent on the specifics of the context considered, the term generally refers to signal impairments due to factors in the environment such as channel propagation properties, other radiated power, and noise.

The second question is concerned with the performance evaluation of interference, namely, what are the quantitative measures that characterize interference, and consequently how should the resulting level of performance be quantified? One interference metric that has been used extensively includes the so-called signal to interference ratio. However, this measure does not characterize completely the resulting performance since performance is often tied to the quality of service requirements, which vary depending on the application considered. Our objective is to provide a list of performance metrics that can accurately quantify the network performance from an application perspective.

Since not all systems behave in the same way given the same level of interference, an important aspect of performance evaluation is to identify parameters that impact performance.