Design of Generalized Spatial Modulation for 2-D Pinching-Antenna Systems

Abstract

Two-dimensional pinching-antenna systems (2D-PASS) provide a flexible transmission architecture by reconfiguring radiation positions over multiple dielectric waveguides. However, the enlarged transmit-state set induced by multi-domain index modulation may generate closely spaced received vectors, hence degrading maximum-likelihood detection reliability. In this letter, we propose a generalized spatial modulation design for 2D-PASS, where the waveguide-index domain and the pinching antenna-aided spatial multiplexing (PASM) phase-index domain are jointly exploited to convey information with a limited number of radio-frequency chains. To improve detection reliability, we further develop a minimum squared Euclidean distance (MSED)-oriented rigid cluster translation method. Different from conventional position optimization that directly adjusts individual pinching antennas, the proposed method translates each antenna cluster as an intact entity, thereby preserving the predefined intra-cluster phase alphabet while reshaping the effective channel geometry. The resulting non-convex MSED maximization problem is then solved by a greedy coordinate-descent algorithm with monotonic convergence. Simulation results show that the proposed design enlarges the Euclidean separation among noise-free received vectors and improves the bit error rate over benchmark schemes.