On Using Multi-State Spectrum Sensing for Joint Detection and Transmission in Opportunistic Spectrum Sharing

In this paper, we investigate the problem of opportunistic spectrum sharing through joint optimization of spectrum hole detection and transmission power control. Unlike conventional spectrum sensing models that classify the state of the primary user as being idle or active, we consider a multi-state spectrum sensing model where there exist multiple states to be chosen as the detection decision. Different states represent the degrees of certainty at the detector regarding the presence of the primary user, and hence are mapped to different levels of transmission powers to be used by the secondary user for spectrum access. Our goal thus is to jointly decide the optimal detection thresholds (state boundaries) and transmission powers such that the achieved capacity at the secondary user is maximized subject to the interference temperature limit constraint at the primary user. We first formulate a non-convex optimization problem based on the system models and then propose an algorithm for solving the problem. By varying the number of states in the multi-state sensing model, we compare the performance of the conventional two-state hard sensing model and the infinite-state soft sensing model, thus motivating further investigation on multi-state spectrum sensing for dynamic spectrum access.