A network device sends a first physical channel to user equipment on resources of one or more candidate physical channels. Correspondingly, the user equipment monitors one or more candidate physical channels in a candidate physical channel set, to receive the first physical channel on the resources of the one or more candidate physical channels. A payload of the first physical channel includes control information and a transport block, the control information includes first information, the first information is used to indicate an acknowledgment resource to the user equipment, and the acknowledgment resource is a resource used by the user equipment to send acknowledgment information to the network device. After receiving the first physical channel, the user equipment sends the acknowledgment information to the network device on the acknowledgment resource; and correspondingly, the network device receives the acknowledgment information on the acknowledgment resource.