Multi-Domain Index Modulation for Flexible Pinching Antenna Systems: Transceiver Design and Performance Analysis

Abstract

This paper investigates multi-domain index modulation for pinching-antenna (PA)-enabled wireless communications. Different from existing PA-based index modulation schemes that mainly rely on a single resource dimension, we propose a PA-aided multi-domain index modulation (PA-MDIM) framework in which information bits are jointly mapped onto waveguide-wise frequency offset selection, intra-waveguide PA activation patterns, and conventional constellation symbols. By jointly exploiting these heterogeneous transmission dimensions, the proposed PA-MDIM scheme more fully utilizes the intrinsic structural flexibility of PA systems, significantly enlarges the multi-domain signaling space, and provides a more efficient way to improve transmission rate than simply increasing the modulation order. The resulting transmit signal has a structured block-sparse form, which motivates the development of a low-complexity ordered block beam search (OBBS) detector for efficient signal recovery. Compared with exhaustive maximum-likelihood (ML) detection, the proposed detector achieves a substantial complexity reduction while retaining near-ML error performance. In addition, the error performance of the proposed PA-MDIM scheme is analyzed over Rician fading channels by deriving the unconditional pairwise error probability and an upper bound on the average bit error probability. Simulation results validate the developed analysis and show that the proposed PA-MDIM scheme achieves a superior tradeoff among spectral efficiency, detection complexity, and reliability compared with existing PA-based benchmark schemes.