{"title":"On Phase Offsets of 802.11 ac Commodity WiFi","authors":"A. Zubow, P. Gawłowicz, F. Dressler","doi":"10.23919/WONS51326.2021.9415548","DOIUrl":"https://doi.org/10.23919/WONS51326.2021.9415548","url":null,"abstract":"We analyze the phase offsets between RF chains of modern IEEE 802.11ac chips. We investigate both the 2.4 and 5 GHz bands on a per OFDM subcarrier level. Results reveal that the phase offset between receive antennas is due to random phase rotations semi-time-invariant with up to four possible values. Moreover, it is frequency-dependent. We propose a simple algorithm, which allows us to correct the phase offset on the fly without any calibration. As proof-of-concept, we implemented angle of arrival (AoA) using MUSIC algorithm. To achieve higher accuracy we stitched the thirteen overlapping 20 MHz channels available in 2.4 GHz band together to effectively have a single 80 MHz channel. Results show very good AoA precision although only two receive antennas were used.","PeriodicalId":103530,"journal":{"name":"2021 16th Annual Conference on Wireless On-demand Network Systems and Services Conference (WONS)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125904051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}