1. A method, comprising:determining, by user equipment, a channel detection cycle;
obtaining, by the user equipment within the channel detection cycle, a first interference strength within system bandwidth, and obtaining a second interference strength on each sub-band within the system bandwidth, wherein the first interference strength indicates a magnitude of an interference signal within the system bandwidth;
comparing, by the user equipment, the first interference strength with a first interference threshold; and
when the first interference strength is less than or equal to the first interference threshold, selecting, by the user equipment, N first sub-bands from the system bandwidth according to the second interference strength on each sub-band within the system bandwidth, and sending a signal on frequency resources corresponding to the N first sub-bands, wherein N is a positive integer, and wherein a first sum of second interference strengths on the N first sub-bands is less than or equal to a second sum of second interference strengths on any N sub-bands other than the N first sub-bands within the system bandwidth.