Where a follow-up playback is realized for content data that is recorded by changing an encryption key at predetermined intervals for copyright protection, fast feed and playback operations are provided that can get close to a video scene of a present point of time. The dry etch process involves placing a substrate to be cleaned into a processing chamber to remove surface oxides. The information becomes readable when heat is applied to the thermochromatic ink and the optical properties of the thermochromatic ink are altered. A TDD offset is calculated based on the TDD configuration difference and an uplink-downlink traffic model of the wireless device.