Disclosed is an apparatus and method for supporting automatic repeat request in a high-speed wireless packet data communication system. The removable functional faceplate employs specially located electrical contacts or pads that mate with similarly located electrical contacts mounted on the portable computer system, e. In one embodiment, these measuring tracks are positioned concentric to each other in a semicircle. This reduces a region to record the control signal, thereby enabling high-density recording and reproduction, reproducing a control signal having a waveform free from distortion, and generating a clock signal in a state of little jitter.