Tae-Won Hwang

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Orthogonal frequency-division multiplexing (OFDM) effectively mitigates intersymbol interference (ISI) caused by the delay spread of wireless channels. Therefore, it has been used in many wireless systems and adopted by various standards. In this paper, we present a comprehensive survey on OFDM for wireless communications. We address basic OFDM and related modulations, as well as techniques to improv

In this paper, we propose iterative methods to reconstruct the cycle prefix for coded single-carrier frequency-domain equalization (SC-FDE) systems that employ insufficient length of cycle prefix at the transmitter. Since the insertion of the cyclic prefix for SC-FDE systems decreases the bandwidth utilization efficiency as the channel's delay span increase, it is desirable to improve the bandwidth utilization efficiency by limiting the length of the cycle prefix. Two novel schemes for reconstru

In this paper, novel iterative equalization for intersymbol interference (ISI) channels is proposed. Different from the existing turbo equalization, the proposed one is based on energy-spreading transform (EST), which separates equalization and coding, and therefore works for uncoded systems. The complexity of the proposed scheme is comparable to that of decision-feedback equalization (DFE). However, analytical and simulation results demonstrate that its performance is very close to the matched-

Tumor specific delivery of anti-cancer drugs is one of the major challenges faced by drug development processes. In this study, we prepared a doxorubicin (DOX)-conjugated liposome (DCL) by incorporating the newly synthesized DSPE-PEG2000-DOX (DPD) into liposomes as a lipid component and tested its anti-tumor activity in vivo. DPD was synthesized by coupling DOX to DSPE-PEG2000-COOH via amide linkage and the chemical structure of resulting DPD was confirmed by (1)H-NMR analysis. DCL having liposo

We consider the transceiver design for multiple-input-multiple-output (MIMO) systems when the channel state information (CSI) is available at the transmitter as well as the receiver. First, we propose an open-loop low-complexity MIMO spatial multiplexing scheme based on the energy spreading transform (EST-SM). The EST-SM can spatially multiplex multiple data streams and iteratively detect the data streams with almost negligible interstream interference at sufficiently high SNR. Then, we propose

Full-diversity full-rate (FDFR) space-time codes achieve both high data rate and good reliability at the cost of high decoding complexity. In this paper, we propose a low-complexity MIMO scheme that achieves both full diversity and full rate over flat fading channels for a sufficiently large number of transmit and receive antennas. The proposed scheme is constructed by applying energy spreading transforms (EST's) to multiple data streams and spatially multiplexing the streams to multiple transmi

A bandwidth efficient block-transmission scheme with frequency-domain equalization that employs insufficient length of cyclic prefix at the transmitter is proposed. Since the the cyclic prefix for block based transmission systems decreases the bandwidth-utilization efficiency, it is desirable to limit the length of the cyclic prefix. The proposed scheme employs insufficient cyclic prefix, but performs near single-carrier systems with frequency-domain equalization (SC-FDE) (D. Falconer et al., 20

Multiple transmit and receive antenna arrays can be used to form multiple input and multiple output (MIMO) systems for diversity and multiplexing in wireless communications. In this paper, we develop iterative signal-detection schemes based on energy spreading transform (EST) (T. Hwang and Y. Li) for MIMO channels. The EST in a MIMO system improves signal-detection performance by spreading the symbol energy over the space and time domain. It also enables iterative signal detection without employ

In this letter, the principle of iterative detection based on energy spreading transform (EST) introduced by Hwang and Li is applied to the multiuser-detection (MUD) problem. Different from turbo principle, EST enables iterative signal detection at the receiver without any bandwidth increase resulting from channel coding. It is shown by analysis as well as computer simulation that a significant performance gain in user separation can be obtained by employing ESTs consisting of different random p

In this correspondence, an improved scheme for energy spreading transform (EST) based equalization is proposed. In the improved scheme, optimal frequency- and time-domain filters that maximize signal-to-interference-noise ratio (SINR) are employed to enhance the performance. The performance improvement of optimal filtering is as large as 7 dB for some channels compared with the original scheme

We use a space-time energy spreading transform (ST-EST) for iterative signal detection in multiple input and multiple output (MIMO) wireless systems. Theoretical and simulation results demonstrate that when the signal-to-noise ratio (SNR) is above a threshold, the performance of the system is very close to that of the genie-aided (interference-free) receiver.

In this paper, we apply recently developed energy spreading transform (EST) technique to down-link MC-CDMA systems for frequency and spatial diversity. The performance of the proposed EST based MC-CDMA systems is independent of the number of active users, which is different from all current MC-CDMA systems. It is demonstrated by computer simulation that the BER for the EST based system is 1.1 times 110 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"

The purpose of this study is to empirically analyze major influence factors that would affect potential customer’s intention to use of Home IoT services based on Technology Acceptance Model and Innovation Diffusion Theory. In developing the research model, we have focused on measuring the influential factors based on previous studies, which are Home IoT product innovativeness, potential customers’ personal innovativeness and perceived usefulness, perceived ease of use, perceived cost, perceived