Interference Avoidance and Adaptive Fraction Frequency Reuse in a Hierarchical Cell Structure

Due to high data rate requirement for indoor radio coverage, femtocells have been proposed as a potential good solution in recent years. Under this configuration, a main design objective is to coordinate the mutual interference between macro and femto cells. In this paper, the flexible assignment of downlink resource in a hierarchical cell structure is investigated. A dynamic frequency assignment technique called adaptive fraction frequency reuse (AFFR) is proposed, by avoidance of severe interference between macro and femto cells. A network model and system level simulations for LTE macrocell/femtocell scenarios are presented. The results show that, AFFR has better average and cell- edge performance compared with co-channel frequency allocation (co-channel FA) and orthogonal frequency allocation (OFA) for both macro and femto cells.