Analysis and Optimization of SVC-Based Secure Caching and Non-Orthogonal Transmission in Wireless Caching Networks
Xuewei Zhang, Zeyu Tian, Yuan Ren, Fan Jiang, Junxuan Wang, Tiejun Lv · IEEE Transactions on Vehicular Technology · 2025
In this paper, we propose a secure content caching and delivery strategy to support multi-level video viewing services based on scalable video coding (SVC). With the appearance of eavesdroppers (Eves), the base layer (BL) and enhancement layers (ELs) encoded by SVC are cached in the macro-cell base station (MBS) and small-cell base stations (SBSs), respectively, using a probabilistic caching strategy. Power domain non-orthogonal transmission is utilized to deliver ELs for SBSs. We analyze the transmission and secrecy performance of the end user. Specifically, employing the tool of stochastic geometry, the successful transmission probabilities (STPs) from the serving MBS and SBS are derived, and the secrecy outage probability (SOP) in the worst case is also analyzed. All derived expressions are in complex forms, and the Gaussian-Chebyshev quadrature is adopted to approximate them in closed forms. After obtaining the expressions for STPs and SOP, the secrecy cache-aided data rate (SCADR) is derived and then maximized by jointly optimizing the random caching probabilities and power allocation coefficients for content caching and non-orthogonal transmission, respectively. The SCADR maximization problem with coupled variables is difficult to solve, and then is divided into two sub-problems for tractability. The two sub-problems are solved independently, and the alternative optimization approach is adopted to obtain the optimal caching probabilities and power allocation coefficients. Simulation results validate the accuracy of derived STPs and SOP, and the approximation effectiveness of the Gaussian-Chebyshev quadrature is demonstrated. Results also show the proposed scheme has great potential to improve the system SCADR, as compared to existing caching and power allocation schemes.