在异构云无线接入网络(Heterogeneous Cloud Radio Access Network, HC-RAN)中，由于无线远端射频单元(Remote Radio Head, RRH)与蜂窝基站工作在underlay模式下，因此两者之间存在严重的干扰。另外，在复杂场景下当多个蜂窝网络共存时，蜂窝网络之间同样存在干扰，这些干扰降低了网络的整体性能。针对上述问题，本项目结合多天线技术以及绿色无线通信技术，对复杂场景下的HC-RAN展开研究。通过对RRHs和蜂窝基站的波束成形向量进行优化，来抑制蜂窝内部干扰和蜂窝间干扰，提高网络的能量效率，降低网络的功耗。主要研究内容包括：基于能效优化的波束成形技术研究、组稀疏波束成形技术研究以及非完美信道信息下的波束成形技术研究。本项目的研究能够为HC-RAN架构设计和关键技术研究提供参考方案和理论支撑。

In heterogeneous cloud radio access network (HC-RAN), since remote radio head (RRH) and cellular base station work in underlay mode, there is a serious interference between RRH and cellular base station. In addition, in complex scene when multiple cellular network coexists, there are also serious interference between cellular networks. These interferences will reduce the overall performance of the HC-RAN. In order to overcome the above problems, this project combines multi antenna technology and green wireless communication technology to study HC-RAN under complex scene. By optimizing the beamforming vectors of RRHs and cellular base station in HC-RAN, we can suppress the internal interference and inter cell interference, improve the energy efficiency, reduce the power consumption of the system. The main research contents include: energy efficient optimization based beamforming technology, group sparse beamforming technology and beamforming technology with imperfect channel state information. The research of this project provides a reference scheme and theoretical support for the design of HC-RAN and the research of key technologies.