【作者】 孙小钧；

【导师】 杜岩；

【作者基本信息】 山东大学 ， 通信与信息系统， 2007， 硕士

【摘要】 分块传输技术目前成为宽带数字通信系统的主要支撑技术之一。频域均衡的分块传输技术包括，正交频分复用(OFDM)和单载波频域均衡(SC-FDE)。二者都具有频谱效率高，抗多径干扰强和均衡简单的优点。因此，在高速宽带通信系统中，分块传输技术受到广泛关注，如多载波码分多址(MC-CDMA)，循环前缀辅助的码分多址(CP-CDMA)，正交频分多址(OFDMA)，傅立叶扩频的正交频分多址(DFT-SOFDM)等。而这些都是分块传输技术与多址技术相结合的产物。本文首先介绍了上述的各种多址技术，以及最优信号子空间理论和基于该理论的SC-FDE系统。同时，最优信号子空间理论也是本文提出的自适应算法的理论基础。基于最优信号子空间理论以及每子信道回传1比特信息的自适应算法，本文提出了自适应多址通信系统，包括CP-OSS-CDMA自适应系统和自适应DFT-SOFDM系统。为了在CP-CDMA系统中应用自适应算法，首先给出了CPA-DS-CDMA系统，并在此基础上结合自适应算法给出了CP-OSS-CDMA自适应系统。由于算法实现简单并且仅回传1比特信息，基于该算法的自适应系统非常适合于移动宽带无线通信系统中。由于上述的自适应DFT-SOFDM系统在固定的子载波分组内进行子载波选择，所以该系统无法利用多用户分集(Multiuser Diversity)从而造成了一定的频谱损失。为了利用多用户分集，本文基于最优信号子空间理论提出了一种在用户间动态分配子载波的自适应算法，有效的提高了系统性能并且频谱损失很少。由于该算法实现比较复杂并且回传信息较多，较适合于信道变化缓慢的环境中。由此，自适应DFT-SOFDM系统可将这两种算法综合应用。更多还原

【Abstract】 Recently, block-wise transmission techniques have become a hot research field of broadband digital communication. The block-wise transmission techniques with frequency domain equalization include OFDM and SC-FDE. Both are featuring high frequency efficiency, robustness to frequency selective fading and simple equalization. The multiplexing techniques based on them have gained great interest, for example MC-CDMA, CP-CDMA, OFDMA, DFT-SOFDM and so on.Firstly, this thesis introduces the present multiplexing techniques, Optimal Signal Subspace theory and OSS-based adaptive SC-FDE system. The Optimal Signal Subspace theory is also the foundation of the adaptive algorithm proposed in this thesis.Secondly, this thesis proposes adaptive multiusers communication system,i.e.,adaptive CP-OSS-CDMA system and adaptive DFT-SOFDM system. These are established on Optimal Signal Subspace theory and the low-cost adaptive scheme that needs only 1 bit feedback information per subchannel. In order to employ the adaptive scheme in CP-CDMA, this thesis introduces CPA-DS-CDMA system and provides the adaptive CP-OSS-CDMA system. Because of low-cost complexity and only 1 bit feedback information per subchannel, the adaptive systems are very suitable for mobile broadband wireless communication.Because the adaptive DFT-SOFDM system, which bases on 1 bit feedback information per subchannel, assigns the subcarriers among the given subcarriers group, the adaptive DFT-SOFDM system can not exploit the Multiuser Diversity. So the frequency efficiency reduces. In order to exploit the multiuser diversity, the paper proposes a new algorithm that assignes the subcarriers among users. This effectively improves the system performance and frequency efficiency. However, the complexity of this system is higher and the feedback information is more. So the system is fit for the slowly fading channel.更多还原