Intelligent power allocation for collaborative spectrum sharing with non-orthogonal cooperative relaying

In this paper, we provide a near-optimal power allocation for collaborative primary and secondary spectrum sharing (CSS) especially when two-phase non-orthogonal cooperative relaying is facilitated. In this two-phase non-orthogonal CSS, primary power is allocated between the two phases in transmitting the same primary signal and, on the other hand, secondary power is allocated between the primary signal to be relayed and a secondary signal at the second phase. After obtaining optimal combining vector and co-phasing weight for the non-orthogonal cooperation, the power allocation problem is formulated as a non-convex problem, for which we provide an iterative algorithm that finds a sub-optimal allocation. Numerical investigation demonstrates the convergence of the algorithm and shows that the investigated non-orthogonal CSS with the proposed power allocation provides greater secondary data rate than existing orthogonal CSS methods.