The Experts below are selected from a list of 13221 Experts worldwide ranked by ideXlab platform
Wen-rong Wu - One of the best experts on this subject based on the ideXlab platform.
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Joint Precoders Design for Full-Duplex MIMO Relay Systems with QR-SIC Detector
2015 IEEE Global Communications Conference (GLOBECOM), 2015Co-Authors: Fan-shuo Tseng, Wen-rong Wu, Fu-jhong JhengAbstract:Full-duplex (FD) relaying has been considered an effective scheme to increase the spectral efficiency of multiple- input multiple-output (MIMO) relay systems. As well-known, the main concern for the FD system is the cancellation of loop interference (LI). In this paper, we consider the joint source/relay precoding to mitigate the LI problem in FD-MIMO relay systems. In our system, spatial multiplexing is exploited for the signal transmission, and the QR successive-interference-cancellation (SIC) receiver is adopted at the destination. Linear Precoders are considered at the source and relay, and the block error rate is used as the criterion for the Precoders design. To facilitate the optimization, we propose using the primal decomposition, translating the original problem into a subproblem and a master problem. In the subproblem, the source precoder is first solved with the geometric mean decomposition (GMD) method. Then, the master problem can be formulated as a convex optimization so that the relay precoder can be solved with Karush-Kuhn-Tucker (KKT) conditions. The proposed Precoders have closed-form expressions, facilitating real- world implementation. Simulation results show that the proposed method significantly improves the performance of FD-MIMO relay systems.
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GLOBECOM - X-structured precoder design for spatial multiplexing MIMO systems
2012 IEEE Global Communications Conference (GLOBECOM), 2012Co-Authors: Wen-rong WuAbstract:In multiple-input multiple-output (MIMO) transmission, precoding has been considered a promising method to improve the system performance. In general, the precoder design criterion depends on the detector used at the receiver. For the maximum-likelihood (ML) detector, the optimum precoder design criterion is equivalent to maximizing the minimum distance of received signal constellations. Several precoding methods have been developed in the literature. However, most of them use numerical searches to derive the Precoders and require table look-ups in realtime applications. In this paper, we propose a simple but effective method to solve the problem. The proposed precoder has a simple closed-form expression and no tables are required to store. Simulation results show that the proposed precoder can provide almost the same performance as existing Precoders.
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Robust Tomlinson-Harashima Source and Linear Relay Precoders Design in Amplify-and-Forward MIMO Relay Systems
IEEE Transactions on Communications, 2012Co-Authors: Fan-shuo Tseng, Min-yao Chang, Wen-rong WuAbstract:Existing transceiver designs in amplify-and-forward (AF) multiple-input-multiple-output (MIMO) relay systems often assume the availability of perfect channel state informations (CSIs). Robust designs for imperfect CSI have less been considered. In this paper, we propose a robust nonlinear transceiver design for the system with a Tomlinson-Harashima precoder (THP), a linear relay precoder, and a minimum-mean-squared-error (MMSE) receiver. Since two Precoders and imperfect CSIs are involved, the robust transceiver design is difficult. To overcome the difficulty, we first propose cascading an additional unitary precoder after the THP. The unitary precoder can not only simplify the optimization but also improve the performance of the MMSE receiver. We then adopt the primal decomposition dividing the original optimization problem into a subproblem and a master problem. With our formulation, the subproblem can be solved and the two-precoder problem can be transferred to a single relay precoder problem. The master problem, however, is not solvable. We then propose a lower bound for the objective function and transfer the master problem into a convex optimization problem. A closed-form solution can then be obtained by the Karush-Kuhn-Tucker (KKT) conditions. Simulations show that the proposed transceiver can significantly outperform existing linear transceivers with perfect or imperfect CSIs.
