For decreasing the multiple access interference of weaker signal acquisition in direct sequence spread spectrum（DSSS） systems,a new single decision algorithm is presented.The maximum value of correlation results is ...For decreasing the multiple access interference of weaker signal acquisition in direct sequence spread spectrum（DSSS） systems,a new single decision algorithm is presented.The maximum value of correlation results is conventionally detected.However,there may be not only one strong peak among correlation results when the cross-correlation noise is strong enough to affect the correlation results.The proposed algorithm decreases the false alarm probability through the decision of the ratio of the maximum value and the second maximum value of the correlation results.Theoretical analysis and simulation results indicate that the proposed algorithm effectively suppresses the acquisition problem of multiple access interference in DSSS system.展开更多
Many blind channel estimation methods have been proposed for direct sequence (DS) code-division multiple access (CDMA) systems, so we can certainly use them to estimate the finite impulse response (FIR) channel for th...Many blind channel estimation methods have been proposed for direct sequence (DS) code-division multiple access (CDMA) systems, so we can certainly use them to estimate the finite impulse response (FIR) channel for the multi-carrier (MC-) CDMA system. In this paper, the MC-CDMA system is interpreted as an equivalent time-domain DS-CD-MA system with specific spreading codes. Then, an equivalently time-domain blind channel estimator is derived for the uplink MC-CDMA, which is based on second-order statistics of the received data. By exploiting singular value decomposition (SVD) and the finite alphabet property of transmitted symbols, the time-domain channel impulse response (CIR) for the uplink MC-CDMA can be accurately identified. Computer simulations illustrate both the validity and the overall performance of the proposed estimator.展开更多
Multiple access interference (MAI) and near-far problem are two major obstacles in DS-CDMA systems. Combining wavelet neural networks and two matched filters, the novel multiuser detector, which is based on multiple v...Multiple access interference (MAI) and near-far problem are two major obstacles in DS-CDMA systems. Combining wavelet neural networks and two matched filters, the novel multiuser detector, which is based on multiple variable function estimation wavelet networks over single path asynchronous channel and space-time channel respectively is presented. Excellent localization characteristics of wavelet functions in both time and frequency domains allowed hierarchical multiple resolution learning of input-output data mapping. The ma thematic frame of the neural networks and error back ward propagation algorithm are introduced. The complexity of the multiuser detector only depends on that of wavelet networks. With numerical simulations and performance analysis, it indicates that the multiuser detector has excellent performance in eliminating MAI and near-far resistance.展开更多
The structure and performance of space-time multiuser detection receiver at base stations of WCDMA system is analyzed, in which smart antenna is employed. WCDMA uplink signal model is established in this paper. Space-...The structure and performance of space-time multiuser detection receiver at base stations of WCDMA system is analyzed, in which smart antenna is employed. WCDMA uplink signal model is established in this paper. Space-time multiuser receiver presented in this paper combines 2D-RAKE with parallel interference cancellation (PIC), and the improved parallel interference cancellation methods are given. A novel space-time multiuser detection scheme, 2DRAKE-GPPIC is proposed. This scheme employs smart antenna to suppress unexpected DOA (Direction Of Arrival) signal, uses RAKE receiver to combine different delays of expected signal, and utilizes grouped partial parallel interference cancellation (GPPIC) algorithm to suppress further the interference signal in the main lobe of array antennas. The simulation results reveal that the scheme of space-time multiuser detection presented in this paper has better performance for WCDMA system.展开更多
High complexity and high latency are key problems for multiuser detection （MUD） to be applied to a mobile station in cellular networks. To tackle these problems, an interleave division multiple access （IDMA） based...High complexity and high latency are key problems for multiuser detection （MUD） to be applied to a mobile station in cellular networks. To tackle these problems, an interleave division multiple access （IDMA） based multiple access scheme, grouped spread IDMA （GSIDMA）, is proposed. In a GSIDMA system, lower complexity and latency for mobile stations can be achieved by appropriately dividing active users into different groups. The system model of GSIDMA is constructed and followed by analysing on its system capacity, complexity and latency, and bit error rate （BER） performance. The extrinsic information transfer （EXIT） chart is used to analyze the convergence behavior of the iteration process. The grouping method and interleavers-reuse issue for GSIDMA are also discussed preliminarily. The analyses and simulation results indicate that the complexity and latency of the proposed scheme are much lower than those of IDMA, whereas its BER performance is close to the latter. The properties of low complexity and low latency make it more feasible for the practical implementation.展开更多
基金supported by the National High Technology ResearchDevelopment Program of China (863 Program) (2008AA0248)
文摘For decreasing the multiple access interference of weaker signal acquisition in direct sequence spread spectrum（DSSS） systems,a new single decision algorithm is presented.The maximum value of correlation results is conventionally detected.However,there may be not only one strong peak among correlation results when the cross-correlation noise is strong enough to affect the correlation results.The proposed algorithm decreases the false alarm probability through the decision of the ratio of the maximum value and the second maximum value of the correlation results.Theoretical analysis and simulation results indicate that the proposed algorithm effectively suppresses the acquisition problem of multiple access interference in DSSS system.
