A Two-Stage Coordination Channel Access Approach for Low-Latency Wi-Fi 7 Multi-Link Operation
TL;DR
Results show that joint STA-side control of contention and TXOP service is effective for low-latency Wi-Fi 7 MLO, and the proposed CIPD-BAT reduces average delay, 95th percentile delay, and jitter.
Abstract
Wi-Fi 7 multi-link operation (MLO) reduces latency by allowing a station (STA) to contend and transmit on multiple links. Under finite load, however, independent per-link contention windows (CWs) and simple aggregation can increase upper MAC (UMAC) backlog, tail delay, and jitter. This letter proposes CIPD-BAT, contention interval probabilities deferment with backlog-aware transmission opportunity (TXOP) selection, a STA-side two-stage scheme for simultaneous transmit and receive (STR) MLO. CIPD-BAT adapts CW/backoff using a smoothed collision estimate, then sets a capped TXOP service size from UMAC backlog and load state. The proposed scheme is evaluated in ns-3 against MLO-STR, EMLSR, IDCW, and LP-MLO under homogeneous links, asymmetric links, and legacy coexistence with Pareto ON/OFF traffic. Across these cases, the proposed CIPD-BAT reduces average delay, 95th percentile delay, and jitter by up to 98.59%, 99.46%, and 99.52% over MLO-STR, and by up to 74.88%, 78.67%, and 80.31% over the other benchmarks, while maintaining near-unity per-STA fairness. These results show that joint STA-side control of contention and TXOP service is effective for low-latency Wi-Fi 7 MLO. The source code is available at https://github.com/itstuyihao/CIPD-BAT-MLO.