• Journal of Satellite, Information and Communications
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• v.10 no.1
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• pp.22-28
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• 2015

In this paper, we propose a new computationally efficient joint iterative multi-input multi-output (MIMO) detection scheme using a soft interference cancellation and minimum mean squared-error (SIC-MMSE) method. The critical computational burden of the SIC-MMSE scheme lies in the multiple inverse operations of the complex matrices. We find a new way which requires only a single matrix inversion by utilizing the Taylor series expansion of the matrix, and thus the computational complexity can be reduced. The computational complexity reduction increases as the number of antennas is increased. The simulation results show that our method produces almost the same performances as the conventional SIC-MMSE with reduced computational complexity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7A
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• pp.743-750
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• 2008

Orthogonal frequency division multiplexing (OFDM) is a attractive modulation scheme for high data rate transmission in frequency-selective channels. However, the time selectivity of wireless channel introduces intercarrier interference (ICI), and consequently degrades system performance. In this paper, we first propose a novel recursive algorithm for minimum mean squared error (MMSE) with successive interference cancellation (SIC). The proposed algorithm can significantly reduce the complexity of the MMSE-SIC scheme and achieve the same performance when optimal ordering is known. Also, the further reduced scheme of the proposed algorithm can be developed based on ICI properties, while preserving performance.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.392-404
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• 2011

In this paper, we address the issue of joint detection schemes for uplink cellular system when base station cooperation is possible for multi-user detection in multi-cell scenario. The ZF, ML, MMSE and SIC detection are analyzed and evaluated as a conventional scheme. ML attains the optimal performance but the complexity increases exponentially, ZF/MMSE have simple structure but have poor detection performance and SIC has better performance but it has large complexity and potential of the error propagation. However, they need the increased decoder complexity as the number of iteration is increased. We propose a new joint ML and ZF/MMSE detection scheme, which combines the partial ML decoding and ZF/MMSE detection, in order to decrease the decoder complexity. Simulation results show that the proposed scheme attains same or a little bit better BER performance and expect reduced decoder complexity, specially in the case of large number of Base Station are cooperated each other.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.3
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• pp.17-22
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• 2011

In this paper, we analyze co-channel interference cancellation performance to be generated in multi-hop military communication system. First, remove interference using zero-forcing (ZF) and minimum mean square error (MMSE) scheme as interference cancellation methods, and then obtain additional diversity gain and improve interference cancellation performance by applying successive interference cancellation (SIC). We consider Rayleigh fading channel and system performance is analyzed as respect of bit error probability. From simulation results, we confirm MMSE improves significantly BER performance than ZF in multi-hop wireless network environment. It is also confirmed ZF and MMSE schemes applying SIC algorithm have better performance comparing to the existing schemes. Therefore, MMSE-SIC method can provide more reliable signal transmission in the multi-hop military communication system.

• ETRI Journal
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• v.40 no.2
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• pp.218-226
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• 2018

Multiuser detection (MUD) and channel estimation techniques in space-division multiple-access aided orthogonal frequency-division multiplexing systems recently has received intensive interest in receiver design technologies. The maximum likelihood (ML) MUD that provides optimal performance has the cost of a dramatically increased computational complexity. The minimum mean-squared error (MMSE) MUD exhibits poor performance, although it achieves lower computational complexity. With almost the same complexity, an MMSE with successive interference cancellation (SIC) scheme achieves a better bit error rate performance than a linear MMSE multiuser detector. In this paper, hybrid ML-MMSE with SIC adaptive multiuser detection based on the joint channel estimation method is suggested for signal detection. The simulation results show that the proposed method achieves good performance close to the optimal ML performance at low SNR values and a low computational complexity at high SNR values.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.161-162
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• 2008

