Pinching-antenna systems (PASS) represent a promising customizable wireless access mechanism in high-frequency bands, enabled by dielectric waveguides and movable dielectric particles, called pinching antennas (PAs). In this work, we study optimal position allocation of PAs in PASS for multicasting in the downlink when a line-of-sight (LoS) link does not necessarily exist between all users and the PAs. The multicasting problem is solved by leveraging minorization-maximization (MM) principle to yield a provably convergent algorithm. In each run of the MM based procedure, we solve a convex surrogate problem using two methods called the candidate search method (CSM) and the bisection search method (BSM). With both BSM and CSM, we not only report superior performance of the multicasting PASS in non-LoS environments compared to conventional antenna systems (CAS), but also determine that BSM yields better overall computational complexity when the number of users and PAs increases. For example, we report that when we have 8 PAs and 25 users, the execution time with the CSM is approximately 2.5 times that with the BSM.

翻译：夹持天线系统（PASS）是一种在高频段具有前景的可定制无线接入机制，其通过介质波导和可移动介质粒子（称为夹持天线（PA））实现。本文研究在下行链路多播场景中，当所有用户与PA之间不一定存在视距（LoS）链路时，PASS中PA的最优位置分配问题。该多播问题通过利用最小化-最大化（MM）原理求解，得到了一种可证明收敛的算法。在基于MM过程的每次迭代中，我们使用两种方法——候选搜索法（CSM）和二分搜索法（BSM）——求解一个凸代理问题。通过BSM和CSM，我们不仅报告了多播PASS在非视距环境中相较于传统天线系统（CAS）的优越性能，还确定了当用户和PA数量增加时，BSM具有更优的整体计算复杂度。例如，当系统配置8个PA和25个用户时，CSM的执行时间约为BSM的2.5倍。