In this paper, sub-channel scheduling, task assignment and power allocation are investigated for orthogonal multiple access (OMA)-based and non-orthogonal multiple access (NOMA)-based mobile edge computing (MEC) systems. Based on different channel conditions and computational capacities, computational tasks are partially offloaded to the MEC server via OMA or NOMA protocols. In order to minimize the total energy consumption, an optimization problem under the task execution latency constraint is formulated and divided into two sub-problems. By utilizing matching theory, the formulated sub-channel allocation problem is solved by a proposed low-complexity algorithm, where the joint optimization of task assignment and power allocation is performed at each iteration. Based on the delay constraint, some insights are obtained, and the closed-form solutions of task assignment coefficients and transmit power are derived. Furthermore, the offloading strategy in both OMA and NOMA schemes is analyzed, which shows that the optimal task assignment coefficient is decided by the energy consumption efficiency (ECE). Simulation results indicate that: i) the proposed sub-channel allocation algorithm and derived closed-form solutions can significantly improve the MEC system in terms of the energy consumption; ii) the provided offloading strategy can be dynamically and efficiently employed with different channel conditions and computational capacities.

中文翻译：

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基于OMA和基于NOMA的MEC系统的子信道调度，任务分配和功率分配

本文研究了基于正交多址（OMA）和基于非正交多址（NOMA）的移动边缘计算（MEC）系统的子信道调度，任务分配和功率分配。根据不同的信道条件和计算能力，通过OMA或NOMA协议将计算任务部分卸载到MEC服务器。为了使总能量消耗最小，制定了任务执行等待时间约束下的优化问题并将其分为两个子问题。利用匹配理论，通过提出的低复杂度算法解决了制定的子信道分配问题，该算法在每次迭代中执行任务分配和功率分配的联合优化。基于延迟约束，可以获得一些见解，推导了任务分配系数和发射功率的闭式解。此外，分析了OMA和NOMA方案中的卸载策略，这表明最优任务分配系数由能耗效率（ECE）决定。仿真结果表明：i）所提出的子信道分配算法和导出的闭式解可以在能耗方面显着改善MEC系统；ii）所提供的卸载策略可以在不同的信道条件和计算能力下动态有效地采用。这表明最佳任务分配系数由能耗效率（ECE）决定。仿真结果表明：i）所提出的子信道分配算法和导出的闭式解可以在能耗方面显着改善MEC系统；ii）所提供的卸载策略可以在不同的信道条件和计算能力下动态有效地采用。这表明最佳任务分配系数由能耗效率（ECE）决定。仿真结果表明：i）所提出的子信道分配算法和导出的闭式解可以在能耗方面显着改善MEC系统；ii）所提供的卸载策略可以在不同的信道条件和计算能力下动态有效地采用。