• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.12
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• pp.26-33
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• 2008

Signal detection is a key technique in wireless communication system. Recently, several detection algorithms have been developed for multiple-input multiple-output (MIMO) wireless communication systems. However, most research in this area had assumed a flat-fading channel environment and all these techniques are based on the assumption that the channel state information (CSI) at the receiver side is perfect. But in practical situation, the available CSI may be imperfect because of channel estimation errors and/or outdated training. In this paper, we will compare the performance of several detection algorithms in MIMO frequency selective fading channel environment with imperfect CSI.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1722-1724
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• 2015

This paper proposes a partial detection scheme using QRD-M, DFE, and iterative schemes for efficiency in terms of detection performance and complexity in a MIMO-OFDM system. The proposed scheme detects signals by using the different detection methods in according to spatial stream. In the proposed scheme, QRD-M with high detection performance and high complexity is used in spatial stream that requires low complexity, and DFE with low detection performance and low complexity is used in spatial stream that requires high complexity. Also, the iterative detection is performed in the detected spatial stream by using DFE. From the simulation, it is confirmed that although proposed scheme has increased complexity, detection performance is greatly improved by the proposed scheme.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.10
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• pp.75-82
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• 2008

In this paper, we propose an efficient symbol detection algorithm for multiple-input multiple-output spatial multiplexing (MIMO-SM) systems and present its design and implementation results. By enhancing the performance of the first detected symbol which causes error propagation, the proposed algorithm achieves a considerable performance gain as compared to the conventional sorted QR decomposition (SQRD) based detection and the ordered successive detection (OSD) algorithms. The bit error rate (BER) performance of the proposed detection algorithm is evaluated by the simulation. In case of 16QAM MIMO-SM system with 4 transmit and 4 receive ($4{\times}4$) antennas, at $BER=10^{-3}$ the proposed algorithm obtains the gai improvement of about 2.5-13.5 dB over the conventional algorithms. The proposed detection algorithm was designed in a hardware description language (HDL) and synthesized to gate-level circuits using 0.18um 1.8V CMOS standard cell library. The results show that the proposed algorithm can be implemented without increasing the hardware costs significantly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1725-1727
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• 2015

In this letter, a QR decomposition based sequential BP detection scheme is proposed for MIMO systems. The proposed scheme performs the sequential updates from the observation node having the smallest degree among all the observation nodes. Our simulation results verify that the proposed scheme achieves an improved error performance with a significantly accelerated detection convergence speed compared to the conventional schemes.

• ETRI Journal
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• v.46 no.2
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• pp.184-193
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• 2024

This paper presents the performance evaluation of an amplify-and-forward (AF) relay-assisted multiuser multiple input-multiple output (MU-MIMO) downlink transmission system for correlated fading channels. The overall system performance was improved by incorporating a double-quadrature spatial modulation (DQSM) scheme. The bit error rate (BER) performance and detection complexity of the AF-MU-MIMO-DQSM system were analyzed and compared with those of a conventional AF-MU-MIMO system under the same conditions and parameters. The results showed that the correlated fading channel severely affected the performance of systems with higher spectral efficiency (SE). Considering an SE of 12 bpcu/user, the AF-MU-MIMO-DQSM system yielded a gain of up to 3 dB in BER performance compared with that of its conventional counterpart for the analyzed cases. In terms of detection complexity, the AF-MU-MIMO-DQSM system showed a reduction of up to 56 % compared with that of the conventional system for the optimal maximum likelihood detection criterion.

• Journal of Communications and Networks
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• v.17 no.6
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• pp.609-621
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• 2015

Recently, a variety of reduced complexity soft-in soft-output detection algorithms have been introduced for iterative detection and decoding (IDD) systems. However, it is still challenging to implement soft-in soft-output detectors for MIMO systems due to heavy burden in computational complexity. In this paper, we propose a soft detection algorithm for MIMO systems which performs close to the full dimensional joint detection, yet offers significant complexity reduction over the existing detectors. The proposed algorithm, referred to as soft-input soft-output successive group (SSG) detector, detects a subset of symbols (called a symbol group) successively using a deliberately designed preprocessing to suppress the inter-group interference. In fact, the proposed preprocessor mitigates the effect of the interfering symbol groups successively using a priori information of the undetected groups and a posteriori information of the detected groups. Simulation results on realistic MIMO systems demonstrate that the proposed SSG detector achieves considerable complexity reduction over the conventional approaches with negligible performance loss.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.1051-1059
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• 2013

This paper proposes a complexity reduced list sphere decoding (LSD) scheme for joint iterative soft detection scheme for coded MIMO system. The conventional LSD scheme is based on searching the candidates with a fixed radius. However, once the candidate list is full, it is highly probable that the radius can be reduced. By reducing the radius, the complexity can be also reduced. We propose a simple and efficient radius update method for complexity reduction of list version sphere decoding and its application to iterative soft MIMO detection. We evaluate the performance of the proposed scheme with a joint soft-input-soft-ouput iterative MIMO detection in combination with turbo codes. Simulation results show that the proposed methods provide substantial complexity reduction while achieving similar bit error rate (BER) performance as the conventional LSD scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.9
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• pp.3907-3923
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• 2020

An enhanced irregular repetition slotted ALOHA (IRSA) protocol is proposed by using polarization characteristic of satellite link and MIMO detection in low earth orbit (LEO) satellite networks, which is dubbed polarized MIMO IRSA (PM-IRSA). In the proposed scheme, one or two packets in one slot can be decoded by employing polarized MIMO detection, and more than two collided packets in multiple slots which can construct the virtual MIMO model can be decoded by the MIMO detection algorithm. The performance of the proposed scheme is analyzed with the density evolution (DE) approach and the degree distribution is optimized to maximize the system throughput by using a differential evolution. Numerical results certify our analysis and show that the normalized throughput of the proposed PM-IRSA can achieve 1.89 bits/symbol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3A
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• pp.231-237
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• 2010

Multi-input multi-output (MIMO) systems are used to improve the transmission rate in proportion to the number of antennas. However, their computational complexity is very high for the detection in the receiver. The sphere decoding (SD) is a detection algorithm with reduced complexity. In this paper, an improved Schnorr-Euchner SD (SE SD) is proposed based on the minimum mean square error (MMSE) and the Euclidean distance criteria without additional complexity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.5
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• pp.974-979
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• 2009

The BER performance of a MIMO detection scheme on frequency selective Rayleigh fading channels is analytically discussed. The presented MIMO detection scheme consists of temporal and spatial combiners followed by a ZF detector. It is shown that for a MIMO system with $N_T$ transmit antennas, $N_R$ receive antennas, and L resolvable multipath components, it achieves the diversity order of $LN_R-N_T+1$. In frequency selective Rayleigh fading channels, an analytical error rate expression of the systems is also provided and the analytical error performance is compared with the simulated results.