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Lee, Hyukyeon,Oh, Kyungmook,Cho, Minjeong,Jang, Yunseok,Kim, Jaeseok IEEE 2018 IEEE Transactions on Circuits and Systems II: Expr Vol. No.
<P>This brief presents the efficient VLSI implementation of coordinate rotation digital computer (CORDIC)-based sorted QR decomposition (SQRD) for multiple-input and multiple-output (MIMO) systems. SQRD is widely adopted in MIMO signal processing to mitigate error propagation. However, its iterative sorting process after every column annihilation requires a large hardware overhead and suffers from a latency issue. The proposed CORDIC-based SQRD modifies a real-value decomposition matrix to utilize symmetry and jointly performs sorting processes and CORDIC rotations with adjacent symmetric columns to reduce the required number of CORDIC rotations and CORDIC stages. Furthermore, the VLSI design of the proposed SQRD has been synthesized and implemented with a Virtex-6 FPGA and a 65-nm CMOS technology, respectively. The 65-nm implementation results show an overall processing latency of 266.5 ns, a throughput of 48.8 MSQRD per second, and can support a 4.7-Gbps MIMO system throughput.</P>
An Effective Synchronization method for Impulse Radio Ultra-wideband System
Sergelren Kwon,Hyukyeon Lee,Jaeseok Kim 대한전자공학회 2017 대한전자공학회 학술대회 Vol.2017 No.1
In this paper, a two-stage synchronization scheme that has low complexity while providing excellent performance and meeting the IEEE 802.15.4a standard was proposed. The proposed scheme adaptively applies the threshold values used in stage processes to compensate for the performance deterioration in the signal-to-noise ratio. The method that uses energy collection in the coarse stage is designed for low power, and this approach is used to accurately find the point where multi-pass fading is gathered; it is used in the fine stage to accurately identify synchronizing points through precise energy correlations. The simulation results show that the proposed two-stage synchronization scheme outperforms the conventional one-stage synchronization scheme.
Low-complexity lattice reduction algorithm for MIMO detectors with tree searching
Kim, Hyunsub,Lee, Hyukyeon,Koo, Jihye,Kim, Jaeseok SpringerOpen 2017 Eurasip Journal on Wireless Communications and Net Vol.2017 No.-
<P>In this paper, we propose a low-complexity lattice reduction (LR) algorithm for multiple-input multiple-output (MIMO) detectors with tree searching. Whereas conventional approaches are based exclusively on channel characteristics, we focus on joint optimisation by employing an early termination criterion in the context of MIMO detection. In this regard, incremental LR (ILR) was previously proposed. However, the ILR is limited to LR-aided successive interference cancellation (SIC) detectors which have considerable bit-error-rate (BER) performance degradation compared to optimal detectors. Hence, in this paper, we extend the conventional ILR to be applicable to the LR-aided detectors with near-optimal performance. Furthermore, we perform the hypothetical analysis and several novel modifications to handle the obstacles for the application of the ILR to LR-aided detectors other than the LR-aided SIC detectors. The simulation results demonstrate that the computational complexity is considerably reduced, with BER performance degradation of 10(-5).</P>
Near-ML MIMO Detection Algorithm With LR-Aided Fixed-Complexity Tree Searching
Hyunsub Kim,Jangyong Park,Hyukyeon Lee,Jaeseok Kim IEEE 2014 IEEE communications letters Vol.18 No.12
<P>In this paper, we propose a low-complexity multipleinput multiple-output (MIMO) detection algorithm with lattice-reduction-aided fixed-complexity tree searching which is motivated by the fixed-complexity sphere decoder (FSD). As the proposed scheme generates a fixed tree whose size is much smaller than that of the full expansion in the FSD, the computational complexity is reduced considerably. Nevertheless, the proposed scheme achieves a near-maximum-likelihood (ML) performance with a large number of transmit antennas and a high-order modulation. The experimental results demonstrate that the performance degradation of the proposed scheme is less than 0.5 dB at the bit error rate (BER) of 10<SUP>-5</SUP> for a 8 × 8 MIMO system with 256 QAM. Also, the proposed method reduces the complexity to about 1.23% of the corresponding FSD complexity.</P>