A technique for generating a single carrier frequency division multiple access signal is described, in which from a set of M input symbols a set of N output symbols is generated. When a user selects a piece of particular audio reproduction control information from the pieces of audio reproduction control information after the packed data is read out, levels of pieces of audio data of the digital audio signal are adjusted according to the particular audio reproduction control information, so that the user can entertain the music at a desired sound quality. The client device receives a first reply message from the server, wherein the first reply message indicates a time period. One or more organic layers may be interposed between the first electrode and the second electrode and include at least an emission layer.