基于强化学习的多IRS辅助的无线可充电传感网充电策略研究

RESEARCH ON CHARGING STRATEGY FOR SENSOR NETWORKS ASSISTED BY MULTIPLE INTELLIGENT REFLECTIVE SURFACES

  • 摘要: 智能反射面(IRSs)被认为是提高无线能量传输(WPT)效率的有效途径,许多学者利用单个IRS辅助无线可充电传感网(WRSNs)进行能量收集,并进一步优化充电策略以延长其使用寿命。相较于单个IRS,部署多IRS不仅有效避免因单个IRS故障所导致的额外波束成形(BF)增益消失问题,还可以同时支持多个节点的充电需求。然而,利用多IRS会导致信道数量呈"指数级"上升,从而导致在求解大规模WRSNs充电策略时遭遇"维度灾难"问题。为此,研究基于强化学习的多IRS辅助的WRSNs充电策略,以降低计算复杂度和资源消耗。采用一种分布式方法来优化多IRS的相位偏移,以最大化节点的接收功率并缩短求解时间;引入博弈论概念,将单一马尔可夫决策过程(MDP)模型转换为多MDP博弈模型,减少了强化学习模型的状态空间;利用纳什Q学习算法,加快了最优充电策略的搜索过程和求解速度。仿真结果表明,该方法能显著提升WRSNs的寿命和能量效率。

     

    Abstract: Intelligent reflective surfaces (IRSs) are recognized as an effective approach to enhance the efficiency of wireless power transfer (WPT). Many scholars have utilized a single IRS to assist wireless rechargeable sensor networks (WRSNs) in energy harvesting, further optimizing charging strategies to extend their lifespan. Compared with a single IRS, deploying multiple IRSs not only effectively prevents the loss of additional Beamforming (BF) gain caused by the failure of a single IRS but also supports the charging needs of multiple nodes simultaneously. However, the use of multiple IRSs leads to an "exponential" increase in the number of channels, thereby facing the "curse of dimensionality" problem when solving large- scale WRSNs charging strategies. To address this, a charging strategy for WRSNs assisted by multiple IRSs based on reinforcement learning is proposed to reduce computational complexity and resource consumption. A distributed method was adopted to optimize the phase shifts of multiple IRSs, aimed to maximize the receiving power of the nodes and shorten the solution time. The concept of game theory was introduced, transforming the single Markov decision process (MDP) model into a multi- MDP game model, thereby reducing the state space of the reinforcement learning model. The Nash Q- learning algorithm was employed to accelerate the search and solution process of the optimal charging strategy. Simulation results demonstrate that this method significantly enhances the lifespan and energy efficiency of WRSNs.

     

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