Localization indoor

I can not do the indoor location between esp8266, I have a server and 4 clients, the server must locate it with trilateracion and give the location coordenads x, Y and with degrees to the client that is requested, but I can not do it someone has seen any forum about this or have information thank you guys

ESP8266 is a WiFi module, why you are using it to get the coordinates, for indoor you should try camera or IMU etc.