On the design of location-invariant sensing performance for secondary users

In this article, we consider the setting of one-shot spectrum hole detection for a uniformly distributed secondary network under fading and path loss. We separate the sensors that are used to detect spectral holes from the secondary transmitters, thus allowing each secondary transmitter to benefit from the decisions of multiple (shared)sensors. The detection performance of the sensors varies with the distance from the primary transmitter. Thus a secondary listens to different average number of sensors as it moves around the cell, making the fusion rule complicated. We coin the term communicating shaping function f that is used by the sensors to modulate the coverage area of the sensors. A shaping function is designed heuristically so that the area of coverage normalised by the detection probability of the sensors is the same throughout the cell. This makes the average number of communicating sensors seen by a secondary invariant to the location of the secondary users, allowing a fixed location-invariant fusion rule to be employed at the secondary transmitter.