Keonkook Lee

Learn More
—It was shown that the required transmit power to support a target achievable rate is inversely proportional to the number of antennas in massive multiple-input multiple-output (MIMO) systems [1]. However, the consumed power of the massive MIMO systems should include not only transmit power but also the fundamental power for operating the circuit at the(More)
—Spectrum leasing via cooperation refers to the possibility for primary users to lease part of the spectral resources to secondary users in exchange for cooperation. This paper proposes a novel implementation of this concept in which secondary cooperation aims at improving the secrecy of the primary link. In particular, a secondary transmission with(More)
—In this letter, we propose an orthogonal space-time-frequency block code for orthogonal frequency division multiplexing (STFBC-OFDM) systems, newly designed to be robust against both time-and frequency-selective fading. The performance of the proposed system is analyzed in spatially uncorrelated time-varying multipath Rayleigh-fading channels. The analytic(More)
correlation value is selected to maximize the SNR. Next, in criterion II, we choose the mode which has smaller interference to reduce the performance degradation due to the interference. Simulation results show that the proposed adaptive switching system outperforms the nonadaptive system. keywords – space-time code (STC), MIMO-OFDM systems, adaptive(More)