基金This project was supported by the National Natural Science Foundation of China (No. 69872029) the Research Fund for Doctoral Program of Higher Education of China (No. 1999069808).
文摘Many blind channel estimation methods have been proposed for direct sequence (DS) code-division multiple access (CDMA) systems, so we can certainly use them to estimate the finite impulse response (FIR) channel for the multi-carrier (MC-) CDMA system. In this paper, the MC-CDMA system is interpreted as an equivalent time-domain DS-CD-MA system with specific spreading codes. Then, an equivalently time-domain blind channel estimator is derived for the uplink MC-CDMA, which is based on second-order statistics of the received data. By exploiting singular value decomposition (SVD) and the finite alphabet property of transmitted symbols, the time-domain channel impulse response (CIR) for the uplink MC-CDMA can be accurately identified. Computer simulations illustrate both the validity and the overall performance of the proposed estimator.
基金This project was supported by the National Natural Science Foundation of China (60073053 60133010).
文摘Multiple access interference (MAI) and near-far problem are two major obstacles in DS-CDMA systems. Combining wavelet neural networks and two matched filters, the novel multiuser detector, which is based on multiple variable function estimation wavelet networks over single path asynchronous channel and space-time channel respectively is presented. Excellent localization characteristics of wavelet functions in both time and frequency domains allowed hierarchical multiple resolution learning of input-output data mapping. The ma thematic frame of the neural networks and error back ward propagation algorithm are introduced. The complexity of the multiuser detector only depends on that of wavelet networks. With numerical simulations and performance analysis, it indicates that the multiuser detector has excellent performance in eliminating MAI and near-far resistance.
文摘The structure and performance of space-time multiuser detection receiver at base stations of WCDMA system is analyzed, in which smart antenna is employed. WCDMA uplink signal model is established in this paper. Space-time multiuser receiver presented in this paper combines 2D-RAKE with parallel interference cancellation (PIC), and the improved parallel interference cancellation methods are given. A novel space-time multiuser detection scheme, 2DRAKE-GPPIC is proposed. This scheme employs smart antenna to suppress unexpected DOA (Direction Of Arrival) signal, uses RAKE receiver to combine different delays of expected signal, and utilizes grouped partial parallel interference cancellation (GPPIC) algorithm to suppress further the interference signal in the main lobe of array antennas. The simulation results reveal that the scheme of space-time multiuser detection presented in this paper has better performance for WCDMA system.
基金supported by the National Natural Science Foundation of China (61171180)the National Basic Resaearch Program (923 Program) (2007CB31(0606))the Natural Sientific Research Innovation Foundation in Harbin Institute of Technology (HIT. NSRIF20011117)
文摘High complexity and high latency are key problems for multiuser detection （MUD） to be applied to a mobile station in cellular networks. To tackle these problems, an interleave division multiple access （IDMA） based multiple access scheme, grouped spread IDMA （GSIDMA）, is proposed. In a GSIDMA system, lower complexity and latency for mobile stations can be achieved by appropriately dividing active users into different groups. The system model of GSIDMA is constructed and followed by analysing on its system capacity, complexity and latency, and bit error rate （BER） performance. The extrinsic information transfer （EXIT） chart is used to analyze the convergence behavior of the iteration process. The grouping method and interleavers-reuse issue for GSIDMA are also discussed preliminarily. The analyses and simulation results indicate that the complexity and latency of the proposed scheme are much lower than those of IDMA, whereas its BER performance is close to the latter. The properties of low complexity and low latency make it more feasible for the practical implementation.
