Browsing by Author "Hsu, Terng-Yin"

Now showing 1 - 20 of 36

A 62.8 mW 4x4 MIMO-OFDM Modem with One-Symbol-Locked Timing Recovery, Frequency-Dependent I/Q Mismatch Estimation and Adaptive Equalization
(2009)
Sun, Ming-Fu
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Lin, You-Hsien
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Lai, Wei-Chi
;
Juan, Ta-Yang
;
Lee, Cheng-Yuan
A 4x4 multi-input multi-output (MIMO) orthogonal frequency-division multiplexing (OFDM) modem with one-symbol-locked timing recovery, anti-I/Q mismatch frequency recovery, frequency-dependent I/Q mismatch estimation and adaptive equalization is implemented in 0.13-mu m CMOS library. This chip occupies 4.6x4.6 mm(2) and consumes 62.8 mW at 1.2 V.
A Bit Allocation Scheme for MIMO Equal Gain Precoders
(2010)
Chao, Chi-Liang
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Tsai, Shang-Ho
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Hsu, Terng-Yin
;
資訊工程學系
;
電機工程學系
We consider the design of the equal gain precoder in flat-fading and limited feedback multiple-input multiple-output (MIMO) systems. The advantage of the equal gain precoder based on the scalar quantization (SQ) is that it is easier to encode the feedback information and no need to construct codebook in advance. In the sort of precoder, the bit allocation methods will dominate the system performance. In this paper, we explore an efficient bit allocation algorithm for the scalar quantized equal gain precoder. The proposed bit allocation scheme can improve the performance of the straightforward scalar quantized equal gain precoder. Compared to the optimal bit allocation scheme with exhaustive search, the proposed algorithm greatly reduces the computational complexity while the performance is near to the optimal scheme.
A Blind Statistical Approach for Optimal Receive Beam Steering in Multipath Environments
(2012)
Tsai, Tsung-Yu
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Ko, Ta
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Lin, You-Hsien
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Tsai, Zsehong
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Hsu, Terng-Yin
A novel blind statistical algorithm for obtaining the optimal receive beam vector with maximum time-domain effective SNR in OFDMA systems under multipath environment is proposed. The basic procedure of the proposed approach is obtained via the coarse cyclic prefix (CP) detection first and the sample average of the correlation matrices is calculated from selected signal samples for later singular value decomposition (SVD) on the averaged correlation matrix. The proposed approach has the following advantages: First, it is accurate even in the presence of high noise power and when the process of the OFDMA sampled signals are not white (i.e. not all subcarriers are allocated for data transmission). Secondly, it can be operated in time-domain with no training signals and no pre-assumption of the antenna array structure. Hence, it could be applied directly to a variety of existing OFDMA systems and its design can be made relatively simple for implementation. Theoretical proofs of its optimality and the guarantee of convergence are also provided in this paper. Finally, simulation results verifies the theoretical analysis and shows that the proposed approach can accurately achieve a near optimal SNR gain even in low SNR environment and has a convergence speed within two OFDM symbols.
A Cost-Effective Adaptive Overlapped Cluster-Based MIMO Detector in a Frequency Domain Reconfigurable Modem
(2019-01-01)
Liao, Yuan-Te
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Hsu, Terng-Yin
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資訊工程學系
;
Department of Computer Science
Not only to reduce the candidates but also to maintain detection performance in multiple-input multiple-output (MIMO) detection, an adaptive overlapped cluster (AOC) scheme to balance detection error and computing cost is built for 4 x 4 and 8 x 8 MIMO-OFDM systems with up to 256 quadrature amplitude modulation (QAM). The constellations are partitioned into several clusters. A cluster with size decided by channel status is chosen for signal decoding. Different partition schemes are combined to minimize the numbers of clusters required to cover a candidate symbol as the pre-estimated signal falls at cluster edges, namely overlapped clustering. The simulations of a 4 x 4 MIMO OFDM with 64 QAM and 8 x 8 MIMO OFDM with 256 QAM hint that the AOC-based detection requires an additional 0.57 dB and 1.02 dB compared to maximum likelihood (ML). Compared with K-best sphere decoding (SD), it is reduced the computing complexity to 24.50% similar to 56.25% in 4 x 4 MIMO OFDM and, 35.00% similar to 56.25% in 8 x 8 MIMO OFDM. In addition, the proposed scheme is ported to a reconfigurable frequency-domain (1-D) modem, which is designed and implemented via TSMC 45-nm technology, with multi-rate clocking and processing elements (PEs) upgrading for supporting the proposed MIMIO detection. The results show that the throughput is 1077.8 Mbps with 4 x 4 64-QAM modulations.
