| 摘要 |
PURPOSE: An apparatus and a method for determining an occupied state of a communication channel of a wireless LAN system are provided to determine easily the occupied state of the communication channel by adding a CCA generator to a modem including an energy detection circuit and an automatic gain control circuit. CONSTITUTION: A variable gain amplifier is used for amplifying received signals according to a controlled gain. A demodulator is used for demodulating the amplified signals as In-phase signals and Quadrature signals. An A/D converter is used for converting the demodulated signals to digital signals. An energy detector(24) is used for detecting the signals having the effective power from the digital signals. An automatic gain controller(25) is used for controlling the gain of the variable gain amplifier in order to add proper levels to the detected signals. A CCA generator(27) is used for comparing the output power of the detected signals with a threshold value and outputting a channel-occupied state signal. |
