“…TOA ranging positioning need to measure the signal arrival time, because the synchronization error has a great influence to the measurement of the distance, so to achieve high positioning accuracy, must be between monitoring targets and monitoring equipment to ensure the strict clock synchronization, however the request this largely increased the complexity of the equipment on the implementation. Despite the RSSI positioning conforms to the requirement of low power, low cost, RSSI positioning in practice, however, because of multipath spread and non-line of sight makes signal propagation model is complex, such as the change of the external environment has a great instability, often cause the RSSI is positioning result there is a big error [13][14][15]. To avoid the complexity of TOA synchronous equipment, find better positioning precision positioning technology at the same time, people is proposed based on TDOA positioning mechanism, it only requires monitoring equipment can meet the clock accurate synchronization between conditions, which greatly reduced the complexity of the equipment, at the same time TDOA technology does not need to know to receive transmission time between the signal from transmitter to receiver, but by the time delay estimation algorithm for time delay value.…”