1. A method, comprising:detecting, by a terminal device, downlink control information (DCI) on a first channel resource, wherein the first channel resource is located in an ith time unit of a subframe and is one of one or more candidate physical downlink control channel resources in the ith time unit, the subframe comprises NT time units, each of the NT time units comprising at least one candidate physical downlink control channel resource, wherein NT is an integer greater than or equal to 2, and i is a positive integer less than or equal to NT; and
decoding, by the terminal device, the DCI;
wherein the first channel resource consists of X resource units, and each of the X resource units of the first channel resource occupies 12 resource elements in one symbol in a time domain and 12 subcarriers in a frequency domain, wherein X is a positive integer;
when NT=2, two time units in the subframe are a first time unit and a second time unit, wherein the first time unit is located in a 1st slot of the subframe, and the second time unit is located in a 2nd slot of the subframe;
if the ith time unit is the first time unit, the first channel resource is a physical downlink control channel in a first control region located at Nsym1 symbols in the 1st slot; and
if the ith time unit is the second time unit, the first channel resource is a physical downlink control channel in a second control region, and the second control region is located at first Nsym2 symbols in the 2nd slot, wherein Nsym1 is any one of 1, 2, or 3, Nsym2 is any one of 1, 2 or 3.