Browsing by Author "Lin, Ying-Tsung"

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A Blind Fine Synchronization Scheme for SC-FDE Systems
(2014-01-01)
Lin, Ying-Tsung
;
Chen, Sau-Gee
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work presents a blind fine synchronization scheme, which estimates and compensates residual carrier-frequency offset (RCFO) and symbol timing offset (STO), for single-carrier frequency-domain equalization (SC-FDE) systems. Existing fine synchronization schemes for SC-FDE systems rely on time-domain unique words (UW) sequences as reference signals to assure the estimation accuracy, at the cost of decreased system throughput. The proposed technique, named simplified weighted least-square method for single-carrier systems (SWLS-SC), combines the decision feedback structure and SWLS estimator for OFDM systems. Together with specifically derived weighting factors, it has much better estimation accuracy than the well-known linear least-square (LLS) method for SC-FDE systems, and its BER performance can approach that of the ideal synchronization condition. The proposed technique is more effective than existing techniques, in terms of both performance and throughput. Theoretical estimation bounds are also derived to verify the effectiveness of the proposed method.
A Data Detection Scheme for Single-Carrier Block Transmission Using Sphere Decoding Algorithm
(2010)
Lin, Ying-Tsung
;
Kuo, Chia-Hsun
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Chen, Sau-Gee
;
Fang, Wai-Chi
;
電子工程學系及電子研究所
In this paper, an efficient sphere decoding algorithm (SDA) applied to solve the inter-symbol-interference (ISI) data detection problem is proposed. This proposed algorithm takes advantages of the SDA to obtain the solution close to ML solution with the simplified K-best tree search method for the ISI data detection under ISI effect. Compared with the frequency-domain MMSE or Zero-Forcing equalization techniques for SCBT (Single-Carrier Block Transmission) systems, this algorithm can perform at least 1.5dB better than frequency-domain equalizers under the environment of randomly generated channel impulse responses.
An Efficient Blind Fine Synchronization Scheme for SCBT Systems
(2012)
Lin, Ying-Tsung
;
Chen, Sau-Gee
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work presents a new technique which can blindly perform the fine synchronization for single-carrier block-transmission (SCBT) systems without using unique words (UW). The proposed technique, called simplified weighted LS method for single-carrier systems (SWLS-SC), combines the concept of the decision feedback structure and SWLS estimator for OFDM systems. Together with specifically derived weighting factors, the proposed scheme has much better estimation accuracy than the well-known linear least-square (LLS) method for SC systems, while its BER performance can approach that of the ideal synchronization condition. With the proposed estimator, the system throughput can be further increased, because there is no need to insert UW for fine synchronization. The theoretical estimation bounds are also derived to prove the effectiveness of the proposed scheme.
An Efficient Searching Algorithm for High DoF Non- Uniform Linear Antenna Array with Constrained Spacing
(2015)
Hsiao, Po-Chung
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Lin, Ying-Tsung
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Chen, Sau-Gee
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work proposes a systematic algorithm to build up a spacing-constrained non-uniform linear array ( NLA) configuration. Obtainable DoF due to the proposed algorithm can have much better performance than existing NLA configurations. By further applying spatial smoothing and array interpolation techniques, performance indices, such as number of incident signal ( NIS) detection and direction of arrival ( DoA) estimation, of an antenna array are also demonstrated to be significantly enhanced. In addition, simulation results also illustrate that beamforming techniques based on the proposed NLA configurations can provide much better signal-to-interference-plus-noise ratio ( SINR) to a wireless communication system than existing NLA approaches.
