Research On Interference Management In Heterogeneous Network

With the increase of the data traffic, there is a need for deploying low power nodes, such as femtocell, in the macrocell to enhance the coverage of indoor and hotspot area. Heterogeneous network is a trend in the development of wireless network. The network architecture can improve the total spectrum efficiency and throughput. However, because of the share of spectrum among the different nodes, the interference management is a critical challenge. In the thesis, the network comprised of a macrocell and several femtocells is consid-ered. In the thesis, the resources allocation is mainly studied, which consists of the spectrum allocation and power allocation, between the macrocell and femtocells to alleviate the interference.The main contributions are as follows:Firstly, a novel cognitive spectrum allocation algorithm is proposed, which consists of the channel recognition and spectrum allocation. To flexibly allo-cate spectrum, the proposed algorithm conducts the channel detection based on the single channel and searches for the available spectrum in the whole fre-quency band. The proposed scheme converts the complex interference environ-ment into several specific channel categories and successfully recognizes these channel patterns. Therefore, the algorithm not only efficiently alleviates the interference between the macrocell and femtocells, but improves the spectrum efficiency.Secondly, a novel power control scheme in heterogeneous Femto-Macro cell networks is proposed. According to the analysis on the conventional non-cooperative power control game (NPG), it is found that the resulting operating point (Nash equilibrium, NE) of such a distributed power control is inefficient in power usage. The following two innovations are made to improve the con-ventional NPG result. On the one hand, the users selection and channel reallo- cation algorithm is carried out before the power control game. The architecture of iterative formulae are improved by combining the conventional PCBGT (Power Control Based on Game Theory) with user selection and channel re-allocation. As a result, the proposed scheme radically improves the NE point. On the other hand, a novel FUE-SINR based MUE link quality protection algo-rithm is proposed to further optimize the proposed scheme. It only reduces the power of FUEs whose SINR equilibria are higher than their targets. Therefore, the proposed MUE link quality protection algorithm protects the MUE SINR with the consideration of FUE SINR.Finally, two research contents in the future are given. Stackelberg equi-librium (SE) maybe introduced to improve the NE point. And, to efficiently alleviate the interference, the spectrum and power resources can be jointly op-timized.