First configuration information is configured for a second device by a first device. The first configuration information is used to indicate a first time-frequency resource allocated by the first device. The first time-frequency resource is different from a second time-frequency resource that is allocated by the first device to a third device in a same group. The first time-frequency resource comprises a third time-frequency resource and a fourth time-frequency resource. The third time-frequency resource is a time-frequency resource used when the first device receives a message sent by the second device. The fourth time-frequency resource is a time-frequency resource used when the first device sends a message to the second device. The third time-frequency resource is different from the fourth time-frequency resource. Control information that includes the first configuration information is sent by the first device.