US 11,057,121 B2
Determining a propagation condition of a wireless channel
Huaiyi Wang, North Royalton, OH (US); and Zhigang Gao, Twinsburg, OH (US)
Assigned to CISCO TECHNOLOGY, INC., San Jose, CA (US)
Filed by Cisco Technology, Inc., San Jose, CA (US)
Filed on Sep. 9, 2019, as Appl. No. 16/564,984.
Prior Publication US 2021/0075523 A1, Mar. 11, 2021
Int. Cl. H04B 17/12 (2015.01); H04W 64/00 (2009.01); H04L 5/00 (2006.01); H04W 24/02 (2009.01); H04B 17/391 (2015.01)
CPC H04B 17/12 (2015.01) [H04L 5/0007 (2013.01); H04W 24/02 (2013.01); H04W 64/006 (2013.01); H04B 17/3911 (2015.01)] 20 Claims
OG exemplary drawing
 
1. A network node, operable to:
obtain one or more packets that have been received over a wireless channel via a first antenna, wherein each packet comprises a plurality of time-frequency resources, each time-frequency resource corresponding to one of a plurality of orthogonal frequency division multiplexing (OFDM) symbols in a time domain and one of a plurality of subcarriers in a frequency domain;
obtain raw data from the one or more packets, the raw data comprising a plurality of raw amplitude values and a plurality of raw phase values, each raw amplitude value and each raw phase value corresponding to a respective time-frequency resource;
process the raw data according to an interference mitigation process that yields a plurality of calibrated amplitude values and a plurality of calibrated phase values;
use the plurality of calibrated amplitude values and the plurality of calibrated phase values to determine a plurality of weighted phase values, each weighted phase value corresponding to a respective subcarrier;
determine a phase variance for the first antenna, the phase variance based on comparing the plurality of weighted phase values across the plurality of subcarriers; and
determine whether the wireless channel experiences line-of-sight propagation or non-line-of-sight propagation based at least in part on the phase variance of the first antenna.