Enhancing Throughput for Wi-Fi 7 MLO With Shared Block ACK in MLD-SLD Coexisting Networks: An Airtime Alignment Approach

Abstract

Multi-link operation (MLO) with STR in IEEE 802.11be Wi-Fi 7 promises significant throughput gains but is hindered by the Block ACK Window (BAW) stall phenomenon, arising from the mandatory shared Block Acknowledgment (BA) mechanism. This letter investigates how to improve the throughput of a multi-link device (MLD) under shared BA constraints in general $L$ -link Wi-Fi networks with coexisting single-link devices (SLDs). By extending an analytical framework, we propose an airtime-aligned approach that optimally allocates MAC Protocol Data Unit (MPDU) aggregation sizes across links to proactively mitigate BAW stalls by balancing expected successful transmission durations. Extensive ns-3 simulations in multi-link coexistence scenarios demonstrate that the proposed scheme consistently outperforms greedy and DAMLA policies in interference-prone scenarios. Notably, the policy autonomously deactivates sub-optimal links and converges to the single-link operation under extreme heterogeneity, ensuring robust MLO gains in diverse deployments.