Multiplex communications – Generalized orthogonal or special mathematical techniques
Reexamination Certificate
2007-05-29
2007-05-29
Phunkulh, Bob A. (Department: 2616)
Multiplex communications
Generalized orthogonal or special mathematical techniques
C370S338000, C370S210000
Reexamination Certificate
active
10145163
ABSTRACT:
A method for estimating carrier frequency offset (CFO) and sampling frequency offset (SFO) in an Orthogonal Frequency Division Multiplexing (OFDM) system having a plurality of pilot tones. The absolute phase angle for each pilot tone is measured, and estimates of the CFO and the SFO are derived using a weighted least-squares methodology. More particularly, the phase of each pilot tone is measured for a number (n) of symbol times; for each of the pilot tones, the slope of a phase angle change from symbol time to symbol time is estimated using a best least-squares fit of the measured phases to a straight line; and a weighted least-squares best-fit straight line is determined to find an estimated phase angle differential value (α(i)) for each pilot tone; wherein a slope of the best-fit straight line yields an estimate of the SFO, and an intercept with the best-fit straight line yields an estimate of the CFO. The plurality of pilot tones may have frequencies which are symmetrically disposed about a reference frequency, and there may be four pilot tones. The OFDM communications system is suitably a wireless LAN (WLAN) implementing a standard such as IEEE 802.11a or HiperLAN/2. Corresponding apparatus is also described.
REFERENCES:
patent: 5228062 (1993-07-01), Bingham
patent: 5363103 (1994-11-01), Inkol
patent: 5732113 (1998-03-01), Schmidl et al.
patent: 6549561 (2003-04-01), Crawford
patent: 6549583 (2003-04-01), Crawford
patent: 6930995 (2005-08-01), Heinonen et al.
patent: 6940933 (2005-09-01), Heinonen et al.
patent: 2002/0065047 (2002-05-01), Moose
patent: 2003/0016169 (2003-01-01), Jandrell
patent: 2003/0072397 (2003-04-01), Kim et al.
patent: 2334836 (1999-01-01), None
patent: 9519671 (1995-07-01), None
patent: 9741672 (1997-11-01), None
patent: 9819410 (1998-05-01), None
Zaman et al; Multitone Synchronization for Fading Channels; 1994 IEEE; pp. 946-949.
Gummadi Srikanth
Murphy Peter A.
Williams Richard G. C.
Brady W. James
Phunkulh Bob A.
Shaw Steven A.
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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