信道非对称下的联合预编码方案

在多基站(BS)协作系统中，信道的非对称导致相互协作的两基站从协作中获得的性能增益不一样。因此，在选择协作基站的过程中，当一方想合作，而另一方更想与其他基站合作的时候，分簇问题变得非常困难，使整个系统性能受限。为解决此问题，定义了协同度的概念，针对此情况提出了一种重叠分簇方案，并在此基础上设计了一种联合迫零-汤姆林森-哈拉希玛预编码（ZF-THP）算法。该方案通过对局部基站进行重叠分簇调整，并利用THP技术消除重叠基站带来的干扰。仿真分析表明，该方案较好地解决了协同度非对称性导致的分簇矛盾，提高了系统的频谱效率，并改善了用户的公平性能。

Joint precoding scheme under condition of channel asymmetry

In a Base Station (BS) cooperation system, the capacity gains of two BSs by cooperating with each other are different owing to the channel asymmetry. Thus, in the process of selecting cooperative BS, when one BS wants to coordinate but another does not want to cooperate with it and prefers others, it will be difficult to judge whether to group the two into a cluster or not and the whole system is capacity-limited. To demonstrate this, the authors proposed an overlapped clustering scheme and then designed a joint precoding algorithm called Zero Force-Tomlinson-Harashima Precoding (ZF-THP) scheme. In this scheme, several BSs were adjusted to be overlapped and THP technique was used to eliminate the interference caused by overlapped BSs. The simulation results show that the proposed scheme solves the clustering contradiction well, efficiently increases the system capacity and enhances the system fairness.