近年來，人們對於無線通訊的需求越來越高。為了滿足新的要求，在4G的標準中，提出了異質網絡的新概念。通過在原有的通訊網路架構中添置新的低功耗，涵蓋範圍更小的微型基地台來改善網絡容量。但因為異質網絡共享同樣的頻帶，導致不同基站間相互的干擾增大。干擾對齊技術是新興的一種干擾管理技術，目前在異質網絡中的應用甚少。
在本論文中，我們將干擾對齊技術應用於異質網絡下行鏈路多輸入多輸出正交多頻分工系統。 選用最新的IMT-A信道模型，針對於室內用戶的通訊情況來進行研究。利用模擬結果比較不同的干擾對齊技術的使用效果。以及針對異質網絡的特性，分析不同基站的傳輸功率對干擾對齊技術應用的影響。

Recently, demands for cellular wireless communication have grown exponentially. To meet the requirements, a creative conception of heterogeneous networks (HetNets) deployment is proposed in the new standard of the fourth-generation (4G) communication era. HetNets deployment where low-power and small-coverage cells are distributed within the macrocell coverage improves the network capacity due to a better average link quality, more efficient usage of spectrum resources, and higher spatial reuse. Meanwhile, the coexistence of heterogeneous networks within the same spectrum also gives rise to more interference. However, there are very few works addressing interference alignment (IA) techniques for use in HetNets due to the different properties between the macro base station and small cell base stations. In the thesis, we target our efforts on applying different IA schemes to the downlink multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) HetNets based on the realistic IMT-Advanced channel model, and focus on the coexistence between two tiers at the physical layer. From the comparisons, we find that some of the algorithms can outperform others in different regimes. And performances of different initializations for iterative IA algorithms are discussed. It is observed that the optimal choice of initialization can improve the performance. Moreover, we try to analyze the impact of transmit power on different IA algorithms.

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