Environment division multiple access (EDMA) has emerged as a promising multiple access paradigm, which mitigates inter-user interference by dynamically adjusting pinching antenna (PA) positions to the underlying propagation environment. This paper investigates a multi-user PA-enabled EDMA framework that accounts for probabilistic line-of-sight (LoS) blockages, random non-LoS (NLoS) scattering, and practical inwaveguide attenuation. With the aim of maximizing the total information rate, we formulate a joint PA deployment and power allocation problem subject to statistical rate outage constraints, the transmit power budget, and the feasible deployment region of PAs. We first consider a canonical two-user two-PA scenario and derive closed-form expressions for the outage probabilities, followed by a low-complexity projected gradient descent (PGD)-based algorithm to address the reformulated problem. Then, we extend our design to the general multi-user multi-PA scenario and derive tractable approximations for the outage probabilities by assuming interfering links to be NLoS and applying the Chernoff bounding technique, where a successive convex approximation (SCA)-based algorithm is proposed to handle the resulting nonconvex problem. Simulations validate the superiority of the proposed PA-enabled EDMA design and the effectiveness of the proposed algorithms. Specifically, both the PGD-based algorithm and the SCA-based algorithm achieve near-optimal performance in comparison with the exhaustive search. Furthermore, the PA-enabled EDMA design yields significant performance gains over both PA-enabled and conventional time division multiple access designs.
Weihao Mao, Yang Lu, Yanqing Xu et al.· 0 citations
In this paper, we consider a backscatter communication (BackCom)-assisted uplink pinching-antenna system in Internet of Things (IoT), where a non-energy-constrained IoT device provides radio frequency signals to support multiple energy-constrained IoT devices, with multiple pinching antennas deployed on a waveguide. We formulate a joint optimization problem to select a energy-constrained device and simultaneously design its power reflection coefficient and pinching antenna locations. The objective is to maximize the achievable rate of the selected device, subject to the quality of service requirements of the non-energy-constrained device, minimum energy harvesting at energy-constrained devices, and collision-free constraints imposed on the pinching antennas. The problem is non-convex and analytically intricate, due to the strong interdependence among device selection, power reflection coefficients, and antenna positions. To overcome these challenges, we propose a block coordinate descent-based successive convex approximation algorithm that iteratively transforms the original non-convex problem into a series of convex subproblems that can be solved efficiently. Additionally, we analyze a special case with a single pinching antenna, deriving the optimal antenna location along with an approximate outage probability expression and the corresponding diversity order. Simulation results demonstrate that the proposed system achieves higher achievable rates, lower outage probability, and improved diversity gain compared to conventional uplink fixed-antenna systems.
Zheng Yang, Jingjing Cui, Gaojie Chen et al.· IEEE Transactions on Wireles...· 0 citations
