Distributed subcarrier and power allocation for OFDMA-based cognitive femtocell radio uplink

In this work, we focus on a cognitive radio (CR) femtocell network that operates in an orthogonal frequency-division multiple access (OFDMA)-based primary user (PU) network. Due to the lack of centralized planning, the home eNode B (HeNB) or base stations of femtocells are installed in an ad-hoc manner by increasing number of home subscribers. Therefore, femtocell network requires proper interference management, preferably in a distributed way, to achieve maximum total spectral efficiency. In this work, we present optimal solutions for subcarrier and power allocation in OFDMA-based femtocell radio uplink. The new results provide us a simple and yet intuitive interpretation on how to optimally allocate the subcarriers to different cognitive radio users. We also explain how the newly derived solutions can be implemented distributively, and present a distributed joint subcarrier and power allocation scheme for the uplink of OFDMA-based cognitive femtocell users. Simulation results are presented to highlight the convergence of the proposed scheme to achieve maximum throughput performance.