In this paper,we present a novel and robust nonlinear precoding(NLP)design and detection structure specifically tailored for multiple-input multipleoutput space division multiple access(MIMO-SDMA)systems toward 6G wir...In this paper,we present a novel and robust nonlinear precoding(NLP)design and detection structure specifically tailored for multiple-input multipleoutput space division multiple access(MIMO-SDMA)systems toward 6G wireless.Our approach aims to effectively mitigate the impact of imperfect channel estimation by leveraging the channel fluctuation mean square error(MSE)for reconstructing a highly accurate precoding matrix at the transmitter.Furthermore,we introduce a simplified receiver structure that eliminates the need for equalization,resulting in reduced interference and notable enhancements in overall system performance.We conduct both computer simulations and experimental tests to validate the efficacy of our proposed approach.The results reveals that the proposed NLP scheme offers significant performance improvements,making it particularly well-suited for the forthcoming 6G wireless.展开更多
Low Earth Orbit(LEO)multibeam satellites will be widely used in the next generation of satellite communication systems,whose inter-beam interference will inevitably limit the performance of the whole system.Nonlinear ...Low Earth Orbit(LEO)multibeam satellites will be widely used in the next generation of satellite communication systems,whose inter-beam interference will inevitably limit the performance of the whole system.Nonlinear precoding such as Tomlinson-Harashima precoding(THP)algorithm has been proved to be a promising technology to solve this problem,which has smaller noise amplification effect compared with linear precoding.However,the similarity of different user channels(defined as channel correlation)will degrade the performance of THP algorithm.In this paper,we qualitatively analyze the inter-beam interference in the whole process of LEO satellite over a specific coverage area,and the impact of channel correlation on Signal-to-Noise Ratio(SNR)of receivers when THP is applied.One user grouping algorithm is proposed based on the analysis of channel correlation,which could decrease the number of users with high channel correlation in each precoding group,thus improve the performance of THP.Furthermore,our algorithm is designed under the premise of co-frequency deployment and orthogonal frequency division multiplexing(OFDM),which leads to more users under severe inter-beam interference compared to the existing research on geostationary orbit satellites broadcasting systems.Simulation results show that the proposed user grouping algorithm possesses higher channel capacity and better bit error rate(BER)performance in high SNR conditions relative to existing works.展开更多
In multi-user multiple-input single-output orthogonal frequency-division multiplexing （MISO-OFDM） downlinks with limited feedback, both linear precoders （LP） and Tomlinson-Harashima precoders （THP） experience pe...In multi-user multiple-input single-output orthogonal frequency-division multiplexing （MISO-OFDM） downlinks with limited feedback, both linear precoders （LP） and Tomlinson-Harashima precoders （THP） experience performance degradation due to inaccurate channel state information at the transmitter （CSIT）. This analysis treats the downlink channels as random quantities and exploits their second order statistics in robust precoding schemes to correct the errors introduced in the feedback procedure. The time-domain channel vectors are found to reduce the feedback overhead more than the frequency-domain vectors. A compression and restoration method and a codebook design are also given to obtain compact feedback quantities. Simulations show that the robust LP and THP are superior to the previous methods with tradeoffs possible between performance and feedback overhead.展开更多
This paper proposes a joint nonlinear transceiver design scheme based on minimum mean square error （MMSE） criterion for non-regenerative multiple input multiple output （MIMO） relay system. The proposed scheme deco...This paper proposes a joint nonlinear transceiver design scheme based on minimum mean square error （MMSE） criterion for non-regenerative multiple input multiple output （MIMO） relay system. The proposed scheme decomposes the error covariance matrix, reformulates the original joint design problem as two separate optimization problems, and then provides a closed-form solution with only local channel state information （CSI） available at the source and destination. Performance evaluation shows that the proposed scheme significantly outperforms linear schemes, and has a competitive performance compared with existing global CSI based nonlinear schemes, both iterative and non-iterative.展开更多