A Cost-Effective Preamble-Assisted Engine With Skew Calibrator for Frequency-Dependent I/Q Imbalance in 4 x 4 MIMO-OFDM Modem
(2013-08-01)
Lai, Wei-Chi
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Liao, Yuan-Te
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Hsu, Terng-Yin
;
資訊工程學系
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Department of Computer Science
Variations in I/Q gains, phases, and filters of the RF frontend, namely frequency-dependent I/Q imbalance (FDI), are an important factor in OFDM-based wireless access. To enable the proper function of a 4 x 4 MIMO-OFDM receiver this work proposes a low-complexity preamble-assisted solution using only one complex divider and one complex multiplier to handle significant FDI distortions. An all-digital multiphase and multi-rate clock generator (MPRCG) was built to support fast dynamic frequency scaling for FDI estimation and compensation and for efficient implementation. Based on the proposed MPRCG, a skew calibration was also realized to tune I/Q timing coherently via multiphase A/D clocking. Performance evaluation showed that the proposed approach incurs an SNR loss of 1.5 dB to maintain a packet-error rate of less than 10% under a 1 dB gain error, 15 degrees phase error and worse filter mismatch. Thus, this solution not only provides adequate performance, but also makes FDI estimation and compensation more cost-effective.
A DIFFERENTIAL FEEDBACK SCHEME FOR EQUAL GAIN TRANSMISSION IN TEMPORALLY CORRELATED CHANNELS
(2012-01-01)
Chao, Chi-Liang
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Tsai, Shang-Ho
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Hsu, Terng-Yin
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資訊工程學系
;
電機工程學系
The adoption of equal gain transmission (EGT) in MIMO systems can greatly reduce the computational complexity and the design effort of power amplifier. In a temporally correlated channel environment, the channel varies slowly and so does the corresponding beamforming vector. If the slowly varying channel condition can be taken into consideration while designing the feedback schemes of EGT, the computational complexity and feedback overhead of EGT are expected to be further diminished dramatically. In this paper, we propose a differential feedback scheme (DFS) with two algorithms to further improve the performance in EGT. Simulation results show the advantages of the proposed DFS in terms of the feedback overhead and the system performance.
A VARIABLE-GAIN TIME AMPLIFIER WITH AUTOMATIC INTERVAL DETECTION
(2015)
Hsiao, Frank
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Lai, Jung-Chin
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Hsu, Terng-Yin
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資訊工程學系
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Department of Computer Science
This paper presents an all-digital standard cell SR-Latch based time amplifier (TA) with a variable gain of 6X and 12X. In this TA, a two-stage gain selection unit is applied to enable the TA to select either the high gain for short input pulse intervals or the low gain for long input pulse intervals. The time amplification gain is 6 in the input range of -700ps similar to 700ps, and reaches 12 if the input range is -300 similar to 300ps. We present a design that automatically detects the input pulse and switches to the proper TA gain. By applying the proposed TA, a standard cyclic TDC implemented in a UMC CMOS
Adaptive Frequency-Domain Channel Estimator in 4 x 4 MIMO-OFDM Modems
(2009-11-01)
Sun, Ming-Fu
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Juan, Ta-Yang
;
Lin, Kan-Si
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Hsu, Terng-Yin
;
資訊工程學系
This work presents an adaptive frequency-domain channel estimator (FD-CE) for equalization of space-time block code multiple-input multiple-output ( MIMO) orthogonal frequency-division multiplexing (OFDM) systems in time-varying frequency-selective fading. The proposed adaptive FD-CE ensures the channel estimation accuracy in each set of four MIMO-OFDM symbols. Performance evaluation shows that the proposed method achieved a 10% packet error rate of 64 quadrature amplitude modulation (QAM) at 29.5 dB SNR under 120 km/h ( Doppler shift is 266 Hz) in 4 4 MIMO-OFDM systems. To decrease complexity, the rich feature of Alamouti-like matrix is exploited to derive an efficient very large-scale integration (VLSI) solution. Finally, this adaptive FD-CE using an in-house 0.13-m CMOS library occupies an area of 3 X 3.1 mm(2), and the 4 X 4 MIMO-OFDM modem consumes about 62.8 mW at 1.2 V supply voltage.
