Coordinated Beamforming (CB) is an effective technique to maximize weighted sum rate (WSR) targeting at on-demand network capacity. However, the channel state information (CSI) of the base stations (BSs) far away can’t be measured accurately, which will lead to the invalidation of the traditional WSR-maximization beamformer design and eventually result in capacity decrease. This letter proposes a tractable user-centric CSI model and a robust CB design to maximize WSR with partially accurate CSI. Specifically, the CSI model of the coordinated BSs is built for each user, where the inaccurate CSI of BSs far away from this user is modeled according to its static statistic characteristic. To derive a robust beamformer, deterministic equivalent method is adopted to obtain an approximate closed-form expression of the ergodic sum rate. Moreover, the performance of the robust CB design with different model parameters is considered to provide guidance for practical network deployment. Simulation results show that the proposed robust CB design has 30% capacity gain through careful interference management compared with traditional beamforming.

中文翻译：

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具有部分准确 CSI 的易于处理的建模和鲁棒协调波束形成设计


协调波束成形（CB）是一种有效的技术，可以最大化针对按需网络容量的加权和速率（WSR）。然而，远距离基站的信道状态信息(CSI)无法准确测量，这将导致传统WSR最大化波束形成器设计失效，最终导致容量下降。这封信提出了一个易于处理的以用户为中心的 CSI 模型和强大的 CB 设计，以通过部分准确的 CSI 最大化 WSR。具体地，针对每个用户建立协作基站的CSI模型，其中距离该用户较远的基站的CSI不准确，根据其静态统计特性进行建模。为了推导鲁棒波束形成器，采用确定性等效方法来获得遍历和速率的近似封闭式表达式。此外，考虑不同模型参数下鲁棒CB设计的性能，为实际网络部署提供指导。仿真结果表明，与传统波束成形相比，通过仔细的干扰管理，所提出的稳健 CB 设计具有 30% 的容量增益。