Abstract: Disclosed is an apparatus and method for signal detection according to frequency bands used in an RFID system. The apparatus includes a low-noise amplifier for low-noise amplifying a received signal, a receiver unit for detecting a CW signal and a tag signal, a transmitter unit for frequency up-converting and outputting an input signal, a PLL for generating a frequency signal according to a transmission signal band or a reception signal band, a receiver unit switch for connecting the receiver unit with the low-noise amplifier or a directional coupler, an antennas switch for connecting the antenna with the directional coupler or low-noise amplifier, and a controller unit for controlling a frequency of the frequency signal generated by the PLL, turning off transmission power in a case of an LBT scheme, controlling the receiver unit switch and the antenna switch, and determining if a corresponding channel is an idle channel.

Abstract: An apparatus and method for adjusting a desired expression section according to input bit values in a mobile communication system that expresses only a defined partial section of the input bit values in order to make the number of output bits be less than the number of the input bits, and maps bit values included in unexpressed sections to a specific value is provided. In the apparatus and method, a measurer divides possible output bit values into at least three sections, and measures output frequencies of output bits for the respective sections for a predetermined time. A controller adjusts the desired expression section, when an output frequency for a specific section is greater than output frequencies for other sections.