Browsing by Author "Lin, You-Hsien"

Now showing 1 - 6 of 6

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
;
Lin, You-Hsien
;
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 Blind Statistical Approach for Optimal Receive Beam Steering in Multipath Environments
(2012)
Tsai, Tsung-Yu
;
Ko, Ta
;
Lin, You-Hsien
;
Tsai, Zsehong
;
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.
Digital Self-Interference Cancellation Via Dynamic Regression for In-band Full-Duplex System
(2016)
Lin, You-Hsien
;
Liao, Yuan-Te
;
Chu, Jian-Ya
;
Su, Po-Ju
;
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.
Low-Complexity All-Digital Sample Clock Dither for OFDM Timing Recovery
(2010-07-01)
Lin, You-Hsien
;
Hsu, Terng-Yin
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資訊工程學系
;
Department of Computer Science
Based on phase adjustment, this work investigates a low-complexity all-digital sample clock dither (ADSCD) to perform coherent sampling for orthogonal frequency-division multiplexing (OFDM) timing recovery. To reduce complexity, only tri-state buffers are acquired to build a multiphase all-digital clock management (ADCM), which can generate more than 32 phases over gigahertz without phase-locked or delay-locked loops. Following divide-and-conquer search and triangulated approximation, the phase adjustment is simple but efficient, such that four preambles are adequate to make analog-to-digital (A/D) sampling coherent. Performance evaluation indicates that the proposed ADSCD can tolerate +/-400-ppm clock offsets with 0.8 similar to 1.3 dB signal-to-noise ratio (SNR) losses at 8% PER in frequency-selective fading. Hence, this scheme involves a little overhead to ensure fast recovery and wide offset tolerance for OFDM packet transmissions.
Low-Complexity Beam Steering Algorithm Based on Binary Search Strategy for Receive Beamform
(2012)
Lin, You-Hsien
;
Tsai, Tsung-Yu
;
Chen, Ying-Liang
;
Ko, Ta
;
Chien, Chun-Che
The complexity of beamforming, such as complexity complex weighting and combining process, are extremely important for implementation. This work presents a low complexity time-domain statistic noise suppression and beam steering algorithm based on binary search strategy to estimate the optimal beam vector at the receivers. The beam steering algorithm based on binary search strategy could achieve closely (about 99%) optimal SNR gain within only two binary search. It is desirable choice to archive the suitable trade-off between the performance and the processing overhead. Hence, it could obtain a near-optimal performance with considerably low complexity and high convergence speed. In addition, this algorithm is well-matched to different specifications.
Synchronous sampling and SNR-based gain control in DS/CDMA systems
(2007)
Lin, You-Hsien
;
Lo, Shih-Lin
;
Lai, Wei-Chi
;
Juan, Ta-Yang
;
Hsu, Terng-Yin
Timing synchronization is an important component in a receiver designed to recover data form sampling digital waveform. A synchronous sampling recovery with dual correlator differential (DCD) based acquisition with effects of auto-gain controller (AGC) is proposed to achieve fast timing acquisition for direct sequence / code division multiple access (DS/CDMA) system over frequency-selective fading channel in this paper. It measures both received DCD difference power to determine the good sampling phase from an all-digital phase interpolator based multiphase generator. This solution can tolerate 50ppm system clock offset (SCO) under frequency-selective fading channel. Hence, we not only to determine the good sampling phase fast, but also to arrive stable variable gain amplifier (VGA) with AGC controller in DS/CDMA system approaches.