[论文解读] Intelligent Reflecting Surface Meets Mobile Edge Computing: Enhancing Wireless Communications for Computation Offloading

Yang Liu, Jun Zhao+5 more|arXiv (Cornell University)|Jan 21, 2020

Advanced Wireless Communication Technologies参考文献 43被引用 46

一句话总结

论文研究在IRS辅助无线网络中的计算卸载，提出可行性检查和优化框架，在保证移动设备速率约束的同时最大化边缘服务器收益。研究表明IRS能够提升卸载的可行性和边缘收益。

ABSTRACT

We consider computation offloading for edge computing in a wireless network equipped with intelligent reflecting surfaces (IRSs). IRS is an emerging technology and has recently received great attention since they can improve the wireless propagation environment in a configurable manner and enhance the connections between mobile devices (MDs) and access points (APs). At this point not many papers consider edge computing in the novel context of wireless communications aided by IRS. In our studied setting, each MD offloads computation tasks to the edge server located at the AP to reduce the associated comprehensive cost, which is a weighted sum of time and energy. The edge server adjusts the IRS to maximize its earning while maintaining MDs' incentives for offloading and guaranteeing each MD a customized information rate. This problem can be formulated into a difficult optimization problem, which has a sum-of-ratio objective function as well as a bunch of nonconvex constraints. To solve this problem, we first develop an iterative evaluation procedure to identify the feasibility of the problem when confronting an arbitrary set of information rate requirement. This method serves as a sufficient condition for the problem being feasible and provides a feasible solution. Based on that we develop an algorithm to optimize the objective function. Our numerical results show that the presence of IRS enables the AP to guarantee higher information rate to all MDs and at the same time improve the earning of the edge server.

研究动机与目标

• 鼓励在边缘计算中进行计算卸载，以减少移动设备的时间成本和能耗。
• 将智能反射表面引入以提高上行速率和网络性能。
• 开发在速率与IRS约束下最大化边缘服务器收益的可行性评估和优化算法。
• 提供关于IRS辅助信道如何影响卸载激励和支付的见解。
• 展示IRS在实现更高信息速率和边缘服务器利润方面的益处。

提出的方法

• 建模在AP具备边缘计算能力、移动设备为单天线的IRS辅助多用户上行链路。
• 构建一个基于效用的决策框架，在速率约束下比较本地计算与边缘计算。
• 推导一个优化问题，在满足速率与IRS幅度约束的前提下最大化边缘服务器支付。
• 引入使用SINR/MSE关系的可行性检查方法来评估速率约束。
• 应用简化问题(P2)以获得可处理的下界并指导IRS优化。
• 提出基于块坐标下降的非凸IRS优化问题求解方法。

实验结果

研究问题

• RQ1 IRS辅助信道是否能够提高在边缘计算卸载场景中满足所有移动设备信息速率约束的可行性？
• RQ2 边缘服务器应如何设置支付以最大化收益，同时确保在有利时移动设备进行卸载？
• RQ3 IRS相位移对共享上行链路中的可达速率与卸载决策的影响？
• RQ4 可处理的优化形式是否能在速率约束下提供接近最优的IRS配置以最大化支付？

主要发现

• 启用IRS的环境增加了所有移动设备满足速率约束的可行性概率。
• 通过调整IRS反射并考虑对卸载设备的支付，优化框架可以提高边缘服务器收益。
• 提出可行性评估程序在给定速率需求时提供充分条件和一个可行解。
• 简化问题提供性能下界，并为边缘计算中IRS设计提供实际见解。
• 结果表明算法收敛更快，且在IRS辅助下边缘服务器收益有实质性提升。