【作者】 陈秀鹏；

【导师】 康桂霞；

【作者基本信息】 北京邮电大学 ， 通信与信息系统， 2010， 硕士

【摘要】 下一代移动通信系统是一个高频谱利用率、高传输速率,并可提供多种服务的无线网络。为了满足这些要求,需要应用新的无线空中接口技术,以正交频分复用技术为核心的超三代移动通信系统应运而生。本文主要就超三代移动通信体系中多小区环境下的信道估计、导频设计进行分析研究。本文首先介绍了无线信道特性及其模型、蜂窝小区、多小区同频干扰模型,以便更深刻地理解仿真设计中所考虑的环境。紧接着,描述了正交频分复用系统的原理和结构,最优导频设计,系统地总结了几种常用信道估计和插值算法,将最小二乘法,最小均方误差法,傅里叶变换法等各种信道估计算法和级联的一维插值算法进行了性能评估,并讨论了实际系统中循环前缀截取对于信道估计性能的影响。在上述工作的基础上,论文重点讨论了在多小区环境下,如何通过导频的优化设计来抑制信道估计过程中来自于其他小区的同频干扰。提出了基于恒包络零自相关(CAZAC, Constant Amplitude and Zero Auto Correlation)序列作为导频序列的改进方案,考虑序列长度为非素数的情况,提出了最优导频序列和次优导频序列混合使用的方法,并与3G长期演进(LTE, Long Term Evolution)系统中的上行导频设计方案进行了比较。通过理论推导和仿真发现,此方法可以更好地抑制小区内多用户干扰和小区间的同频干扰。进一步地,本文研究了在获得信道估计的基础上,如何在发送端、接收端充分利用该信道信息来优化系统设计的问题。本文详细介绍了一种在多小区环境下基于多天线正交频分复用系统的自适应算法,利用闭环链路反馈的部分信道信息来抑制小区间干扰和小区内的高斯白噪声,提升多小区环境下的信干比,从而更有效地使用所获取的信道信息。更多还原

【Abstract】 The next generation mobile communication systems will have higher spectrum efficiency, higher transmission rate, and provide multimedia services to the users. In order to achieve above targets, new wireless air interface technologies must be applied. Orthogonal Frequency Division Multiplexing is one of the candidate technologies in B3G systems. This thesis focuses on the channel estimation and pilot design technology in OFDM-based B3G systems under multi-cell environment.For deeper understanding of the simulation-design in our considered environment, this thesis first describes the wireless channel characteristics and models, cellular cell and multi-cell model with co-frequency interferences. And then, this thesis introduces the principle and structure of OFDM systems and the issue of optimal pilot design, summarizes several common channel estimation techniques and interpolation algorithms in OFDM system, and evaluates the performance of LS, MMSE, DFT channel estimation algorithms, and discusses the influence of cyclic prefix interception on channel estimation performance in the actual system.Based on above works, this thesis pays attention to the issue of pilot design technologies to suppress the co-frequency interferences from other cells in the process of channel estimation in multi-cell environments. This thesis presents a pilot design proposal based on constant amplitude and zero autocorrelation (CAZAC) sequence. The proposal breaks the sequence length limit of prime number in long term evolution (LTE) system. Instead, the length is expanded to a broader scope. This proposal also proposes a method by mixed use the optimal pilot sequences and sub-optimal pilot sequences, so that improves the original design of pilot in the uplink of LTE system. It is found that this method can significantly inhibit the intra-cell multi-user interference and the inter-cell co-frequency interference.Furthermore, this thesis investigates how to make use of the channel information at the transmitter and the receiver after we get knowledge of channel through channel estimation. This thesis describes an adaptive algorithm in multi-cell environment, which uses partial channel information feedback from closed-loop link to suppress inter-cell interference and intra-cell Gaussian noise. This adaptive algorithm is shown to enhance the signal-to-interference ratio in multi-cell environment and make use of the channel state information more efficiently.更多还原