Existing minimum-mean-squared-error (MMSE) transceiver designs in amplified-and-forward (AF) multiple-input multiple-output (MIMO) two-way relay systems all assume a linear precoder at the sources. Non-linear source p...Existing minimum-mean-squared-error (MMSE) transceiver designs in amplified-and-forward (AF) multiple-input multiple-output (MIMO) two-way relay systems all assume a linear precoder at the sources. Non-linear source precoders in such a system have not been considered yet. In this paper, we study the joint design of source Tomlinson-Harashima precoders (THPs), relay linear precoder and MMSE receivers in two-way relay systems. This joint design problem is a highly nonconvex optimization problem. By dividing the original problem into three sub-problems, we propose an iterative algorithm to optimize precoders and receivers. The convergence of the algorithm is ensured since the updated solution is optimal to each sub-problem. Numerical simulation results show that the proposed iterative algorithm outperforms other algorithms in the high signal-to-noise ratio (SNR) region.展开更多
The application of the orthogonal time frequency space(OTFS)modulation in multiple-antenna systems is investigated.The diversity and/or the multiplexing gain can be achieved by deploying various multiple-antenna techn...The application of the orthogonal time frequency space(OTFS)modulation in multiple-antenna systems is investigated.The diversity and/or the multiplexing gain can be achieved by deploying various multiple-antenna techniques,and thus the reliability and/or the spectral efficiency are improved correspondingly.We provide two classes of OTFSbased multiple-antenna approaches for both the open-loop and the closed-loop systems.Spe⁃cifically,in the open-loop system,a transmitting diversity approach,which resembles the space-time coding technique,is proposed by allocating the information symbols appropriate⁃ly in the delay-Doppler domain.In the closed-loop system,we adopt the Tomlinson-Harashi⁃ma precoding in our derived delay-Doppler equivalent transmission model.Numerical evalu⁃ations demonstrate the advantages of applying the multiple-antenna techniques to the OTFS.At last,several challenges and opportunities are presented.展开更多
预编码技术能够有效的抑制MIMO信道中的多用户干扰,能显著提高系统容量,同时也能大大简化接收机的算法。主要对MIMO-OFDM系统的非线性预编码技术进行了深入研究,通过搭建出的MIMO-OFDM仿真平台对DPC(Dirty Paper Coding,脏纸编码)和THP(...预编码技术能够有效的抑制MIMO信道中的多用户干扰,能显著提高系统容量,同时也能大大简化接收机的算法。主要对MIMO-OFDM系统的非线性预编码技术进行了深入研究,通过搭建出的MIMO-OFDM仿真平台对DPC(Dirty Paper Coding,脏纸编码)和THP(Tomlinson Harashima Precoding,模代数TH编码)两种非线性预编码算法进行了性能仿真,比较了这两种算法的BER(误码率),同时也比较了它们与线性ZF(Zero Forcing,迫零)预编码算法的BER差异,并指出了不同算法的适用性。展开更多
基金supported in part by National Key R&D Program of China(2020YFB1807203)National Science Foundation of China under Grant number 62071111+2 种基金the Fundamental Research Funds for the Central Universities under Grant 2242022k60006Natural Science Foundation of Sichuan Province under Grant number 2022NSFSC0487the National Key Laboratory of Wireless Communications Foundation under Grant IFN20230104。
文摘In this paper,we present a novel and robust nonlinear precoding(NLP)design and detection structure specifically tailored for multiple-input multipleoutput space division multiple access(MIMO-SDMA)systems toward 6G wireless.Our approach aims to effectively mitigate the impact of imperfect channel estimation by leveraging the channel fluctuation mean square error(MSE)for reconstructing a highly accurate precoding matrix at the transmitter.Furthermore,we introduce a simplified receiver structure that eliminates the need for equalization,resulting in reduced interference and notable enhancements in overall system performance.We conduct both computer simulations and experimental tests to validate the efficacy of our proposed approach.The results reveals that the proposed NLP scheme offers significant performance improvements,making it particularly well-suited for the forthcoming 6G wireless.
