Browsing by Author "Lin, Ko-Yen"

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Hybrid Beamforming for Two-User SDMA in Millimeter Wave Radio
(2010)
Wu, Sau-Hsuan
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Lin, Ko-Yen
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Chiu, Lin-Kai
;
Chiang, Ming-Chen
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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.
Hybrid Beamforming Using Convex Optimization for SDMA in Millimeter Wave Radio
(2009)
Wu, Sau-Hsuan
;
Lin, Ko-Yen
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Chiu, Lin-Kai
;
電信工程研究所
;
Institute of Communications Engineering
A radio-frequency and baseband hybrid beamforming (HBF) scheme is presented for spatial division multiple access (SDMA) of 60GHz applications using planar antenna arrays (PAA). PAA with phase shifters for each element antenna is partitioned into sub-blocks and each block is applied a common baseband beamforming weight. To suppress the grating lobes of beam pattern and to maintain the signal to interference plus noise ratio (SINR) of users in the SDMA system, we study the design of this HBF using convex optimization. Two design criteria are considered herein: one minimizes the transmit power subject to a SINR constraint, and the other maximizes the worst case SINR subject to a total power constraint. Simulation results show that both the SINR and directivity of HBF can be significantly improved by making use of the convex optimization technique.
Planar Arrays Hybrid Beamforming for SDMA in Millimeter Wave Applications
(2008)
Wu, Sau-Hsuan
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Chiu, Lin-Kai
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Lin, Ko-Yen
;
Chung, Shyh-Jong
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電信工程研究所
A radio-frequency and baseband beamforming scheme is presented for spatial division multiple access (SDMA) of 60GHz applications using planar antenna arrays (PAA). PAA with phase shifters for each element antenna is partitioned into sub-blocks and each block or multiple blocks are applied to a user in the SDMA system. According to the analysis for the signal to interference plus noise ratios (SINRs) of the users in the SDMA system, it is shown that different users may have different permissible operating regions in order to maintain the SINRs for all users in the system. A procedure is proposed to identify the permissible operating regions for each user in the SDMA system. Based on these results, more flexible hybrid beamforming schemes are currently studied to support SDMA in a more efficient way for 60GHz millimeter wave applications.
Robust Hybrid Beamforming with Phased Antenna Arrays for Downlink SDMA in Indoor 60 GHz Channels
(2013-09-01)
Wu, Sau-Hsuan
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Chiu, Lin-Kai
;
Lin, Ko-Yen
;
Chang, Tsung-Hui
;
電信工程研究所
A hybrid architecture is presented for downlink beamforming (BF) with phased antenna arrays (PAA) in indoor 60 GHz spatial division multiple access (SDMA) channels. To manage the multiple access and inter-symbol interferences (MAI/ISI) encountered in SDMA with limited feedbacks, a cost-effective time-domain hybrid BF (HBF) method is presented to exploit the directivity provided by PAA in radio frequency (RF) beam patterns and the spatial diversity offered by multiple baseband processing modules. To maintain signal qualities under unpredictable MAI/ISI in wireless multimedia streaming to which indoor 60 GHz radio mainly applies, robust beamformers are designed to maintain the signal to interference-plus-noise ratio (SINR) for each user with minimum total transmit power. The percentages in which the target SINRs can be satisfied with the proposed HBF schemes are found sensitive to uncertainties in the phase shifters of PAA. Two kinds of robust formulations are thus proposed to jointly combat the MAI, ISI and phase uncertainties. Robust beamformers with semi closed-form expressions can be obtained with a nonlinear kind of them, whose SINR satisfaction ratio can attain 80% or more by extensive simulations in an indoor two-user 60 GHz environment if RF beam patterns of the users do not highly overlap in space.