下一代WLAN分组目标唤醒时间调度改进方案

密集WLAN(Wireless Local Area Network,无线局域网)中,大规模站点同时接入信道引起激烈竞争,从而导致网络性能急剧下滑.IEEE工作组着手研发下一代WLAN标准IEEE 802.11ax,该标准结合基于正交频分复用多址技术提出了上行多用户随机接入和广播目标唤醒时间(Target Wake Time,TWT)机制.为降低碰撞和减轻干扰,进一步提高吞吐率和能效,本文结合广播TWT机制提出了一种基于网络密度的改进分组信道接入方案.该方案在原有广播TWT调度方法的基础上,依据网络密度选择不同的休眠决策策略;通过将站点分配在不同TWT服务期来控制同时服务站点数并确定站点分组,在TWT服务期内达到最大化吞吐率的目标,实现高效的信道接入.仿真结果分析表明所提策略具有更高的吞吐率和能效.

Improved Target Wake Time Scheduling Scheme with Grouping for Next Generation WLANs

In a dense Wireless Local Area Networks(WLANs),a large scale of stations may access the limited channels simultaneously,which leads to a severe deterioration on the overall performance because of collision.Hence,the IEEE task group named ax was established to develop a new amendment of IEEE 802.11 standard,i.e.IEEE 802.11ax,for dense scenarios.The new amendment introduced the orthogonal frequency division multiplexing multiple(OFDMA) technology,OFDMA based random access,and the broadcast target wake time(TWT) mechanism to improve the performance.We propose an improved TWT schedulingscheme(ITSS) to further improve the overall throughput and energy efficiency by leveraging the new capability of multi-user transmission.The ITSS,which is adaptive to network density,utilizes the respective advantages of different listen interval scheduling strategies.Besides,aiming at maximizing the overall throughput during the following TWT service period with effective random access,the ITSS allocates the stations into different TWT service period so as to control the maximum number of simultaneously active stations.Simulation results show that the proposed scheme achieves higher throughput and better energy efficiency.