基金supported by the Key R&D Project of the Ministry of Science and Technology of China(2020YFB1808005)。
文摘Low Earth Orbit(LEO)multibeam satellites will be widely used in the next generation of satellite communication systems,whose inter-beam interference will inevitably limit the performance of the whole system.Nonlinear precoding such as Tomlinson-Harashima precoding(THP)algorithm has been proved to be a promising technology to solve this problem,which has smaller noise amplification effect compared with linear precoding.However,the similarity of different user channels(defined as channel correlation)will degrade the performance of THP algorithm.In this paper,we qualitatively analyze the inter-beam interference in the whole process of LEO satellite over a specific coverage area,and the impact of channel correlation on Signal-to-Noise Ratio(SNR)of receivers when THP is applied.One user grouping algorithm is proposed based on the analysis of channel correlation,which could decrease the number of users with high channel correlation in each precoding group,thus improve the performance of THP.Furthermore,our algorithm is designed under the premise of co-frequency deployment and orthogonal frequency division multiplexing(OFDM),which leads to more users under severe inter-beam interference compared to the existing research on geostationary orbit satellites broadcasting systems.Simulation results show that the proposed user grouping algorithm possesses higher channel capacity and better bit error rate(BER)performance in high SNR conditions relative to existing works.
基金Supported by the National Natural Science Foundation of China (No.60675002)
文摘In multi-user multiple-input single-output orthogonal frequency-division multiplexing （MISO-OFDM） downlinks with limited feedback, both linear precoders （LP） and Tomlinson-Harashima precoders （THP） experience performance degradation due to inaccurate channel state information at the transmitter （CSIT）. This analysis treats the downlink channels as random quantities and exploits their second order statistics in robust precoding schemes to correct the errors introduced in the feedback procedure. The time-domain channel vectors are found to reduce the feedback overhead more than the frequency-domain vectors. A compression and restoration method and a codebook design are also given to obtain compact feedback quantities. Simulations show that the robust LP and THP are superior to the previous methods with tradeoffs possible between performance and feedback overhead.
基金supported by National Basic Research Program of China (2009CB320401)the National Key Scientific and Technological Project of China (2010ZX03003-001,2012ZX03004005-002)the National Natural Science Foundation of China (61171100,61171099)
文摘This paper proposes a joint nonlinear transceiver design scheme based on minimum mean square error （MMSE） criterion for non-regenerative multiple input multiple output （MIMO） relay system. The proposed scheme decomposes the error covariance matrix, reformulates the original joint design problem as two separate optimization problems, and then provides a closed-form solution with only local channel state information （CSI） available at the source and destination. Performance evaluation shows that the proposed scheme significantly outperforms linear schemes, and has a competitive performance compared with existing global CSI based nonlinear schemes, both iterative and non-iterative.
基金the China National Science and Technology Major Project "New generation broadband wireless-mobile communication networks" (No. 2011ZX03001-002-01)
文摘Existing minimum-mean-squared-error (MMSE) transceiver designs in amplified-and-forward (AF) multiple-input multiple-output (MIMO) two-way relay systems all assume a linear precoder at the sources. Non-linear source precoders in such a system have not been considered yet. In this paper, we study the joint design of source Tomlinson-Harashima precoders (THPs), relay linear precoder and MMSE receivers in two-way relay systems. This joint design problem is a highly nonconvex optimization problem. By dividing the original problem into three sub-problems, we propose an iterative algorithm to optimize precoders and receivers. The convergence of the algorithm is ensured since the updated solution is optimal to each sub-problem. Numerical simulation results show that the proposed iterative algorithm outperforms other algorithms in the high signal-to-noise ratio (SNR) region.
基金supported in part by the Fundamental Research Funds for the Central Universities under Grant Nos.2020JBM081 and 2020JBZD005in part by the National Key R&D Program of China under Grant 2020YFB1806903in part by the National Natural Science Foundation under Grant No.U1834210.
文摘The application of the orthogonal time frequency space(OTFS)modulation in multiple-antenna systems is investigated.The diversity and/or the multiplexing gain can be achieved by deploying various multiple-antenna techniques,and thus the reliability and/or the spectral efficiency are improved correspondingly.We provide two classes of OTFSbased multiple-antenna approaches for both the open-loop and the closed-loop systems.Spe⁃cifically,in the open-loop system,a transmitting diversity approach,which resembles the space-time coding technique,is proposed by allocating the information symbols appropriate⁃ly in the delay-Doppler domain.In the closed-loop system,we adopt the Tomlinson-Harashi⁃ma precoding in our derived delay-Doppler equivalent transmission model.Numerical evalu⁃ations demonstrate the advantages of applying the multiple-antenna techniques to the OTFS.At last,several challenges and opportunities are presented.
