Disclosed are a transmitter and a receiver for providing multi-layered multimedia services, and a method thereof. The upper case of the battery pack is inserted, in use, into a battery pack receiving space formed in the grip portion of a power tool. The capacitive elements include at least one variable capacitive element such as a MOS capacitor, the capacitance of which is varied in accordance with a voltage applied thereto. The sensor assembly is held fast between the belt inner surface and the treadmill bed with a J bracket. The system may then determine statistical parameter of data in the statistical data collector, and add data including an indication of the respective number of sub-part iterations, a cost of finding the metric values for the respective solutions, and the statistical parameters of the trial to the parametric data collector. The highly doped GaAlN layer is then formed having electron densities beyond 1\xd71020 cm\u22123 at Al mole fractions up to 65% are obtained.