A first node used for wireless communication, comprising: a first receiver set, configured to receive a first wireless signal in a first time-frequency resource pool, wherein the first wireless signal carries a first block of bits; and a first transmitter set, configured to send first signaling in a second time-frequency resource pool, wherein the first signaling is used to indicate whether the first block of bits is correctly decoded; the first receiver set is configured to monitor a second wireless signal in a third time-frequency resource pool, and the second wireless signal carries the first block of bits; when the first signaling indicates that the first block of bits is not correctly decoded, the first transmitter set sends second signaling in a fourth time-frequency resource pool by using a first power value; when the first signaling indicates that the first block of bits is correctly decoded and the second wireless signal is detected, the first transmitter set sends the second signaling in the fourth time-frequency resource pool by using a second power value; when the first signaling indicates that the first block of bits is correctly decoded and the second wireless signal is not detected, the first transmitter set maintains zero transmit power in the fourth time-frequency resource pool; and the second signaling is used to indicate whether the first block of bits is correctly decoded, wherein the second power value is greater than the first power value; wherein the second wireless signal is detected, and only when the fourth time-frequency resource pool is not reserved for a first type of transmission, the second signaling is sent by the first transmitter set in the fourth time-frequency resource pool, the second time-frequency resource pool is not reserved for the first type of transmission, and the first type of transmission comprises HARQ-ACK for first transmission of a transport block. a first receiver set, configured to receive a first wireless signal in a first time-frequency resource pool, wherein the first wireless signal carries a first block of bits; and a first transmitter set, configured to send first signaling in a second time-frequency resource pool, wherein the first signaling is used to indicate whether the first block of bits is correctly decoded; the first receiver set is configured to monitor a second wireless signal in a third time-frequency resource pool, and the second wireless signal carries the first block of bits; when the first signaling indicates that the first block of bits is not correctly decoded, the first transmitter set sends second signaling in a fourth time-frequency resource pool by using a first power value; when the first signaling indicates that the first block of bits is correctly decoded and the second wireless signal is detected, the first transmitter set sends the second signaling in the fourth time-frequency resource pool by using a second power value; when the first signaling indicates that the first block of bits is correctly decoded and the second wireless signal is not detected, the first transmitter set maintains zero transmit power in the fourth time-frequency resource pool; and the second signaling is used to indicate whether the first block of bits is correctly decoded, wherein the second power value is greater than the first power value; wherein the second wireless signal is detected, and only when the fourth time-frequency resource pool is not reserved for a first type of transmission, the second signaling is sent by the first transmitter set in the fourth time-frequency resource pool, the second time-frequency resource pool is not reserved for the first type of transmission, and the first type of transmission comprises HARQ-ACK for first transmission of a transport block.