Browsing by Author "Chiang, Ming-Chen"

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Empirical MIMO Capacity of a 2x2 Dual-Polarized Planar Antenna Array in Indoor 60 GHz Channels
(2013)
Chiu, Lin-Kai
;
Chiang, Ming-Chen
;
Chiang, Pei-Li
;
Chi, Yu-Jen
;
Wu, Sau-Hsuan
The channel capacity of a multiple input multiple output (MIMO) system that uses a hybrid beamforming (HBF) mechanism for a 2x2 dual-polarized (DP) planar antenna array (PAA) is studied in this work for indoor 60 GHz channels. On one hand, the DP-PAA can resolve the receiving dead zone problem often seen in single-polarized PAA. On the other hand, the HBF architecture allows us to explore the advantages of spatial multiplexing or beamforming, or even both, in order to overcome the severe power loss problems often encountered from blocking or reflections in indoor 60 GHz radio propagations. Simulation results show that different architectures have advantages at different transmission power. In typical operating conditions of indoor 60 GHz radio, directivity offered by beamforming provides a higher capacity than does the spatial multiplexing provided by multiple baseband processing modules.
Hybrid Beamforming for Two-User SDMA in Millimeter Wave Radio
(2010)
Wu, Sau-Hsuan
;
Lin, Ko-Yen
;
Chiu, Lin-Kai
;
Chiang, Ming-Chen
;
傳播研究所
An effective joint radio-frequency (RF) and baseband (BB) hybrid beamforming (HBF) scheme is presented for two-user spatial division multiple access (SDMA) in 60GHz radio using planar antenna arrays (PAA). Taking into account the physical constraints of the phase shifters of PAA, we study the design of downlink HBF from two perspectives of conic optimization: transmit power minimization subject to a lower limit on the signal-to-interference plus noise ratio (SINR), and the maximization of the minimum SINR subject to an upper limit on the transmit power. For the power minimization problem, we obtain closed-form expressions for the BB beam forming (BF) weights. And for the SINR maximization, a simple iterative scheme is obtained based on the closed-form expressions for the first problem. Simulation results show that the bit error rates with HBF can significantly outperform the ones with RF BF only when the desired user's signal is severely jammed by the interfering user's signal.
New approach to construct freeform surface by numerically differential formulation
(2014-03-01)
Tsai, Yu-Lin
;
Chiang, Ming-Chen
;
Chang, Ray
;
Tien, Chung-Hao
;
Wu, Chin-Tien
We proposed a new design method for single freeform reflective (or refractive) surface tailored to redistribute the radiant flux onto a prescribed illumination pattern. Unlike the conventional optimization approaches based on the grid mapping, in this study we estimated each segmental freeform surface by locally solving a second-order differential equation, which formulates the energy transportation between each domain cell. With finite element method via Hermite element, we validated a series of smooth reflective/refractive surfaces to reallocate the radiant flux from a point source toward a target plane with specific patterns. The proposed technique offers a large flexibility by varying the vectors of each ray with multiple refraction (or reflection), which imposes no restriction on the target distribution, collective solid angle, or even target topography. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.