User equipment, wherein the user equipment comprises: a receiving module, configured to receive initial beam index information sent by a base station, wherein the initial beam index information is used to indicate an initial beam, allocated by the base station for the user equipment, of a millimeter wave band; and a sending module, configured to send a radio resource management RRM measurement report, wherein the RRM measurement report is obtained after the user equipment performs RRM measurement on the initial beam that is indicated by the initial beam index information, and the RRM measurement report is used to instruct the base station to determine the initial beam index information that is used for communication with the user equipment, characterized in that the receiving module is further configured to receive alternative beam index information sent by the base station, wherein the alternative beam index information is used to indicate an alternative beam, allocated by the base station for the user equipment, of a millimeter wave band; and further characterized by a measurement module, configured to: when reference signal information of the initial beam is less than a second threshold, perform RRM measurement on an alternative beam indicated by each piece of alternative beam index information, wherein the reference signal information comprises at least one of RSRP or RSRQ; and a determining module, configured to determine, according to the RRM measurement performed by the measurement module, first alternative beam index information of which reference signal information is greater than a third threshold; and the sending module is further configured to send the first alternative beam index information determined by the determining module to the base station, in order to enable the base station to communicate with the user equipment according to an alternative beam corresponding to the first alternative beam index information. a receiving module, configured to receive initial beam index information sent by a base station, wherein the initial beam index information is used to indicate an initial beam, allocated by the base station for the user equipment, of a millimeter wave band; and a sending module, configured to send a radio resource management RRM measurement report, wherein the RRM measurement report is obtained after the user equipment performs RRM measurement on the initial beam that is indicated by the initial beam index information, and the RRM measurement report is used to instruct the base station to determine the initial beam index information that is used for communication with the user equipment, characterized in that the receiving module is further configured to receive alternative beam index information sent by the base station, wherein the alternative beam index information is used to indicate an alternative beam, allocated by the base station for the user equipment, of a millimeter wave band; and further characterized by a measurement module, configured to: when reference signal information of the initial beam is less than a second threshold, perform RRM measurement on an alternative beam indicated by each piece of alternative beam index information, wherein the reference signal information comprises at least one of RSRP or RSRQ; and a determining module, configured to determine, according to the RRM measurement performed by the measurement module, first alternative beam index information of which reference signal information is greater than a third threshold; and the sending module is further configured to send the first alternative beam index information determined by the determining module to the base station, in order to enable the base station to communicate with the user equipment according to an alternative beam corresponding to the first alternative beam index information.