Electronics and Telecommunications Research Institute

Samsung Electronics Co., Ltd.

Kt Corporation

Sk Telecom Company, Ltd.

Hanaro Telecom., Inc.

Ktfreetel Co., Ltd

Yonsei University

Seung-Ku Hwang

Sok-Kyu Lee

Seung-Chan Bang

Il-Gu Lee

Eun-Young Choi

Hee-Jung Yu

Deuk-Su Lyu

Jung-Bo Son

Chan-Ho Yoon

Tae-hyun Jeon

Seung-Wook Min

Youn-Ok Park

Dong-Seung Kwon

In-Kyeong Choi

Seong-Rag Kim

Byung-Han Ryu

Chul-Sik Yoon

Jae-Heung Kim

Yu-Ro Lee

Jong-Ee Oh

Kwang-Jae Lim

Hyoung-Soo Lim

Kun-Min Yeo

Chang-Wahn Yu

Soon-Yong Lim

Seung-Joon Lee

Young-Ha Lee

Choong-Il Yeh

Young-Seog Song

Doo-Hyeon Kim

Jae-Young Lee

Jae-Hee Cho

Yun-Joo Kim

Jun-Woo Kim

Chung-Yong Lee

Min-Hee Cho

Seong-Keun Oh

Kyung-Yeol Sohn

Myeong-Cheol Shin

Kwang-Seop Eom

Kwhang-Hyun Ryu

Kyoung-Ju Noh

Sang-Beom Kim

Jang-Sik Choi

Moon-Il Lee

Kyoung-Hee Song

Seok-Joo Shin

Boong-Gee Song

Hyung-Chul Kim

Sung-Ho Ahn

Min-Gyu Kang

Jin-Hak Bae

Byoung-Ki Min

Kwang-Seop 406-103 Sangrokmaeulboseong Apt Eom

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

The present invention relates to a multi-input multi-output (MIMO) system for enhancing transmission performance. The MIMO system uses space-time encoding and transmit antenna selection methods, and includes a transmitter () and a receiver (). The transmitter () includes N transmit antennas (--) that are more than M transmit antennas (--) used for transmitting a signal to space channel, selects the M transmit antennas (--) among the N transmit antennas (--), and transmits symbol by space-time encoding the symbol. The receiver () includes M receive antenna (--) for receiving a signal from the space channel, detects an information symbol by using the signal received through the receive antenna (--), generates transmit antenna selection information for selecting M transmit antennas (--) among transmit antennas (i--) with reference to a channel estimate, and returns the information to the transmitter.

Multi-input multi-output system for enhancing transmission performance

A space-time code used for a transmitter to transmit a plurality of data symbols to a receiver in a MIMO system, the space-time code including a code word matrix for transmitting an amount of data symbols corresponding to a product of the number of transmit antennas and a spatial multiplexing rate during one block period, wherein a row index indicates combined signals transmitted through different transmit antennas and a column index indicates time slots that correspond to the number of transmit antennas, and wherein the number of data symbols allocated to each transmit antenna in a code block corresponds to the spatial multiplexing rate, and the data symbols are combined by different combining coefficients for each transmit antenna at every time slot, and simultaneously transmitted through different transmit antennas, and each transmit antenna transmits a different set of data symbols at every time slot.

Structured space-time code achieving the full diversity and full rate and generating method thereof, and multi-input multi-output system

A mobile station transmitting and receiving method and a corresponding mobile station transmitter and receiver of a smart antenna system for forming uplink eigenbeams of the OFDM/TDD (orthogonal frequency division multiplex/time division duplex), wherein OFDM symbols are received from a base station through a downlink via multiple antennas () and an FFT (fast Fourier transform) is performed on the received OFDM symbols by the FFT units (). By means of a channel estimator () the channels are estimated and a beam weight generator () generates respective beam weights from the channels of the respective pilot tones of the respective subcarriers according to the channel estimation result. A beam weight multiplier () forms the uplink beam by multiplying the respective beam weights with the output of the signal repeater () and IFFT units () generate respective OFDM symbols which are transmitted via multiple antennas () through an uplink.

Smart antenna system and method thereof for forming uplink eigenbeam of OFDM/TDD

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

Disclosed is a power saving mode control system () and method in a wireless portable Internet system. Stations in the sleep mode are grouped by aligning listening intervals of the stations which enter the sleep mode in the power saving management system wherein the sleep interval for receiving no traffic data is exponentially increased. Therefore, the sleep mode of the grouped subscriber stations are easily managed, and power saving efficiency is enhanced and system complexity is lowered by easily and quickly detecting data states provided to the corresponding stations.

