Yong-Up Jang

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—A two-way relay channel (TWRC) in which two terminals and exchange orthogonal frequency division multiplexing (OFDM) signals with the help of an amplify-and-forward (AF) relay is considered here, and an efficient technique for allocating powers to parallel tones of OFDM is developed. A sum rate maximization problem is formulated by replacing the individual(More)
Presented in this paper is a study of the capacity evaluation of various multiuser MIMO schemes in cellular environments. The throughputs per user of the generalized zero-forcing with rank adaptation and vector perturbation schemes are compared with the capacity bound of the Gaussian MIMO broadcast channel, obtained by dirty paper coding under proportional(More)
—This paper considers a multiuser two-way relay channel (MU-TWRC) in which a base-station and a selected mobile-station (MS) among í µí°¾ number of MSs exchange messages during two time slots with the help of a half-duplex amplify-and-forward relay. We analyze the performances of a MU-TWRC. The closed-form expressions of the lower bound of the average rates(More)
This paper proposes a block diagonalization (BD) method, which nullifies the multiuser interference and, hence, increases the sum capacity in a multiuser multiple-input multiple-output (MU-MIMO) downlink system. The proposed BD scheme employs all users' receive processing as well as channel information. In addition, this paper proposes three adaptive mode(More)
A limited feedback-based transmit beamforming technique for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) is investigated in time-varying channels. The performance of the system is significantly degraded by outdated feedback information even when the channel varies slowly. To compensate for the impairment in(More)
— We introduce a multiuser (MU) scheduling method for amplify-and-forward (AF) relay systems, which opportunis-tically selects both the transmission mode, i.e., either one-or two-hop transmission, and the desired user. A closed-form expression for the average achievable rates is derived under two transmissions with MU scheduling, and its asymptotic solution(More)
—This paper describes the design of a time-division duplexing frame with a variety of pilots for multiuser multiple-input–multiple-output orthogonal frequency-division multiple access (MU-MIMO OFDMA) systems, where the base station and users are equipped with four and two transmitting and receiving antennas, respectively. In addition, a simplified(More)