A first base station, comprising: a memory, a transceiver and a processor, wherein the memory is configured to store an instruction, and the processor is configured to execute the instruction; the transceiver is configured to receive a first control instruction generated by a controller, wherein the first control instruction comprises an offloading policy and is used to instruct the first base station to offload a data stream, the offloading policy comprises information used to indicate that the data stream processed by a Packet Data Convergence Protocol, PDCP, module is offloaded and the data stream is processed by at least a PDCP module of the first base station and then is offloaded; the processor is specifically configured to: divide the data stream into at least two sub-data streams according to the offloading policy of the first control instruction, and continue to sequentially process communication data of one sub-data stream of the at least two sub-data streams by a Radio Link Control, RLC, module of the first base station according to an ordered set of processing actions of processing the communication data in a protocol stack according to the first control instruction; the transceiver is configured to separately send another sub-data stream of the at least two sub-data streams obtained by performing division by the processor to a second base station assisting the first base station in processing downlink data, so that a RLC module of the second base station continues to process the another sub-data stream; and the transceiver is further configured to send the sub-data stream processed by the processor to a user equipment. a memory, a transceiver and a processor, wherein the memory is configured to store an instruction, and the processor is configured to execute the instruction; the transceiver is configured to receive a first control instruction generated by a controller, wherein the first control instruction comprises an offloading policy and is used to instruct the first base station to offload a data stream, the offloading policy comprises information used to indicate that the data stream processed by a Packet Data Convergence Protocol, PDCP, module is offloaded and the data stream is processed by at least a PDCP module of the first base station and then is offloaded; the processor is specifically configured to: divide the data stream into at least two sub-data streams according to the offloading policy of the first control instruction, and continue to sequentially process communication data of one sub-data stream of the at least two sub-data streams by a Radio Link Control, RLC, module of the first base station according to an ordered set of processing actions of processing the communication data in a protocol stack according to the first control instruction; the transceiver is configured to separately send another sub-data stream of the at least two sub-data streams obtained by performing division by the processor to a second base station assisting the first base station in processing downlink data, so that a RLC module of the second base station continues to process the another sub-data stream; and the transceiver is further configured to send the sub-data stream processed by the processor to a user equipment. divide the data stream into at least two sub-data streams according to the offloading policy of the first control instruction, and continue to sequentially process communication data of one sub-data stream of the at least two sub-data streams by a Radio Link Control, RLC, module of the first base station according to an ordered set of processing actions of processing the communication data in a protocol stack according to the first control instruction; the transceiver is configured to separately send another sub-data stream of the at least two sub-data streams obtained by performing division by the processor to a second base station assisting the first base station in processing downlink data, so that a RLC module of the second base station continues to process the another sub-data stream; and the transceiver is further configured to send the sub-data stream processed by the processor to a user equipment.