【作者】 范国平；

【导师】 樊平毅；

【作者基本信息】 清华大学 ， 通信与信息系统， 2003， 硕士

【摘要】 发送分集技术是对抗无线信道衰落的重要手段，它能将发送天线的空间分集转化为接收机可以利用的分集方式，以改善前向链路的性能。将发送分集与编码调制技术相结合，进一步产生了空时编码技术，由于空时编码技术具有优异的抗衰落性能，并且能通过发送分集和接收分集提供高速率、高质量的数据传输，因此它已经成为第三代移动通信技术的重要组成部分，并将继续在下一代移动通信技术的发展中发挥重要作用。根据接收端是否利用信道信息进行解码，发送分集技术可以分为：相干发送分集和非相干发送分集技术两大类。由于相干发送分集技术依赖于对信道的准确估计，在信道处于快时变时，工程上难以实现，因此无需信道估计的非相干发送分集技术引起了学者们广泛的关注，差分发送分集就是其中十分引人注目的重要组成部分。本论文采用联合分集的方式将差分发送分集技术与接收分集技术相结合，进一步探讨了空间分集在抗衰落方面的潜力，并对基于联合分集技术的多天线通信系统进行了研究。主要成果如下：⑴针对不同的接收分集技术提出了一个简单、通用的检测算法；⑵采用实验仿真手段，对不同合并方法的性能进行了比较，发现计算复杂度最小的等增益合并方法在性能上接近最大比合并方法并优于选择性合并方法；⑶对系统的衰落参数、相关系数和载波频偏等因素的作用规律进行了研究，根据误码门限获得了使系统正常工作所需的各参数的有效范围，为实际系统的设计提供了有用信息。为了将联合分集系统的应用拓展到Nakagami信道上，论文还对Nakagami衰落信道的仿真理论、估计理论和生成算法进行了总结整理，并提出了验证Nakagami仿真信道有效性的三个指标，分别为：信道衰落参数一致性、概率密度一致性和相关信道协方差矩阵一致性。更多还原

【Abstract】 Among the effective methods to mitigate the fading in wireless communications is transmit diversity, which can utilize the space diversity of transmit antennae to generate the receive diversity and improve the performance of the forward link. Space time coding was proposed by combining transmit diversity and coding technology to improve the system performance, such as error bit rate, data rate, and system capacity. In particular, Space-time block coding (STBC) schemes, proposed originally by Alamouti were adopted by the 3G standardization committees as one key technique in 3G wireless systems.According to the channel state information (CSI), transmit diversity was classified into coherent transmit diversity and non-coherent transmit diversity. Coherent transmit diversity usually depends on the accurate CSI, which is difficult to acquire as the channel varies relatively fast. So the non-coherent transmit diversity becomes more interesting. Among the non-coherent transmit diversity technologies, differential transmit diversity is a remarkable technique.In this thesis we consider the combining diversity of the differential transmit diversity and receive diversity. The potential of space diversity was discussed and the error performance of combining diversity system was investigated. The main results are as follows. (1) A generalized detection algorithm was proposed for all the 3 combining methods. (2) According to the simulations and the analysis, the error performance of the easiest equal gain combing (EGC) was found to be as good as maximal ratio combining (MRC) and better than selective combining. (3) The effect of fading parameter, correlation coefficient and carrier frequency offset on the system performance was also investigated. Some available regions of parameters were acquired according to the error threshold.<WP=5>To extend the investigation of the performance of combining diversity system to Nakagami fading channels, we summarized the Nakagami channel simulation theory, Nakagami fading parameter estimation theory and the Nakagami channel simulation algorithm. On this condition, we proposed 3 indicators to evaluate the validity of the Nakagami simulation channel. They are fading parameter consistency, probability density function consistency and covariance matrix consistency.更多还原