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Joint source/relay Precoders design in amplify-and-forward relay systems: A geometric mean decomposition approach
2009 IEEE International Conference on Acoustics Speech and Signal Processing, 2009Co-Authors: Fan-shuo Tseng, Wen-rong WuAbstract:Existing precoder designs for an amplify-and-forward (AF) cooperative system often assume a linear receiver at the destination, and a precoder at the relay. The performance enhancement of such a system is then limited. In this paper, we consider a nonlinear successive interference cancellation (SIC) receiver, and at the same time take the source precoder into consideration. Using the geometric mean decomposition (GMD), we propose a joint source/relay Precoders design method, fully exploring information provided by direct and relay links. With our method, the design problem can be transformed to a standard scalar concave optimization problem, and a closed-form solution can be obtained. Simulations show that the proposed design can significantly enhance the performance of a MIMO AF cooperative system.
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joint source relay Precoders design in amplify and forward relay systems a geometric mean decomposition approach
International Conference on Acoustics Speech and Signal Processing, 2009Co-Authors: Fan-shuo Tseng, Wen-rong WuAbstract:Existing precoder designs for an amplify-and-forward (AF) cooperative system often assume a linear receiver at the destination, and a precoder at the relay. The performance enhancement of such a system is then limited. In this paper, we consider a nonlinear successive interference cancellation (SIC) receiver, and at the same time take the source precoder into consideration. Using the geometric mean decomposition (GMD), we propose a joint source/relay Precoders design method, fully exploring information provided by direct and relay links. With our method, the design problem can be transformed to a standard scalar concave optimization problem, and a closed-form solution can be obtained. Simulations show that the proposed design can significantly enhance the performance of a MIMO AF cooperative system.
Fan-shuo Tseng - One of the best experts on this subject based on the ideXlab platform.
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Joint Precoders Design for Full-Duplex MIMO Relay Systems with QR-SIC Detector
2015 IEEE Global Communications Conference (GLOBECOM), 2015Co-Authors: Fan-shuo Tseng, Wen-rong Wu, Fu-jhong JhengAbstract:Full-duplex (FD) relaying has been considered an effective scheme to increase the spectral efficiency of multiple- input multiple-output (MIMO) relay systems. As well-known, the main concern for the FD system is the cancellation of loop interference (LI). In this paper, we consider the joint source/relay precoding to mitigate the LI problem in FD-MIMO relay systems. In our system, spatial multiplexing is exploited for the signal transmission, and the QR successive-interference-cancellation (SIC) receiver is adopted at the destination. Linear Precoders are considered at the source and relay, and the block error rate is used as the criterion for the Precoders design. To facilitate the optimization, we propose using the primal decomposition, translating the original problem into a subproblem and a master problem. In the subproblem, the source precoder is first solved with the geometric mean decomposition (GMD) method. Then, the master problem can be formulated as a convex optimization so that the relay precoder can be solved with Karush-Kuhn-Tucker (KKT) conditions. The proposed Precoders have closed-form expressions, facilitating real- world implementation. Simulation results show that the proposed method significantly improves the performance of FD-MIMO relay systems.
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Robust Tomlinson-Harashima Source and Linear Relay Precoders Design in Amplify-and-Forward MIMO Relay Systems
IEEE Transactions on Communications, 2012Co-Authors: Fan-shuo Tseng, Min-yao Chang, Wen-rong WuAbstract:Existing transceiver designs in amplify-and-forward (AF) multiple-input-multiple-output (MIMO) relay systems often assume the availability of perfect channel state informations (CSIs). Robust designs for imperfect CSI have less been considered. In this paper, we propose a robust nonlinear transceiver design for the system with a Tomlinson-Harashima precoder (THP), a linear relay precoder, and a minimum-mean-squared-error (MMSE) receiver. Since two Precoders and imperfect CSIs are involved, the robust transceiver design is difficult. To overcome the difficulty, we first propose cascading an additional unitary precoder after the THP. The unitary precoder can not only simplify the optimization but also improve the performance of the MMSE receiver. We then adopt the primal decomposition dividing the original optimization problem into a subproblem and a master problem. With our formulation, the subproblem can be solved and the two-precoder problem can be transferred to a single relay precoder problem. The master problem, however, is not solvable. We then propose a lower bound for the objective function and transfer the master problem into a convex optimization problem. A closed-form solution can then be obtained by the Karush-Kuhn-Tucker (KKT) conditions. Simulations show that the proposed transceiver can significantly outperform existing linear transceivers with perfect or imperfect CSIs.
