We consider the uplink of a multiuser, multiple-input multiple-output (MIMO), frequency-time-domain spread, multi- carrier (MC), direct sequence code division multiple access (DS-CDMA) system. As other CDMA-like syste...We consider the uplink of a multiuser, multiple-input multiple-output (MIMO), frequency-time-domain spread, multi- carrier (MC), direct sequence code division multiple access (DS-CDMA) system. As other CDMA-like systems, the multiple access interference (MAI) effect still exists in such an MC DS-CDMA system. To mitigate the MAI effect, we propose user-based and group-based layered detection schemes. Specifically, to enable a trade-off between the performance and the computational complexity, the schemes only use one user's/group's soft decisions for user-based/ group-based layered detection. The results of simulations demonstrate that the proposed schemes outperform existing approaches, and their computational complexity is modest.展开更多
This paper proposes Steepest Decreasing Constant Modulus Algorithm (SDCMA) detection in fre-quency domain for MultiCarrier Direct Sequence-Code Division Multiple Access (MC DS-CDMA) systems. The proposed algorithm is ...This paper proposes Steepest Decreasing Constant Modulus Algorithm (SDCMA) detection in fre-quency domain for MultiCarrier Direct Sequence-Code Division Multiple Access (MC DS-CDMA) systems. The proposed algorithm is used to equalize independent fadings of all subcarriers. At the same time we com-pare the SDCMA blind detection with subspace-based Minimum Mean-Squared Error (MMSE) detection. The simulation results show that the performance of SDCMA blind detection is superior to that of subspace-based MMSE detection and the complexity of the former is much lower than that of the latter.展开更多
A graph model is constructed for the Multi-user Detection of DS-CDMA system. Based on it, a Hopfield-like algorithm is put forward for the implementation of optimum receiver. Compared with the Hopfield approach, it ha...A graph model is constructed for the Multi-user Detection of DS-CDMA system. Based on it, a Hopfield-like algorithm is put forward for the implementation of optimum receiver. Compared with the Hopfield approach, it has a higher computational complexity but better performance.展开更多
This article presents a novel multicarrier direct sequence code-division multiple-access （MC DS-CDMA） scheme based on the loosely synchronous （LS） codes, which can achieve very high spectral efficiency. Instead of...This article presents a novel multicarrier direct sequence code-division multiple-access （MC DS-CDMA） scheme based on the loosely synchronous （LS） codes, which can achieve very high spectral efficiency. Instead of the single subcarrier modulation in a conventional MC DS-CDMA scheme, this novel scheme introduces the nonorthogonal subcarrier-group modulation, whose interferences caused by the non-orthogonal spacing in a subcarrier group can be reduced by a multicode detector. A detailed analysis for this system architecture and also a multiple-input-multiple output （MIMO） MC DS-CDMA solution to satisfy the requirement of beyond 3G mobile communication system are proposed. Simulated results demonstrate that this scheme can obtain excellent bit error rate （BER） performance, as well as achieve more than twice the spectral efficiency as that of conventional MC DS-CDMA systems.展开更多
文摘We consider the uplink of a multiuser, multiple-input multiple-output (MIMO), frequency-time-domain spread, multi- carrier (MC), direct sequence code division multiple access (DS-CDMA) system. As other CDMA-like systems, the multiple access interference (MAI) effect still exists in such an MC DS-CDMA system. To mitigate the MAI effect, we propose user-based and group-based layered detection schemes. Specifically, to enable a trade-off between the performance and the computational complexity, the schemes only use one user's/group's soft decisions for user-based/ group-based layered detection. The results of simulations demonstrate that the proposed schemes outperform existing approaches, and their computational complexity is modest.
基金Supported by the National Natural Science Foundation of China (No.60472104).
文摘This paper proposes Steepest Decreasing Constant Modulus Algorithm (SDCMA) detection in fre-quency domain for MultiCarrier Direct Sequence-Code Division Multiple Access (MC DS-CDMA) systems. The proposed algorithm is used to equalize independent fadings of all subcarriers. At the same time we com-pare the SDCMA blind detection with subspace-based Minimum Mean-Squared Error (MMSE) detection. The simulation results show that the performance of SDCMA blind detection is superior to that of subspace-based MMSE detection and the complexity of the former is much lower than that of the latter.
文摘A graph model is constructed for the Multi-user Detection of DS-CDMA system. Based on it, a Hopfield-like algorithm is put forward for the implementation of optimum receiver. Compared with the Hopfield approach, it has a higher computational complexity but better performance.
基金This study is supported by the National Natural Science Foundation of China （90604035）.
文摘This article presents a novel multicarrier direct sequence code-division multiple-access （MC DS-CDMA） scheme based on the loosely synchronous （LS） codes, which can achieve very high spectral efficiency. Instead of the single subcarrier modulation in a conventional MC DS-CDMA scheme, this novel scheme introduces the nonorthogonal subcarrier-group modulation, whose interferences caused by the non-orthogonal spacing in a subcarrier group can be reduced by a multicode detector. A detailed analysis for this system architecture and also a multiple-input-multiple output （MIMO） MC DS-CDMA solution to satisfy the requirement of beyond 3G mobile communication system are proposed. Simulated results demonstrate that this scheme can obtain excellent bit error rate （BER） performance, as well as achieve more than twice the spectral efficiency as that of conventional MC DS-CDMA systems.
