1. A communication method on an unlicensed frequency band in a UE, the communication method comprising:Step A: receiving a high layer signaling; wherein the high layer signaling indicates that a first carrier is scheduled by a control signaling transmitted on a second serving cell; the high layer signaling indicates that the first carrier is scheduled by a control signaling transmitted on the first carrier or a first carrier is scheduled by a control signaling transmitted on the first carrier by default;
Step B: receiving a first control signaling on a first sub frame of the first carrier; receiving a first physical layer data on the first carrier according a schedule of the first control signal and transmitting a first ACK/NACK or transmitting a first physical layer data and receiving a first ACK/NACK; and
Step C: receiving a second control signaling on a second sub frame of the second serving cell; receiving a second physical layer data on the first carrier according to a schedule of the second control signaling and transmitting a second ACK/NACK or transmitting a second physical layer data and receiving a second ACK/NACK;
wherein the first carrier is deployed on an unlicensed spectrum, the second serving cell is deployed on a licensed spectrum, the first sub frame and the second sub frame are two different sub frames in a time domain, the first ACK/NACK indicates whether the first physical layer data is accurately received, and the second ACK/NACK indicates whether the second physical layer data is accurately received.