Estimate distance measurement using NodeMCU ESP8266 based on RSSI technique

The use of WiFi is now a part of each human life. Airports, railways, bus-stand, home, markets everywhere now people uses WiFi because its reliability and low-cost. WiFi is also applicable in future tech of IoT (Internet of Things). In this work we used two NodeMCU (ESP8266 WiFi module) which is a easily programmable. NodeMCU which acts itself as a sensor node can be used as Access Point (AP) or as a STAtion (STA). We used one node as a AP and another as a STA. To locate a device distance measurement one of most important issue. There are lots of technique to find out the distance between two nodes (e.g. Time of Arrival (TOA), Time Difference of Arrival (TDOA) or Received Signal Strength (RSS) algorithms etc). In this work we use RSSI technique to determine the distance. First, we take around 300 sample data (RSSI values) and find the standard deviation to calculate how much the RSSI values are spread out and use curve fitting technique to find suitable equation for estimate distance. Then, we compared the estimated distance with actual distance to find the error level in percentage. We are success to reduce the average error level up to 8.32%.