Tripping in Basketball

[GFS-1]

Team A Point Guard is dribbling down court on a fast break. Team B defender
is running up behind him and trips him. 2 questions here, First what foul do you
have kicking, blocking, make up your own? Second what signal is used again
kicking, blocking, make up your own? I saw this happen in the Varsity Game and
nothing was called. Was nothing called because we down have a signal or the
defense never gained a advantage because Team A recovered the loose ball.
What would be your call and signal.

Thanks for your time
Third year Referee