第四代行動通訊階層式基地台於時間維度合作以降低干擾技術之研究

Abstract

增強型細胞間干擾消除(Enhanced inter-cell interference coordination, eICIC)為一種有效降低細胞間干擾的重要方法相同頻帶。由於在異質性網路中，佈建低功率小基地台可以提升原有細胞的覆蓋範圍以及提升總體吞吐量，因此使用者原有大基地台的範圍下積極佈建，但卻導致小基地台使用者遭受來自大基地台的嚴重訊號干擾。在本論文中，我們針對增強型細胞間干擾消除的時間維度的方法來有效降低細胞間的干擾，並且在細胞範圍延伸(Cell Range Expansion, CRE)保護小細胞的範圍，以及空白子片段(Almost Blank Subframe, ABS)的技術使用下，提出一個以干擾為基礎之適應性空白子片段配置(Interference-aware adaptive ABS allocation)來最大化每個子片段的吞吐量總和，並且提升細胞邊緣使用者的吞吐量。模擬結果顯示可以提升細胞邊緣使用者的吞吐量達50%，本論文所提出的方法可用來有效提升細胞邊緣干擾減低的重要參考方法。

In this thesis, we present an interference-aware slot allocation technique for improve the system performance of the low-power pico-cells and overlaying macro-cells. In the 3rd Generation Partnership Project (3GPP) Long-Term Evolution- Advanced (LTE-A), this kind of interference between pico-cells and its overlaying macro-cell is called the interference in heterogeneous network (HetNet), which will decrease the coverage area of pico-cells and overall system throughput. In the 3GPP LTE-A cellular system, enhanced inter-cell interference coordination (eICIC) technique adopts Almost Blank Subframes (ABS) to control the inter-cell interference between pico-cells and macro-cells. However, because of the fixed ratio ABS design, the current eICIC techniques will degrade the macrocellular performance severely and the improvement of throughput of pico-cells is also limited in a dynamic traffic environment. Thus, we propose an interference-aware slot allocation technique to adjust the ratio of ABS dynamically based on the estimated interference between macro-cells and pico-cells. Furthermore, the proposed interference-aware slot allocation technique distributively designate the blank slots. Our results show that the proposed interference-aware slot allocation technique can improve the throughput for both macro-cells and pico-cells simultaneously. In the considered case, the throughput of pico-cells and macro-cell cell edge users are improved by at least 13% and 7% respectively, compared to the current fixed ratio ABS design approach.