SPMA Analysis Framework Based on Hierarchical Priority

To address the issue that the existing Statistical Priority-based Multiple Access (SPMA) protocol failure to jointly optimize node-level significance and service-level urgency, this letter proposes an SPMA analysis framework based on hierarchical priority (HSPMA). Unlike traditional SPMA, which treats all nodes as homogeneous and prioritizes only intra-queue services, HSPMA introduces a comprehensive priority index that integrates node priorities and queue priorities via weighted normalization. The framework optimizes the backoff mechanism by dynamically adjusting contention windows based on the comprehensive priority, where higher-priority nodes or services reduce their backoff intervals and can preempt low-priority transmissions. Using preemptive queuing theory, we derive the preemptive slot transmission probability (PSTP) for each priority level and establish fixed-point equations to characterize steady-state network performance, including transmission success rate and throughput. Furthermore, we quantify the impact of key parameters, which provides a theoretical basis for the parameter configuration of the HSPMA protocol.