Abstract: In the present invention, data generated from a source unit are distributed to at least one bandwidth; the data distributed to the respective bandwidths are encoded in order to perform an error correction; the encoded data are distributed to at least one antenna; a subcarrier is allocated to the data distributed to the respective antennas, and an inverse Fourier transform is performed; a short preamble and a first long preamble corresponding to the subcarrier are generated; a signal symbol is generated according to a data transmit mode; and a frame is generated by adding a second long preamble between the signal symbol and a data field for the purpose of estimating a channel of a subcarrier which is not used.

Abstract: In the present invention, data generated from a source unit are distributed to at least one bandwidth; the data distributed to the respective bandwidths are encoded in order to perform an error correction; the encoded data are distributed to at least one antenna; a subcarrier is allocated to the data distributed to the respective antennas, and an inverse Fourier transform is performed; a short preamble and a first long preamble corresponding to the subcarrier are generated; a signal symbol is generated according to a data transmit mode; and a frame is generated by adding a second long preamble between the signal symbol and a data field for the purpose of estimating a channel of a subcarrier which is not used.

Abstract: In the present invention, data generated from a source unit are distributed to at least one bandwidth; the data distributed to the respective bandwidths are encoded in order to perform an error correction; the encoded data are distributed to at least one antenna; a subcarrier is allocated to the data distributed to the respective antennas, and an inverse Fourier transform is performed; a short preamble and a first long preamble corresponding to the subcarrier are generated; a signal symbol is generated according to a data transmit mode; and a frame is generated by adding a second long preamble between the signal symbol and a data field for the purpose of estimating a channel of a subcarrier which is not used.

Abstract: The present invention relates to a method for detecting a signal in an MIMO system. In the method, a received signal is detected in a zero forcing (ZF) method, and a first detection interval is established from the signal detected in the ZF method. The received signal is detected within the first detection interval in a maximum likelihood (ML) method, a second detection interval is established from the signals respectively detected in the ZF method and the ML method. A final solution is determined by detecting the received signal within the second detection interval in the ML method.

Abstract: Disclosed is a link margin adaptation method using feedback information of a wireless communication system. For transmission and reception of data between two nodes of the wireless communication system, a transmission node requests a receiving node to transmit a link margin. The transmission node receives the link margin, and selects one of a white noise table or a delay spread table according to a delay spread value between the two nodes. Then, the transmission node adapts a link between the two nodes to a transmission mode and decides a transmission rate to transmit data at the decided transmission rate, thereby improving transmission capacity of the wireless communication system, obtaining the optimum link state, extending power utilization time of stations, and reducing interference between stations.

Abstract: An apparatus for detecting symbol synchronization in a received signal including a first preamble and a second preamble which is consecutive to the first preamble, the apparatus including a first correlator calculating a first correlation value between the received signal and a first pattern of a first period among iterative patterns of the first preamble, a second correlator calculating a second correlation value between the received signal and a second pattern of a second period among iterative patterns of the second preamble, a third correlator calculating a third correlation value between the first correlation value and the second correlation value, and a detector detecting symbol synchronization from the third correlation value.

Abstract: In the present invention, data generated from a source unit are distributed to at least one bandwidth; the data distributed to the respective bandwidths are encoded in order to perform an error correction; the encoded data are distributed to at least one antenna; a subcarrier is allocated to the data distributed to the respective antennas, and an inverse Fourier transform is performed; a short preamble and a first long preamble corresponding to the subcarrier are generated; a signal symbol is generated according to a data transmit mode; and a frame is generated by adding a second long preamble between the signal symbol and a data field for the purpose of estimating a channel of a subcarrier which is not used.

Abstract: An apparatus for adaptively modulating/demodulating signals in a multi-input multi-output (MIMO) system having a layered time-space architecture detector and a method thereof is disclosed. The apparatus includes: a bit and power allocation information calculator for deciding an equivalent channel gain in a reverse order of Vertical-Bell laboratories Space Time (V-BLAST) based on MIMO channel information feedbacked from a receiver and determining the number of bits and transmission power to be transmitted to each transmitting antenna by using the equivalent channel gain; and adaptive modulation means for modulating signal of each layer with corresponding modulation method based on the determined number of bits and transmitting power, controlling the transmitting power and transmitting the adaptively modulated signal through each transmitting antenna.

Abstract: The present invention relates to an automatic gain controller in a wireless packet communication system and an automatic gain control method thereof. The automatic gain controller includes a variable gain amplifier, a signal saturation determining unit, a power calculator, and a gain controller. The gain controller includes a first gain selector and a second gain selector. In the automatic gain control method, an establishment gain of a variable gain amplifier is reduced when the number of samples greater than a predetermined reference is greater than a predetermined number. After a received power value is measured, the establishment gain is controlled by a difference between the received power value and a reference power value.

