An image forming apparatus includes a controller, a database, an image carrier, a transfer unit, a fixing device including a temperature detector and a first drive device, a speed changer, and an electric-current detector. The compaction chamber having compaction surface oriented between and substantially perpendicular to compaction chamber sidewalls. 11a standard is modified to facilitate MIMO channel estimation. The apparatus according to an embodiment of the present invention has a master-client structure. The building automation device may also use radio frequency information for communicating with other devices.