Browsing by Author "Hsiao, CY"

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Multiuser detection for MFSK frequency-hopped multiple access systems
(1996)
Su, YT
;
Hsiao, CY
;
Hung, CP
;
電信工程研究所
;
Institute of Communications Engineering
On the detection of a class of fast frequency-hopped multiple access signals
(2001-11-01)
Su, YT
;
Shen, YS
;
Hsiao, CY
;
電信工程研究所
;
Institute of Communications Engineering
The capacity of a fast frequency-hopped multiple access (FHMA) system is dictated by two major related design concerns: the hopping pattern and the receiver structure. This paper studies the impact of these two factors. We present a maximum likelihood (ML) diversity combiner for detecting asynchronous FHMA multilevel FSK (MFSK) signals in Rician fading channels and analyze the performance of a close approximation of the ML receiver. We compare systems using random hopping patterns and those using optimal hopping patterns of Einarsson [8]. Performance comparisons between chip-synchronous and chip-asynchronous systems are made as well. We propose and examine the effectiveness of a two-stage multiuser detector, in which the first stage makes an initial decision while the second stage tries to reduce multiple access interference (MAI) and resolve the ambiguity left by the first stage detector. The MAI caused by undesired users is constituted by a cochannel interference (CCI) contribution and an interchannel interference (ICI) contribution. This detector is of modest complexity and is capable of removing most of the CCI and part of the ICI. Two methods for mitigating MAI are also examined.
Semiconducting single-walled carbon nanotubes exposed to distilled water and aqueous solution: Electrical measurement and theoretical calculation
(2006-01-30)
Lu, MP
;
Hsiao, CY
;
Lo, PY
;
Wei, JH
;
Yang, YS
We fabricate and measure a single-walled carbon nanotube transistor having a liquid-gate electrode. The ratio value of I-on/I-off is as high as 10(4), indicating the presence of a semiconducting channel. A passivation layer over the source/drain electrode greatly suppresses the liquid-gate leakage by about three orders of magnitude. The channel currents are noticeably distinct between two liquid samples: distilled water and aqueous solution (1x10(-4) M NaCl). This biological sensing ability is attributed to the different electrical double-layer capacitances with respect to the bulk part of the channel. The corresponding theoretical calculation is carried out in detail. (c) 2006 American Institute of Physics.