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Station Grouping Method for Non-uniform Station Distribution in IEEE 802.11ah based IoT Networks

IEEE802.11ah introduces the restricted access window (RAW) mechanism to mitigate intense channel access contentions in IoT networks with a huge number of connected devices. In this mechanism, the wireless station (STA) grouping method has a significant impact on the network performance, and therefore several methods have been proposed for the STA grouping. Although the existing methods target the networks with geographical uniform STA distribution, the STAs may be deployed non-uniformly in real environments. Consequently, the conventional methods do not always provide better performance under the network with the non-uniform STA distribution. This paper proposes a twolevel STA grouping method to improve the network performance even under the such conditions of STA distribution. The evaluation through computer simulation shows that the proposed method improves the network throughput and the fairness in user throughput among STAs, compared with the conventional methods.