UAV-Assisted Intelligent Data Collection and Computation Offloading for Railway Wireless Sensor Networks
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摘要: 针对铁路复杂环境运维时无线传感网存在监测点网络信号差、传感器更换电池难及监测数据计算量大等挑战,该文提出一种多无人机辅助的铁路无线传感网智能数据收集与计算任务卸载方法。为保障铁路运营安全,方案考虑了铁路安全保护区对无人机飞行的限制,并对不同类型无线传感业务进行优先级划分,优先保障安全型传感业务传输性能,利用基站与列车的可用计算资源进行传感数据计算处理,设计了 基于多智能体软演员-评论家(MASAC)深度强化学习算法的多无人机飞行轨迹与数据卸载决策联合优化,实现无人机能耗、无线传感网能耗以及数据信息年龄的加权和最小化。仿真结果表明,所提算法能够显著提升系统整体能耗和数据信息新鲜度性能。
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关键词:
- 铁路无线传感网 /
- 无人机 /
- 计算卸载 /
- 多智能体深度强化学习
Abstract:Objective Ensuring the safety and stability of train operations is essential in the advancement of railway intelligence. The growing maturity of Wireless Sensor Network (WSN) technology offers an efficient, reliable, low-cost, and easily deployable approach to monitoring railway operating conditions. However, in complex and dynamic maintenance environments, WSNs encounter several challenges, including weak signal coverage at monitoring sites, limited accessibility for tasks such as sensor node battery replacement, and the generation of large volumes of monitoring data. To address these issues, this study proposes a multi-Unmanned Aerial Vehicle (UAV)-assisted method for data collection and computation offloading in railway WSNs. This approach enhances overall system energy efficiency and data freshness, offering a more effective and robust solution for railway safety monitoring. Methods An intelligent data collection and computation offloading system is constructed for multi-UAV-assisted railway WSNs. UAV flight constraints within railway safety protection zones are considered, and wireless sensing services are prioritized to ensure preferential transmission for safety-critical tasks. To balance energy consumption and data freshness, the system optimization objective is defined as the weighted sum of UAV energy consumption, WSN energy consumption, and the Age of Information (AoI). A joint optimization algorithm based on Multi-Agent Soft Actor-Critic (MASAC) is proposed, which balances exploration and exploitation through entropy regularization and adaptive temperature parameters. This approach enables efficient joint optimization of UAV trajectories and computation offloading strategies. Results and Discussions (1) Compared with the Multi-Agent Deep Deterministic Policy Gradient (MADDPG), MASAC-Greedy, and MASAC-AOU algorithms, the MASAC-based scheme converges more rapidly and demonstrates greater stability ( Fig. 4 ), ultimately achieving the highest reward. In contrast, MADDPG exhibits slower learning and less stable performance. (2) The comparison of multi-UAV flight trajectories under different algorithms shows that the proposed MASAC algorithm enables effective collaboration among UAVs, with each responsible for monitoring distinct regions while strictly adhering to railway safety protection zone constraints (Fig. 5 ). (3) The MASAC algorithm yields the best objective function value across all evaluated algorithms (Fig. 6 ). (4) As the number of sensors and the AoI weight increase, UAV energy consumption rises for all algorithms; however, the MASAC algorithm consistently maintains the lowest energy consumption (Fig. 7 ). (5) In terms of sensor node energy consumption, MADDPG achieves the lowest value, but at the expense of information freshness (Fig. 8 ). (6) Regarding average AoI performance, the MASAC algorithm performs best across a range of sensor densities and AoI weight settings, with the greatest improvements observed under higher AoI weight conditions (Fig. 9 ). (7) The AoI performance comparison by sensor type (Table 2 ) confirms that the system effectively supports priority-based data collection services.Conclusions This study proposes a MASAC-based intelligent data collection and computation offloading scheme for railway WSNs supported by multiple UAVs, addressing critical challenges such as limited WSN battery life and the high real-time computational demands of complex railway environments. The proposed algorithm jointly optimizes UAV flight trajectories and computation offloading strategies by integrating considerations of UAV and WSN energy consumption, data freshness, sensing service priorities, and railway safety protection zone constraints. The optimization objective is to minimize the weighted sum of average UAV energy consumption, average WSN energy consumption, and average WSN AoI. Simulation results demonstrate that the proposed scheme outperforms baseline algorithms across multiple performance metrics. Specifically, it achieves faster convergence, efficient multi-UAV collaboration that avoids resource redundancy and spatial overlap, and superior results in UAV energy consumption, sensor node energy consumption, and average AoI. -
表 1 仿真参数
参数名称 取值 参数名称 取值 带宽$ B $ (MHz) 1 旋翼桨叶的叶尖速度$ {U}_{\mathrm{t}\mathrm{i}\mathrm{p}} $ (m/s) 120 传感数据$ r $ (Mbits) 8 平均旋翼感应速度$ {v}_{0} $ (m/s) 4.03 计算密度 (CPU周期/比特) 1000 机身阻力比$ {d}_{0} $ 0.6 噪声功率$ {\sigma }^{2} $ (dBm) –110 旋翼坚固程度$ s $ 0.05 无人机高度$ H $ (m) 50 空气密度$ \rho $ (kg/m3) 1.225 无人机最大速度$ V $ 20 旋翼盘面积$ A $ (m2) 0.503 载波频率$ {f}_{c} $ (GHz) 2 有效电容系数 $ \kappa $ 10-28 时隙个数$ N $ 30 经验回放缓存区D 300000 时隙长度$ {\delta }_{t} $ (s) 2 Actor网络学习率 0.00001 计算资源$ {f}_{a},{f}_{b},{f}_{c} $ (Gcycles/s) 2, 5, 3.5 Critic网络学习率 0.0001 SN覆盖范围$ {D}_{\mathrm{c}\mathrm{o}\mathrm{v}\mathrm{e}\mathrm{r}} $ (m) 30 SN能耗放缩因子$ \beta $ 10 无人机能耗放缩因子$ \alpha $ 0.01 折扣因子$ \gamma $ 0.95 无人机最大连接数$ {N}^{max} $ 2 迭代回合数 20,000 桨叶轮廓功率$ {P}_{0} $ (W) 79.86 批次大小 1024 感应功率$ {P}_{i} $ (W) 88.63 学习间隔 5 表 2 不同类型SN的AoI性能对比
算法 安全关键型
SN的AoI结构监测型
SN的AoI环境监测型
SN的AoIMASAC 7.3178 13.8370 14.0416 MASAC-Greedy 9.9738 15.6170 10.7290 MASAC-AOU 14.2142 13.2253 18.2617 MADDPG 14.2068 17.3939 19.2440 -
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