A Distributed Dynamic Spectrum Access and Power Allocation Algorithm for Femtocell Networks

Femtocells deployed in the Macrocell to improve the indoor coverage share the same spectrum with the Macrocells. The dynamic spectrum access (DSA) and power allocation (PA) for the users of Femtocells and Macrocells has an important influence on the mutual interference and system performance in Femtocell networks. In this paper, the USA and PA problem is first modeled as an optimization problem. Then, we study and obtain the upper bound of the interference intensity among Femtocells, which is showed to be very small. By ignoring this slight interference, a simplified model is derived, and its near-optimal solution is obtained by utilizing the 'time-sharing' property. A distributed USA and PA algorithm is proposed based on the solution. This algorithm only requires a little information exchange, and the complexity grows linearly with the multiplication of the number of Femtocells and channels. Simulation results show that this algorithm can reduce the interferences suffered by Macrocell users and increase the supportable number of Femtocells significantly.