Research On WLAN Sensing Scheduling Scheme For Mobile Scenarios

Adding sensing to WLAN has promising prospects.Without additional hardware,WLAN sensing can complete localization and moving speed measurement,human activity recognition,fall detection,and gesture recognition.WLAN sensing can be divided into two forms: radar and CSI(Channel State Information).WLAN sensing signal in radar mode can be measured by a single PPDU(Physical layer Protocol Data Unit)containing sensing signals,while WLAN sensing in CSI mode needs to compare the changes of CSI characteristics in multiple PPDUs.In order to get the absolute position of the target in the environment,it is necessary to locate the STA at the same time.However,if STA has mobility,frequent localization of STA will result in high signaling interaction overhead which will affect the sensing result.This thesis studies WLAN sensing scheduling scheme in single AP scenarios.This thesis introduces and analyzes the technology of FTM(Fine Timing Measurement)in IEEE802.11 az standard.FTM is a ranging process for active positioning,which can obtain the distance from one STA to another STA or AP.Therefore,this thesis proposes an active and passive fusion WLAN sensing scheme,which inserts the receiving and transmitting process of sensing signal into the FTM process,and designs the corresponding frames in the process,so that the position and speed information of STA can be obtained in real time in the process of WLAN sensing,so as to eliminate the impact of STA mobility.Simulation results show that the proposed scheme can effectively solve the problem of STA mobility in indoor scenarios,and can save more than a quarter of signaling interaction overhead on the basis of existing technology.In localization and other sensing applications,combining multiple STAs together for measurement can improve the accuracy of sensing results.Therefore,this thesis extends the STA mobility problem to multi-AP scenarios,and proposes a radar-based WLAN sening scheduling scheme and a CSI-based WLAN sensing scheduling scheme.In the two schemes,the active and passive localization are completed in the same process,and the localization results are be obtained based on the principle of multilateral localization.Multiple STAs carry out sensing measurement sequently under the scheduling of the main AP.In order to further solve the mobility problem of STA,the selection algorithm of sensing STA is given in the radar-based WLAN sening scheduling scheme.The algorithm excludes STA with excessive speed and makes selection based on the principle of maximizing sensing information,so as to achieve the best sensing effect.Different from radar-based scheme,the CSI-based WLAN sensing scheduling scheme ensures the periodicity of NDP(Null Data PPDU)transmission,which is highly beneficial to the processing of CSI data.Simulation results show that the CSIbased WLAN sensing scheduling scheme can meet the periodicity requirements of NDP in indoor scenarios in different working frequency bands.