【作者】 胡诗维；

【导师】 张平； 张建华；

【作者基本信息】 北京邮电大学 ， 通信与信息系统， 2010， 硕士

【摘要】 无线信道传播特性的测量和建模工作,对于无线系统的评估验证,新型传输技术的研究,以及实际无线网络的部署都具有基础意义。随着通信技术的发展,宽带、多入多出(multiple-input and multiple-output, MIMO)和中继协作式通信(Relay)的出现将极大的增加下一代移动通信系统的容量或者覆盖。本论文围绕下一代移动通信宽带、MIMO、中继技术的传播特性测量和建模进行讨论,按照实地测量结合理论分析的研究路线,完成从传播特性抽取到建模的研究,主要的工作包括三个方面：(1) IMT-Advanced信道模型简化和校准。IMT-Advanced信道模型是基于几何簇的一种信道模型,它能够精确的反映多个场景的无线信道特性,并包含了100MHz带宽,多天线,以及极化阵列等多个新特性。然而正由于IMT-Advanced信道模型的精确程度高,包含的信道特性丰富,使得其模型的复杂度提升,模型实现困难。针对这个问题,本论文提出了一套基于相关矩阵结构的IMT-Advanced信道模型简化方法,其考虑了天线增益,角度功率谱,多普勒谱的特性,尽量保持信道的频—时—空域的特性保持不变。并将模型复杂度下降了一个数量级。同时本论文也给出了一套IMT-Advanced信道模型的校准框架,能逐步比较不同的模型的实现结果,从而使不同公司、厂商信道模型实现平台的结果尽量一致。(2)莱斯信道下K因子的建模与提取。莱斯信道下存在一部分信道分量的功率保持固定,不受多径衰落的影响而明显变化,从而使信道包络服从莱斯分布。而传播环境的不同,信道的固定分量的组成也不一样。基于在北邮校内室内固定点多天线测量的结果,本论文研究了宽带无线固定接入信道的传播特性,给出了一种新的莱斯因子K的建模方法。新的模型不认为莱斯信道下信道的固定分量都是由直射径造成的,从而得出的结论是信道在各个时延处都存在固定分量,即服从莱斯分布。这种现象出现的原因是室内宽带固定接入信道的固有特点。新的建模方法可以通过改变模型参数来适用于不同的场景,从而更具有普适性。另一方面,针对使用全向阵列进行测量时,无法准确的提取信道参数K因子的情况。本论文提出了基于高精度信道参数估计算法的新型K因子提取方法。新的方法适用于室外移动测量的情况,认为信道的功率固定的分量主要是由直射径引起的。通过进行信道多径分量的筛选和搜索,找到最有可能的直射径分量。进一步可以得到相应的莱斯因子K。(3) Relay场景的信道相关性参数提取分析。在LTE-Advanced技术的评估过程中,IMT-Advanced信道模型被接受为评估模型。而IMT-Advanced信道模型缺乏Relay场景的模型参数,尤其是IMT-Advanced信道模型新引入的信道相关性参数。基于在多个Relay场景的实地测量结果,本论文给出了一套适用于IMT-Advanced信道模型的Relay场景的信道相关性参数,并结合场景特点将其与城区微／宏小区的参数进行了对比分析以验证Relay场景参数的可靠性。以上是本文主要得工作内容和创新点,其中第(3)点在2009年8月深圳召开的3GPP RAN1第55次会议上被接收,第(1)在2009年8月的LTE+推进组会议上被接受。这些结果将为下一代移动通信技术仿真评估提供一定的测量和理论参考。更多还原

【Abstract】 The research of radio channel propagation characteristics is significant to evaluation of wireless system, design of novel transmission technology and deployment of wireless networks. As the evolution of wireless communication, the emergence of broadband, multiple-input and multiple-output (MIMO) and cooperative communication (Relay) will greatly increase the capacity and coverage of next-generation mobile communication system. This thesis will focus on the channel propagation characteristics and modeling of next-generation wireless system based on wireless channel measurements. The main work of this thesis includes three points:(1) Calibration and simplification of IMT-Advanced channel evaluation model. IMT-Advanced channel model is a model based on geometry clusters. Several new features like 100MHz bandwidth, MIMO and polarization array have been introduced in IMT-Advanced channel model. However, these new features also make the IMT-Advanced channel model rather complex to use and realize. To solve this problem, this thesis has proposed a simplified model based on Kronecker product, which takes the antenna gain, angle power spectrum and Doppler spectrum characteristics into account. All of these are aimed at keeping simplified model’s characteristics of frequency, time and spatial domain similar to IMT-Advanced model. The simulation results show that, the complexity of simplified model is only ten percent of that of the original model. In the other hand, a flowchart of calibration work of IMT-Advanced channel model is also been proposed to provide a criteria for the comparison of different model implementations, and this ensures the uniformity of channel model in the evaluation work.(2) The modeling and extraction of K factor in Ricean channel. Under the Ricean channel, some of the channel components’power is static and the channel envelope follows Ricean distribution. The constitution of channel power-static components is different according to the different conditions of environments. Based on the indoor stationary MIMO measurement results in Beijing University of Posts and Telecommunications, this thesis has studied the broadband fixed wireless access (BFWA) channel propagation characteristics, and proposed a new modeling method of Ricean factor K. This new model doesn’t regard the line-of-sight (LOS) channel component as the only time-invariant component, and finds out that the channel time-invariant components exist in different delays and in which channel envelopes follow Ricean distribution. The origin of this phenomenon is the propagation characteristic of BFWA channel. The new modeling method is universal since it can be applied in different scenarios by changing the model parameters. In the other hand, when omni-directional array are used in channel measurements, the extraction of Ricean factor K will be inaccurate. The thesis presents a novel K-factor extraction method based on high-precision channel parameter estimation algorithm. The new method is suitable for mobile-receiver measurement scenario. It searches the most likely LOS component of channel and regards the LOS component as the only power-static component.(3) The extraction and analysis of correlation characteristics of Relay channel. The channel model of IMT-Advanced is applied as the evaluation model of LTE-Advanced system. However, the IMT-Advanced channel model lacks of the parameters of Relay scenarios, especially the correlation parameters newly introduced by IMT-Advanced channel model. In this thesis, a set of channel correlation parameters were given based on wireless channel measurements in the Relay scenarios. Furthermore, these parameters are compared with the same type of parameters of urban micro/macro cell for the sake of parameters validationThe main work and innovation of this thesis are stated above. The third point above was accepted by 3GPP RAN1 #55 meeting in Shenzhen, China. The first point was accepted by LTE+ promotion group in October 2009. All of these results are informative for the evaluation and simulation of next-generation wireless system.更多还原