Self-Organizing Dynamic Fractional Frequency Reuse in OFDMA Systems

We describe an algorithm for sub-carrier and power allocation that achieves out-of-cell interference avoidance through dynamic fractional frequency reuse (FFR) in downlink of cellular systems based on orthogonal frequency division multiple access (OFDMA). The focus in on the constant-bit-rate (CBR) traffic type flows (e.g., VoIP). Our approach is based on the continuous "selfish" optimization of resource allocation by each sector. No a priori frequency planning and/or inter-cell coordination is required. We show, both analytically (on a simple illustrative example) and by simulations (of a more realistic system), that the algorithm leads the system to "self-organize" into efficient frequency reuse patterns.