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Joint source/relay Precoders design in amplify-and-forward relay systems: A geometric mean decomposition approach
2009 IEEE International Conference on Acoustics Speech and Signal Processing, 2009Co-Authors: Fan-shuo Tseng, Wen-rong WuAbstract:Existing precoder designs for an amplify-and-forward (AF) cooperative system often assume a linear receiver at the destination, and a precoder at the relay. The performance enhancement of such a system is then limited. In this paper, we consider a nonlinear successive interference cancellation (SIC) receiver, and at the same time take the source precoder into consideration. Using the geometric mean decomposition (GMD), we propose a joint source/relay Precoders design method, fully exploring information provided by direct and relay links. With our method, the design problem can be transformed to a standard scalar concave optimization problem, and a closed-form solution can be obtained. Simulations show that the proposed design can significantly enhance the performance of a MIMO AF cooperative system.
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joint source relay Precoders design in amplify and forward relay systems a geometric mean decomposition approach
International Conference on Acoustics Speech and Signal Processing, 2009Co-Authors: Fan-shuo Tseng, Wen-rong WuAbstract:Existing precoder designs for an amplify-and-forward (AF) cooperative system often assume a linear receiver at the destination, and a precoder at the relay. The performance enhancement of such a system is then limited. In this paper, we consider a nonlinear successive interference cancellation (SIC) receiver, and at the same time take the source precoder into consideration. Using the geometric mean decomposition (GMD), we propose a joint source/relay Precoders design method, fully exploring information provided by direct and relay links. With our method, the design problem can be transformed to a standard scalar concave optimization problem, and a closed-form solution can be obtained. Simulations show that the proposed design can significantly enhance the performance of a MIMO AF cooperative system.
K.k. Parhi - One of the best experts on this subject based on the ideXlab platform.
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design of parallel tomlinson harashima Precoders
IEEE Transactions on Circuits and Systems Ii-express Briefs, 2008Co-Authors: Yongru Gu, K.k. ParhiAbstract:Like decision feedback equalizers (DFEs), Tomlinson-Harashima Precoders (TH Precoders) contain nonlinear feedback loops, which limit their use for high-speed applications. Unlike in DFEs, where the output levels of the nonlinear devices are finite, in TH Precoders the output levels of the modulo devices are either infinite or finite but very large. Thus, it is difficult to apply look-ahead and pre-computation techniques to speed up TH Precoders, which were successfully applied to design parallel and pipelined infinite impulse response (IIR) filters and DFEs in the past. However, a TH precoder can be viewed as an IIR filter with an input equal to the sum of the original input to the TH precoder and a finite-level compensation signal. Based on this point of view, a novel parallel architecture is proposed to speed up TH Precoders. This architecture can be used in many high-speed applications, such as 10-Gb Ethernet over copper.
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Design of Parallel Tomlinson–Harashima Precoders
IEEE Transactions on Circuits and Systems II: Express Briefs, 2008Co-Authors: Yongru Gu, K.k. ParhiAbstract:Like decision feedback equalizers (DFEs), Tomlinson-Harashima Precoders (TH Precoders) contain nonlinear feedback loops, which limit their use for high-speed applications. Unlike in DFEs, where the output levels of the nonlinear devices are finite, in TH Precoders the output levels of the modulo devices are either infinite or finite but very large. Thus, it is difficult to apply look-ahead and pre-computation techniques to speed up TH Precoders, which were successfully applied to design parallel and pipelined infinite impulse response (IIR) filters and DFEs in the past. However, a TH precoder can be viewed as an IIR filter with an input equal to the sum of the original input to the TH precoder and a finite-level compensation signal. Based on this point of view, a novel parallel architecture is proposed to speed up TH Precoders. This architecture can be used in many high-speed applications, such as 10-Gb Ethernet over copper.
