Seongjin Kim

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This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Abstract—In this paper, the power allocation problem is solved in the context of maximizing the energy efficiency (EE) of orthogonal frequency division multiplexing (OFDM) signaling over a two-way(More)
—We consider digital predistortion (DPD) for linearizing power amplifiers (PAs) of hybrid MIMO systems with subarrays. Designing such a DPD scheme is difficult because one DPD should linearize all PAs of a subarray whose beamforming coefficients are time-varying. We develop an adaptive DPD technique for each subarray based on direct learning method(More)
—We consider bit allocation for channel state information (CSI) feedback in coordinated beamforming (CB) systems. The optimization problem under consideration is to minimize the total transmission power subject to the target signal to interference and noise ratio (SINR) constraints. We obtain a suboptimal solution to the problem that provides closed-form(More)
—This paper describes the design, fabrication, and measurement of backward-wave-cancelled distributed traveling-wave photodetectors. One of the fundamental issues in traveling-wave photodetectors is the generation of backward waves , which reduces bandwidth or, in the case of matched input termination, reduces their radio-frequency (RF) efficiencies by up(More)
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