The joint channel and power allocation in the downlink transmission of multi-user multi-carrier code division multiple access（MC-CDMA） systems are investigated and the throughput maximization problem is considered a...The joint channel and power allocation in the downlink transmission of multi-user multi-carrier code division multiple access（MC-CDMA） systems are investigated and the throughput maximization problem is considered as a mixed integer optimization problem. For simplicity of analysis, the problem is divided into two less complex sub-problems： power allocation and channel allocation, which can be solved by a suboptimal adaptive power allocation （APA）algorithm and an optimal adaptive channel allocation （ACA） algorithm, respectively. By combining APA and ACA algorithms, an adaptive channel and power allocation scheme is proposed. The numerical results show that the proposed APA algorithm is more suitable for MC-CDMA systems than the conventional equal power allocation algorithm, and that the proposed channel and power allocation scheme can significantly improve the system throughout performance.展开更多
在通信系统中,一直存在着频率选择性的衰落,以及噪声的干扰和码间串扰。衰落包括快衰落和慢衰落。这些问题都会让通信系统的性能和质量受到严重的影响。正交频分复用技术OFDM(Orthogonal Frequency Division Multiplexing),此技术常常...在通信系统中,一直存在着频率选择性的衰落,以及噪声的干扰和码间串扰。衰落包括快衰落和慢衰落。这些问题都会让通信系统的性能和质量受到严重的影响。正交频分复用技术OFDM(Orthogonal Frequency Division Multiplexing),此技术常常会被用于抵抗外界干扰较差的地方的传输介质中。就是解决这些问题的方法之一。本文将详细的分析和研究该技术。展开更多
This paper investigates Carrier Frequency Offset (CFO) estimation in the uplink of the Orthogonal Frequency-Division Multiple Access (OFDMA) systems with the interleaved subcarrier assignment. CFOs between the transmi...This paper investigates Carrier Frequency Offset (CFO) estimation in the uplink of the Orthogonal Frequency-Division Multiple Access (OFDMA) systems with the interleaved subcarrier assignment. CFOs between the transmitters and the uplink receiver will destroy orthogonality among different subcarriers, hence resulting in inter-carrier interference and multiuser interference. A two-stage frequency offset estimation algorithm based on subspace processing is proposed. The main advantage of the proposed method is that it can obtain the CFOs of all users simultaneously using only one OFDMA block. Compared with the previously known methods, it not only has a relatively low implementation complexity but is also suitable for random subchannel assignment.展开更多
基金Major Project of the National Natural Science Founda-tion of China(No.60496311)the National High Technology Research and Development Program of China(863Program)(No.2007AA01Z207)the Program for New Century Excellent Talents in University
文摘The joint channel and power allocation in the downlink transmission of multi-user multi-carrier code division multiple access（MC-CDMA） systems are investigated and the throughput maximization problem is considered as a mixed integer optimization problem. For simplicity of analysis, the problem is divided into two less complex sub-problems： power allocation and channel allocation, which can be solved by a suboptimal adaptive power allocation （APA）algorithm and an optimal adaptive channel allocation （ACA） algorithm, respectively. By combining APA and ACA algorithms, an adaptive channel and power allocation scheme is proposed. The numerical results show that the proposed APA algorithm is more suitable for MC-CDMA systems than the conventional equal power allocation algorithm, and that the proposed channel and power allocation scheme can significantly improve the system throughout performance.
文摘在通信系统中,一直存在着频率选择性的衰落,以及噪声的干扰和码间串扰。衰落包括快衰落和慢衰落。这些问题都会让通信系统的性能和质量受到严重的影响。正交频分复用技术OFDM(Orthogonal Frequency Division Multiplexing),此技术常常会被用于抵抗外界干扰较差的地方的传输介质中。就是解决这些问题的方法之一。本文将详细的分析和研究该技术。
基金the Specialized Research Fund for the Doctoral Program of Higher Education, China Ministry of Education (No.20030003039).
文摘This paper investigates Carrier Frequency Offset (CFO) estimation in the uplink of the Orthogonal Frequency-Division Multiple Access (OFDMA) systems with the interleaved subcarrier assignment. CFOs between the transmitters and the uplink receiver will destroy orthogonality among different subcarriers, hence resulting in inter-carrier interference and multiuser interference. A two-stage frequency offset estimation algorithm based on subspace processing is proposed. The main advantage of the proposed method is that it can obtain the CFOs of all users simultaneously using only one OFDMA block. Compared with the previously known methods, it not only has a relatively low implementation complexity but is also suitable for random subchannel assignment.
