空时格码迹准则的改进

本文研究空时格码迹设计准则的改进问题.原迹准则的不足在于仅考虑了码的最小迹,故不能有效的选取最优码.针对这一不足,本文首先提出了以迹分布作为衡量码性能主要依据的思路.然而迹分布仍不能完全决定码的性能,于是文中导出了一个新的错误概率上界,并在此基础上又提出了以特征值和方/方和比分布来补充和完善迹分布的思路.最后综合以上两个分布,本文给出了一个改进的空时格码设计准则,并根据这一准则找到了一些新码,仿真结果表明这些新码的性能为目前已知码中最优的.     

移动通信系统中空时格码的改进设计

本文根据空时格玛在快瑞利衰落信道下的成对错误概率上界，得出不同发射天线的码设计具有独立性，进而提出一种改进的快瑞利衰落信下空时格码的设计准则，当信道衰落快慢介于准静态和快瑞利衰落之间时，空时格码的设计方法也可做相应的改进，分析及仿真结果表明，由改进方法设计的空时格码比由传统方法得出的具有更优的性能。     

Rayleigh衰落信道下空时网格码的性能研究

为了比较准确地评价空时网格码(STTC)的编码性能.利用矩量母函数(MGF)分析方法,推导出了在不相关Rayleigh衰落信道中STYC成对差错概率的单变量积分形式的准确表达式,通过对STYC成对差错概率(PEP)的研究,发现利用PEP单变量积分形式能够更精确地估计STTC的性能.同时研究了编码器状态数、收发天线数和天线相关系数对STTC影响,并基于此分析了其误码率和误帧率性能,最后给出Rayleigh衰落条件下的空时网格编码的误码率和误帧率性能仿真结果,验证了理论分析的有效性.     

PCM遥测系统最佳帧同步码分析

本文阐述了PCM遥测系统帧同步码的基本要求及其最佳准则，推导了帧同步码的误同步概率和漏同步概率的计算公式，介绍了用“穷举法”搜 索最佳帧同步码的计算机程序框图，并给出了计算机搜索的容错数E＝1，码元错误概率P0＝0．1，码长n=7-25的最佳帧同步码的结果。结果表明：当码长n=7,8,9,11,16时，最佳码比有关遥测方面的文献所推荐的帧同步码要好。     

一种准静态平坦衰落信道下空时编码设计的新方法

空时码在准静态平坦瑞利衰落信道下的设计准则被广泛采用的是秩准则和行列式准则,但这些准则并不是很紧的。为此,提出了准静态平坦瑞利衰落信道下一种新的更紧的设计准则,采用这种准则还大大降低了穷举搜索空时好码的复杂度,仿真结果表明,搜索得到的空时好码性能优于现有的其它好码。     

空频码设计的新思路及快速检测算法

对于一个系统化设计的空频码而言,成对错误概率的分析是导出相应编码准则的关键.常用的Chernoff域方法只能提供一个比较松的上界,并不能有效体现空频码设计的一些特点.提出了一种宅频码设计的新思路,通过将多径信道下的空频码传输转化为平衰落信道下的空时码传输,从而利用空时码设计中的性能分析有效地导出了空频码设计的相应准则,在获取宽带系统频率分集的基础上优化了编码增益,提出了码设计的一些特点.该分析方法比现有的方法更加具有一般性,也更直观.还提出了一种空频码字的快速检测算法,它利用格形译码的方法大大简化了检测过程,比最大似然检测具有更小的复杂度,有利于系统的实现.     

基于Fourier矩阵的酉空时码设计

基于Fourier矩阵提出了一种新的酉空时码设计技术,依据满分集增益的定义证明了该码能获得满分集增益。在此基础上推导了该空时码成对错误概率的闭式上界,充分利用了该码的结构特点设计了一种快速极大似然解码算法,最后给出了误码性能的仿真结果。     

空间相关信道下酉空时码误码性能的数值计算

该文旨在通过数值计算技术来分析信道空间相关对酉空时码的性能影响。基于成对错误概率给出了平均误比特率和误码字率的上界。同时给出了当MIMO信道独立时,该文结果与现有结果的等价性证明。Mento-Carlo仿真表明,酉空时码的误码性能随着信道空间相关的增加而恶化,并且恶化的程度直接决定于信道相关的强弱。     

