An Analysis on Wireless Edge Caching in In-Band Full-Duplex FR2-IAB Networks

This article develops a 3GPP inspired analytical framework for cache-enabled in-band full-duplex (IBFD) integrated access and backhaul (IAB) heterogeneous network in the FR2 (millimeter wave) band. In particular, by assuming wide-band FR2 channel model, we analyze the performance of cache-enabled IAB nodes that serve multiple users in access in IBFD mode through hybrid beamforming architectures. Since, IBFD transmission is considered, the IAB nodes are able to retrieve any non-cached files simultaneously through backhaul from the IAB donor nodes, which also use hybrid beamforming architectures. Utilizing stochastic geometry tools, we first derive the lower-bound for the average success probability (ASP) of file delivery for the considered system model, using which we evaluate two quintessential performance metrics: latency and average throughput of file delivery under a cache-enabled content delivery phase. Further, as a baseline for comparison, we also consider conventional half-duplex techniques, namely time division duplex and frequency division duplex transmission and evaluate their performance with respect to cache size, node density, content popularity, antenna numbers, blockage density, and residual self-interference. Numerical results demonstrate the precedency of using wireless edge caching as a cost-effective measure for improving the FR2-IAB network's performance. More importantly, we provide several design insights for the implementation of wireless edge caching in IBFD FR2-IAB networks, with respect to required residual self interference cancellation, increasing antenna number, increasing target data rate and IAB node density.