A method for sending a signal by user equipment, 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 is used to indicate a magnitude of an interference signal within the system bandwidth; characterized by comparing (S103, S402), by the user equipment, the first interference strength with a first interference threshold; and if 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, wherein a sum of second interference strengths on the N first sub-bands is less than or equal to a sum of second interference strengths corresponding to any N sub-bands other than the N first sub-bands within the system bandwidth wherein the method further comprises: if the first interference strength is greater than the first interference threshold, determining (S201, S404), by the user equipment, whether transmission resource applying duration reaches preset maximum transmission resource applying duration; and if the transmission resource applying duration is greater than or equal to the maximum duration, selecting (S202, S405), by the user equipment, M 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 M first sub-bands, wherein M is a positive integer, wherein a sum of second interference strengths on the M first sub-bands is less than or equal to a sum of second interference strengths corresponding to any M sub-bands other than the M first sub-bands within the system bandwidth. 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 is used to indicate a magnitude of an interference signal within the system bandwidth; characterized by comparing (S103, S402), by the user equipment, the first interference strength with a first interference threshold; and if 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, wherein a sum of second interference strengths on the N first sub-bands is less than or equal to a sum of second interference strengths corresponding to any N sub-bands other than the N first sub-bands within the system bandwidth wherein the method further comprises: if the first interference strength is greater than the first interference threshold, determining (S201, S404), by the user equipment, whether transmission resource applying duration reaches preset maximum transmission resource applying duration; and if the transmission resource applying duration is greater than or equal to the maximum duration, selecting (S202, S405), by the user equipment, M 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 M first sub-bands, wherein M is a positive integer, wherein a sum of second interference strengths on the M first sub-bands is less than or equal to a sum of second interference strengths corresponding to any M sub-bands other than the M first sub-bands within the system bandwidth. if the first interference strength is greater than the first interference threshold, determining (S201, S404), by the user equipment, whether transmission resource applying duration reaches preset maximum transmission resource applying duration; and if the transmission resource applying duration is greater than or equal to the maximum duration, selecting (S202, S405), by the user equipment, M 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 M first sub-bands, wherein M is a positive integer, wherein a sum of second interference strengths on the M first sub-bands is less than or equal to a sum of second interference strengths corresponding to any M sub-bands other than the M first sub-bands within the system bandwidth.