Abstract: Disclosed are an apparatus and a method for estimating a channel in a base station when using a Partial Usage of Sub-Channels (PUSC) mode in an uplink channel of the communication system supporting Orthogonal Frequency Division Multiplexing/Orthogonal Frequency Division Multiple Access (OFDM/OFDMA). For this, the channel estimation apparatus used in the communication system supporting the OFDM/OFDMA comprises a phase estimation/compensation unit estimating and compensating phase change of a channel by using pilots included in signals input by sub-channel; and a channel estimation unit estimating the channel by averaging the pilots of the signals of which the phase is compensated.

Abstract: Disclosed are an apparatus and a method for estimating a channel in a base station when using an Optional Partial Usage of Sub-Channels (OPUSC) mode in an uplink channel of a communication system supporting Orthogonal Frequency Division Multiplexing/Orthogonal Frequency Division Multiple Access (OFDM/OFDMA). In order to estimate the channel in the OFDM/OFDMA communication system, according to the present invention, pilots and data are extracted from input signals, phase change caused by time delay is estimated using the extracted pilots and data, and a channel estimation value is obtained by reflecting the estimated phase change.

Abstract: Device for recovering a carrier including a first signal converter for multiplying a complex carrier caused by a phase error to a digitized passband VSB signal, to provide a baseband VSB signal, a second signal converter for multiplying a complex value of a frequency to the signal from the first signal converter, to convert the baseband VSB signal into an OQAM signal, an error estimating part for generating a signal having carrier phase error information by using a real component and an imaginary component of the OQAM signal, and an oscillator for generating a complex carrier according to the carrier phase error information, thereby making carrier recovery regardless of a pilot component of TV signal, accurately.

Abstract: An apparatus and method of detecting whether the carrier frequency is locked for confirming recovering carrier is normally performed is disclosed. The apparatus includes a lock detector for judging whether the carrier frequency is locked by extracting DC value form real number component and imaginary component of an OQAM signal, and comparing the accumulated DC value to set value.

Abstract: Device for recovering a carrier including a first signal converter for multiplying a complex carrier caused by a phase error to a digitized passband VSB signal, to provide a baseband VSB signal, a second signal converter for multiplying a complex value of a frequency to the signal from the first signal converter, to convert the baseband VSB signal into an OQAM signal, an error estimating part for generating a signal having carrier phase error information by using a real component and an imaginary component of the OQAM signal, and an oscillator for generating a complex carrier according to the carrier phase error information, thereby making carrier recovery regardless of a pilot component of TV signal, accurately.

Abstract: An apparatus and method of detecting whether the carrier frequency is locked for confirming recovering carrier is normally performed is disclosed. The apparatus includes a lock detector for judging whether the carrier frequency is locked by extracting DC value form real number component and imaginary component of an OQAM signal, and comparing the accumulated DC value to set value.

Abstract: A system for the controlling the operational mode of an adaptive equalizer quickly determines the operational mode of the adaptive equalizer by measuring the amplitude variation of a DC offset for every segment.