9. A network for handling data transmission in an unlicensed band, comprising:a storage device; and
a processing circuit, coupled to the storage device, wherein the storage device stores, and the processing circuit is configured to execute instructions of:
transmitting an uplink (UL) grant in the unlicensed band to a communication device for indicating the communication device to transmit data in a first plurality of resource blocks of the unlicensed band; and
performing a hybrid automatic repeat request (HARQ) process corresponding to the data with the communication device, after receiving a preamble from the communication device in a second plurality of resource blocks of the unlicensed band, wherein the preamble indicates the transmission of the data;
wherein the preamble further indicates at least one of a channel quality of the unlicensed band and a traffic load of the unlicensed band.