1. A wireless sensor network, comprising: a data processing module, outputting a sense command; and a data collection module, receiving the sense command outputted from the data processing module, and collecting a source data and returning to the data processing module, wherein: the data processing module finds a trend of the source data to establish a prediction model; the data processing module updates the sense command and sends the updated sense command to the data collection module based on the established prediction model; the data collection module determines whether data collection is performed or not at a sense time point according to the sense command; the data collection module collects the source data and returns to the data processing module if data collection is performed; the data processing module obtains a predicted data according to the previous source data if data collection is not performed; and the data processing module shifts the source data to obtain a shifted data, the data processing module compares a similarity between the source data and the shifted data to obtain a period of the source data; or the data processing module transforms the source data from a time domain into a frequency domain, filters out a low frequency component of the transformed source data, and takes an inverse of a high-frequency value of the transformed source data to obtain the period of the source data.