Study On Coordinated Multi-Cell Radio Resource Management In Heterogeneous Networks

The introduction of heterogeneous networks has changed the network topology of traditional network, and has been expected to be one of the major performance enhancement enablers of LTE-Advanced.A HetNet uses a mix of macrocells, remote radio heads (RRH) and low-power nodes such as picocells, and relays in order to bring the network closer to end users. In that way, radio link quality can be enhanced due to the reduced distance between transmitter and receiver, and the larger number of cells and therefore larger data rates. However, due to the adaption of orthogonal frequency division multiplexing and frequency reuse factor of one in LTE/LTE-A, dense base station deployments will inevitably lead to more serious inter-cell interference problem. Meanwhile, existing collaborative radio resource management schemes become inapplicable.This thesis mainly analyzes the collaborative radio resource management problem in heterogeneous networks of LTE/LTE-A system, and a detailed analysis of elCIC/feICIC-based small cells interference cancellation scheme,CoMP-based small cells interference cancellation scheme,CA-based small cells interference cancellation scheme has been made. The contribution of this paper are as follows.In order to solve the serious interference problems caused by CRE, the performance demand between Macro eNodeB and Pico eNodeB need to be balanced, and a dynamic ABS pattern setting scheme is needed. This paper presents a dynamic ABS pattern setting scheme based on user fairness for heterogeneous networks. The simulation evaluation shows that the proposed ABS pattern setting scheme can reduce the interference of CRE UE, and meets the throughput demand of victim users while improving the overall system performance. When high Bias value is taken, this scheme maintains higher user fairness comparing to the traditional method.To mitigate the more complex wireless networks transmission problem caused by the coexist scene of Macrocell and small cell, this thesis proposes an effective CoMP JT scheme for heterogeneous networks. The proposed CoMP JT scheme performs serving cell selection according to path loss instead of CRE Bias value and employ a more effective scheduling scheme. The simulation evaluation shows that the proposed scheme improves the overall throughput without decreasing the average throughput of Macrocell. Meanwhile, compared with other interference coordination schemes, the proposed scheme achieves the best performance gain of the cell-edge user spectral efficiency and the average spectral efficiency.