WI-FI INDOOR POSITIONING USING MICROCONTROLLERS

Abstract

Indoor Wi-Fi Positioning Systems (WPS) are used in many areas of the economy to monitor the location of people and assets. The paper provides an overview of the methods that are used in modern commercial positioning systems. Based on the analysis, it was concluded that most WPS use received signal strength measurement (RSSI) to find out the location of observation objects. The main advantage of this method is the use of an existing Wi-Fi network with no additional equipment. However, further analysis of positioning algorithms based on RSSI shows that all of them impose additional requirements on the existing Wi-Fi network infrastructure to ensure accuracy sufficient for practical tasks. And these requirements impose significant additional costs for infrastructure modernization. An approach is proposed for building a WPS based on the use of IoT modules as Wi-Fi network listening devices that operate in the mode of continuous monitoring of its channels. This approach allows to reduce additional costs for the positioning system due to the absence of additional requirements for the existing network infrastructure and its equipment. The paper describes the architecture of the positioning system prototype based on a microcontrollers. The ESP8266 Wi-Fi module, Arduino Uno microcontroller and ENC28J60 Ethernet module were chosen to build a prototype system. The ESP8266 module tapes Wi-Fi client packets and parses them. After parsing a packet, a json file is created with structured data that contains the RSSI values, the AP MAC address, the sender MAC address and the timestamp. Next, the data is transmitted via the serial port to the Arduino microcontroller, which sends it to the server using the ENC28J60 module. To determine the location of observation objects, the method for building a radio map of the room and the method of K nearest neighbors (KNN) were chosen. The functions of the server include collecting, processing and storing data from microcontrollers, processing operator requests, building a radio map, positioning objects and displaying them on the floor plan. Experiments carried out on a prototype positioning system showed that the proposed approach provides location capabilities similar to systems based on access points.