The invention relates to the technical field of communication anti-jamming, in particular to a superposition coded modulation (SCM) technology communication system, subcarrier index modulation (SIM) and related time domain detecting technologies. According to an SCM method based on SIM-orthogonal frequency division multiplexing (OFDM), ideas of SIM-OFDM and spatial modulation (SM) are used as reference, a part of a string of bit data is used for transmission, the other part of the string of bit data is used as indexing bits, and the indexing bits are respectively coded. During transmission in an OFDM system, particular subcarrier is selected for transmitting data according to the bit data after coding of the indexing bits. A maximum likelihood method is used at a receiving end to obtain soft information of the indexing bits, and the indexing bits are decoded. Compared with prior SCM methods, the SCM method based on the SIM-OFDM has the advantages that the SCM superposition layers are reduced, the complexity is reduced, and error rate performances can be maintained or even improved to a certain degree. Meanwhile, the SCM is used for replacing quadrature amplitude modulation (QAM), and performances can be improved under the same transmission efficiency.