Patent ID: 7349462

Claim:
A method for adjusting gain setting, receiver clock frequency, and symbol timing in an OFDM radio receiver, the method comprising the steps of: (i) receiving a symbol sequence ({x n }) of data samples (x n ), the symbol sequence ({x n }) comprising a preamble and user data, and the preamble comprising a first signal with a first periodicity (P 1 ) based on a repetitive transmission of a first training symbol and a second signal with a second periodicity (P 2 ) based on a repetitive transmission of a second training symbol; (ii) storing the data samples (x n ) in a register ( 12 ); (iii) deriving a signal energy estimate (E n ) from the stored data samples (x n ) for correcting the gain setting; (iv) deriving a first periodicity metric (m n P 1 ) and a second periodicity metric (m n P 2 ) from the stored data samples (x n ) for detecting the presence of the first signal with the first periodicity (P 1 ) and the presence of the second signal with the second periodicity (P 2 ); (v) deriving a first phase rotation (Ø n P 1 ) between the stored data samples (x n ) of the first signal spaced one first period (P 1 ) apart and a second phase rotation (Ø n P 2 ) between the received data samples (x n ) of the second signal spaced one second period (P 2 ) apart for determining the frequency offset between transmit and receive clock; (vi) detecting the reception of first training symbols, second training symbols, and the end of the second signal with the second periodicity (P 2 ) by using correlators; and (vii) responsive to the derivations (iv, v) and detections (vi), adjusting the gain setting, receiver clock frequency, and symbol timing under use of a finite-state-machine ( 50 ).