In this paper, the authors describe the basic idea about the different methods of data collection in WSN. The freshness of data is maintained as the process of data collection is as much faster as possible. Many existing techniques have ability to cope with the issues like energy consumption, packet collision, retransmission, delay etc. For quick data collection, schemes are required to be scheduled in effective manner. One of the good techniques is TDMA. It is a type of MAC in contention-free medium, allocating the time slots to links or nodes.