共查询到17条相似文献,搜索用时 78 毫秒
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在分析多载波CDMA(MC-CDMA)技术原理的基础上,利用优化的多带复小波作为多载波调制以及turbo 编码作为信道编码,提出一种基于优化多带复小波和turbo编码的MC-CDMA系统,研究了其在瑞利衰落信道下的误比特率性能。该系统能克服通常MC-CDMA系统插入循环前缀(CP)所带来频谱效率的降低,并能充分利用turbo 码的良好抗信道衰落能力,进一步提高系统性能。理论分析和仿真结果表明该系统性能要好于通常MC-CDMA系统,具有与采用CP的MC-CDMA系统相比较的优势。同时turbo编码的应用显著增强了系统抗多径衰落和多址干扰的能力。 相似文献
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提出一种基于多带复小波和空时编码的多载波CDMA系统,研究了其在瑞利衰落信道下的误比特性能。理论分析和仿真结果表明该系统要明显优于通常MC-CDMA系统,具有与采用循环前缀(CP)的MC-CDMA相比较的优势,而且能够克服通常MC-CDMA系统插入CP所带来能量的减少和频谱效率的降低。同时空时编码技术的应用,显著增强了系统抗多径干扰和多址干扰的能力,进一步提高了系统性能。 相似文献
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该文提出了一种新的多载波码分多址(MC-CDMA)系统。与传统的MC-CDMA系统相比,其主要区别是要发送的数据比特先串并转换为多个并行分支,每一个分支用一组正交子载波进行调制。在每个分支上,使用相同扩频序列的不同码片调制子载波。这种系统能更有效地利用传输带宽,实现频率分集。由于该系统降低了每个子载波上的数据速率,扩频序列更容易同步。最后给出了在瑞利衰落信道下的性能分析。 相似文献
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A novel capacity analyzing method for multimedia CDMA systems based on power level allocation 总被引:1,自引:1,他引:0
Pan Su Tung Sang Ng Feng Guangzeng 《电子科学学刊(英文版)》2006,23(6):842-847
A novel method is proposed to analyze the capacity of future Code Division Multiple Access (CDMA) systems carrying multimedia services. The power level allocation is firstly investigated to meet each call's Bit Error Rate (BER) requirement, then the system capacity is defined from the conditions lbr the existence of the physical meaning of these power levels. Simulation results have shown that the capacity analyzing methods can be well used in the performance evaluation of the system accommodating heterogeneous services and the spectral efficiency of this scheme is higher than the existing ones. 相似文献
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Pan Su Liu Shengmei 《电子科学学刊(英文版)》2007,24(4):557-559
A novel method for improving the capacity of multi-code multimedia Code Division Mul- tiple Access (CDMA) systems is proposed. By factitiously improving the transmission bit rate of the call, the number of the orthogonal codes used by a user is increased which leads to the decreasing of the interference. Simulation results shows that the proposed scheme results in better throughput than traditional multi-code CDMA systems. 相似文献
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Xiangbin Yu Xiaodong Zhang Dazhuan Xu Guangguo Bi 《Wireless Personal Communications》2007,41(2):193-206
In this paper, the multiband complex wavelet used as multi-carrier basis function is optimized. On the basis of analyzing
the principle of multi-carrier code division multiple access (MC-CDMA), a new multiband complex wavelet based MC-CDMA (MBCW-MC-CDMA)
system model is proposed, and space diversity combining (SDC) technique is employed to improve the system performance further.
The uplink performance of proposed MBCW-MC-CDMA system with SDC technique is investigated in Rayleigh fading channel, and
corresponding bit error rate (BER) analysis is given in detail. Without any cyclic prefix (CP), the system can avoid the decrease
of spectrum efficiency and data rate of conventional MC-CDMA with CP. By comparison, our scheme outperforms real wavelet packet
based MC-CDMA and slightly outperforms conventional MC-CDMA with CP via utilizing superior properties of the optimized multiband
complex wavelet. Theoretical analysis and simulation result show that the application of SDC technique can improve the proposed
system ability to combat spatial fading and various interferences effectively. Moreover, the proposed system based on SDC
technique has superior BER performance over conventional DFT and SDC based MC-CDMA system and real wavelet packet and SDC
based MC-CDMA system.
Xiangbin Yu received the M.S degrees in Communication and Information Systems from Hohai University, Nanjing, China, in 2001; and his
Ph.D. in Communication and Information Systems in 2004 from National Mobile Communications Research Laboratory at Southeast
University, China. Now he is working as a Postdoctoral Researcher in Information and Communication Engineering Postdoctoral
Research Station at Nanjing University of Aeronautics and Astronautics, Nanjing, China. His research interests include multi-carrier
digital communication, space-time coding and digital signal processing in modern communications.
Xiaodong Zhang received the M.S degrees from Nanjing University of Posts and Telecommunications, Nanjing, China, in 1998. In 2002, he received
the Ph.D. degree from Southeast University, Nanjing, China. His research interests include contemporary signal processing
and digital communications.
DaZhuan Xu received the M.S degrees and Ph.D. in Communication and Information Systems from Nanjing University of Aeronautics and Astronautics
in 1986 and 2001, respectively. He is now a full professor in Nanjing University of Aeronautics and Astronautics, Nanjing,
China. Prof.Xu is a Senior Member of China Institute of Electronics (CIE). His research interests include digital communications,
soft radio, coding theory, medical signal processing.
Guangguo BI was graduated from Nanjing Institute of Technology, Nanjing, China, in 1960. He is now a professor in the Department of Radio
Engineering of Southeast University, Nanjing, China. Prof.Bi is a fellow and a member of the board of Director of the China
Institute of Communications, and a senior member of IEEE. His research interests include digital communications, personal
communications network, spread spectrum communications, and intelligent information processing. He has published more than
200 papers in above areas. 相似文献
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YangWei ChenJunshi TanZhenhui TakisMathiopoulos 《电子科学学刊(英文版)》2005,22(3):220-228
In this paper, a Direction Of Arrival (DOA) estimation algorithm is proposed for multiuser signals through uplink asynchronous multipath Code Division Multiple Access (CDMA) channels. The algorithm is based directly on the correlation matrices of matched filter bank outputs of desired user‘s multipath signals and it does not require that the elements of base station antenna array outnumber the multipath signals, which is necessary for the conventional sub-space based direction-finding algorithm. Simulation results show that the proposed algorithm estimates the DOA of multipath signals effectively and acceptably. The proposed algorithm has the prominent advantages of low complexity, simpleness and practicality, which make it much more suitable for practical application. 相似文献
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该文针对射频识别(RFID)领域中的安全认证协议和多标签防碰撞算法两个研究热点,设计了一种基于码分多址防碰撞算法的RFID安全认证协议。协议支持密钥的动态更新并引入标志位机制选择备用密钥来抵御数据库同步攻击,同时结合码分多址技术,应用重传随机数进行扩频码的选择,实现一次重传解决多标签识别中因数据碰撞造成的标签不识别的问题。首先,描述协议的流程及防碰撞原理;其次,应用SVO逻辑对认证协议的正确性进行证明;最后,对应用该认证协议的系统吞吐效率进行数值分析,分析表明其吞吐效率高于传统防碰撞算法。 相似文献