The coexistence of conventional marcro cells and lowpower small cells form the heterogeneous multitiered networks,which can significantly improve the capacity of wireless communications systems.However,the interferences between the marco cells and small cells due to sharing the same frequency band severely degrade the quality of communications and prevent the system capacity from being further enhanced.With the wide application of multiple-input-multiple-output(MIMO) for the 4th generation(4G) mobile communications systems,the interference suppression techniques using MIMO precoding and spatially fading properties have become an attracting and popular research area.The recent progress in the areas of MIMO precoding based interference suppression was introduced.Using the two tier downlink networks as the typical example scenario,the heterogeneous interference model was analyzed and that the key task for interference suppression which pointed out was to jointly design the precoding matrices at transmitters and the processing matrices at receivers and to solve for them in a successive order.Following this principle,several recently emerged MIMO-precoding schemes were further introduced.Finally,the future research direction for interference suppression over heterogenous multi-tiered networks was discussed.%传统宏蜂窝(macro cell)与低功率小蜂窝(small cell)共存的分层异构组网方案能有效地提高无线通信系统的容量.但宏蜂窝与小蜂窝间的同频干扰严重影响了通信质量,并阻碍了系统容量的进一步提升.近年来,利用MIMO预编码及空域衰落特性进行干扰抑制的相关技术成为新的研究热点.本文着重介绍分层异构无线网络中基于MIMO预编码的干扰抑制技术的研究进展.以典型的双层异构下行网络为例,分析了利用多天线预编码进行干扰抑制的基本方法,并在此基础上介绍了多种基于MIMO预编码的新型干扰抑制方案,最后讨论了分层异构网络中干扰抑制技术的未来研究方向.
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