Abstract
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 di fferent properties between the macro base station and small cell base stations. In the thesis, we target our e fforts on applying di fferent 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 diff erent regimes. And performances of di fferent 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 diff erent IA algorithms.