Research On Time Domain EICIC And CoMP Technology In Heterogenous Networks

Heterogeneous networks (HetNet) changed the network topology of traditional network and introduced low power nodes (LPNs). It is regarded as an important technology that improves the system throughput in LTE-A. In co-channel HetNet deployment, the macro cell provides a wide coverage umbrella while the LPNs are deployed in a more targeted manner to alleviate coverage indoor zones and hotspots. LPNs improve the network performance greatly, but also bring some negative effects. With the increasement in the number of LPNs, the cross-tier interference between the Macro cell and the new cell or the co-tier interference between the new cells becomes more seriously.This thesis mainly analyzes the interference in Macro-Pico heterogeneous network scenario.To solve the problems of load imbalance and inequity of scheduling between the macro UEs and pico UEs, the cell range extension (CRE) technology has been proposed by3GPP, which allows more users to access to the Pico eNB.CRE can improve the system throughput, but the pico cell CRE UEs may suffer severe interference from the Macro eNB. Accordingly,3GPP proposed the enhanced inter-cell interference coordination (eICIC) technology to slove the interference problem in HetNet deployment.In order to solve the interference problem for the pico cell CRE users, this thesis analyzes the CRE and LP-ABS (Lower Power Almost Blank Subframe) technology of time domain eICIC.On this basis, it verifies a Pico CRE bias setting algorithm based on the location of the Pico eNB,and presents a LP-ABS ratio setting algorithm based on the fairness of UEs.After the simulation evaluation we find that the proposed LP-ABS ratio setting algorithm can ensure the fairness and improve the cell-edge user throughput under various power of LP-ABS.In addition, this thesis analyzes the different performance simulation of heterogeneous networks under various power of LP-ABS,and provides an optimal LP-ABS power setting recommendations.If LP-ABS method is used separately, interference problem may still exit in Macro-Pico heterogeneous networks. To guarantee the robustness, we propose a CoMP based LP-ABS interference coordination scheme, combining the LP-ABS and CoMP, and taking the advantage of both two technologies to reduce interference in heterogeneous networks.The scheme can ensure the throughput of Macro cell and reduce the interference of Pico cell CRE users located in the outer cell, can improve the throughput of Pico cell CRE users located in the inner cell.The system-level simulation result proves that, compared with other interference coordination schemes, the proposed scheme achieves the best performance gain of the cell-edge throughput and average throughput.