The Inter-cell Interference Coordination Scheme Research Based On OFDMA

With the development of mobile communication technology, users of mobile communicationhave put forward higher requirements. They wish to enjoy higher data rate services. However,performance of the cell-edge users is unreliable and even deteriorating, which has seriously affectedthe overall performance of the mobile communication system. Moreover, frequency reuse is aneffective inter-cell interference coordination strategy to improve the performance of cell edge users.However, the spectrum efficiency of traditional 1/3 and 1/7 method of frequency reuse is too low,and OFDMA system uses soft fractional frequency reuse (SFFR). While the SFFR improvescell-edge users’performance, it can ensure higher spectrum efficiency. As a result, the technologyof MIMO can improve system capacity effectively without increasing the transmission bandwidth.The SFFR method with inter-cell MIMO can further improve the performance of cell edge users.The optimization of power allocation for cell users can increase their performance, but the researchon optimization of power allocation for cell-edge users is relatively small.In order to solve the problem of poor performance of cell-edge users in OFDMA system, thispaper researches the inter-cell interference coordination strategy. Firstly, the basic theories about theradio channel model, the basic principles and models of OFDM/OFDMA system and the basicprinciples of MIMO transmission technology are introduced. Then two typical SFFR schemewithout inter-cell MIMO are introduced. And a scheme of SFFR with inter-cell MIMO is proposedbased on the FFR with Macro Diversity. By setting a threshold of the difference of the channelgains, we divide cell edge users into two classes served by two cells and three cells respectively,which can improve frequency efficiency. The performance of the SFFR is given through simulation.In order to further improve the performance of the cell-edge users, this paper researches the powerallocation problem for the cell-edge users. Based on inter-cell MIMO, a linear water-filling powerallocation algorithm in a cell-edge user under a multi-cell environment is proposed. In the algorithm,the co-channel interference from the adjacent cells, which cell-edge users suffer, is eliminated byusing inter-cell MIMO. Then the linear water-filling algorithm is used to optimize the powerallocation in a cell-edge user. And the performance of the algorithm is given through simulation.