相移相关功耗模型下基于 PIN 二极管的 IRS 辅助系统波束成形
Beamforming for PIN Diode-Based IRS-Assisted Systems Under a Phase Shift-Dependent Power Consumption Model
AI总结：
针对基于 PIN 二极管的 IRS 功耗随相移变化的问题，本文建立 PS-DPC 模型，提出单用户与多用户联合功率分配及波束成形优化方法，显著提升系统速率。
摘要：
智能反射面（IRS）被认为是未来无线通信系统中一种很有前景的使能技术。在已有文献中，IRS 通常被视为不消耗功率，或被假定具有恒定功耗。然而，近期实验结果表明，对于基于正-本征-负（PIN）二极管的 IRS，其功耗会随相移配置动态变化。这种相移相关功耗（PS-DPC）给基站（BS）与 IRS 之间带来了具有挑战性的功率分配问题。为解决该问题，本文在实际 PS-DPC 模型下研究 IRS 辅助系统的速率最大化问题。针对单用户场景，我们提出一种基于广义 Benders 分解的波束成形方法，在满足系统总功耗约束的同时最大化可达速率。此外，我们还提出一种低复杂度波束成形设计，其中分配给 BS 和 IRS 的功率基于统计信道状态信息进行离线优化。进一步地，针对多用户场景，我们通过两种不同的联合功率分配与相移优化方法，求解一个等价的加权均方误差最小化问题。仿真结果表明，与基准方案相比，所提方法能够灵活优化 BS 与 IRS 之间的功率分配，从而取得更优性能。优化后的功率分配策略强烈依赖于系统功率预算。当系统功率预算较高时，PS-DPC 并非系统功耗的主导因素，IRS 可以根据需要开启尽可能多的 PIN 二极管，以实现高波束成形质量。而当系统功率预算受限时，更多功率倾向于分配给 BS 以增强发射功率，导致 PS-DPC 预算减少，从而使 IRS 的波束成形质量降低。
英文摘要：
Intelligent reflecting surfaces (IRSs) have been regarded as a promising enabler for future wireless communication systems. In the literature, IRSs have been considered power-free or assumed to have constant power consumption. However, recent experimental results have shown that for positive-intrinsic-negative (PIN) diode-based IRSs, the power consumption dynamically changes with the phase shift configuration. This phase shift-dependent power consumption (PS-DPC) introduces a challenging power allocation problem between base station (BS) and IRS. To tackle this issue, in this paper, we investigate a rate maximization problem for IRS-assisted systems under a practical PS-DPC model. For the single-user case, we propose a generalized Benders decomposition-based beamforming method to maximize the achievable rate while satisfying a total system power consumption constraint. Moreover, we propose a low-complexity beamforming design, where the powers allocated to BS and IRS are optimized offline based on statistical channel state information. Furthermore, for the multi-user case, we solve an equivalent weighted mean square error minimization problem with two different joint power allocation and phase shift optimization methods. Simulation results indicate that compared to baseline schemes, our proposed methods can flexibly optimize the power allocation between BS and IRS, thus achieving better performance. The optimized power allocation strategy strongly depends on the system power budget. When the system power budget is high, the PS-DPC is not the dominant factor in the system power consumption, allowing the IRS to turn on as many PIN diodes as needed to achieve high beamforming quality. When the system power budget is limited, however, more power tends to be allocated to the BS to enhance the transmit power, resulting in a lower beamforming quality at the IRS due to the reduced PS-DPC budget.
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