System and method for controlling power saving mode in wireless portable network system

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.

Automatic gain control device having variable gain control interval and method thereof

Information for different subscribers of a service with the same modulation and channel encoding method is transmitted by allocating radio resources in a wireless portable Internet system. Also, identifier information on the subscriber of a concurrently allocated radio resource is transmitted through common control information. Therefore, information for a plurality of subscribers coexists in a single radio resource block, and it can be easily transmitted. Since a subscriber station which has received downlink information can know to which radio resource block the information for the corresponding station is allocated through the subscriber identifier information transmitted as common control information, the subscriber station can access desired information by accessing a specific radio resource block to which information for the subscriber is allocated in the received frame.

Method and device for allocating radio resources in wireless portable network system

Disclosed is an apparatus and method for processing a ranging channel in an OFDMA system. The apparatus converts received ranging complex signals to polar coordinate signals having a signal magnitude and a phase, and the received converted signals are each represented by a signal magnitude component and a phase component. A predetermined phase component of a signal according to a phase rotation is used to estimate a time delay by an addition operation of the phase of the received signal and the phase according to the phase rotation. Accordingly, the time delay and the power of each reverse link user of the OFDMA mobile communication system can be calculated by arithmetic operations of addition components instead of multiplication components, resulting in the reduction of complexity.

Apparatus and method for processing ranging channel in orthogonal frequency division multiple access system

In the uplink of an OFDMA system, a preamble is used to estimate a channel and then the pilot tones of a data symbol are used for channel estimation to update the channel estimate. The channel estimate is used for channel compensation, and the phase of the channel is corrected using the channel estimate obtained from the pilot tones. In this way, the channel estimation performance and hence the compensation ability can be enhanced.

Uplink channel estimation system for orthogonal frequency division multiple access system and method thereof

Disclosed is a ranging system and method in an OFDMA system. The ranging system includes complex exponential twiddle storage units for respectively storing complex exponential twiddle factors corresponding to a timing error, complex multipliers for respectively complex-multiplying the complex exponential twiddle factors by received uplink ranging data, code correlators for respectively correlating the outputs of the complex multipliers and ranging codes, and threshold comparators for respectively comparing the outputs of the code correlators with a threshold.

Uplink ranging system and method in OFDMA system

In the method for managing a variable bit rate so as to provide a streaming service and in the record medium capable of being read through a computer having a record of a program to realize the inventive method, a frame rate controlling system through a removal of a frame and a fidelity controlling system are used to change a bit rate of multimedia video data and thereby provide a multimedia streaming service based on the various bit rates according to a bandwidth change of a communication network, the fidelity controlling system being gotten by differently providing selection ranges for discrete cosine transform (DCT) coefficients in a unit of a block within a frame. This inventive method comprises a first step of decomposing an original video bit stream stored already, into a file type capable of supporting the variable bit rate, and then storing it; a second step of merging data based on the decomposed type by considering a traffic state of a communication network; and a third step of providing the streaming service by using the video bit stream merged, whereby effectuating in a use of an information communication system etc.

Method for providing variable bit rate in streaming service

In a cooperative computer based system for editing a web document including a plurality of clients a server, the cooperative computer based system includes means for generating editing instructions, converting editing instructions to a message related to editing and transmitting the message related to editing to the server; means for determining if the web document can be modified, based on the message related to editing; modifying contents of a copied web document stored in the server in conform to the message related to editing; and transmitting the message related to editing to the plurality of the clients; and means for modifying contents of the copied web document stored in each of the plurality of the clients in conform to the message related to editing transmitted from the server.

System and method for cooperative editing of web document

Disclosed is a quantization/inverse quantization circuit including a differential pulse code modulator (DPCM). Video CODEC standards (i.e., JPEG, H.261, H.263, MPEG-1, and MPEG-2) include various functions for an image compression and an image reconstruction. The conventional quantization/inverse quantization circuit has been designed to be fit for only one desired standard, so that the quantization/inverse quantization circuit used for one standard cannot be directly used for another standard. Accordingly, in relation to a difference between standards and required function therebetween in order to use the present invention in all video CODEC standards, the present invention discloses a quantization/inverse quantization circuit which can support all modes (i.e., a quantization mode in coding, an inverse quantization mode in decoding, and a reconstruction mode) by employing one quantization circuit as a quantization/inverse quantization circuit which can be used in all video CODEC standards.

Quantization/inverse quantization unit selectably accommodating multiple

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Seoul, South Korea

Seung-Ku Hwang