Electronics and Telecommunications Research Institute

Vk Corporation

Kwon-Hue Choi

Soo-Young Kim

Deock-Gil Oh

Kwang-Jae Lim

Do-Seob Ahn

Kun-Seok Kang

Sun-Heui Ryoo

Provided is an iterative residual frequency and phase compensation apparatus for an OFDM system and a method thereof. The apparatus includes: a first classifying unit for classifying symbol sequences by each subcarrier wave; a soft-decision calculating unit for calculating a soft-decision value of a data symbol using a soft-decision reliability obtained from iterative decoding performed by the iterative decoder; a classifying unit for classifying the soft-decision values by a carrier wave; a frequency estimating unit for estimating a residual frequency error of each carrier wave using the soft-decision value; a phase estimating unit for estimating an average residual phase error using the soft-decision value; a frequency and phase compensating unit for compensating frequencies and phases for input symbols of each carrier wave using the estimated frequency error and the estimated phase error; and a buffer for temporally storing the compensated symbols to provide it to the first classifying unit.

Apparatus and method for correcting iterative residual frequency and phase in turbo coded OFDM system

Disclosed is an MC-CDMA scrambling system and method, and a recording medium for storing a program thereof. A transmitter receives user's bit streams, uses a fixed scrambling code, determined according to the user's orthogonal code combinations or the number of users and having a length equal to the number of subcarriers, and generates and outputs multicarrier signals. A receiver uses the scrambling code equal to that used by the transmitter, and receives the multicarrier signals from the transmitter, thereby converting the scrambling codes according to the users' orthogonal code combinations irrespective of user data, and easily reducing the PAPR (peak-to-average power ratio).

Scrambling system and method for peak power reduction in MC-CDMA, and recording medium for storing corresponding program

Provided are multi-carrier (MC)/multi-carrier direct sequence (MC-DS) dual-mode adaptable CDMA apparatus, the method thereof, and a computer program that implements the method. The apparatus can vary the user modulation degree and the transmission repetition degree independently, and convert a spreading scheme between the time-based spreading scheme (MC-DS-CDMA) and the frequency-based spreading scheme (MC-CDMA) in a MC-CDMA system. The apparatus includes: a user signal processing unit for performing symbol modulation, repetition and spreading of bit stream for each user based on a transmission mode suitable for channel environment of each user, and generating spread chip streams for the user; a combining unit for adding up all the spread chip streams for the users; a first interleaving unit for interleaving the chip streams added up in the combining unit and generating a first interleaved stream; and a second interleaving unit for optionally performing a second interleaving on the first interleaved stream.

MC/MC-DS dual-mode adaptive multi-carrier code division multiple access (CDMA) apparatus and method thereof

Apparatus and method for closed-loop power control in mobile satellite communication system, which can compensate round trip delay. The apparatus for closed-loop power control includes the means of; a) converting power control order from base earth station into power control step; b) measuring channel change rate from power of pilot channel; c) making tab coefficient using said channel change rate; d) compensating channel change due to loop delay using power control step; and e) renovating received signal power using said power control step.

Closed-loop power control apparatus for mobile satellite communication system and method thereof

Disclosed is a method for using a different symbol timing for users so as to reduce a multiple access interference component in a multi-carrier code division multiple access (MC-CDMA) system. For this purpose, the presented invention involves dividing the users of the MC-CDMA system into two groups and applying an offset to the symbol timing between the user groups to cause a symbol transition of the opposite user group in the middle of the symbol interval, thereby reducing the multiple access interference component included in a symbol decision variable after a chip combination.

Channel transmission symbol generating system for a multi-carrier communication system for reduction of multiple access interference and method thereof

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Daejeon, South Korea

Kwon-Hue Choi