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    基于卸载策略的物联网边缘计算任务调度优化

    Task Scheduling Optimization of Internet of Things Edge Computing Based on Offloading Strategy

    • 摘要: 移动边缘计算(Mobile Edge Computing, MEC)通过将计算任务卸载到边缘服务器,为用户提供了低延时、低能耗的服务,解决了传统云计算的不足。在移动边缘计算中,如何进行卸载决策是提供低延时、低能耗服务的关键技术之一。除此之外,由于无线信道的带宽资源有限,不合理的带宽分配会使用户设备的能耗和延时增加,因此如何进行合理的资源分配也是边缘计算实现的关键。为联合优化时延、能耗与计算资源,本文提出了一个基于蒙特卡洛树搜索的多通道探索算法(Multi-Channel Search Algorithm based on Monte Carlo Tree Search,MCS-MCTS)。首先,以延时和能耗的成本为优化目标,将计算资源分配决策及传输功率建模决策建模为凸优化问题,采用梯度下降法求解最优传输功率分配问题,通过拉格朗日乘子法及卡罗需-库恩-塔克(Karush-Kuhn-Tucker, KKT)条件求解最优计算资源分配问题。随后,通过MCS-MCTS算法处理二进制卸载决策问题,为避免搜索结果陷入局部最优,引入模拟退火算法。数值结果表明,MCS-MCTS算法能在线性相干时间内得到接近最优的卸载决策与资源分配决策,与现有的启发式搜索算法相比,该算法可以在减少时间复杂度和提高系统能量有效性的同时,达到接近最优的性能。

       

      Abstract: Mobile edge computing (MEC) provides users with low latency and low energy consumption services by unloading computing tasks to MEC servers, overcoming the shortcomings of traditional cloud computing. In mobile edge computing, how to make unloading decision is one of the key technologies to provide low latency and low energy consumption services. In addition, due to the limited bandwidth resources of wireless channel, unreasonable bandwidth allocation will increase the energy consumption and delay of user devices. Therefore, how to reasonably allocate resource is also the key to the implementation of edge computing. To jointly optimize delay, energy consumption, and computational resources, this paper proposes a multi-channel search algorithm based on Monte Carlo tree search (MCS-MCTS). Firstly, with the cost of delay and energy consumption as the optimization objective, the decision on computing resource allocation and transmission power modeling is modeled as a convex optimization problem. The optimal transmission power allocation problem is solved by using gradient descent method, and the optimal computational resource allocation problem is solved by means of Lagrange multiplier method and Karush-Kuhn-Tucker (KKT) condition. Subsequently, the MCS-MCTS algorithm is used to deal with the binary unloading decision problem. Besides, the simulated annealing algorithm is introduced to avoid the search results falling into local optimum. The numerical results show that MCS-MCTS algorithm can obtain near optimal unloading decision and resource allocation decision in linear coherent time. Compared with existing heuristic search algorithms, this algorithm can achieve near optimal performance while reducing time complexity and improving system energy efficiency.

       

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