In this paper, a coordination protocol was proposed to
share unlicensed spectrum among LTE-U and WiFi coexistence systems. Decision tree learning and repeated game were
applied to the coordination protocol. The decision tree was
built for operators by learning the latest information about own
previous network status and the resource allocation decisions
from the opponent. As operators did not know the network
status of each other, operators could deduce the opponent’s
network status according to the decision tree. So operators
could make accepted decisions about sharing spectrum to maximize spectrum utilization. In order to guarantee the timeliness
of decision tree, the data set was updated and the decision tree