Example signal sending methods and apparatus are described. One example method includes receiving a media access control (MAC) control element (CE) from a terminal device. The MAC CE indicates a power headroom in a first power headroom set or a power headroom in a second power headroom set. If the MAC CE indicates the power headroom in the first power headroom set, the power headroom in the first power headroom set is determined based on a second bit field comprised in the MAC CE, where the MAC CE includes a first bit field and the second bit field, and the first bit field is a reserved bit field. If the MAC CE indicates the power headroom in the second power headroom set, the power headroom in the second power headroom set is determined based on a third bit field comprised in the MAC CE, where the third bit field includes a bit of the first bit field and a bit of the second bit field.