Before revision:  Aiming to handle the incompleteness problem as well as estimate travel speed accurately, in this paper, we propose an approach named STC in which spatial-temporal correlation among travel speeds of roads is leveraged. More specifically, in STC, we use cross correlation function to quantize the correlation among roads.
After revision:  Aiming to handle the incompleteness problem as well as estimate travel speed accurately, in this paper, we propose an approach named STC in which spatial-temporal correlation among travel speeds for roads by introducing the time-lagged cross correlation function to quantize the correlation among roads.