MIMO异构网络下行链路干扰对齐

针对由多输入多输出异构网络的下行链路存在的干扰，提出了一种基于零空间的干扰对齐方案．该方案通过联合设计微基站的发射波束成形矩阵和宏用户的接收波束成形矩阵，从而消除微基站到宏用户的干扰．该方案支持任意多个宏用户，同时提供闭式解．另外，该方案适用传统干扰对齐方案的不可行区域．最后，仿真结果展示了基于零空间的干扰对齐方案所能达到的自由度．

Interference alignment for MIMO downlink heterogeneous networks

We propose a null space based interference alignment (IA) scheme for the downlink of a heterogeneous network. By jointly designing the transmit beamforming matrix at pico base stations and the receive beamforming matrix at macro users, the proposed null space based IA scheme can effectively cancel the interference from pico base stations to macro users. Furthermore, the proposed scheme supports an arbitrary number of macro users and provides one closed form solution. Moreover, the proposed null space based IA scheme is valid for the region where the traditional IA schemes are infeasible. Finally, simulation results are provided to demonstrate the achievable degrees of freedom (DoF) by the proposed null space based IA scheme.