All-Digital Mismatched Calibrator and Compensator for SR Latch-Based Variable-Gain Time Amplifier
(2020-01-01)
Chao, Kuan-Chieh
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Lai, Jung-Chin
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Hsu, Terng-Yin
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資訊工程學系
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Department of Computer Science
Two major mismatches in SR latch-based time amplifiers (TA) include input skew, which causes gain imbalance, and loading mismatch, which reduces gain accuracy. Accordingly, we propose an all-digital mismatched self-calibrator and compensator for an SR latch-based variable-gain TA. Tunable matching cells and variable capacitors are built into TAs to compensate for input skew (gain imbalance) and loading mismatch (gain inaccuracy). To ensure that the proposed calibration works efficiently and accurately, the TA must provide at least high and low gains where the low gain calibrates the most significant bit (MSB) and the high gain calibrates the least significant bit (LSB). This self-calibrator costs 4375 gates, and the power consumption is 2.8 mA for the TA gain with 2 and 3.2 mA for the TA gain with 16 at a sampling rate of 10 MHz.
An IoT-Based Cloud-Fog Computing Platform for Creative Service Process
(2017-01-01)
Hsu, Tse-Chuan
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Hsu, Terng-Yin
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Yang, Hongji
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Chung, Yeh-Ching
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資訊工程學系
The creative service process is an innovative process that uses newly developed technologies to improve the service models currently used. In this paper, we proposed an IoT-based Cloud-Fog computing platform for the creative service process. The proposed Cloud-Fog computing platform is a distributed computing platform where compute, storage, and network systems of Cloud and Fog are working independently or collaboratively depending on the services performed by the platform. If a service requires resources either from Cloud or Fog, then only the designated Cloud or Fog will be involved. Otherwise, both Cloud and Fog will be collaborated to each other for the service. During the collaboration, the required data may be back and forth in between Cloud and Fog. To demonstrate the usage of the proposed platform for the creative service process, two service examples, smart classroom and city surveillance, are discussed
Bit Allocation Schemes for MIMO Equal Gain Precoding
(2011-05-01)
Chao, Chi-Liang
;
Tsai, Shang-Ho
;
Hsu, Terng-Yin
;
資訊工程學系
;
電機工程學系
We design equal gain precoders with scalar quantization in MIMO systems with limited feedback, which do not require the predefined codebook. In such precoders, bit allocation can be used to quantize the precoding vector/matrix to further improve the system performance. There are two conventional bit allocation schemes. One is the uniform bit allocation and the other is the optimal bit allocation obtained by using exhaustive search. The uniform bit allocation is simple but turns out to have obvious performance degradation. On the other hand, the exhaustive search method leads to the optimal performance. However, its computational complexity is extremely high and may be somewhat impractical to be realized. In this paper, we propose two bit allocation schemes for the MIMO equal gain precoder with scalar quantization. Both of the proposed methods are with low complexity and their performance is close to the optimal scheme. Consequently, the proposed bit allocations provide good trade-off between performance and complexity.
Channel Estimator and Aliasing Canceller for Equalizing and Decoding Non-Cyclic Prefixed Single-Carrier Block Transmission via MIMO-OFDM Modem
(2011-01-01)
Cheng, Shau-Yu
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Tsai, Chueh-An
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Hsu, Terng-Yin
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資訊工程學系
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Department of Computer Science
Without a cyclic prefix (CP), most single-carrier (SC) transmissions can not adopt frequency-domain equalizer (FDE) directly. This work utilizes frequency-domain channel estimator (FD-CE) and decision-feedback aliasing canceller (DF-AC) to produce single-FFT SC-FDE. In this way, non-CP single-carrier block transmission (SCBT) can be decoded using sphere decoder of MIMO-OFDM modems to support multimode and backward compatibility under an acceptable complexity in IEEE 802.11 very high throughput (VHT). An N-point FFT is sufficient to measure channel frequency responses (CFR) from L-sample preambles (L <= N/2). And then, M-bit block codes (M <= L) are decodable over frequency domains with DF-AC's help. Simulations and measurements imply that this work can ensure adequate performance, even if there is no CP existed against the distortions of multipath propagation.
