Browsing by Author "Ho, Chung-Lien"

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Closed-loop grouped space-time block code: Encoding, decoding and codeword selection
(2008-03-01)
Ho, Chung-Lien
;
Tseng, Fan-Shuo
;
Lee, Ta-Sung
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資訊工程學系
;
電信工程研究所
A design of closed-loop grouped space-time block codes (G-STBCs) including encoding, decoding and codeword selection is proposed for the downlink over Rayleigh flat-fading channels. In particular, at the transmitter, the antenna array is partitioned into a number of groups, each of which is encoded based on the orthogonal STBC (O-STBC). At the receiver, by exploiting the algebraic structure of orthogonal codes, a low-complexity, in recursion form, group-wise ordered successive interference cancellation (OSIC) detector is developed. Moreover, the G-STBC codeword is designed and a G-STBC codeword selection criterion that minimizes the BER performance under the constraints of a fixed spectral efficiency and total transmit power is then proposed. The selection index of the G-STBC codeword and the associated modulation type are determined at the receiver and conveyed to the transmitter with a limited feedback overhead to choose an appropriate mode for transmission. Finally, Numerical examples are used for illustrating the performance of the proposed G-STBCs, OSIC based detection and G-STBC codeword selection criterion.
Detection of multiuser orthogonal space-time block coded signals via ordered successive interference cancellation
(2006-07-01)
Wu, Jwo-Yuh
;
Ho, Chung-Lien
;
Lee, Ta-Sung
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電信工程研究所
;
Institute of Communications Engineering
This paper investigates multiuser orthogonal spacetime block coded signal detection within the ordered successive interference cancellation (OSIC) framework. Both the zero-forcing and minimum-mean-square-error ordering criteria are considered. When each user terminal is equipped with no more than four transmit antennas, it is shown that orthogonal transmit redundancy leads to an appealing signal ordering property: in each processing layer the transmitted symbols of an arbitrary user are associated with an identical ordering metric. This guarantees the feasibility of (user based) group-wise symbol recovery through the OSIC mechanism. Analytic bit-error-rate performance is given. Computer simulations and flop count evaluations are also provided for comparing the OSIC based solution with existing multiuser detection schemes reported for the considered system.
Group-wise V-BLAST detection in multiuser space-time dual-signaling wireless systems
(2006-07-01)
Ho, Chung-Lien
;
Wu, Jwo-Yuh
;
Lee, Ta-Sung
;
資訊工程學系
;
電信工程研究所
This paper studies the V-BLAST detection in a general multiuser space-time wireless system, in which each user's data stream is either (orthogonal) space-time block coded (OSTBC) for transmit diversity or spatially multiplexed (SM) for high spectral efficiency. The motivation behind this work is that each user adopting a signaling scheme better matched to his own channel condition proves to improve the individual link performance but the resultant co-channel interference mitigation problem is scarcely addressed thus far. By exploiting the algebraic structure of orthogonal code, it is shown that the V-BLAST detector in the considered dual-signaling environment allows for an attractive group-wise implementation: at each iteration a group of symbols, transmitted either from an OSTBC station or from an antenna of an SM terminal, are jointly detected. The group detection property, resulting uniquely from the use of orthogonal codes, potentially improves the dual-mode signal separation efficiency, especially when the OSTBC terminals are dense in the cell. The imbedded structure of the channel matrix is also exploited for deriving a computationally efficient detector implementation. Flop count evaluations and numerical examples are used for illustrating the performance of the proposed V-BLAST based solution.
Method of symbol detection for MIMO dual-signaling uplink CDMA systems
(2006-11-30)
Ho, Chung-Lien
;
Wu, Jwo-Yuh
;
Lee, Ta-Sung
The invention provides a block V-BLAST detection algorithm for a general multi-input multi-output CDMA system over the frequency-selective channels, in which each user's data stream can be either orthogonal space-time block encoded for transmit diversity or spatially multiplexed for high spectral efficiency according to the channel conditions. For such the considered dual-signaling system, the receiver could suffer from the large dimension data processing. A two-stage group V-BLAST detection algorithm is thus proposed to further reduce the computational complexity.