【作者】 许良凤；

【导师】 潘孟贤；

【作者基本信息】 合肥工业大学 ， 信号与信息处理， 2003， 硕士

【摘要】 码分多址(CDMA)通信系统以频谱利用率高、系统容量大、频率管理容易，软切换、移动台发射功率低、信道的传输速率高等优点代表了新一代移动通信，在未来的无线通信系统中必将扮演极为重要的角色。但是在实际的通信系统中地址码很难做到完全正交，以致于在用户数比较大时，存在不可避免的严重的多址干扰，极大地降低了通信服务地质量。要想真正消除干扰，大幅度提高系统的容量，就必需采用多用户检测技术。 本论文主要介绍扩频技术在通信中的运用，针对CDMA通信系统的特点，研究了现有的一些多用户检测技术，希望通过研究找到一种有效的CDMA通信的多用户检测的方法。同时还要考虑尽可能小的比特误码率(BER)。考虑到模拟退火算法和遗传算法各自的优缺点，将两者有效的结合起来，通过模拟退火算法来减轻遗传算法的选择压力，利用模拟退火算法的Boltzmann机制来接收交叉和变异后的个体，并且结合CDMA通信系统多用户检测的特点，采用了遗传退火算法对CDMA通信系统的多用户进行检测的研究。为了验证这一思想，我们进行了计算机仿真实验，并对仿真结果进行了分析，结果表明这种算法的应用使系统性能得到提高，优于传统的检测方法。实验结果表明了这一检测方法的有效性。 本文进行的主要工作如下： 1．对CDMA扩展频谱通信进行了系统的介绍，并详细介绍了CDMA的多用户检测方法，分析一些多用户检测算法的优缺点。 2．介绍了模拟退火算法和遗传算法，在分析两种算法的优缺点的基础上将两者有效的结合起来得到一种算法即遗传退火算法，并将遗传退火算法应用到频率分配中与遗传算法进行比较。 3．结合CDMA通信系统多用户检测的特点，采用遗传退火算法来进行CDMA的多用户检测。更多还原

【Abstract】 Code division multiple access(CDMA) communications systems being possessed of the merits of great capacity and soft hand-off and so on must have taken a significant role in future wireless communications systems. Because PN sequences used in communications systems are been vertical completely , when numbers of user are more, there are multiple access interference(MAI) in CDMA and serving quality in communications systems is reduced. If interference are avoided and capacity of systems is increased, multi-user detection technology must be used in CDMA.This paper introduces the application of the spread spectrum technology in communications. Aiming characteristic in CDMA communication systems, after we discuss some multi-user detection technology at present, and want to find a effective multi-user detection method with a small bit error rate in CDMA communication. Considering respective merits and disadvantages at simulated annealing algorithm and genetic algorithm, we combine them .By using simulated annealing algorithm(SA) to mitigate the stress of culling in genetic algorithm(GA) and utilizing the Boltzmann mechanism of simulated annealing algorithm to control the acceptance of the individuals generated by copulated and varied, a CDMA multi-user detection method based on genetic annealing algorithm is adopted. The computer simulative experiment is conducted. Satisfying result is got after analyze the simulation result. The result proved that the use of this algorithm will improve the performance of system and that the performance of system is better than the decorrelating multi-user detection. Experiments proved its efficiency.The following is what I have done in this paper:1.The paper systematically introduced the fundamental knowledge of Spread Spectrum Communication in CDMA , introduced multi-user detection technology in CDMA, and analysed advantages and flaws of multiuser detection technology.2.The paper introduced SA and GA. Through the analysis of faults and merits of two algorithms,we combined Genetic Algorithm with Simulated Annealing Algorithm and formed a genetic annealing algorithm and applied to frequence assignment.3.The paper used a multi-user detection based on genetic annealing algorithm.更多还原