Distributed Channel Selection Principles for Femtocells with Two-tier Interference

It goes without saying that the femtocells will be widely employed in the next generation wireless networks since the femtocells improve indoor capacity and coverage with low power and less cost. However, as the femtocells become popular, the femtocell users suffer from the complicated two-tier interference, including the macrocell-to-femtocell and femtocell-to-femtocell interference. Therefore, the femtocells pose a difficult challenge on managing the interference in a autonomous and distributed manner. In this paper, we investigate how to distributedly select the sub-channels for the OFDMA-based femtocell systems to reduce interference and to improve indoor capacity under a link reliability requirement. We develop the channel-gain oriented and interference-avoidance oriented distributed channel selection schemes. Simulation results show that the interference from the macrocell and other femtocells significantly degrades femtocell link reliability and capacity. However, by properly adjusting the number of used sub-channels, the developed channel selection schemes can improve capacity and ensure the link reliability.