Study On Scheduling Algorithms In Network MIMO Systems With Non-ideal Channel Information

Network multiple-input multiple-output or coordinated multi-point has drawn a great attention owing to its features of improving cell-edge performance as well as high spectral efficiency by exploiting ICI. It can provide dramatic performance gain with accurate channel information.However, channel estimation error is inevitable in real environment because of disturbance of various noises, interference and unknown factors. Channel estimation error will bring harmful effect on coordinated scheduling algorithms, whereas inappropriate scheduling results may lead to a severe performance degradation and a low frequency efficiency. In this thesis, we focus on the coordinated scheduling algorithms in network MIMO systems under channel estimation error. We study the traditional scheduling algorithms and try to propose new algorithms with reasonable performance improvement. The main research contents can be summarized as follows:A novel user pairing and coordinated scheduling algorithm is proposed based on an adaptive channel estimation error model for the uplink network MIMO system. Based on the new defined channel estimation error sensitivity criterion, users are divided into different groups and applied to different scheduling approaches. Simulation results show that the proposed algorithm outperforms traditional coordinated scheduling algorithms in practical scenario with channel estimation error.Furthermore, it can also achieve a better tradeoff between throughput and fairness compared to the robust user pairing algorithm.A novel coordinated scheduling criterion is proposed. Different scheduling criteria suit different users with different channel states.Considering the advantages and disadvantages of various scheduling criteria, a unified scheduling criterion may not be appropriate for all users distributed in the whole cell. Therefore a sensibility calibration factor is defined and introduced to the traditional scheduling criterion. Simulation results show that it has a great performance improvement compared to traditional scheduling criterion.A novel user distribution based hybrid CSI-RS resources scheduling scheme is proposed. 3GPP proposed two main kinds of CSI-RS for 2D active antenna array, non-precoded CSI-RS and beamformed CSI-RS.After studying and analyzing the advantages and disadvantages of these two kinds of CSI-RSs, we propose a hybrid CSI-RS resources scheduling scheme. Simulation results show that it has a better performance compared to non-precoded CSI-RS scheme and beamformed CSI-RS scheme.This thesis focuses on the coordinated scheduling algorithms in network MIMO systems under channel estimation error. We study the scheduling algorithms from the above three aspects, the performance and effectiveness of the proposed algorithms are verified by simulation results.In the conclusion, the possible study directions are forecast and whole thesis is summarized.