Briefly, in accordance with one or more embodiments, two or more cells are configured to perform coordinated multipoint transmission for one or more user equipment devices with a common media access control or a common radio resource control. The mobile power device with storage feature includes a battery, an output module, a central processing unit, and a data storing module. The device includes a maintenance device for temporarily maintaining the angular indexing of the encoder relative to the sensing element in an angular position, wherein the encoder generates in the sensing element a reference signal.