摘要： Restricted Access Window (RAW) mechanism is a significant Medium Access Control(MAC) enhancement in IEEE 802.11ah standard. An optimized RAW scheme is proposed to improve the performance of heavy-loaded networks. Based on the original RAW mechanism, threshold and optimal RAW group size decision was introduced into the proposed scheme, which further highlighted the advantage of RAW. Compared to traditional DCF method, the proposed scheme improves the network performance in saturated scenario with large number of stations. Simulation results confirmed the advantages of proposed scheme in throughput, power consumption and fairness. This scheme can therefore be adopted in practical 802.11ah use cases to improve the network performance.