Browsing by Author "Chang, Hao-Hsiang"

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43.63-Gbit/s Multiple-User SC-FDMA PON with sub-Nyquist Receiver and PAPR Reduction
(2018-01-01)
Chang, Hao-Hsiang
;
Lin, Chi-Hsiang
;
Fang, Ruei
;
Lin, Chun-Ting
;
Wei, Chia-Chien
We demonstrate 43.63-Gbps SC-FDMA with 0.5-GSample/s sampling-rate receiver (1/32 Nyquist sampling rate) for each 32-user, which was experimentally demonstrated in commercial optical transmitter and receiver. A brief introduction of traditional SC-FDMA including L-FDMA and I-FDMA is contained. Meanwhile, a PAPR reduction is included in the proposed SC-FDMA system. The method of PAPR reduction makes the PAPR of SC-FDMA be isolated with the number of users and be lower than that of OFDM over 1-dB. Compared to OFDM, such reduction enables SC-FDMA to carry higher-order modulation format, achieving 12.5% capacity improvement (i.e. increases from 37.76 Gbit/s to 43.63 Gbit/s). Moreover, receivers' FFT size will be reduce to 1/32 of that in conventional SC-FDMA. We also compare results with L-FDMA, I-FDMA, and OFDM utilizing high sampling-rate ADC.
ENRICHING MANDARIN SPEECH RECOGNITION BY INCORPORATING A HIERARCHICAL PROSODY MODEL
(2011)
Yang, Jyh-Her
;
Liu, Ming-Chieh
;
Chang, Hao-Hsiang
;
Chiang, Chen-Yu
;
Wang, Yih-Ru
This paper presents a new probabilistic framework of Mandarin speech recognition by incorporating a sophisticated hierarchical prosody model into the conventional HMM-based system. The prosody model describes the relations of linguistic cues of various levels, break types and prosodic states which represent the prosody hierarchical structure, and prosody-related acoustic features. Aside from producing the recognized word sequences, the system also decodes other information including word's part-of-speech, punctuation marks, inter-syllable break types, and prosodic states of syllables. Experimental results on the TCC300 corpus, which consists of paragraphic utterances, showed that the proposed system significantly outperformed the baseline system. The word and character error rates decreased from 24.4% and 18.1% to 20.7% and 14.4% (or 15.2% and 20.4% relative improvements), respectively.