[ 8 ] One blocker moving ( Walking speed ) 20 dBi , 10 ˚ 1 . 1 m 0 . 75 m 67 GHz tD = 370 ms ~ 820 mstdecay = 230 ms ( mean ) , 92 ms ( s . d ) ( Threshold 20 dB ) trising = 220 ms ( mean ) , 100 ms ( s . d ) ( Threshold 20 dB )