Two-Timescale Joint 3C Optimizations for RIS-Assisted MIMO-OFDM Wireless Networks

To deal with the increasing demands of compute-and data-intensive applications, effective optimization of caching, computing, and communication (3C) resources for wireless networks becomes critical. This paper thus examines the two-timescale joint optimization of 3C resources in single-base station (BS) multi-user wireless edge networks where the multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) system is adopted along with the aid of reconfigurable intelligent surfaces (RISs). We formulate a two-timescale network latency minimization problem that optimizes the caching decisions on the large timescale, while optimizing the computing and communication resources on the small timescale. To develop the optimization approaches, we decompose the problem into large-timescale and small-timescale problems and propose solution approaches for them. Complexity analysis of our approaches is provided. Computer simulations are conducted to evaluate our approaches. Results show that our approaches can outperform the reference schemes in networks with and without the aid of RISs. Furthermore, the results indicate that when RISs are appropriately deployed, the use of RISs can significantly improve the network.