【作者】 彭海燕；

【导师】 张利华；

【作者基本信息】 华东交通大学 ， 交通信息工程及控制， 2011， 硕士

【摘要】 随着社会的进步与发展,DS-CDMA移动通信技术也得到了飞跃的发展。到目前为止,已经发展到第三代(3G)移动通信,它给人们的日常生活和工作带来了更加方便、快捷的服务。但随着多媒体业务以及高速数据业务内容的不断丰富,这就要求新一代的移动通信必须具有更高的系统容量。在目前所采用的DS-CDMA移动通信系统中,随着用户数量的增多,用户之间的干扰也越来越严重,其中最主要的干扰就是多址干扰(MAI),它是一种小区内用户之间的干扰。它的存在严重制约了移动通信系统的性能和系统容量。这迫使研究者们去寻找一种能消除多址干扰的技术,由此提出了多用户检测技术。多用户检测技术的基本思想就是把多址干扰作为一种有用的用户信息加以利用,而不是将其简单地看作干扰噪声来处理掉,它能有效地消除多址干扰或将多址干扰减少到最低,从而达到提高系统的性能和容量的目的。由于现有的量子克隆遗传算法在算法中增加了免疫克隆策略,避免了算法的盲目性和随机性,能避免早熟,具有加速收敛的特点,但是该算法性能的提升是以扩大空间搜索范围,增加计算时间为代价的;而且,算法中采用根据量子的叠加特性和量子跃迁的理论而设计的量子旋转门的变异策略,使得量子门的全局最优搜索方向的确定存在盲目性。为此,针对这些缺陷,在李阳阳[5]给出的量子克隆遗传算法的基础上,在进化早期,采用小生境协同进化策略初始化量子种群,便于最优染色体的寻优;在进化中期,引入量子全干扰交叉,在整个种群内进行信息传递,避免陷入局部极值点,加速算法收敛,同时使用自适应量子旋转角更新策略,加速最优解的搜索;在进化后期,为避免早熟和进化停滞,采用量子灾变策略,使用优体全干扰交叉,使种群从各个不同方向搜索目标解,由此给出了一种改进的量子克隆遗传算法(Improved Quantum Clone Genetic Algorithm, IQCGA)。经全局收敛性证明和性能测试表明,IQCGA算法具有种群多样性好、全局寻优能力强、搜索效率高、收敛速度快、算法效率适当的特点,可以应用到组合优化问题中。多用户检测是一个组合优化问题,基于IQCGA,给出了DS-CDMA系统的多用户检测算法。利用Matlab将其与基于遗传算法的多用户检测器(GA-MUD)、基于量子遗传算法的多用户检测器(QGA-MUD)和基于量子克隆遗传算法的多用户检测器(QCGA-MUD)进行仿真对比,仿真结果表明:IQCGA-MUD的误码率、收敛速度、抗多址干扰能力和抗“远近”效应的能力均优于GA-MUD、QGA-MUD和QCGA-MUD。更多还原

【Abstract】 With the progress and the development of the society, the mobile communication technology of DS-CDMA also developed saltantly. So far, it has been already developed to the third generation (3G), it brings more convenient and shoutcut service to the work and the daily life of the people. However, with the continual enriched content of the multi-media operation and high speed data operation, it demands the mobile communication of the new generation must have the bigger system capability.At the present, with the increasing of the user’s number, the interference among users gets more and more severiouly in DS-CDMA system. Here, the multi-address interference is the uppermost interference, it is a villagal interference among users. Its existence restricts seriously the performance and capability of the mobile communication system. It compels investiqators search a technology of eliminate multi-address interference (MAI). Sequently, investiqators put forward multi-user detection. The basic idea of multi-user detection is that it takes the MAI as a useful user information, other than deal with it simplily as a interfere noise. It makes use of the relevancy among users to carry through unite detection at the most extent, it can eliminate the MAI validly or decrease the MAI to the minimum. Therefore, it can achieve the aim of enhance the performance and the capability of the system.Since the quantum clone genetic algorithm was added immunity clone strategy, it had the characteristics of avoiding blindness and randomness of the algorithm, could avoid prematurity and accelerate converquence, but the enhance of the algorithm’s performance was extending space search range and increasing calculate quantity for cost, moreover, the algorithm adopted the variation stratege of quantum rotate gate according to the quantum composition features and the theory of quantum transition, which made the comfirm of the global search direction of quantum gate existed blindness.Therefore, against these defects, at the foundation of quantum clone genetic algorithm which was given by Li Yangyang, in the early state of the evolution, adopting the niche cooperate with evolution strategy to inilialize quantum conoly, which is convenient to the optimal search of the optimal chromosome; in the metaphase of the evolution, inducting quantum with all cross, which is carried through the information transfer in the whole colony and avoids getting into local optimal value, accelerating the converquence of the algorithm, while, the algorithm uses adaptive quantum rotate gate strategy, which can accleralate the search of the optimal solution; in the later stage of the evolution, in order to avoid the prematurity and evolution stagnancy, adopting quantum catastrophe strategy, which uses the all interference cross of the individual and makes the colony search the optimal solution through each direction, therefore, the text give a Improved Quantum Clone Genetic Algorithm (IQCGA).By the evidence of the global converquence and the demonstration of the performance test, the algorithm of IQCGA has the merits of good conoly diversity, strong ability of global search optimal, high efficiency of the search, fast speed of converquence and the proper efficiency of the algorithm. It can be applied to the combined optimal problem.The multi-user detection is a combined optimal question, the text gives a multi-user detection algorithm of DS-CDMA based on IQCGA. And compared with GA-MUD, QGA- MUD and QCGA-MUD by using Matlab to process the simulation, the result of the simulation demonstrates: the bit error, the converquece speed, the resist performance of MAI and the resist performance of“near-far”effect of IQCGA-MUD are all better than GA-MUD, QGA-MUD and QCGA-MUD.更多还原