Dynamic Spectrum Access Decisions

Chapter 3Receiver Operating Characteristics and Decision Fusion

Receiver operating characteristic (ROC) is not a unique methodology to DSA decision making. It is widely used in many areas where statistical decisions are adaptively made based on myriad metrics. ROC is a generic approach developed for low computational and implementation complexities. This chapter covers different DSA scenarios that rely on using ROC models. A ROC model can be used when probing a frequency band to discover if it is occupied or not at a certain geographical location (e.g., a secondary user is sensing if a primary user is using this frequency band or not). Another scenario that uses a different ROC model is the case of same‐channel in‐band sensing where the ROC model can hypothesize the presence or absence of an interfering signal. The detected energy of the sensed frequency band is compared to an adaptive threshold to hypothesize the presence of the interfering signal. This threshold adaptation is highly dependent on noise estimation and is decided based on tradeoffs driven by the design needs. Estimating ROC models' thresholds can be challenging when noise variance increases and when signal power is too low.¹ The spectrum sensor can be looking into interference from other signals overlaid with the noise without being able to distinguish between the interfering signal power and the noise power. In other cases, the spectrum sensor can be looking at an overlay of different signals occupying the ...