Korea Advanced Institute of Science and Technology

Moo-Hong Lee

Hwang-Soo Lee

Byung-Jik Keum

Young-Serk Shim

Jeong-Han Jeong

There are provided an apparatus for synchronizing an OFDM signal using an open-loop frequency synchronization method, which can estimate and compensate for various types of frequency errors generated in a frequency modulation broadcasting/communication system to which the open-loop frequency synchronization method is applied, and a frequency offset estimation scheme using the apparatus. To this end, the apparatus for synchronizing an OFDM signal using the open-loop frequency synchronization method comprises a time offset estimator, a time offset compensator, a fractional frequency offset estimator, an integer frequency offset estimator, a frequency offset controller and a frequency offset compensator. Accordingly, in the OFDM demodulation broadcasting/communication system using the open-loop frequency synchronization method, a frequency offset, which is generated due to the carrier frequency difference between a transmitter and a receiver, a frequency shift generated due to the mobile environment of a receiver, the temperature characteristic of a local oscillator, and the like, can be estimated and compensated.

Apparatus for synchronizing OFDM signal using open-loop frequency synchronization method and frequency offset estimation scheme using the apparatus

Disclosed are an apparatus and a method for preventing data read error for OFDM symbol demodulation. An average time synchronization offset estimating unit estimates average time synchronization offset between a pilot symbol of a time synchronized data frame and pilot symbols of data frames next to the time synchronized data frame. A data buffer control unit acquires a start location of a data frame to be read using the estimated average time synchronization offset, and controls reading of written data frames using the acquired start location information of the data frame to be read. In the apparatus and the method, a data buffering using a ring buffer construction may compensate time synchronization offset of samples containing real data in an OFDM symbol and prevent an erroneous read error in order to improve a receiving performance of a receiver.

Apparatus and method for preventing data read error for orthogonal frequency division multiplexing symbol demodulation

There is provided an apparatus for receiving a T-DMB signal. The apparatus for receiving a T-DMB signal comprises an input buffer receiving and buffering a T-DMB signal comprising a null symbol and a phase reference symbol (PRS); an initial synchronizing unit estimating and compensating for time and frequency offsets of the T-DMB signal using the null symbol and the PRS; a frame tracking unit performing estimation of the time offset and measurement of a strength of an output signal from the input buffer; an OFDM signal demodulating unit performing I/Q demodulation, frequency compensation, OFDM demodulation and de-interleaving with respect to an output signal of the frame tracking unit; a channel decoding unit performing channel decoding with respect to an output signal of the OFDM signal demodulating unit and checking quality of the channel-decoded signal; and a controller controlling operations of the initial synchronizing unit, the OFDM signal demodulating unit and the channel decoding unitbased on the strength of the signal measured by the frame tracking unit and the quality of the signal checked by the channel decoding unit. Accordingly, unnecessary calculating processes arc reduced by measuring the strength and quality of an input signal, thereby maximizing power efficiency of the apparatus.

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Daejeon, South Korea

Moo-Hong Lee