A data transmission method by a network side device, comprising: the network side device uses multiple narrow high-frequency analog beams; determining, S transmission subbands for a user equipment, UE, wherein the S transmission subbands do not overlap each other, and S is an integer greater than or equal to 2; separately sending, a set of reference signals on the S transmission subbands, so that the UE selects at least two transmission subbands from M transmission subbands in the S transmission subbands based on channel quality measurements on the M transmission subbands, and separately accesses the at least two transmission subbands, wherein M is an integer greater than or equal to 2 and less than or equal to S; and receiving a report on the at least two selected subbands from the UE; and separately sending a data channel signal to the UE on the at least two transmission subbands; and wherein after the separately sending a set of reference signals on the S transmission subbands, the method further comprises: simultaneously sending at least one set of signals, comprising at least one signal of: the set of reference signals, a synchronization signal, a broadcast channel, BCH signal, or a control channel signal on a common transmission subband, and the common transmission subband is one of the at least two transmission subbands; wherein the simultaneously sending the at least one set of signals uses at least one different analog beam of the multiple analogue beams. the network side device uses multiple narrow high-frequency analog beams; determining, S transmission subbands for a user equipment, UE, wherein the S transmission subbands do not overlap each other, and S is an integer greater than or equal to 2; separately sending, a set of reference signals on the S transmission subbands, so that the UE selects at least two transmission subbands from M transmission subbands in the S transmission subbands based on channel quality measurements on the M transmission subbands, and separately accesses the at least two transmission subbands, wherein M is an integer greater than or equal to 2 and less than or equal to S; and receiving a report on the at least two selected subbands from the UE; and separately sending a data channel signal to the UE on the at least two transmission subbands; and wherein after the separately sending a set of reference signals on the S transmission subbands, the method further comprises: simultaneously sending at least one set of signals, comprising at least one signal of: the set of reference signals, a synchronization signal, a broadcast channel, BCH signal, or a control channel signal on a common transmission subband, and the common transmission subband is one of the at least two transmission subbands; wherein the simultaneously sending the at least one set of signals uses at least one different analog beam of the multiple analogue beams. simultaneously sending at least one set of signals, comprising at least one signal of: the set of reference signals, a synchronization signal, a broadcast channel, BCH signal, or a control channel signal on a common transmission subband, and the common transmission subband is one of the at least two transmission subbands; wherein the simultaneously sending the at least one set of signals uses at least one different analog beam of the multiple analogue beams.