Kitaek Bae

Samsung | samsung

In this paper, we propose an architecture of scalable radio processor targeting an OFDM based wireless modem. The architecture is based on the coarse-grained reconfigurable array (CGRA), which provides programmable and flexible accelerators by reconfiguring hardware resources at run time. On the other hand, the architecture maximizes the data paral...

In the second generation terrestrial digital video broadcasting (DVB-T2) systems, one of the important features is the usage of rotated quadrature amplitude modulation (QAM) to exploit signal space diversity. However, the implementation of soft-demapper is very challenging and becomes more complex as the modulation order increases. Recently, a √(M)...

In the second generation terrestrial digital video broadcasting (DVB-T2) systems, one of the important features is the rotated quadrature amplitude modulation (QAM) with cyclic Q delay exploiting signal space diversity to improve detection performance. However, the complexity of soft-demapper is increased, because it needs to calculate the Euclidea...

To improve detection performance of quadrature amplitude modulation (QAM), signal space diversity (SSD) has been exploited and adopted for the second generation of digital video broadcasting (DVB-T2) system. Maximum-likelihood detection (MLD) to get full SSD is avoided because of enormous computational complexity. Its max-log approximated detection...

In the presence of nonlinearity, we analyze the impact of the selected mapping (SLM) technique on bit-error-rate (BER) performance of orthogonal frequency division multiplexing (OFDM) systems in an additive white Gaussian noise channel. The peak-to-average-ratio (PAR) reduction gain of SLM can be increased by improving the PAR statistics at the cos...

This paper describes the feasibility of software implementation of DVB-T2 receiver with DTG-106 [1] mode using the coarse-grained reconfigurable array (CGRA) based processor. This paper focuses mainly on DVB-T2 system design and implementation of major software functions of DVB-T2 demodulator: FFT, frequency interpolation, multi-level de-interleavi...

In this paper, we present a software-defined radio (SDR) implementation of the 4×4 MIMO-OFDM baseband receivers on a coarse-grained reconfigurable array (CGRA) processor operating at 1 GHz clock for IEEE 802.11ac, which can support over 1Gbps data rate. However, software implementation of 802.11ac is very challenging because of the increasing compu...

Multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) technology has become a promising solution in current wireless communication systems. However, the implementation of MIMO-OFDM systems imposes a heavy complexity burden of equalizer matrix calculation on the training symbols due to the strict processing delay re...

Signal space diversity (SSD) has been exploited to improve detection performance of quadrature amplitude modulation (QAM) over fading channels and recently adopted for the second generation of digital video broadcasting system (i.e., DVB-T2). To fully exploit SSD, maximum likelihood (ML) detection has been used for soft-demapping. Because of expone...

The rotated constellation with cyclic Q-delay provides the diversity gain for the signal space over the fading channel when properly demapped at the receiver. However, the implementation of optimal soft demapper is impractical due to the exponentially increasing complexity with modulation order. In this paper, we propose a two-stage soft demapper w...

In Orthogonal Frequency Division Multiplexing, a simple clipping method is widely used in order to reduce the peak-to-average power ratio since it is easy to implement. The performance analysis of the clipping approach has been previously introduced in the literature. Clipping, however, is a nonlinear process and may cause two major undesirable eff...

The active constellation extension (ACE) technique is attractive for reducing peak power in OFDM systems. It is simple and easy to implement and provides suboptimal gain in peak power reduction. However, its peak power reduction capacity is sensitive to low target clipping ratios. In this paper, we propose a novel ACE algorithm using pilot symbols....

For PAR reduction in OFDM systems, the clipping-based Active Constellation Extension (ACE) technique is simple and attractive for practical implementation. However, we observe it cannot achieve the minimum PAR when the target clipping level is set below an initially unknown optimum value. To overcome this low clipping ratio problem, we propose a no...

Selected mapping (SLM) techniques have been used to reduce the high peak-to-average power ratio (PAR) in orthogonal frequency division multiplexing (OFDM) systems. The capacity of PAR reduction can be increased by improving the PAR statistics at the cost of complexity of the OFDM transmitter. However, it is difficult to clarify the performance degr...

Despite their many advantages, orthogonal frequency division multiplexing (OFDM) systems have been limited by nonlinear devices such as power amplifiers and DACs due to OFDM's inherently high peak-to-average power ratio (PAR). This high PAR limits the use of high efficiency amplification devices. To reduce the PAR in OFDM systems, some low complexi...