Abstract: In the present invention, data generated from a source unit are distributed to at least one bandwidth; the data distributed to the respective bandwidths are encoded in order to perform an error correction; the encoded data are distributed to at least one antenna; a subcarrier is allocated to the data distributed to the respective antennas, and an inverse Fourier transform is performed; a short preamble and a first long preamble corresponding to the subcarrier are generated; a signal symbol is generated according to a data transmit mode; and a frame is generated by adding a second long preamble between the signal symbol and a data field for the purpose of estimating a channel of a subcarrier which is not used.

Abstract: A method for tracking carrier frequency and sampling frequency offsets in an OFDM wireless communication system comprises: (a) detecting data received from the transmitter using a first signal, and tracking a phase offset caused by the carrier frequency offset using the detected received data; (b) detecting the data received from the transmitter using the first signal, and tracking the phase offset caused by the sampling frequency offset using the detected received data; (c) compensating for the phase offset caused by the carrier frequency offset between the transmitter and the receiver according to the phase offset tracked in (a); and (d) compensating for the phase offset caused by the sampling frequency offset between the transmitter and the receiver according to the phase offset tracked in (b).

Abstract: The present invention is directed to an apparatus for symbol timing detection for a wireless communication system. According to the present invention, the samples of the output of an analog-to-digital converter are utilized prior to the completion of the automatic gain control function to detect symbol timing using autocorrelations of the samples, and a structure supporting an average window size and a delay value is provided to optimize the complexity and allow a signal demodulation of high reliability.

Abstract: A method for channel quality estimation and link adaptation for an OFDM wireless communication system includes: (a) estimating a channel gain and a noise power, and measuring an SNR in consideration of the estimated channel gain and noise power; (b) calculating a correlation value between an externally received preamble signal and a known preamble signal, and estimating a delay spread; (c) measuring the quality status of a channel in consideration of the measured SNR and the estimated delay spread; and (d) determining parameters including transmit power, data modulation mode, and data rate, according to the measured quality status of the channel, and performing a link adaptation using a protocol for acknowledging a normal signal transmission as well as using the SNR and the delay spread.

Abstract: An error tracking apparatus and method for tracking a residual frequency error, a phase error, a timing error, and a signal amplitude variation to enhance a phase error tracking performance and a tracking speed in an orthogonal frequency division multiplexing (OFDM) system is provided.

Abstract: An apparatus for detecting symbol synchronization in a received signal including a first preamble and a second preamble which is consecutive to the first preamble, the apparatus including a first correlator calculating a first correlation value between the received signal and a first pattern of a first period among iterative patterns of the first preamble, a second correlator calculating a second correlation value between the received signal and a second pattern of a second period among iterative patterns of the second preamble, a third correlator calculating a third correlation value between the first correlation value and the second correlation value, and a detector detecting symbol synchronization from the third correlation value.

Abstract: The present invention relates to an automatic gain controller in a wireless packet communication system and an automatic gain control method thereof. The automatic gain controller includes a variable gain amplifier, a signal saturation determining unit, a power calculator, and a gain controller. The gain controller includes a first gain selector and a second gain selector. In the automatic gain control method, an establishment gain of a variable gain amplifier is reduced when the number of samples greater than a predetermined reference is greater than a predetermined number. After a received power value is measured, the establishment gain is controlled by a difference between the received power value and a reference power value.

Abstract: The present invention relates to a method for detecting a signal in an MIMO system. In the method, a received signal is detected in a zero forcing (ZF) method, and a first detection interval is established from the signal detected in the ZF method. The received signal is detected within the first detection interval in a maximum likelihood (ML) method, a second detection interval is established from the signals respectively detected in the ZF method and the ML method. A final solution is determined by detecting the received signal within the second detection interval in the ML method.

Abstract: Disclosed is a link margin adaptation method using feedback information of a wireless communication system. For transmission and reception of data between two nodes of the wireless communication system, a transmission node requests a receiving node to transmit a link margin. The transmission node receives the link margin, and selects one of a white noise table or a delay spread table according to a delay spread value between the two nodes. Then, the transmission node adapts a link between the two nodes to a transmission mode and decides a transmission rate to transmit data at the decided transmission rate, thereby improving transmission capacity of the wireless communication system, obtaining the optimum link state, extending power utilization time of stations, and reducing interference between stations.

Abstract: The present invention is directed to an apparatus for symbol timing detection for a wireless communication system. According to the present invention, the samples of the output of an analog-to-digital converter are utilized prior to the completion of the automatic gain control function to detect symbol timing using autocorrelations of the samples, and a structure supporting an average window size and a delay value is provided to optimize the complexity and allow a signal demodulation of high reliability.

Abstract: An apparatus for adaptively modulating/demodulating signals in a multi-input multi-output (MIMO) system having a layered time-space architecture detector and a method thereof is disclosed. The apparatus includes: a bit and power allocation information calculator for deciding an equivalent channel gain in a reverse order of Vertical-Bell laboratories Space Time (V-BLAST) based on MIMO channel information feedbacked from a receiver and determining the number of bits and transmission power to be transmitted to each transmitting antenna by using the equivalent channel gain; and adaptive modulation means for modulating signal of each layer with corresponding modulation method based on the determined number of bits and transmitting power, controlling the transmitting power and transmitting the adaptively modulated signal through each transmitting antenna.