In this paper we design an irregular low-density parity-check (LDPC) code for a multi-input multi-output (MIMO) system. The considered MIMO system is minimum mean square error soft-interference cancellation (MMSE-SIC) detector. The MMSE-SIC detector and the LDPC decoder exchange soft information and consist a turbo iterative detection and decoding receiver. Extrinsic information transfer (EXIT) charts are used to obtain the edge degree distribution of the irregular LDPC code which is optimized for the input-output transfer chart of the MMSE-SIC detector. It is shown that the performance of the designed LDPC code is much better than that of conventional LDPC code optimized for the AWGN channel.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.86-87
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• 2011

본 논문에서는 상향링크 다중 사용자 MIMO-OFDM 시스템을 위한 새로운 자원 할당 기법을(resource allocation) 제안한다. 제안된 자원 할당 기법에서는 각 사용자별 전송전력 제한을 만족하면서 주파수 효율이(spectral efficiency) 최대화 되도록 사용자들에게 부반송파와(subcarrier) 전력을(power) 할당한다. 모의 실험 결과에서는 제안된 기법이 기존 기법에 비해 주파수 효율이 증가됨을 보이고 있다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.91-94
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• 2008

본 논문에서는 준 정적(quasi-static) 레일레이 페이딩(Rayleigh fading) 채널에서 상향링크 다중 사용자 MIMO-OFDM 시스템을 위한 최소평균제곱오차-순차간섭제거(MMSE-SIC: Minimum mean square error-successive interference cancellation) 수신기에 대해 연구한다. 송신 안테나가 하나인 사용자와 수신 안테나가 다수인 기지국에서 MMSE-SIC 수신기를 기반으로 신호를 검출하는 시스템에서는 하나의 부대역 내에서 동시에 전송 가능한 사용자의 수가 기지국에서의 수신안테나 수보다 작아야 하는 제한 조건을 가지고 있다. 따라서 사용자간 공정성을 보장하고 시스템의 효율성을 높이기 위해 낮은 복잡도를 가지는 비례 공정(Proportional fair) 스케줄링 알고리즘을 제안한다. 제안된 비례 공정 스케줄링 알고리즘에서는 부대역 내에서 다중 사용자 채널 행렬을 기반으로 동시에 전송하는 사용자들의 집합을 찾는다. 평균 채널 이득이 사용자마다 다른 환경에서의 모의실험을 통해 제안된 비례 공정 스케줄링 기법의 성능을 알아본다. 제안된 비례 공정 스케줄링 기법은 기존의 공정성을 기반으로 하는 스케줄링 알고리즘보다 더 큰 일반 비례 공정(General proportional fair) 기준과 더 높은 셀 수율(Cell throughput)을 가지는 것을 보이고 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2A
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• pp.105-111
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• 2010

Random unitary beamforming (RUB) is a very low complexity and practical transmission scheme for multiuser MIMO broadcast channel. In this paper, we propose the scheme that obtains the spatial multiplexing gain on the extension of the conventional RUB, that is, the receiver with two antennas is compared to that with one antenna in a conventional RUB, which results in the increased capacity. So, we propose the new codebook and the minimum mean square error successive interference cancellation (MMSE-SIC) receiver filter. We show the simulation result that the sum-rate of proposed system is increased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9A
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• pp.917-923
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• 2008

The D-STTD system obtains the diversity gain through the STTD scheme and the Multiplexing gain through parallel structure of the encoder using the STTD scheme known Alamouti Code. We are difficult to use Combining scheme of the STTD scheme for the D-STTD detection in the decoder because the D-STTD system transmits mutually different data in each other STTD encoder for multiplexing gain. Therefore, in this paper we combine the D-STTD system with Linear algorithm, SIC algorithm and OSIC algorithm known multiplexing detection scheme based on MMSE scheme and compare the performance of each system. And we propose the detection scheme of the D-STTD using MAP Algorithm and analyze the performance of each system. The simulation results show that the detector using iterative algorithm has better performance than Linear MMSE Detector. Especially, we show that the detector using MAP algorithm outperforms conventional detector.