A home system includes a server having a first wireless communication port and a first non-wireless communication port. One or more fobs include a second wireless communication port adapted to communicate with the first wireless communication port of the server. One or more sensor nodes or device nodes...http://www.google.de/patents/US7869392?utm_source=gb-gplus-sharePatent US7869392 - Home system and method of determining if a fob is in range or out of range of wireless communication with a server
