Energy-Efficient Design for Downlink Pinching-Antenna Systems with QoS Guarantee

TL;DR

The paper addresses energy-efficient downlink communication in a TDMA system supported by multiple pinching antennas, jointly optimizing transmit powers, time allocations, and antenna positions to satisfy per-user QoS. It first derives optimal pinching-antenna placements and a feasibility condition, then employs a BCD framework to alternately optimize power (via Dinkelbach-based fractional programming) and time allocations (optimal fixed-power timing), ensuring convergence to a stationary point. Numerical results show the proposed scheme significantly improves EE over conventional fixed-antenna setups and benchmark pinching schemes while guaranteeing QoS, with gains amplified as the number of antennas increases. The study demonstrates the practical viability of reconfigurable pinching-antenna environments for energy-efficient mmWave downlink systems.

Abstract

Pinching antennas have recently garnered significant attention due to their ability to dynamically reconfigure wireless propagation environments. Despite notable advancements in this area, the exploration of energy efficiency (EE) maximization in pinching-antenna systems remains relatively underdeveloped. In this paper, we address the EE maximization problem in a downlink time-division multiple access (TDMA)-based multi-user system employing one waveguide and multiple pinching antennas, where each user is subject to a minimum rate constraint to ensure quality-of-service. The formulated optimization problem jointly considers transmit power and time allocations as well as the positioning of pinching antennas, resulting in a non-convex problem. To tackle this challenge, we first obtain the optimal positions of the pinching antennas. Based on this, we establish a feasibility condition for the system. Subsequently, the joint power and time allocation problem is decomposed into two subproblems, which are solved iteratively until convergence. Specifically, the power allocation subproblem is addressed through an iterative approach, where a semi-analytical solution is obtained in each iteration. Likewise, a semi-analytical solution is derived for the time allocation subproblem. Numerical simulations demonstrate that the proposed pinching-antenna-based strategy significantly outperforms both conventional fixed-antenna systems and other benchmark pinching-antenna schemes in terms of EE.

Figures (4)

• Figure 1: A downlink pinching-antenna system.
• Figure 2: EE versus the maximum transmit power constraint at the users.
• Figure 3: EE versus the minimum rate requirement at the users.
• Figure 4: EE versus the number of pinching antennas.