A channel assignment and power setting scheme by fuzzy logics for OFDMA-based macro-femto systems

In this paper, we propose a fuzzy-based channel assignment and power setting (FCAP) scheme for OFDMA-based macro-femto systems to effectively mitigate the interference caused by the deployment of femto base stations (FBSs). The FCAP scheme is a distributed solution for the spectrum allocation and interference mitigation problems in the macro-femto systems. By using the fuzzy logics, it dynamically determines the total number of available subchannels for the considering FBS. According to this determination, the FBS selects its preference subchannels to avoid using the same subchannels as its neighboring FBSs. Also, the FCAP scheme sets the transmission power by using the fuzzy logics to achieve a balance between the throughput maximization and the interference mitigation. Simulation results show that, the FCAP scheme can enhance the average SINR of femto users by 8.5 % and 29.4 % compared to the optimal downlink spectrum sharing scheme and the flexible spectrum usage and power control scheme, respectively.