FERMI : A FEmtocell Resource Management System for Interference Mitigation in OFDMA Networks Tech . Report for Paper ID : 260

The demand for increased spectral efficiencies is driving th e next generation broadband access networks towards deploying smaller cells (femtocells) and sophisticated air inter face technologies (Orthogonal Frequency Division Multiple Access or OFDMA). The dense deployment of femtocells however, makes interference and hence resource management both critical and extremely challenging. In this paper, we design and implement one of the first resource management systems, FERMI, for OFDMA-based femtocell networks. As part of its design, FERMI (i) provides resource isolation in the frequency domain (as opposed to time) to leveragepower poolingacross cells to improve capacity; (ii) uses measurement-driven triggers to intelligently distinguis h clients that require just link adaptation from those that requi re resource isolation; (iii) incorporates mechanisms that en ble the joint scheduling of both types of clients in the same frame; and (iv) employs efficient, scalable algorithms to de termine a fair resource allocation across the entire networ k with high utilization. We implement FERMI on a prototype four-cell WiMAX femtocell testbed and show that it yields significant gains over conventional approaches.