The present disclosure relates to a terminal device, in which a sending module sends, in a first uplink subframe on a first carrier, an uplink reference signal to a network device, where the first carrier is a carrier on which the terminal device sends neither uplink data nor uplink control information in uplink; and a processing module determines a first power headroom PHR, where the first PHR is a PHR of a transmit power of the terminal device in the first uplink subframe or a PHR of a transmit power of the terminal device in the first uplink subframe on the first carrier. Special carriers are introduced, and uplink reference signals are sent on the special carriers, so that information, such as downlink channel characteristics, of these special carriers can be obtained by the network device.