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high speed architecture design of tomlinson harashima Precoders
IEEE Transactions on Circuits and Systems, 2007Co-Authors: Yongru Gu, K.k. ParhiAbstract:Like decision feedback equalizers (DFEs), Tomlinson-Harashima Precoders (TH Precoders) contain nonlinear feedback loops, which limit their use for high-speed applications. Unlike in DFEs where the output levels of the nonlinear devices are finite, in TH Precoders, theoretically, the output levels of the modulo devices are infinite. Thus, it is difficult to apply look-ahead and pre-computation techniques to pipeline TH Precoders, which were successfully applied to pipeline infinite-impulse response (IIR) filters and DFEs in the past. In this paper, three approaches are proposed to design high-speed TH Precoders. In the first approach, the traditional block processing technique for DFEs is generalized to the design of high-speed TH Precoders. In the second approach, based on the equivalent form of a TH precoder where the precoder can be viewed as an IIR filter with an input equal to the sum of the original input to the TH precoder and a finite-level compensation signal, two high-speed pipelined designs are developed. In the third approach, parallel processing techniques for fast IIR filters are generalized to the design of parallel TH Precoders.
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High-Speed Architecture Design of Tomlinson–Harashima Precoders
IEEE Transactions on Circuits and Systems I: Regular Papers, 2007Co-Authors: Yongru Gu, K.k. ParhiAbstract:Like decision feedback equalizers (DFEs), Tomlinson-Harashima Precoders (TH Precoders) contain nonlinear feedback loops, which limit their use for high-speed applications. Unlike in DFEs where the output levels of the nonlinear devices are finite, in TH Precoders, theoretically, the output levels of the modulo devices are infinite. Thus, it is difficult to apply look-ahead and pre-computation techniques to pipeline TH Precoders, which were successfully applied to pipeline infinite-impulse response (IIR) filters and DFEs in the past. In this paper, three approaches are proposed to design high-speed TH Precoders. In the first approach, the traditional block processing technique for DFEs is generalized to the design of high-speed TH Precoders. In the second approach, based on the equivalent form of a TH precoder where the precoder can be viewed as an IIR filter with an input equal to the sum of the original input to the TH precoder and a finite-level compensation signal, two high-speed pipelined designs are developed. In the third approach, parallel processing techniques for fast IIR filters are generalized to the design of parallel TH Precoders.
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Pipelining Tomlinson-Harashima Precoders
2005 IEEE International Symposium on Circuits and Systems, 2005Co-Authors: Yongru Gu, K.k. ParhiAbstract:Like decision feedback equalizers (DFEs), Tomlinson-Harashima Precoders (TH Precoders) contain nonlinear feedback loops, which limit their use for high speed applications. Unlike in DFEs where the output levels of the nonlinear devices are finite, in TH Precoders the output levels of the modulo devices are infinite, or finite but very large. Thus, it is difficult to apply look-ahead and pre-computation techniques to pipeline TH Precoders, which were successfully applied to pipeline IIR filters and DFEs in the past. However, a TH precoder can be viewed as an IIR filter with an input equal to the sum of the original input to the TH precoder and a finite-level compensation signal. Based on this point of view, this paper presents a novel approach to pipeline the TH precoder.
Yongru Gu - One of the best experts on this subject based on the ideXlab platform.
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design of parallel tomlinson harashima Precoders
IEEE Transactions on Circuits and Systems Ii-express Briefs, 2008Co-Authors: Yongru Gu, K.k. ParhiAbstract:Like decision feedback equalizers (DFEs), Tomlinson-Harashima Precoders (TH Precoders) contain nonlinear feedback loops, which limit their use for high-speed applications. Unlike in DFEs, where the output levels of the nonlinear devices are finite, in TH Precoders the output levels of the modulo devices are either infinite or finite but very large. Thus, it is difficult to apply look-ahead and pre-computation techniques to speed up TH Precoders, which were successfully applied to design parallel and pipelined infinite impulse response (IIR) filters and DFEs in the past. However, a TH precoder can be viewed as an IIR filter with an input equal to the sum of the original input to the TH precoder and a finite-level compensation signal. Based on this point of view, a novel parallel architecture is proposed to speed up TH Precoders. This architecture can be used in many high-speed applications, such as 10-Gb Ethernet over copper.
