Multiplex communications – Communication over free space – Combining or distributing information via time channels
Reexamination Certificate
2006-04-11
2006-04-11
Ngo, Ricky (Department: 2663)
Multiplex communications
Communication over free space
Combining or distributing information via time channels
C370S503000, C375S260000, C375S316000
Reexamination Certificate
active
07027429
ABSTRACT:
A method and apparatus for joint time and frequency synchronization for orthogonal frequency division multiplexing (OFDM) systems. A multitone pilot signal is sent in a designated OFDM symbol period. The receiver synchronizes to the pilot signal in a two-stage procedure. The first stage estimates the frequency offset coarsely with a frequency-domain correlation method and estimates the time offset with smoothed time-domain correlation. In a multipath channel, the smoothed time offset estimate is used to locate a cyclic prefix interval which captures the maximum total signal energy. The second stage improves the frequency estimate with a computationally efficient numerical optimization method.
REFERENCES:
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patent: 6021110 (2000-02-01), McGibney
patent: 6487252 (2002-11-01), Kleider et al.
patent: 6654429 (2003-11-01), Li
Laroia Rajiv
Li Junyi
Rangan Sundeep
Sampath Hemanth T.
Chang Richard
Flarion Technologies, Inc.
Ngo Ricky
Straub Michael P.
Straub & Pokotylo
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