导　　师： 蒋铃鸽

学科专业： 081001

授予学位： 博士

作　　者： ;

机构地区： 上海交通大学

摘　　要： 2002年，美国联邦通信委员会通过了超宽带/(UWB/)技术可以进入商业应用的协议，并批准了它在通信系统、汽车雷达系统和遥控系统中的使用，点燃了工业界、大学、政府部门对UWB技术研究和开发的热情。2004年,美国有线新闻网将其评选为本年度十大热门技术之首。目前，UWB无线通信已成为短距离、高速无线网络最热门的物理层技术之一。然而，由于实际通信环境的不理想，无线信道的衰落效应限制了UWB系统的误码率性能、吞吐量、容量和网络灵活性。如果信道条件已知，那么由传输信道引起的失真效应，通常可以在接收机得到补偿。尽管传统通信系统采用非相干检测避免了复杂的信道估计，从而简化接收机设计，但对于高斯白噪声信道而言，非相干检测比相干检测有高达3dB左右的性能损失，而在具有大时延扩展的UWB信道中，性能损失可能会更加严重。因此，信道估计，即如何准确恢复信道状态信息，是UWB通信系统的关键技术之一，并且是一个重要的研究课题。本论文重点研究了UWB系统中信道估计的理论和方法，提出了多个信道估计算法，并对每个算法进行了详细的性能分析和计算机仿真验证。主要的研究内容及成果如下： /(1/)在单入多出的互关系/(CR/)子空间内，研究了基于二阶统计量的信道盲辨识问题。传统的批处理盲辨识算法由于需要进行特征值分解或奇异值分解，所以计算量大且不易实时执行。近来提出的多信道牛顿/(MCN/)和多信道最小均方/(MCLMS/)盲自适应估计方法避免了矩阵分解，但估计误差均存在地板效应。其中，收敛速度较快的MCN方法复杂度较高，而复杂度低的MCLMS方法收敛速度较慢。为克服传统方法的缺点，本文首先从数值分析的角度，提出一种基于逆乘幂法的迭代子空间盲信道辨识方法。该方法收敛速度较快 In2002, the US frequency regulator Federal Communications Commission allows theentrance of UWB technology to the commercial application. Since that time, industrial, academicand governmental research in that area has abounded. Moreover, US cable news networks remarkthe UWB technology as the top one in the ten most popular technologies in2004. At present, UWBwireless communication has been one of the popular physical layer technologies in the shortdistance and high-rate wireless networks. However, due to non-ideal communication environment,the frequency selectivity and fading of wireless channel restrains bit error rate performance,throughput, capacity and network flexibility of UWB systems. In case of knowing the givenchannel condition or obtaining accurate channel estimates, in general, the receiver can compensatethe distortion effects incurred by the transmission channel. Although the incoherent detectionadopted by the traditional communication systems can simplify the construction of the receiverthrough avoiding the complicated channel estimation, for AWGN channels, the penalty for the useof incoherent reception is only about3dB whereas this number increases significantly as the delayspread increases just like UWB channels. Similar to the existing communication systems, researchon channel estimation is a key issue and an important subject for UWB communications, i.e. howto retrieve the channel state information aimed at channel impulse response or channel frequencyresponse. Hence, we focus on the research of channel estimation theory and methods for UWBsystems. Several channel estimation methods have been proposed in this dissertation, whereestimation performance is analyzed in detail and simulations are also provided. The main contentsand contributions of this paper are listed as follows. /(1/) Presented is the research on blind identification based on SOS for the SIMO channels withthe cross relations /(CR/). Since the conventional batched algorithms concern singular valuedecomposition /(SVD/) or eigenval

关 键 词： 超宽带无线通信 信道估计 盲辨识 噪声方差估计 频域均衡

领　　域： [电子电信] [电子电信]