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- 저자 : Shoichi Higuchi (검색결과 3 건)
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Reduced complexity and latency for a massive MIMO system using a parallel detection algorithm
Shoichi Higuchi,안창준 한국통신학회 2017 ICT Express Vol.3 No.3
In recent years, massive MIMO systems have been widely researched to realize high-speed data transmission. Since massive MIMO systems use a large number of antennas, these systems require huge complexity to detect the signal. In this paper, we propose a novel detection method for massive MIMO using parallel detection with maximum likelihood detection with QR decomposition and M-algorithm (QRM-MLD) to reduce the complexity and latency. The proposed scheme obtains an R matrix after permutation of an H matrix and QR decomposition. The R matrix is also eliminated using a Gauss–Jordan elimination method. By using a modified R matrix, the proposed method can detect the transmitted signal using parallel detection. From the simulation results, the proposed scheme can achieve a reduced complexity and latency with a little degradation of the bit error rate (BER) performance compared with the conventional method.
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Satoshi Taroda,Ken Tezuka,Shoichi Higuchi,안창준,Kazuki Maruta 한국통신학회 2019 ICT Express Vol.5 No.4
Due to large peak-to-average power ratio (PAPR) at the time domain OFDM signal, various peak signal reduction methods for OFDM systems have been proposed. However, in a transmit OFDM beamforming, multiplication of the transmit signal using the weights causes transmit power imbalance between antennas and increases peak signal. We propose two approaches to mitigate these problems. Adding the pseudo-noise to covariance matrix at the process of weight calculation can alleviate the transmit power imbalance. Furthermore, the companding transform of time domain signal can reduce the peak signals. We show details of proposed methods and evaluate PAPR and BER performance.
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Variable-channel Threshold-based Hybrid AF-DF Cooperative Communications with Packet Splitting
Ken Tezuka,Satoshi Taroda,Shoichi Higuchi,Kazuki Maruta,Chang-Jun Ahn 대한전자공학회 2018 IEIE Transactions on Smart Processing & Computing Vol.7 No.5
Cooperative communications has been widely researched as an attractive way to improve wireless communications systems with a small number of antennas and low power consumption. However, forward processing in the relay terminals means consuming the power of relays in other terminals. Therefore, the waste of electricity from forwarding is to be reduced as much as possible. In this paper, we propose and analyze a new relay system for three-node, hybrid, cooperative communications systems, where the relay terminal may choose to transmit messages using amplifyand-forward (AF) with expansion of the channel matrix or using decode-and-forward (DF) with packet-splitting transmission. This is based on the qualities of the channels in the source–relay and source–destination links. Then, in the proposed system, the decision on the forwarding scheme is made in order to calculate a threshold based on the equation of the channel capacity. From the simulation results, the proposed system can improve the bit error rate and reduce the load from forward processing latency at the relay.
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