On-Demand Resource Allocation for OFDMA Small Cells Overlaying CDMA System

By offloading mobile traffic for macrocells, small cells can help to alleviate the pressure on conventional cellular networks from explosive data growth. On the other hand, the severe spectrum scarcity problem has prompted the research on spectrum sharing recently. In this paper, a spectrum sharing system of OFDMA small cells overlaying CDMA networks is considered, in which each OFDMA user in the small cells requests a specific transmission rate. We investigate the interferences among entities in the spectrum sharing system, from which a resource allocation problem is formulated along with the rate constraints, with the objective to meet the target rates of OFDMA users and to simultaneously protect CDMA system. This high- complexity and intractable problem is transformed into two separable problems by calculating the minimum required interference and selecting the activated users. We propose the on-demand resource allocation scheme to solve the resource allocation problem efficiently by deploying a semi-distributed algorithm. Simulation results are provided to evaluate the effectiveness and performance of the proposed scheme.