It's probably gradient descent based inversion. You take measurements of the signal in the room with no people in it as your baseline, then introduce 1 person and observe the difference in signal responses and build a 3D forward model which accurately reconstructs the observed data due to the pertabation of the signal by the human.
PM_ME_NUNUDES t1_j5v40mo wrote
Reply to comment by [deleted] in WiFi Routers Used to Produce 3D Images of Humans by iboughtarock
It's probably gradient descent based inversion. You take measurements of the signal in the room with no people in it as your baseline, then introduce 1 person and observe the difference in signal responses and build a 3D forward model which accurately reconstructs the observed data due to the pertabation of the signal by the human.