RIS-Assisted Industrial URLLC With Interference-Aware Max-Matching Diversity

Abstract

Industrial ultra-reliable low-latency communication (URLLC) is challenging under blocked propagation, dense radio deployments, and residual co-channel interference. This paper develops an outage-driven analytical and subband-allocation framework for RIS-assisted industrial radio access networks. The considered downlink system combines an RIS-assisted blocked serving link, cooperative remote radio heads (RRHs) that provide redundant desired-signal transmission, and non-cooperating RRHs that generate subband-dependent interference over shared OFDMA resources. The desired received power is approximated using moment-matched Gamma random variables, whereas the aggregate interference is characterized through a hypoexponential distribution. Based on these models, tractable closed-form per-subband outage expressions are derived for RIS-only and RIS-assisted cooperative transmission. The resulting outage probabilities are used to construct reliability weights for an interference-aware max-matching diversity (MMD) subband assignment. For fixed feasible interference-activity and cooperation patterns, the proposed MMD method attains the same minimum outage objective as exhaustive search at the design threshold, while requiring only subband-wise weight computation and sorting. Monte Carlo simulations validate the analytical expressions. The results further show that MMD closely outperforms fixed and random allocation and closely follows the single-user proportional fair (PF) benchmark, while RRH cooperation, frequency diversity, dominant-interferer protection, additional transmit antennas, and larger RIS sizes improve reliability and effective goodput.