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Design of Parallel Tomlinson–Harashima Precoders
IEEE Transactions on Circuits and Systems II: Express Briefs, 2008Co-Authors: Yongru Gu, K.k. ParhiAbstract:Like decision feedback equalizers (DFEs), Tomlinson-Harashima Precoders (TH Precoders) contain nonlinear feedback loops, which limit their use for high-speed applications. Unlike in DFEs, where the output levels of the nonlinear devices are finite, in TH Precoders the output levels of the modulo devices are either infinite or finite but very large. Thus, it is difficult to apply look-ahead and pre-computation techniques to speed up TH Precoders, which were successfully applied to design parallel and pipelined infinite impulse response (IIR) filters and DFEs in the past. However, a TH precoder can be viewed as an IIR filter with an input equal to the sum of the original input to the TH precoder and a finite-level compensation signal. Based on this point of view, a novel parallel architecture is proposed to speed up TH Precoders. This architecture can be used in many high-speed applications, such as 10-Gb Ethernet over copper.
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high speed architecture design of tomlinson harashima Precoders
IEEE Transactions on Circuits and Systems, 2007Co-Authors: Yongru Gu, K.k. ParhiAbstract:Like decision feedback equalizers (DFEs), Tomlinson-Harashima Precoders (TH Precoders) contain nonlinear feedback loops, which limit their use for high-speed applications. Unlike in DFEs where the output levels of the nonlinear devices are finite, in TH Precoders, theoretically, the output levels of the modulo devices are infinite. Thus, it is difficult to apply look-ahead and pre-computation techniques to pipeline TH Precoders, which were successfully applied to pipeline infinite-impulse response (IIR) filters and DFEs in the past. In this paper, three approaches are proposed to design high-speed TH Precoders. In the first approach, the traditional block processing technique for DFEs is generalized to the design of high-speed TH Precoders. In the second approach, based on the equivalent form of a TH precoder where the precoder can be viewed as an IIR filter with an input equal to the sum of the original input to the TH precoder and a finite-level compensation signal, two high-speed pipelined designs are developed. In the third approach, parallel processing techniques for fast IIR filters are generalized to the design of parallel TH Precoders.
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High-Speed Architecture Design of Tomlinson–Harashima Precoders
IEEE Transactions on Circuits and Systems I: Regular Papers, 2007Co-Authors: Yongru Gu, K.k. ParhiAbstract:Like decision feedback equalizers (DFEs), Tomlinson-Harashima Precoders (TH Precoders) contain nonlinear feedback loops, which limit their use for high-speed applications. Unlike in DFEs where the output levels of the nonlinear devices are finite, in TH Precoders, theoretically, the output levels of the modulo devices are infinite. Thus, it is difficult to apply look-ahead and pre-computation techniques to pipeline TH Precoders, which were successfully applied to pipeline infinite-impulse response (IIR) filters and DFEs in the past. In this paper, three approaches are proposed to design high-speed TH Precoders. In the first approach, the traditional block processing technique for DFEs is generalized to the design of high-speed TH Precoders. In the second approach, based on the equivalent form of a TH precoder where the precoder can be viewed as an IIR filter with an input equal to the sum of the original input to the TH precoder and a finite-level compensation signal, two high-speed pipelined designs are developed. In the third approach, parallel processing techniques for fast IIR filters are generalized to the design of parallel TH Precoders.
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Pipelining Tomlinson-Harashima Precoders
2005 IEEE International Symposium on Circuits and Systems, 2005Co-Authors: Yongru Gu, K.k. ParhiAbstract:Like decision feedback equalizers (DFEs), Tomlinson-Harashima Precoders (TH Precoders) contain nonlinear feedback loops, which limit their use for high speed applications. Unlike in DFEs where the output levels of the nonlinear devices are finite, in TH Precoders the output levels of the modulo devices are infinite, or finite but very large. Thus, it is difficult to apply look-ahead and pre-computation techniques to pipeline TH Precoders, which were successfully applied to pipeline IIR filters and DFEs in the past. However, a TH precoder can be viewed as an IIR filter with an input equal to the sum of the original input to the TH precoder and a finite-level compensation signal. Based on this point of view, this paper presents a novel approach to pipeline the TH precoder.
