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Aiming at the problem that the standard RAW mechanism cannot adjust to changes in the network and the grouping depends on continuous AIDs,a RAW regrouping method based on a pseudo-random sequence was proposed.The AP assigned a pseudo-random sequence to the node as the address code during the association phase,and used compound code to carry groups information during the grouping phase.It implemented online regrouping of discontinuous AID nodes and reduced the overhead of regrouping.In order to rationally allocate resources in RAW and solve the problem of load imbalance between groups,a RAW regrouping method based on expected channel time was proposed.Based on channel utilization,the RAW groups,RAW duration,and numbers of RAW were optimized.NS3 simulation results show that the proposed method significantly improves the performance of IEEE 802.11ah protocol networks.

In view of need of safety monitoring wireless sensor network in special communication environment of underground coal mine and limitation of access device number and transmission distance of existing safety monitoring wireless sensor network, IEEE 802.11ah was applied to underground safety monitoring wireless sensor network, and NS-3 simulation platform was used to analyze its performances, such as transmission distance, throughput, delay, energy consumption.The analysis results show that the transmission distance of IEEE 802.11ah is much longer than that of traditional WiFi communication technology,and the packet loss rate of IEEE 802.11ah is still 0 when the transmission distance is 600 m. When the number of nodes is small and the network is not saturated, and the channel competition and collision of nodes are not serious, the performance advantages of IEEE 802.11ah in terms of throughput, time delay and energy consumption are not obvious. However,when the number of access nodes is large, IEEE 802.11ah can well guarantee the performances of throughput, time delay, energy consumption. As the number of access nodes increases after network saturated, performance of the traditional WiFi communication technology network continues to drop sharply, performance of IEEE 802.11ah declines less and becomes gradually stable. In addition, performance of IEEE 802.11ah network uplink data transmission is related to selection of restricted access window parameters, accurate selection of restricted access window parameters can better exploit performance advantages of underground safety monitoring wireless sensor network based on IEEE 802.11ah.

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Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)