Browsing by Author "Yu, Tsang-Wei"

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A Low-complexity Power Allocation for Cooperative Bit-interleaved Coded Modulation Systems with Adaptive Decode-and-Forward Relaying
(2011)
Yu, Tsang-Wei
;
Sheen, Wern-Ho
;
Wang, Chung-Hsuan
;
電機工程學系
;
Department of Electrical and Computer Engineering
Transmit power allocation between source and relays is a critical design issue in a cooperative relaying system where source and relays are powered by batteries. In this paper, a low-complexity power allocation method is proposed for a 3-node cooperative bit-interleaved coded modulation system with adaptive decode-and-forward relaying, aiming to minimize the bit-error-rate at the destination. The key novelty of the method lies in transforming the power allocation into a max-min optimization problem which can be solved in a first-order equation with very low-complexity. Computer simulations show that the proposed method outperforms the equal gain power allocation with large margins in different channel conditions.
A Pragmatic Labeling Design of MIMO BICM-ID Systems Based on EXIT Chart
(2009)
Yu, Tsang-Wei
;
Wang, Chung-Hsuan
;
Sheen, Wern-Ho
;
電信工程研究所
;
Institute of Communications Engineering
We propose a pragmatic labeling design based on the extrinsic information transfer (EXIT) chart for bit-interleaved coded modulation with iterative decoding on multiple-input-multiple-output channels. In our design, the EXIT chart is used to determine a candidate set of labelings which have representative demapper transfer curves. Then, a procedure to generate these labelings is provided based on the genetic algorithm. Given fixed channel code and signal-to-noise ratio (SNR), we can search within this candidate set for a most-suitable labeling to minimize the bit-error-rate (BER) with low complexity. Simulation results show that the labeling chosen from the candidate set exhibits a controllable BER performance gap compared to the optimal labeling found through exhaustive search. Besides, even though the channel code or the SNR is changed, the same candidate set can still be directly adopted to reduce the time on re-searching a new labeling.
EXIT-chart based labeling design for bit-interleaved coded modulation with iterative decoding
(2007)
Yu, Tsang-Wei
;
Wang, Chu-Yan
;
Wang, Chung-Suan
;
Sheen, Wern-Ho
;
電信工程研究所
In this paper, labeling is jointly designed with the outer code by the EXIT chart based analysis to improve the performance of bit-interleaved coded modulation with iterative decoding. A systematic design methodology is proposed for regular modulation schemes which can easily obtain a set of labelings with various slopes. Given an outer code, the optimal labeling which has the steepest slope but still makes the tunnel between the decoder and demapper transfer curves open can then be chosen to optimize the BER performance. Verified by the simulation results, our design can provide remarkable SNR gain over the conventional ones.
Power Allocation for Cooperative Bit-Interleaved Coded Modulation Systems with Decode-Remap-and-Forward Relaying
(2012-05-01)
Yu, Tsang-Wei
;
Sheen, Wern-Ho
;
Wang, Chung-Hsuan
;
電機工程學系
;
Department of Electrical and Computer Engineering
Cooperative bit-interleaved coded modulation (BICM) is a key technology for the next-generation wireless communication systems. This paper investigates power allocation for the cooperative BICM systems with decode-remap-and-forward (DRF) relaying. Unlike the conventional decode-and-forward relays, the DRF relays may choose different constellation mappings from that of source so as to obtain a remapping gain. In spite of its importance, the power allocation in such a system has not yet been explored in the literature. Two new power allocation methods are proposed, aiming to minimize bit error rate at the destination. The first uses a cost function based on the minimum weighted squared-Euclidean distance (called PA-MWSED) and is optimized with the sub-gradient method. The second is based on a generalized MWSED (called PA-GMWSED) and is optimized with the Simplex method after the optimization is re-cast as a linear programming problem. Generally speaking, PA-MWSED has a better performance than PA-GMWSED but requires a higher complexity. Numerical results show that both of the proposed methods outperform the equal gain power allocation with large margins.