Latency Minimization for Intelligent Reflecting Surface Aided Mobile Edge Computing
Latency Minimization for Intelligent Reflecting Surface Aided Mobile Edge Computing
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DOI：
10.1109/jsac.2020.3007035
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发表时间：
2020-11-01
影响因子：
16.4
通讯作者：
Hanzo, Lajos
中科院分区：
文献类型：
--
作者：
Bai, Tong;Pan, Cunhua;Hanzo, Lajos
移动的边缘计算（MEC）系统中的计算卸载构成了在移动的设备上支持资源密集型应用的有效范例。然而，当用于卸载计算任务的通信链路是敌对的时，MEC的益处不能被充分利用。幸运的是，传播引起的损伤可以通过智能反射表面（IRS）来减轻，其能够提高光谱效率和能量效率。具体地，IRS包括IRS控制器和大量无源反射元件，每个无源反射元件可以对入射信号施加相移，从而协作地改善传播环境。在本文中，IRS在MEC系统中的有益作用进行了研究，其中单天线设备可以选择在IRS的帮助下通过多天线接入点将其计算任务的一部分卸载到边缘计算节点。相关的延迟最小化问题制定为单设备和多设备的情况下，受到实际约束的边缘计算能力和IRS相移设计。为了解决这个问题，调用块坐标下降（BCD）技术，将原问题解耦为两个子问题，然后使用低复杂度的迭代算法交替优化计算和通信设置。它表明，我们的IRS辅助MEC系统是能够显着优于传统的MEC系统运行没有IRS。在数量上，在300 m半径的单个小区和5个有源设备中，依靠5天线接入点，在传统MEC系统上实现了约20%的计算延迟减少。
Computation off-loading in mobile edge computing (MEC) systems constitutes an efficient paradigm of supporting resource-intensive applications on mobile devices. However, the benefit of MEC cannot be fully exploited, when the communications link used for off-loading computational tasks is hostile. Fortunately, the propagation-induced impairments may be mitigated by intelligent reflecting surfaces (IRS), which are capable of enhancing both the spectral- and energy-efficiency. Specifically, an IRS comprises an IRS controller and a large number of passive reflecting elements, each of which may impose a phase shift on the incident signal, thus collaboratively improving the propagation environment. In this paper, the beneficial role of IRSs is investigated in MEC systems, where single-antenna devices may opt for off-loading a fraction of their computational tasks to the edge computing node via a multi-antenna access point with the aid of an IRS. Pertinent latency-minimization problems are formulated for both single-device and multi-device scenarios, subject to practical constraints imposed on both the edge computing capability and the IRS phase shift design. To solve this problem, the block coordinate descent (BCD) technique is invoked to decouple the original problem into two subproblems, and then the computing and communications settings are alternatively optimized using low-complexity iterative algorithms. It is demonstrated that our IRS-aided MEC system is capable of significantly outperforming the conventional MEC system operating without IRSs. Quantitatively, about 20 % computational latency reduction is achieved over the conventional MEC system in a single cell of a 300 m radius and 5 active devices, relying on a 5-antenna access point.