Electronics and Telecommunications Research Institute

Jung-Bo Son

Sok-Kyu Lee

Il-Gu Lee

Eun-Young Choi

Yu-Ro Lee

Seung-Chan Bang

Hee-Jung Yu

Deuk-Su Lyu

Seung-Ku Hwang

Chan-Ho Yoon

Tae-hyun Jeon

Seung-Wook Min

Chanho Yoon

Hun-Sik Kang

Hyun-Kyu Chung

Yun-Joo Kim

Minho Cheong

Je-Hun Lee

Kyoung-Ju Noh

Kwhang-Hyun Ryu

Kyoung-Hee Song

The present invention relates to a method and an apparatus for transmitting control and training symbols to improve transmission efficiency in a multi-user wireless communication system. The method for transmitting the control and training symbols in the multi-user wireless communication system according to one embodiment of the present invention comprises the steps of: determining whether a required transmission rate of each data can be satisfied through channel estimation in each of terminals when different data are simultaneously transmitted to each of the terminals; and transmitting a data frame to each of the terminals, the data frame being composed to discriminate the control and training symbols in each of the terminals using a combination of time, frequency, and code area when the required transmission rate of each data is not satisfied according to the determined result.

Method for transmitting control and training symbols in multi-user wireless communication system

The present invention relates to an orthogonal frequency division multiplexing wireless local area network (LAN) transmitting/receiving system for providing expanded service coverage, and a method thereof. A first OFDM modulation is performed for an even-numbered time, and a second OFDM modulation is performed for an odd-numbered time. A transmitting frame including a plurality of signal fields according to the first and second OFDM modulation is transmitted. The receiving system determines whether a signal field is repeatedly generated in the frame. If the signal field is not repeatedly generated, corresponding demodulation is performed. If repeatedly performed, the signal field is demodulated by using first bit allocation information and second bit allocation information having a &#xbd; value of the first bit allocation information. A data field is demodulated according to the demodulated signal field.

Transmitting and receiving systems for increasing service coverage in orthogonal frequency division multiplexing wireless local area network, and method thereof

An apparatus for detecting a packet end point in a wireless communication system includes: a signal reception unit configured to receive a signal from an outside, convert the signal into a baseband signal, perform analog-digital conversion of the baseband signal, and perform a digital front end; a storage unit configured to store an output of the signal reception unit; a frequency offset estimation unit configured to estimate a frequency offset using the output of the storage unit; a frequency offset correction unit configured to compensate for a frequency error using the estimated frequency offset; an offset correlation unit configured to calculate correlation of the frequency offset and a cyclic prefix; an auto-correlation operation unit configured to calculate auto-correlation of the cyclic prefix; and a packet end detection unit configured to check a packet end point using the auto-correlation.

Apparatus and method for detecting packet end point in wireless communication system

The apparatus includes a radio frequency (RF) unit configured to arrange a plurality of symbols received through an antenna at a frequency domain, an analog to digital (AD) converter configured to converts the plurality of symbols arranged at the frequency domain to digital symbols, a fast Fourier transform (FFT) unit configured to transform the digital symbols through a fast Fourier transform scheme, a compensator configured to compensate a gain mismatch between an I-channel and a Q-channel of the transformed digital symbols, a mapping unit configured to the compensated digital symbols to a constellation diagram, and a detector configured to correlate the mapped symbols, extract correlation results, and detect a high throughput (HT) signal using the extracted correlation results.

Apparatus and method for detecting signal in wireless communication system

Provided are a receiving apparatus and method for a wireless communication system using multiple antennas. A receiving method for a wireless communication system using multiple paths, the receiving method comprising: receiving signals through a predetermined number of multiple paths; sensing a carrier according to saturation state degrees of the signals, and providing saturation state information; calculating automatic gain components of the received signals by using the received signals and the saturation state information of the received signals; and performing a noise matching process to amplify noises on the predetermined multiple paths according to the automatic gain components during a predetermined period.

Signal receiving apparatus and method for wireless communication system using multiple antennas

A data receiving apparatus includes a receiving unit configured to receive a beacon packet from at least one base station, a searching unit configured to search an index of a subchannel including an optimal channel state among subchannels allocated to a sector divided through spatial multiplexing based on the base station using the beacon packet, a calculating unit configured to calculate a final back off time by adding a slot time of the subchannel index and a random time, and a transmitting unit configured to include the searched subchannel index in a beacon response packet and transmit the beacon response packet after the calculated final back off time.

Apparatus and method for receiving/transmitting data in wireless communication system

Provided is an apparatus and method for encoding a Low Density Parity Check (LDPC) code using a message passing algorithm. The apparatus, includes: a parity calculating unit for operating a check node value on an input bit and a predetermined parity bit according to the message passing algorithm and calculating a parity bit; a parity correcting unit for correcting the calculated parity bit according to a parity check result of the calculated parity bit; and an output transform unit for combining the input bit and the corrected parity bit.

Apparatus and method for encoding LDPC code using message passing algorithm

A frame format discrimination method in a wireless communication system is provided. The frame format discrimination method includes: calculating a power of an in-phase signal and a power of a quadrature signal in a predetermined section of a frame; comparing the power of the in-phase signal with the power of the quadrature signal; and determining the format of the frame in accordance with the comparison result.

Apparatus and method for discriminating frame format in wireless communication system

Provided are a receiving apparatus for a multiple input multiple output (MIMO) system and a method thereof. The receiving apparatus includes a QR decomposing unit for calculating a single (Q) matrix vector and an upper triangle (R) matrix vector for a receiving signal vector; a first symbol estimation unit for estimating predetermined symbols using the calculated Q matrix vector and R matrix vector; a log likelihood ratio (LLR) calculating unit for calculating log likelihood ratios of unit bits for the estimated symbols; an interference removing unit for receiving a decoded signal that is decided using the calculated log likelihood ratios and removing interference from the receiving signal vector; and a second symbol estimation unit for linearly estimating remaining symbols for the interference removed signal.

Receiving apparatus and method for MIMO system

Provided is a QR decomposition apparatus and method that can reduce the number of computers by sharing hardware in an MIMO system employing OFDM technology to simplify a structure of hardware. The QR decomposition apparatus includes a norm multiplier for calculating a norm; a Q column multiplier for calculating a column value of a unitary Q matrix to thereby produce a Q matrix vector; a first storage for storing the Q matrix vector calculated in the Q column multiplier; an R row multiplier for calculating a value of an upper triangular R matrix by multiplying the Q matrix vector by a reception signal vector; and a Q update multiplier for receiving the reception signal vector and an output of the R row multiplier, calculating an Q update value through an accumulation operation, and providing the Q update value to the Q column multiplier to calculate a next Q matrix vector.

QR decomposition apparatus and method for MIMO system

A digital system design method uses a higher programming language. In order to realize a digital system, an algorithm is verified based on a program written by the higher programming language and a program is programmed considering the higher programming language-hardware characteristics before the program is written in the lower programming language, and thus conversion into the lower programming language may be easily performed.

Method for digital system modeling by using higher software simulator

An exemplary automatic gain control device includes: a radio frequency receiver for receiving a plurality of first signals through a plurality of antennas, respectively controlling gains of the plurality of first received signals, and outputting the plurality of the first signals having the controlled gain as a plurality of second signals; a signal saturation detecting unit for outputting a saturation index determination value when the number of plurality of second signals that are greater than a threshold value is greater than a predetermined number; and a gain controlling unit for comparing power values of the plurality of second signals to detect one power value, and outputting a gain value determined based on a detected power value and a saturation index determination value to the radio frequency receiver.

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Daejeon, South Korea

Jung-Bo Son