An SNR-Aware Inter-Symbol Data-Mapping Precoding Scheme for Single-Carrier Systems
(2012)
Lin, Ying-Tsung
;
Chen, Sau-Gee
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work proposes an inter-symbol data-mapping (ISDM) precoding scheme, which allows the receiver to adaptively select its most suitable data decoder based on the estimated SNR or channel conditions, for single carrier systems. For conventional modulation schemes, the only decoding method for traditional modulations, such as PSK and QAM, is to apply the maximum likelihood (ML) method after channel equalizations. Moreover, if the estimated SNR is unreliable enough to correctly decode the incoming signal, the received frame is usually discarded. As such, the communication system has to lower the symbol modulation order and re-transmit the data. The proposed ISDM scheme rearranges and re-maps a block of data bits to be transmitted so that they are correlated. Then, the receiver can decode the received signal by dynamically selecting the following three proposed decoders: postequalization ML (PEML) decoder, full-rate most-significant-bit (FR-MSB) decoder and down-rate (DR) decoder based on estimated channel SNRs. For the FR-MSB decoder, its performance is close to the conventional BPSK decoder. On the other hand, PEML decoder can have roughly 2dB better performance than the FR-MSB one, while the DR decoder performs poorer than the FR-MSB one but with a lower computational complexity. Although the DR decoder has lower performance than the other two, its major advantage is able to decrease the ADC sampling rate with the help of multi-phase PLL. As such, the ISDM precoding scheme can provide the system better flexibility in data decoding.
LOW-COMPLEXITY AND HIGH-PERFORMANCE NON-COHERENT CELL IDENTIFICATION DETECTION SCHEMES FOR OFDM-BASED SYSTEMS
(2013)
Lin, Ying-Tsung
;
Wang, Yi-Hsiang
;
Chen, Sau-Gee
;
Chen, Chih-Liang
;
電子工程學系及電子研究所
This work proposes two low-complexity and high-performance cell ID detection schemes for cellular communication systems. The first one, called real-correlation multiple differential detection (RMDD), derived from our previous work on cell ID detection called CERCD method, has much less complex multiplication operations while maintains the same performance. Although CERCD algorithm is more robust than existing cell detection methods in AWGN and multipath channel conditions, its performance still can be further improved. As such, the second scheme, called multiple differential detection (MDD), is proposed to improve CERCD method. Simulation results show that MDD has much better performance in frequency-selective channels. Performances and computational complexities of proposed schemes are also evaluated and analyzed under different channel environments to demonstrate their effectiveness.(1)
Robust Distributed Beamforming Design in Amplify-and-Forward Relay Systems with Multiple User Pairs
(2015)
Hsieh, Pei-Wen
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Lin, Ying-Tsung
;
Chen, Sau-Gee
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電子物理學系
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Department of Electrophysics
In this work, a signal-to-interference-plus-noise ratio (SINR)-based robust distributed beamforming scheme is proposed for one-way amplify-and-forward (AF) relay systems with multiple user pairs. The proposed scheme obtains its optimal beam vectors by utilizing convex semi-definite programming (SDP) optimization with newly derived bounds for signal and interference powers. Compared with existing works, the proposed scheme has much higher probability of obtaining the optimal solution than schemes applying approximate bounds exploiting Cauchy-Swartz (CS) inequality. In addition, in terms of transmit power consumption, the proposed scheme requires less transmit power than existing works while still satisfying the SINR constraints. Simulation results also demonstrate that the proposed SDP-based method outperforms the existing SDP-based methods.
Self-steepening of prechirped amplified and compressed 29-fs fiber laser pulse in large-mode-area erbium-doped fiber amplifier
(2007-11-01)
Lin, Gong-Ru
;
Pan, Ci-Ling
;
Lin, Ying-Tsung
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光電工程學系
;
Department of Photonics
Prechirped amplification, soliton compression, and self-pulse-steepening of a 300-fs stretch-pulse mode-locked erbium-doped fiber laser (EDFL) pulse in an ultrashort length large-mode-area erbium-doped fiber amplifier (LMA-EDFA) and large-effect-area fiber (LEAF) link are investigated. In situ amplified compression of the single-mode-fiber prechirped EDFL pulse (broadened to 1.2 ps) is initiated in the LMA-EDFA at a pumping power of > 160 mW, which provides a 20-fold pulsewidth-compressing ratio for the incoming EDFL pulse and supports a maximum output power of > 20 dBm. With an extremely short LEAF-based fifth-order soliton stage, the amplified EDFL pulse can further be compressed down to a pulsewidth of 29 fs, which gives rise to a total pulsewidth-compressing ratio of as high as 40. The LMA-EDFA-based prechirped and amplified soliton compression leaves a small pedestal on the EDFL pulse with an energy confinement ratio of 74%, providing a 20-dB magnified pulse energy of 2.3 nj and a 10-dB spectral linewidth of 150 nm The self-steepening-induced blue-side spectral stretch by 1.3 THz is elucidated.