Maryline Helard - One of the best experts on this subject based on the ideXlab platform.
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Linear Precoder Performance for Massive MIMO Systems in near LOS Environments: Application to mmWave Transmission
2015Co-Authors: Antoine RozÉ, Matthieu Crussière, Maryline Helard, Charlotte LanglaisAbstract:As the wireless communication network is driven toward densification with small cell deployments, massive MIMO technology shows great promises to boost capacity and energy efficiency. This paper aims at showing how raising carrier frequencies impacts the performance of the linear Precoders used in Massive MIMO systems. By means of a geometrical deterministic channel model, we simulate a dense outdoor scenario and highlight the influence of the direct and multi-paths components. More importantly we prove that, in a Line-of-Sight configuration, the discriminating skills of the well known Zero Forcing precoder is much more sensitive to the antenna array architecture and the user location than the Conjugate precoder.
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make it real Precoders for mimo ofdm oqam without inter carrier interference
Global Communications Conference, 2013Co-Authors: Dinhthuy Phanhuy, Pierre Siohan, Maryline HelardAbstract:Low complexity Multiple Input Multiple Output (MIMO) Precoders for Orthogonal Frequency Division Multiplex (OFDM), such as Maximum Ratio Transmission (MRT) and Minimum Mean Square Error (MMSE) Precoders enable to multiplex data streams in the spatial domain, without breaking OFDM orthogonality in the frequency domain, and therefore achieve a high spectral efficiency. OFDM using Offset Quadrature Amplitude Modulation (OFDM/OQAM) is an alternate modulation which is more spectrally efficient than OFDM. Unfortunately, when applied to OFDM/OQAM, traditional low complexity Precoders introduce an inter-carrier interference (ICI) which is complex to cancel at the receiver side. This paper proposes a new family of low complexity Precoders, called “Make-It-Real” (MIR) Precoders. These Precoders are designed so that the equivalent channel including precoding and propagation is “made real” and does not break the orthogonality of OFDM/OQAM in the frequency domain. At the receiver side, a simple extraction of the real part of the demodulated signal is necessary. Simulations show that OFDM/OQAM with MIR MMSE precoder outperforms all studied MIMO OFDM solutions, without requiring a complex ICI cancellation at the receiver.
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“Make-It-Real” Precoders for MIMO OFDM/OQAM without inter carrier interference
2013 IEEE Global Communications Conference (GLOBECOM), 2013Co-Authors: Dinh-thuy Phan-huy, Pierre Siohan, Maryline HelardAbstract:Low complexity Multiple Input Multiple Output (MIMO) Precoders for Orthogonal Frequency Division Multiplex (OFDM), such as Maximum Ratio Transmission (MRT) and Minimum Mean Square Error (MMSE) Precoders enable to multiplex data streams in the spatial domain, without breaking OFDM orthogonality in the frequency domain, and therefore achieve a high spectral efficiency. OFDM using Offset Quadrature Amplitude Modulation (OFDM/OQAM) is an alternate modulation which is more spectrally efficient than OFDM. Unfortunately, when applied to OFDM/OQAM, traditional low complexity Precoders introduce an inter-carrier interference (ICI) which is complex to cancel at the receiver side. This paper proposes a new family of low complexity Precoders, called “Make-It-Real” (MIR) Precoders. These Precoders are designed so that the equivalent channel including precoding and propagation is “made real” and does not break the orthogonality of OFDM/OQAM in the frequency domain. At the receiver side, a simple extraction of the real part of the demodulated signal is necessary. Simulations show that OFDM/OQAM with MIR MMSE precoder outperforms all studied MIMO OFDM solutions, without requiring a complex ICI cancellation at the receiver.
