US 6,633,616 B2
OFDM pilot tone tracking for wireless LANGeneral
US 6,633,616 B2
OFDM pilot tone tracking for wireless LAN
Tech Center:
2600 Communications
Examiner:
Young T. Tse
Art Unit:
2634 Digital and Optical Communications
Inventors:
James A. Crawford
Assignee:
Priority:
02/21/01
Filed:
08/21/01
Granted:
10/14/03
Expiration:
02/21/21
Abstract
A pilot phase tracking loop for an OFDM receiver including a phase rotator receiving an incoming signal, a fast Fourier transform coupled to a phase rotator output, and a pilot phase error metric including a discrete Fourier transform portion coupled to the phase rotator output. The pilot phase error metric determines a phase error estimate associated with a received OFDM symbol, e.g., a data symbol, from the phase rotator output. A loop filter is coupled to the pilot phase error metric output and an oscillator is coupled to the loop filter output. The oscillator output is coupled to the phase rotator to adjust the phase of subsequent OFDM symbols of the incoming signal. Phase noise introduced by a radio portion of the OFDM receiver and OFDM transmitter is reduced by the baseband portion of the OFDM receiver improving OFDM signal tracking under poor SNR conditions.
Cooperative Patent Classification (CPC)
H04H04L2027/0067H04L