Cost-Effective Time-to-Digital Converter Using Time-Residue Feedback
(2017-06-01)
Lai, Jung-Chin
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Hsu, Terng-Yin
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資訊工程學系
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Department of Computer Science
This paper proposes a time-residue feedback scheme to balance resolution and complexity in a cell-based time-to-digital converter (TDC). The time residue is amplified and fed back into a cyclic-ring Vernier recursively until it cannot be detected correctly. Only one variable-resolution cyclic-ring Vernier and one tunable delay-chain time amplifier (TA) are adopted. Both coarse and fine oscillators of the proposed Vernier which are designed by the same variable-resolution digital controlled oscillator can be switched off to decrease ground bounce during TA activities. With various control codes, the TDC resolution is also programmable. The test application-specified integrated circuit which has a 13-b resolution and occupies 0.02 mm(2) in TSMC 65-nm CMOS process can operate in either feedback or feedforward mode. In feedback mode, the measurements of sampling rate, resolution, input range, differential nonlinearity, and integral nonlinearity are 10 MHz, 0.98 ps, 5.76 ns, +/- 0.8 LSB, and +/- 2.2 LSB, respectively; it also consumes 3 mW at 1 V supply voltage. The sampling rate, resolution, and power dissipation of the feedforward operation are 250 MHz, 6.01 ps, and 17.5 mW, respectively.
Cost-Efficiency FFT Using Hardware-Reduction and Dynamic Current Scaling Approaches
(2014)
Chen, Ying-Liang
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Hsu, Terng-Yin
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資訊工程學系
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Department of Computer Science
In this paper, we disclosure a cost-efficiency FFT via hardware-reduction and dynamic current scaling (DCS) schemes in a low-power OFDM modem. These reductions are realized by the pipelined data path modifying and the hardware sharing at two stages. For low power, the operating current is scalable to reduce power consumption, namely DCS. All our works are synthesized and simulated by the TSMC 65nm CMOS technology. It can perform high efficient computing power at FFTs/Energy.
Cost-Efficient Frequency-Domain MIMO-OFDM Modem With an SIMD ALU-Based Architecture
(2015-12-01)
Yeh, Shao-Ying
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Liao, Yuan-Te
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Lai, Wei-Chi
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Hsu, Terng-Yin
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資訊工程學系
In this paper, a single instruction multiple data (SIMD) arithmetic logic unit (ALU)-based architecture is proposed to improve hardware efficiency in a 4 x 4 frequency-domain multiple input multiple output-orthogonal frequency division multiplexing modem based on a space-time block code (STBC). The majority of mathematic units in the proposed architecture are centralized so that any mathematic unit can be shared with any algorithm. Six advanced instructions are also defined in the ALU: 1) complex multiplication; 2) complex division; 3) correlation; 4) channel estimation; 5) 4 x 4 matrix inversion; and 6) STBC-based decoding. A scheduler is essential to handle all data paths and signaling flows smoothly with the use of an SIMD ALU. As a result, it is relatively easy to reconfigure the proposed design for different specifications. The very large scale integration implementation of this chip, using an in-house 65-nm CMOS process, consumes a total of 1.87 M gates and draws 33.7 mW at a supply voltage of 1 V.
Cross-Validation Estimation for Frequency-Dependent I/Q Imbalance in MIMO-OFDM Receivers
(2010-07-01)
Lai, Wei-Chi
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Juan, Ta-Yang
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Hsu, Terng-Yin
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Chiou, Sheng-Lun
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資訊工程學系
The effects of variation in RF, such as I/Q imbalance and filter mismatch, are extremely important for OFDM wireless accesses. This work presents a low-computational estimation of I/Q imbalances with filter mismatches to improve performance in MIMO-OFDM receivers. For N x N MIMO-OFDM systems, the proposed cross-validation estimation is such that, only N + 1 preambles are required to extract the mismatches of filters, gains and phases. With the estimated parameters, frequency-domain filters are exploited to correct frequency-dependent I/Q imbalances. Through performance evaluation of a 2 x 2 MIMO-OFDM system, with ideal channel estimations this study incurs a SNR loss of 1-1.2 dB to maintain a 10% PER at 1-dB gain error, 10A degrees-phase error and the worst 180A degrees-filter mismatch. In addition, this algorithm is well-matched to IEEE 802.11n and new specifications discussed in IEEE 802.11 VHT study group.
