The present invention provides a signal sending apparatus, a signal detection apparatus, a signal sending and detection system, a signal sending method, and a signal detection method. The apparatus determines a time unit that is in each time window and that is used to transmit a synchronization signal, and transmits the synchronization signal in the determined time unit in each time window. Therefore, a synchronization signal is always located in a time unit that has a fixed location in each time window, so that a device at a receive end needs to perform detection only in a fixed time unit in each time window, thereby reducing complexity of designing and detecting the synchronization signal.