Joint Power Control and Scheduling Strategies for OFDMA Femtocells in Hierarchical Networks

With the increasing demands for high data rate applications with high quality of service in the next generation networks, OFDMA based femtocell technology is a promising solution for indoor coverage extension and network capacity boosting with its automatic and easy deployment features in contrast to the high CAPital Expenditure (CAPEX) and OPerating EXpense (OPEX) investments for macrocell deployments and operations. Lots of researches have been done on interference mitigation and resource allocation in femtocell networks. However, little attention has been paid to the analysis of the upper bound of macro/femtocell hierarchical network capacity by using the joint femtocell scheduling and optimization strategies. Therefore, this paper has formulated the problem by optimizing the weighted sum capacity of the macro/femtocell hierarchical network with two levels of solutions: one is the optimal solution; the other is a suboptimal local solution, which is raised to approximate the optimal setting with reduced complexity. And a distributed Soft Frequency Reuse (SFR) based approach named Soft Control (SC) is proposed for the fully localized solution. Simulation results verify that the proposed suboptimal and distributed solutions can provide the good performance and approximate the optimal solution with low complexity, with only small loss of the weighted capacity.