Conventional multi-beam forming with fixed-position antenna (FPA) arrays needs to trade-off between maximizing the beamforming gain over desired directions and minimizing the interference power over undesired directions. In this letter, we study the enhanced multi-beam forming with a linear movable-antenna (MA) array by exploiting the new degrees of freedom (DoFs) via antennas' position optimization. Specifically, we jointly optimize the antenna position vector (APV) and antenna weight vector (AWV) to maximize the minimum beamforming gain over multiple desired directions, subject to a given constraint on the maximum interference power over undesired directions. We propose an efficient alternating optimization algorithm to find a suboptimal solution by iteratively optimizing one of the APV and AWV with the other being fixed. Numerical results show that the proposed multi-beam forming design with MA arrays can significantly outperform that with the traditional FPA arrays and other benchmark schemes in terms of both beamforming gain and interference suppression.

翻译：传统固定位置天线（FPA）阵列的多波束形成需要在最大化目标方向波束形成增益与最小化非目标方向干扰功率之间进行权衡。本文利用线性可移动天线（MA）阵列通过天线位置优化带来的新自由度（DoFs），研究了增强型多波束形成技术。具体而言，我们联合优化天线位置向量（APV）和天线权重向量（AWV），在非目标方向最大干扰功率的给定约束下，最大化多个目标方向的最小波束形成增益。我们提出了一种高效的交替优化算法，通过迭代固定其中一个变量（APV或AWV）来优化另一个变量，从而获得次优解。数值结果表明，与传统的FPA阵列及其他基准方案相比，所提出的基于MA阵列的多波束形成设计在波束形成增益和干扰抑制方面均具有显著优势。