We consider an intelligent reflecting surface (IRS)-aided mobile edge computing (MEC) system, where an IRS is deployed to assist computation offloading from two users to an access point connected with an edge cloud. For the IRS-aided data transmission, in contrast to the conventional non-orthogonal multiple-access (NOMA) and time-division multiple-access (TDMA), we propose a new flexible time-sharing NOMA scheme that allows users to flexibly divide their data into two parts transmitted via NOMA and TDMA, respectively, thus encapsulating both conventional NOMA and TDMA as special cases. We formulate an optimization problem to minimize the sum delay of the two users by designing the IRS passive reflection and users' computation-offloading scheduling under the IRS discrete-phase constraint. Although this problem is non-convex, we obtain its optimal solution for both the cases of infinite and finite cloud computing capacities. Furthermore, we show that NOMA and TDMA based transmissions are preferred in different scenarios, depending on the users' cloud-computing time as well as the rate discrepancy between NOMA and TDMA with IRS.

中文翻译：

---

IRS 辅助移动边缘计算的延迟优化调度

我们考虑了智能反射面 (IRS) 辅助移动边缘计算 (MEC) 系统，其中部署了 IRS 以协助将计算从两个用户卸载到与边缘云连接的接入点。对于 IRS 辅助数据传输，与传统的非正交多址 (NOMA) 和时分多址 (TDMA) 相比，我们提出了一种新的灵活分时 NOMA 方案，允许用户灵活地划分他们的数据分为两部分，分别通过 NOMA 和 TDMA 传输，从而将传统的 NOMA 和 TDMA 都封装为特殊情况。我们通过在 IRS 离散相位约束下设计 IRS 被动反射和用户的计算卸载调度来制定优化问题，以最小化两个用户的总延迟。虽然这个问题是非凸的，我们在无限和有限云计算能力的情况下都获得了其最优解。此外，我们表明在不同场景中首选基于 NOMA 和 TDMA 的传输，具体取决于用户的云计算时间以及 NOMA 和 TDMA 与 IRS 之间的速率差异。