Disclosed is a method of fabricating a semiconductor device, comprising: providing a bare semiconductor substrate, the substrate having a frontside and a backside; forming one or more protective films on the backside of the substrate; and performing one or more wafer fabrication steps. The fuel cell stack is adapted to provide heat to the steam generator and the steam generator is adapted to provide steam to the water purification unit. The reestablishment request includes a temporary identity assigned by the target AP for the UE.