A network comprising a first base station, BS, and a second BS, the network 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: the first BS connecting to a communication device (20, 100) via a primary cell, PCell, of the first BS with a first signalling radio bearer, SRB; the second BS as a secondary node, SN, connecting to the communication device (20, 100) via a primary secondary cell, PSCell, with a second SRB while the first BS as a master node, MN, connects to the communication device (20, 100) via the PCell with the first SRB; the second BS transmitting a radio resource control, RRC, message on the second SRB on the PSCell to the communication device (20, 100), wherein the RRC message configures a secondary cell, SCell, to the communication device (20, 100) for a carrier aggregation, CA, and comprises a random access, RA, channel, RACH, configuration for the communication device (20, 100) to perform a RA to the SCell, the RACH configuration configures at least one RACH resource and the RRC message configures an association configuration associating the at least one RACH resource to a synchronization signal block, SSB, or a channel state information reference signal, CSI-RS, transmitted on the SCell; the second BS receiving a RRC response 1 message for responding to the RRC message from the communication device (20, 100) on the second SRB on the PSCell; the second BS receiving a RA preamble transmitted by the communication device (20, 100) on the SCell according to the at least one RACH resource; and the second BS transmitting a RA response, RAR, to the communication device (20, 100) in response to the first RA preamble. 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: the first BS connecting to a communication device (20, 100) via a primary cell, PCell, of the first BS with a first signalling radio bearer, SRB; the second BS as a secondary node, SN, connecting to the communication device (20, 100) via a primary secondary cell, PSCell, with a second SRB while the first BS as a master node, MN, connects to the communication device (20, 100) via the PCell with the first SRB; the second BS transmitting a radio resource control, RRC, message on the second SRB on the PSCell to the communication device (20, 100), wherein the RRC message configures a secondary cell, SCell, to the communication device (20, 100) for a carrier aggregation, CA, and comprises a random access, RA, channel, RACH, configuration for the communication device (20, 100) to perform a RA to the SCell, the RACH configuration configures at least one RACH resource and the RRC message configures an association configuration associating the at least one RACH resource to a synchronization signal block, SSB, or a channel state information reference signal, CSI-RS, transmitted on the SCell; the second BS receiving a RRC response 1 message for responding to the RRC message from the communication device (20, 100) on the second SRB on the PSCell; the second BS receiving a RA preamble transmitted by the communication device (20, 100) on the SCell according to the at least one RACH resource; and the second BS transmitting a RA response, RAR, to the communication device (20, 100) in response to the first RA preamble. the first BS connecting to a communication device (20, 100) via a primary cell, PCell, of the first BS with a first signalling radio bearer, SRB; the second BS as a secondary node, SN, connecting to the communication device (20, 100) via a primary secondary cell, PSCell, with a second SRB while the first BS as a master node, MN, connects to the communication device (20, 100) via the PCell with the first SRB; the second BS transmitting a radio resource control, RRC, message on the second SRB on the PSCell to the communication device (20, 100), wherein the RRC message configures a secondary cell, SCell, to the communication device (20, 100) for a carrier aggregation, CA, and comprises a random access, RA, channel, RACH, configuration for the communication device (20, 100) to perform a RA to the SCell, the RACH configuration configures at least one RACH resource and the RRC message configures an association configuration associating the at least one RACH resource to a synchronization signal block, SSB, or a channel state information reference signal, CSI-RS, transmitted on the SCell; the second BS receiving a RRC response 1 message for responding to the RRC message from the communication device (20, 100) on the second SRB on the PSCell; the second BS receiving a RA preamble transmitted by the communication device (20, 100) on the SCell according to the at least one RACH resource; and the second BS transmitting a RA response, RAR, to the communication device (20, 100) in response to the first RA preamble.