Provided in the present invention are a device, system, and method for signal transmission and detection. A time unit used for transmission of a synchronous signal in each time window is determined via the device; the synchronous signal is transmitted on the determined time unit of each time window. This implements fixing of the synchronous signal onto the time unit at a fixed position in each time window, thus requiring a receiving-end device to detect only on the fixed time unit in each time window, and reducing the complexity in the design and detection of the synchronous signal.