Rice衰落下RS码级联空时分组码系统的性能分析

从理论上给出一种Rice衰落条件下Reed-Solomon码级联空时分组码系统的差错性能分析方法,并推导给出级联码误比特率上界的数学表达式。理论分析和仿真结果表明,随着信噪比的增加,级联码系统的性能曲线迅速变好,获得了很高的编码增益。在误比特率为10-4时,与Reed-Solomon码的级联可以使衰落条件下空时分组码的性能提高大约5 dB。     

协同通信中的分布式线性疏散码

该文提出一种分布式线性疏散码解决无线网络中协同节点不能确定时的空时编码问题。参与协同的节点采用独立的疏散矢量进行编码,推导协同节点减少时分布式线性疏散码的互信息损失,并以此建立一种分布式疏散码的编码准则。仿真结果验证了这种分布式线性疏散码的误比特性能及编码准则的可行性。     

Reliable information rate of signal‐time coding for half‐duplex additive white Gaussian noise relay networks

Signal‐time coding (STC) is a newly proposed transmission scheme for half‐duplex relay networks, which is able to achieve higher information flow rate by combining the traditional encoding/modulation mode in the signal domain with the signal pulse phase modulation in the time domain. However, most of the results for STC are only obtained under the ideal assumptions that the signal detections at physical layer are perfect and there are still a lot of fundamental problems to be explored. This paper considers the implementing issues of STC at physical layer in additive white Gaussian noise relay networks. Firstly, a performance evaluation criterion, the reliable information per symbol (RIPS), is proposed to characterize the performance of STC in noisy wireless networks. Secondly, a new construction scheme based on route ID for the codeword of STC is presented, and some structural properties of the codeword of STC are investigated. Thirdly, the error probabilities of STC in both the signal domain and the time domain are discussed. Furthermore, two implementing schemes, that is, the energy detection based STC (ED‐STC) and the symbol detection based STC (SD‐STC), are proposed, and their performance bounds in terms of RIPS are discussed. Numerical analyses show that both ED‐STC and SD‐STC outperform traditional transmission methods in terms of effective information rate even under some practical conditions. Copyright © 2011 John Wiley & Sons, Ltd.     

Space–Time Trellis Codes Based on Channel-Phase Feedback

Space-time coding (STC) has been proposed recently for multiple-antenna wireless communication systems. Most of the proposed STC schemes use the assumption that either no channel-state information, or the channel mean/covariance information, is available at the transmitter. In this paper, we propose a new STC scheme for a closed-loop transmission system, where quantized channel-phase information is available at the transmitter. A new performance criterion is derived for the quasi-static fading channel. This design criterion is then used to construct a new class of space-time trellis codes (STTCs). The proposed code construction is based on the concatenation of a standard multiple trellis-coded modulation outer code with an inner code. The inner code is selected from a series of inner codes using the channel-phase feedback. The series of inner codes are constructed based on the systematic set partitioning of several classes of space-time signal designs. Simulation results show significant performance improvement over the other STTCs in the literature. In addition, the proposed coding scheme enjoys low peak-to-average-power ratio, simple decoding, and power-efficient low-cost implementation     

一种引入预测机制的时空上下文跟踪算法

针对时空上下文(STC)算法在抗遮挡目标跟踪中的不足,提出使用上下文模型相似度作为判别遮挡的条件和改进上下文模型更新方程的修正系数,同时采用预测算法修正搜索区域,构建了一种基于时空上下文跟踪的抗遮挡目标跟踪算法,并通过标准目标跟踪视频库对原算法和改进后算法的跟踪性能进行仿真和对比。实验证明,在原算法的基础上提高了抗遮挡跟踪的鲁棒性,在一些图像序列中跟踪成功率的提高最高可达30%。     

