A base station, BS, for handling bandwidth parts, BWPs, comprising: at least one storage device; and at least one processing circuit, coupled to the at least one storage device, wherein the at least one storage device stores, and the at least one processing circuit is configured to execute instructions of: communicating with a communication device via a first downlink, DL, BWP and a first uplink, UL, BWP in a first cell belonging to the BS; transmitting a radio resource control, RRC, message in the first DL BWP to the communication device, wherein the RRC message configures at least one of a second DL BWP and a second UL BWP in the first cell to the communication device and does not configure any configuration for a random access, RA; receiving a RRC response message responding to the RRC message from the communication device in the first UL BWP or in the second UL BWP; and communicating with the communication device via the at least one of the second DL BWP and the second UL BWP, wherein the instructions further comprise: receiving a first indication from the communication device in the first UL BWP or in the second UL BWP, wherein the first indication indicates a first synchronization signal block, SSB, or a first channel state information reference signal, CSI-RS, received by the communication device in the second DL BWP; and transmitting data to the communication device in the second DL BWP on a first transmit, Tx, beam associated to the first SSB or the first CSI-RS. at least one storage device; and at least one processing circuit, coupled to the at least one storage device, wherein the at least one storage device stores, and the at least one processing circuit is configured to execute instructions of: communicating with a communication device via a first downlink, DL, BWP and a first uplink, UL, BWP in a first cell belonging to the BS; transmitting a radio resource control, RRC, message in the first DL BWP to the communication device, wherein the RRC message configures at least one of a second DL BWP and a second UL BWP in the first cell to the communication device and does not configure any configuration for a random access, RA; receiving a RRC response message responding to the RRC message from the communication device in the first UL BWP or in the second UL BWP; and communicating with the communication device via the at least one of the second DL BWP and the second UL BWP, wherein the instructions further comprise: receiving a first indication from the communication device in the first UL BWP or in the second UL BWP, wherein the first indication indicates a first synchronization signal block, SSB, or a first channel state information reference signal, CSI-RS, received by the communication device in the second DL BWP; and transmitting data to the communication device in the second DL BWP on a first transmit, Tx, beam associated to the first SSB or the first CSI-RS. communicating with a communication device via a first downlink, DL, BWP and a first uplink, UL, BWP in a first cell belonging to the BS; transmitting a radio resource control, RRC, message in the first DL BWP to the communication device, wherein the RRC message configures at least one of a second DL BWP and a second UL BWP in the first cell to the communication device and does not configure any configuration for a random access, RA; receiving a RRC response message responding to the RRC message from the communication device in the first UL BWP or in the second UL BWP; and communicating with the communication device via the at least one of the second DL BWP and the second UL BWP, wherein the instructions further comprise: receiving a first indication from the communication device in the first UL BWP or in the second UL BWP, wherein the first indication indicates a first synchronization signal block, SSB, or a first channel state information reference signal, CSI-RS, received by the communication device in the second DL BWP; and transmitting data to the communication device in the second DL BWP on a first transmit, Tx, beam associated to the first SSB or the first CSI-RS. receiving a first indication from the communication device in the first UL BWP or in the second UL BWP, wherein the first indication indicates a first synchronization signal block, SSB, or a first channel state information reference signal, CSI-RS, received by the communication device in the second DL BWP; and transmitting data to the communication device in the second DL BWP on a first transmit, Tx, beam associated to the first SSB or the first CSI-RS.