A communication apparatus of the present disclosure comprises a first receiver which, in operation, receives a downlink data frame from a base station; a decoder which, in operation, decodes data included in the received downlink data frame; a signal generator which, when the decoded data indicates that there is no buffered traffic for the communication apparatus, generates an uplink frame that includes acknowledgement information and a wake-up radio (WUR) mode request indicating a request to transit to the WUR mode from a primary connectivity radio (PCR) mode; and a transmitter which, in operation, transmits the uplink frame to the base station.