Patent ID: 7746966

Claim:
An apparatus for automatic gain control (AGC) of a mobile station in an orthogonal frequency division multiplexing (OFDM) system, comprising; an initial synchronization inspector that determines whether an initial synchronization for an input block sample signal (k) has been performed; a frame divider that divides a frame into predetermined intervals B(k) for the input block sample (k) signal when the initial synchronization has not been performed; a reference value inspector that compares a difference value Pref−Pcalc, between a predetermined reference value Pref and sample data average energy Pcalc, with a predetermined value; a count controller that increases or decreases a count when the difference value Pref−Pcalc is greater or less than the predetermined value; a count inspector which inspects whether the count is greater or less than 0 when the input block sample (k) has reached a maximum value MAX; and a gain controller which increases or decreases the gain, level by level, according to the count inspection result of the count inspector.