Design and Integration of Fiber Fronthaul with Soft PHY for OAI-BASED RAN
(2018-01-01)
Huang, Wei-Hsin
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Hsu, Terng-Yin
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資訊工程學系
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Department of Computer Science
For high-speed communications need, Fronthaul, a new mobile architecture related to RAN-based networks, has been widely used in 4G/5G mobile network. Compared with the traditional architecture of the baseband station, Fronthaul is divided into baseband unit (BBU) and remote radio head (RRH). Due to the separation, the interface between BBU and RRH requires more effort to handle the data rate transmission. In this paper, we propose the fiber Fronthaul to achieve the high bandwidth requirement. The BBU includes the SoftPHY OAI running on Intel 17-6700 CPU and the data collector implemented by Xilinx VC707. The RRH is implemented by Xilinx ZC706. And the RF front-end is implemented by Analog Devices AD-FMCOMMSS-EBZ. The interface between the SoftPHY OAI and the data collector is PCIe, and the interface between the data collector and the RRH is optical fiber. It is important that we design the synchronization scheme to synchronize and calibrate the real-time clock (RTC) of different RRH. Therefore, the proposed fiber Fronthaul with SoftPHY OAI can achieve the long distance, stability and high speed transmission.
Design of applying FlexRay-bus to federated archiectecture for triple redundant reliable UAV flight control system
(2017-01-01)
Wu, Chang-Han
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Chen, Ti-Jui
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Hsu, Terng-Yin
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Tsai, Shang-Ho
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Chang, Hsung-Pin
For an Unmanned Aerial Vehicle (UAV) performing a mission, any failure of the flight control system can result in fatal disaster. Therefore, reliability requirement for UAV flight control system becomes increasingly important and then the redundancy technology is considered as a solution to enhance system reliability. This paper studies the designs of reliability, system architecture, and redundancy management logic for UAV flight control system. Therefore, a reliable federated architecture design for triple redundant UAV flight control system is introduced, in which the distributed hardware design combined with centralized software framework was adopted as well. The number of subsystems in the case study is more than that of centralized architecture and less for distributed architecture. Next, the fault detection and fault tolerant design can be achieved, and simultaneously the design problems associated with distributed software framework was reduced. Furthermore, by using the distributed hardware, system's reliability requirement of single hardware module was decreased. Consequently, the goal of high reliability for the entire system reached. Finally, FlexRay bus with time-trigger mechanism was chosen to simulate the communication of such a federated architecture designed. The experimental results show that the design is reasonable and satisfy the high reliability, high performance-price ratio and high expandability requirements of UAV flight control system.
Digital Self-Interference Cancellation Via Dynamic Regression for In-band Full-Duplex System
(2016)
Lin, You-Hsien
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Liao, Yuan-Te
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Chu, Jian-Ya
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Su, Po-Ju
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Hsu, Terng-Yin
For enhancing spectrum efficiency, in-band full duplex technology is one of the candidate technical solution. Rut, self-interference (SI) signal causes dramatically degrade the performance. In practically, memory effect which cause harmonic in amplifier will be hard to be estimated. Therefore, we utilizes the dynamic regression (DR) to implement digital interference cancellation (DIC) for mitigate the memory effect. Two platforms are constructed to evaluate this mechanism. In both platforms, the SI signal could effectively reduction and the residual signal could be attenuated close to noise floor. In software-defined radio (SDR) platform also proves that the proposed dynamic regression based DIC (DRDIC) is sufficient to attenuate the SI signal, where successfully perform video streaming demonstration.
Error-Tolerant and Energy-Efficient FFT with Dynamic Current and Frequency Scaling (DCFS)
(2015)
Chen, Ying-Liang
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Hsu, Terng-Yin
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資訊工程學系
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Department of Computer Science
This work utilizes the dynamic current scaling (DCS) to control the pMOS array for outputting the sufficient operating current. It makes the FFT modules work under the lower power-consummation operating mode. Furthermore, to guarantee the DCS current is enough for the whole system. We need the online error detection. In this work, we just apply the adaptive sequential elements to determine the critical path delay and whether the timing constraint is met or not. When the error occurred, the system will perform the re-computing process to increase clock rate to recover errors via dynamic frequency scaling (DFS). All this work was synthesized and simulated with TSMC 65nm technology.