Browsing by Author "Cheng, Chung-Chao"

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A 501mW 7.61Gb/s Integrated Message-Passing Detector and Decoder for Polar-Coded Massive MIMO Systems
(2017-01-01)
Chen, Yan-Tong
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Cheng, Chung-Chao
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Tsai, Tsung-Lin
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Sun, Wei-Cheng
;
Ueng, Yeong-Luh
This work presents the first integration of a message-passing detector (MPD) and a polar decoder. A soft-output MPD, which is essential to approach the channel capacity, is first proposed. Compared to the state-of-the-art design, the proposed MPD achieves a 6.9x higher throughput with 49% lower energy, despite the soft outputs. The proposed polar decoder achieves a 1.35x higher throughput with comparable energy. The chip delivers a throughput of 7.61Gb/s for massive MIMO systems with up to 128 antennas and 32 users.
A Fully Parallel LDPC Decoder Architecture Using Probabilistic Min-Sum Algorithm for High-Throughput Applications
(2014-09-01)
Cheng, Chung-Chao
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Yang, Jeng-Da
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Lee, Huang-Chang
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Yang, Chia-Hsiang
;
Ueng, Yeong-Luh
This paper presents a normalized probabilistic min-sum algorithm for low-density parity-check (LDPC) codes, where a probabilistic second minimum value, instead of the true second minimum value, is used to facilitate fully parallel decoder realization. The comparators in each check-node unit (CNU) are connected through an interconnect network based on a mix of tree and butterfly networks such that the routing and message passing between the variable-node units (VNUs) and CNUs can be efficiently realized. In order to further reduce the hardware complexity, the normalization operation is realized in the VNU rather than in the CNU. An early termination scheme is proposed in order to prevent unnecessary energy dissipation for both low and high signal-to-noise-ratio regions. The proposed techniques are demonstrated by implementing a (2048, 1723) LDPC decoder using a 90 nm CMOS process. Post-layout simulation results show that the decoder supports a throughput of 45.42 Gbps at 199.6 MHz, achieving the highest throughput and throughput-to-area ratio among comparable works based on a similar or better error performance.
An Integrated Message-Passing Detector and Decoder for Polar-Coded Massive MU-MIMO Systems
(2019-03-01)
Chen, Yan-Tong
;
Sun, Wei-Cheng
;
Cheng, Chung-Chao
;
Tsai, Tsung-Lin
;
Ueng, Yeong-Luh
For a coded massive multi-user multiple-input multiple-output (MIMO) system, a soft-output MIMO detector is essential since it can provide a significant coding gain, e.g., 3 dB, compared with a hard-output detector. However, the computational complexity of the soft-output MIMO detector is usually much greater than that of the hard-output detector. This paper presents the first soft-output message-passing detector (MPD), which is also integrated with a high-throughput polar decoder. The algorithm and architecture are designed concurrently to improve the hardware performance. The proposed techniques, including the adaptive variance estimation and reliable symbol detection, reduce the complexity of the MPD by 98.3%, and enable soft output for the outer polar decoder. Compared to the state-of-the-art hard-output design, the proposed MPD achieves a 5.86x higher throughput-to-area ratio (TAR) with 54.3% lower energy dissipation, despite the soft output. The proposed bidirectional-propagation belief propagation decoder is devised to reduce the critical path and to increase the throughput. The proposed polar decoder can improve the TAR by 35% with a comparable area and energy compared with the state-of-theart polar decoder. A polar-coded massive MIMO receiver that supports a length-1024 rate-1/2 polar code, 128 receive antennas, and eight users is designed and implemented, and delivers a throughput of 7.61 Gb/s.