Identification via compressed data

A new coding problem is introduced for a correlated source (Xⁿ,Yⁿ)_n=1^∞. The observer of Xⁿ can transmit data depending on Xⁿ at a prescribed rate R. Based on these data the observer of Yⁿ tries to identify whether for some distortion measure ρ (like the Hamming distance) n^-1 ρ(Xⁿ,Y ⁿ)⩽d, a prescribed fidelity criterion. We investigate as functions of R and d the exponents of two error probabilities, the probabilities for misacceptance, and the probabilities for misrejection. In the case where Xⁿ and Yⁿ are independent, we completely characterize the achievable region for the rate R and the exponents of two error probabilities; in the case where Xⁿ and Yⁿ are correlated, we get some interesting partial results for the achievable region. During the process, we develop a new method for proving converses, which is called “the inherently typical subset lemma”. This new method goes considerably beyond the “entropy characterization” the “image size characterization,” and its extensions. It is conceivable that this new method has a strong impact on multiuser information theory     

基于MBER的联合预编码与空时编码GFDM功率分配策略

为改善频率选择性衰落信道上广义频分复用（GFDM）系统的误比特率和频带利用率性能,基于最小误比特率（MBER）准则,提出一种联合预编码和空时编码（STC）的 GFDM 系统及其相应的功率分配策略,可将该功率分配策略的优化目标由MBER转化为最小化其噪声增强因子,并推导了联合预编码与空时编码 GFDM 系统的功率分配、误比特率和频带利用率性能解析表达式。数值计算和仿真结果表明,与预编码STC-GFDM系统相比,基于MBER准则的预编码STC-GFDM系统的误码性能在误比特率为10^-3时改善约0.4 dB,频带利用率性能在信噪比为12 dB时提高约0.24 bit/(s·Hz)。     

基于制导误差的激光压制干扰效果评估研究

以红外成像制导反舰导弹为干扰对象,通过建模仿真,研究了制导误差对命中概率的影响,确定了3倍制导误差的激光压制干扰效果评估准则,提出了外场模拟评估设备要求和评估方法。     

智能测量系统中粗大误差的处理

本文基于数理统计参数估值理论,介绍了用格拉布斯判别准则去剔除粗大误差方法,文中还给出计算标准偏差的新公式,并用格拉布斯判别准则和传统的莱特准则分别对一组一个实验采样数据进行处理。结果表明,在高精度智能测量系统中,尤其在采样次数较少的测量系统中,应用格拉布斯判别准则可有效提高测量数据的精度。     

Asymptotic analysis of space?time codes in generalized fading channels

Considering the practically important case of two transmit and an arbitrary number of receive antennas, we provide a simple closed?form expression for the asymptotic pairwise error probability (PEP) of space?time codes (STCs) in generalized fading including Rayleigh, Ricean, Nakagami?q, Nakagami?m, Weibull, and generalized?K fading. The presented analysis provides new insights into STC design and can be used to obtain tight asymptotic upper bounds for the bit, symbol, and frame error probabilities of arbitrary STCs.     

Generalized threshold chase algorithms

 Three generalized threshold Chase algorithms called GTC Ⅰ,GTC Ⅱ and STC are proposed in this paper.They are the combination of the generalized minimum distance(GMD)decoding algorithm with the Chase algorithm.Although the decoding error probabilities of these algorithms are very close to that of the Chase algorithm,the decoding speeds are faster,especially at higher signal-to-noise ratio(SNR),hence they are of greater practical value.The results of computer simulations are given,showing the advantages of these algorithms.     

中继协作异构网用户对级联方案及安全概率分析

文章提出了一种基于中继协作的多层异构网(heterogeneous networks,HetNets)模型,其由不同类型的中继和在中继协助下通信的用户对构成,这些网络元素均建模为独立的泊松点过程(Poisson point process, PPP)。不同于传统的单跳网络,该网络中用户对的级联由两跳链路决定,为此,文章面向该网络首先提出了最大 最小用户对级联(maximum-minimum user-pair association,MM-UPA)方案。同时,为了克服MM UPA准则的瓶颈效应,文章又提出了联合考虑两跳链路质量的最大和谐均值用户对级联(maximum harmonic mean user-pair association,MHM-UPA)方案。其次,借助于随机几何和PPP方法,分别得到了MM-UPA和MHM-UPA方案的用户对级联概率。最后,作为所提方案的应用,研究了网络物理层安全性能,获得了网络平均安全概率。研究结果表明,两种方案均联合考虑了信源-中继和中继-信宿两跳链路的性能,优于基于单跳的用户级联方案,适用于中继协作的多层HetNets。