Multiplex communications – Generalized orthogonal or special mathematical techniques – Particular set of orthogonal functions
Reexamination Certificate
2007-05-08
2007-05-08
Le, Danh (Department: 2617)
Multiplex communications
Generalized orthogonal or special mathematical techniques
Particular set of orthogonal functions
C370S335000, C370S342000, C375S308000, C375S355000
Reexamination Certificate
active
10434002
ABSTRACT:
A method of determining a training signal so as to facilitate acquisition of symbol sync, frequency offset estimation, and channel estimation in an orthogonal frequency division multiplexing (OFDM) system, and an apparatus and method for receiving a baseband OFDM signal using the training signal are provided. The method of determining the training signal, which is transmitted from an OFDM transmitter to an OFDM receiver using N subcarriers in order to allow the OFDM receiver to perform symbol synchronization, frequency synchronization, and channel estimation in the OFDM system, includes determining a first training symbol by setting odd-numbered subcarriers to 0 in a frequency domain, obtaining even-numbered subcarriers using M-ary phase-shift keying (M-PSK), and performing differential modulation so that a change in the phase difference between remote two subcarriers is constant; and determining a second training symbol by setting even-numbered subcarriers to 0 in the frequency domain, obtaining odd-numbered subcarriers using M-PSK, and performing differential modulation so that a change in the phase difference between remote two subcarriers is constant. By performing all of symbol timing recovery, frequency offset estimation, and channel estimation using the training signal determined as described above, time taken for frequency offset estimation can be reduced, hardware complexity can be decreased, a frequency acquisition range can be expanded up to ½ of the entire bandwidth, and influence of a multi-path channel can be counterbalanced.
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Choi Jang-Jin
Seo Bo-Seok
Cantor & Colburn LLP
Dizipia Inc.
Le Danh
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