1. A communication method, comprising:receiving, by a terminal device, on an unlicensed frequency band, downlink control information sent by a network device, wherein the downlink control information is within a first time unit in a candidate time unit set in a plurality of candidate time unit sets, wherein the candidate time unit set is at least one of a plurality of consecutive time units, and wherein candidate time unit sets of the plurality of candidate time unit sets are at an equal interval in the plurality of consecutive time units;
determining, by the terminal device according to a time at which the downlink control information is sent, a time window for sending uplink information;
sending, by the terminal device, the uplink information within the time window, wherein a start moment of the time window (T1) is within the first time unit or a second time unit immediately after the first time unit, and wherein an end moment of the downlink control information is T2; and
skipping receiving, by the terminal device, downlink user data within a time interval between T1 T2.