Optimal fair downlink fractional frequency reuse for cellular wireless networks

We consider adaptive rate scheduling mechanisms used by densely deployed base station (BS) nodes in cellular wireless networks. These BS nodes share downlink channels under the employment of omnidirectional and directional antennas. We study the throughput capacity rates achieved under reuse-k scheduling schemes, for k = 1, 3, with and without the incorporation of fractional frequency reuse (FFR) assignments. We consider an absolute fairness requirement, aiming to maximize the minimum level of the throughput rate realized per mobile. For this purpose, under the inclusion of FFR schemes, we propose an optimal classification for interior and exterior mobiles coupled with optimal bandwidth allocation to each class of mobiles. When omnidirectional antenna beams are employed, we show these schemes to yield a significantly enhanced performance when compared to non-FFR based operations. In turn, when directional antenna beams are used, we show that the FFR scheme does not lead to much performance enhancement.