一种基于盲源分离的DOA估计方法

文中基于特征矩阵联合近似对角化JADE（Joint Approximate Diagonalization of Eigen-matrices）的盲分离算法提出了一种DOA估计新方法。该方法对阵列流型矩阵进行了盲估计,并将阵列流型中的方向矢量看成是由多个复正弦信号线性混合而成,进而利用频谱分析的方法实现信号的DOA估计。实验结果表明：该方法在同等条件下完成同样的方位分辨要优于多重信号分类MUSIC（Multiple Signal Classification）的方法,而且还可以实现对相干信号源进行分辨。     

TD-SCDMA系统扰码规划算法及仿真

根据TD-SCDMA码资源特点,在深入分析复合码循环相关特性的基础上,提出了归一化码字相关值的概念,作为衡量扰码互相干扰的相关特性值,以此为依据可以构建扰码对的互相关值评价矩阵。并在3GPP TS25.102协议给出的1.28 Mc/s TDD的三种多径衰落信道环境下,进行扰码规划算法的仿真测试。研究表明,TD-SCDMA系统的扰码间相关值越小系统性能越好。     

TDMA网络的FH-OFDM同步算法研究

首先对比了FH-OFDM（跳频OFDM）两种组成形式的优缺点,据此选择了其中一种形式构建了TDMA网络的FH-OFDM的系统模型;然后分别讨论了该系统中跳频同步、时分多址（TDMA）网同步和正交频分复用（OFDM）同步的算法以及三者之间的关系;并对OFDM同步算法进行了深入讨论,构造了基于数据辅助估计的FH-OFDM跳帧结构;利用短训练符号进行了OFDM同步的Matlab仿真,分析了影响频偏估计的因素,并提出了一种工程上选择训练符号的参考方法。     

无线多址信道中的协作模型研究

在无线多址信道环境下,为了充分利用协作分集技术提高系统的传输速率和通信质量,引入了多址接入中继信道（MARC）模型。通过加入一个专门的中继节点,MARC模型中的发送节点类似操作在普通的多址信道下,从而使得现有的系统可平滑过渡到协作系统,实用性强。把MARC模型应用在直序扩频CDMA系统中,在Rayleigh信道下对其误码率进行仿真,结果表明,采用MARC模型的协作网络能获得显著的性能增益。     

频域导频联合OFDM信道估计

0引言 正交频分复用（OFDM）将高速数据流串并转换到正交并行子载波上,以较低的比特率发送,从而具有很强的抗无线信道多径衰落和抗脉冲干扰的能力。目前这种技术已经广泛应用于数字音频广播（DAB）、高清晰度电视（DVB）,IEEE802．11a,IEEE802．11g以及3G标准之一的WiMAX中。     

TD-SCDMA系统中联合检测算法及实现过程

0引言 TD－SCDMA系统是一个干扰受限系统,需要通过降低干扰信号的功率来提高系统容量。在单径且同步的情况下,选择相互正交的扩频码可以完全抑制多址干扰（MAI）,但由于无线信道的多径传播特性,即使各用户到达基站的信号完全同步,通过扩频码匹配滤波也不可能完全滤除MAI。     

Practical robust uniform channel decomposition scheme for CSI mismatch in limited feedback MIMO systems

Uniform channel decomposition (UCD) has been proven to be optimal in bit error rate (BER) performance and strictly capacity lossless when perfect channel state information (CSI) is assumed to be available at both the transmitter and receiver side. In practice, CSI can be obtained by channel estimation at receiver and conveyed to transmitter via a limited-rate feedback channel. In such case, the implementation of traditional UCD by treating the imperfect CSI as perfect CSI cause significant performance degradation due to inevitable channel estimation error and vector quantization error. To overcome this problem, a practical robust UCD scheme was proposed in this paper, which includes two steps, firstly, a matching architecture was proposed to eliminate the mismatch between CSI at receiver (CSIR) and CSI at transmitter (CSIT), secondly, an MMSE based robust UCD scheme considering channel estimation error and vector quantization error as an integral part of the design was derived. Simulation results show that the proposed practical robust UCD scheme is capable of improving the BER performance greatly in the context of channel estimation error and vector quantization error compared with the traditional UCD scheme.     

Robust Tomlinsion-Harashima precoding design with outdated CSIT

The channel state information at transmitter (CSIT) acquisition plays a key role in the multi-input multi-output (MIMO) system, especially for the precoding schemes. However it is unrealizable to acquire perfect CSIT in practice. In this article, an effective and practical dynamic CSIT model is introduced to acquire imperfect channel state information. For practicability, the channel temporal and spatial correlations are considered and the channel estimate and its error covariance are obtained by utilizing the outdated channel state information. Based on the dynamic CSIT mode, closed-form solution of robust Tomlinsion-Harashima precoding (THP) is derived by a Lagrangian approach. Numerical simulations are presented to demonstrate the performance.     

Group-blind multi-user detection under multi-path channel

This article proposes an improved generalized side-lobe canceller(GSC)receiver structure based on a new group constraint,which is suitable to eliminate multiple-access interference(MAI),inter-symbol interference(ISI)in direct-sequence code-division multiple access(DS/CDMA)downlink multi-user system.The new group constraint is deduced to construct the group-blind adaptive multi-user detector.The analysis indicates that the improved GSC under the new constraint not only retains the property of suppressing ISI and canceling MAI,but also can extract useful information from the succeeding bit for the desired user.The simulations show that the improved GSC filter can cancel the MAI efficiently whether the wireless channel length is short or long,and achieve better performance than other compared filters.     

基于OFDM通信的铁路客车广播线信道研究

在广播线信道上选择合适的通信方式对保障铁路客车发电机监测系统稳定通信具有重要意义。结合广播线信道的强干扰性及衰减特性,基于正交频分复用（OFDM）通信方式,建立一个新的广播线信道简化模型。仿真结果表明,相比传统通信方式,OFDM通信应用于广播线通信信道上具有衰减较少,误码率较低的特性。