Wireless powered mobile edge computing (MEC) leveraging hybrid passive backscatter communications (BackCom) and active transmissions (AT) for efficient data offloading has been investigated in Internet of Things (IoT) networks, where however the delay minimization problem has not been sufficiently studied. In this letter, we propose to minimize the overall delay for data offloading and computing of all IoT nodes in a hybrid BackCom-AT based wireless powered MEC network. We formulate an optimization problem to jointly optimize the operation time of a power beacon, and the computing frequency, transmit power, and portions of task bits for BackCom offloading, AT offloading and local computing of each IoT node. By introducing auxiliary variables and slack variables, the formulated non-convex optimization problem is transformed into an equivalent but more tractable form and is optimally solved by our proposed bisection-based iterative algorithm (BBIA). Computer simulations verify the quick convergence of the BBIA, and show that our proposed algorithm achieves a much shorter overall delay of all IoT nodes than the baseline schemes.

中文翻译：

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利用混合 BackCom 和 AT 实现无线供电移动边缘计算的延迟最小化


利用混合无源反向散射通信 (BackCom) 和主动传输 (AT) 实现高效数据卸载的无线供电移动边缘计算 (MEC) 已在物联网 (IoT) 网络中得到研究，但延迟最小化问题尚未得到充分研究。在这封信中，我们建议最大限度地减少基于混合 BackCom-AT 的无线供电 MEC 网络中所有物联网节点的数据卸载和计算的总体延迟。我们制定了一个优化问题来联合优化功率信标的运行时间以及每个物联网节点的 BackCom 卸载、AT 卸载和本地计算的计算频率、发射功率和任务位部分。通过引入辅助变量和松弛变量，将公式化的非凸优化问题转化为等效但更容易处理的形式，并通过我们提出的基于二分的迭代算法（BBIA）进行优化求解。计算机模拟验证了 BBIA 的快速收敛性，并表明我们提出的算法比基线方案实现了所有物联网节点的总体延迟更短。