A signal transmission method and apparatus, a signal reception method and apparatus and a communication system. The signal transmission apparatus is provided in a network device and includes: a transmitting unit configured to transmit indication information indicating that one information block of at least one information block transmitted by the network device within a time interval is transmitted at one candidate resource in at least two candidate resources within the time interval. The transmission resources of the information blocks are indicated by the indication information, hence, even though the default correspondence between the information block indices and the transmission resources is to be changed, the transmission resources to which the information blocks correspond may be determined, and the terminal equipment is facilitated in downlink synchronization.