【作者】 阎凌；

【导师】 赵春明；

【作者基本信息】 东南大学 ， 通信与信息系统， 2006， 硕士

【摘要】 在CDMA移动通信系统的反向信道中,由于用户间扩频码不严格正交,多个用户之间会产生多址干扰,导致性能的恶化。多用户检测技术可以有效地减少多址干扰,提高系统容量。同时的,用户在多径衰落信道中传输,多径也会引起多址干扰的出现,均衡技术可以有效地消除多径形成的多址干扰,其性能要优于RAKE接收机。本文的第一部分专注于讨论多径环境下的多用户检测技术。与以往的异步多径环境下的多用户检测技术不同,没有直接推导用户间的符号多址干扰,而是首先在多用户系统中应用联合均衡技术,减小了系统多径的影响,然后在联合均衡的基础之上,进行符号上的多址干扰的消除。本文还使用了block-FFT为主的频域技术,在频域进行均衡和多用户检测,有效地减少了系统的计算复杂度。其中第二章简要介绍了多用户检测和均衡技术的相关基础;第三章详细推导block-FFT的多用户均衡和判决反馈干扰抵消的多用户检测技术;第四章将以上的多径环境下的多用户检测技术在CDMA 2000 1x EVDO系统的反向信道中进行了应用、分析和讨论。本文的第二部分主要为CDMA 2000 1x EVDO系统基站侧的C语言定点实现和FPGA实现,对设计方案进行叙述并对部分性能进行了仿真。更多还原

【Abstract】 In the reverse channel of CDMA mobile multi-user systems, the performance suffers from the multiple access interference (MAI). The multi-user detection (MUD) technique can reduce the MAI efficiently. At the same time, the MAI can also caused by multi-path fading channel. And the equalize technique, which has a better performance than RAKE receiver, can mitigate the influence of multi-path fading channel.The first part of the thesis will concentrate on the MUD technique in multi-path fading channel. In the thesis, we propose a system that counteracts the MAI of different user after equalizing the multi-user signals. Also, we use block-FFT to do the equalization and MUD in the frequency domain. The first part is organized as follows. During the second chapter, we make a simple introduction of MUD and equalization techniques. At the third chapter, the block-FFT multi-user equalization and decision feed back interference cancellation are discussed in detail. In chapter 4, we carry on the simulation in the CDMA 2000 1x EVDO system and make the analyses.In the last chapter we discuss the base band systems of CDMA 2000 1x EVDO base station. The C and the FPGA implement are both introduced.更多还原