Weight-convergence analysis of adaptive antenna arrays based on SMI algorithm

Weight-convergence analysis of adaptive antenna arrays based on the sample matrix inversion (SMI) algorithm is presented. First, we derive a required number of samples for weight computation to achieve an output signal-to-interference-plus-noise ratio -10 log/sub 10/ r dB (r /spl les/ 1) below an optimum value. Next, we evaluate weight convergence of code-division multiple-access adaptive antenna arrays based on the SMI algorithm, where two types of weight computational methods are compared between "chip-level computation" and "symbol-level computation". Analytical and simulation results reveal that "chip-level computation", before despreading process, enables faster convergence than "symbol-level computation", after the despreading process.     

基于符号判决反馈均衡的联合检测算法

传统的联合检测算法使用的块线性均衡和块判决反馈均衡,它们是以整个数据块为单位进行均衡和检测的,导致系统矩阵比较庞大,计算复杂度较高.本文将系统矩阵分成可检测的最小单位--数据符号,来进行逐个符号的联合检测,产生基于符号线性均衡的联合检测.并且将块判决反馈均衡原理应用其中,得到基于符号判决反馈均衡的联合检测算法.此算法系统矩阵尺寸小得多,因此复杂度也小得多.符号判决反馈均衡既能减小噪声项,又能减小前一符号判决误差项,因此总体的性能接近于块判决反馈均衡.仿真实验表明了这一点.本文还讨论了不同用户不同扩频因子情形下该算法的改造,并提出按用户扩频因子大小排列用户数据符号的改进,仿真实验验证了这个改进的好处.     

Parallel adaptive decision feedback equalizers

Several algorithms for parallel implementation of adaptive decision feedback equalizers (DFEs) are proposed. The first is a double-row DFE algorithm that outperforms previous approaches. Under the no-error-propagation assumption, the algorithm will perform exactly like a serially adapting DFE. The multiplication complexity of the double-row DFE algorithm is of the same order as that of the parallel DFE algorithm and the extended least-mean-square (LMS) method. The previous algorithms and the double-row DFE algorithm may become impractical to implement due to their large computational complexity, so three additional parallel implementations of the DFE, which lead to considerable hardware savings and avoid the coding loss of the former approaches, are presented. The different algorithms are compared on the basis of convergence analysis and simulation results     

Fuzzy adaptive decision feedback equaliser

As a new approach to the equalisation of nonlinear channels, a fuzzy adaptive decision feedback equaliser based on a fuzzy adaptive filter is proposed. With perfect knowledge of the channel, the proposed method not only improves equalisation performance but also reduces the computational complexity compared with the conventional fuzzy adaptive filter     

基于自适应量化矩阵的硬判决量化算法

在视频编码中,视频量化一般分为硬判决量化(HDQ)和软判决量化(SDQ),HDQ与SDQ相比,编码性能虽有所损失,但其编码复杂度低,易于硬件实现的优点依旧是主流编码器所主要采用的量化算法.人眼具有对图像中的高频细节不敏感的特性.因此,基于Bayes最小误判概率约束,离线构建基于视频内容自适应的量化矩阵,在模拟感知SDQ算法机理下,对高频低频分量采用不同的量化步长,提高视频的主观质量和HDQ算法性能.仿真实验表明,相比于传统的HDQ算法,该文算法能达到平均5.048％的码率节省,其中WVGA和WQVGA格式平均达到10.65％的码率节省.相比于感知SDQ算法,平均码率增加仅有1.464％;算法复杂度方面,编码一帧的时间相比于感知SDQ节省了32.956％.     

基于自适应深度预测的快速变换单元判决算法

新一代视频编码标准HEVC相比之前标准,在提升编码效率的同时显著增加计算复杂度。针对这一问题,本文提出了一种基于自适应深度预测的快速变换单元(TU)判决算法,利用残差四叉树(RQT)深度自身分布特点以及时空相邻RQT最大深度的相关性预测不同尺寸编码单元(CU)的RQT深度,跳过不必要的深度计算。仿真结果表明,在标准编码配置条件下,相比全部深度判决方法,本算法在保证编码效果的前提下,平均降低50%的TU运算时间,极大减少计算复杂度;同时相比于同类算法在处理复杂序列时的低效率,本算法很好地解决了此类问题。     

Performance of adaptive multisensor decision feedback equaliser fortime-varying frequency selective radio channels

A multisensor decision feedback equaliser based on the minimum mean squared error (MMSE) criterion is studied. The superiority of the performance of the multisensor equaliser is shown by simulation of a whole communication system in which the adaptive equaliser is incorporated. The recursive least squares (RLS) algorithm is used to update the coefficients. From the results obtained for a time-varying urban terrain channel model, the extremely interesting tracking capability of the multisensor equaliser is shown     

不完美反馈自适应多天线跨层系统的性能分析

为提高网络无线通信的频谱利用率,提出一种自适应闭环多输入多输出(MIMO)跨层设计方案。该方案是融合物理层的自适应调制技术(AM)和数据链路层的自动重传技术(ARQ);发射端利用反馈信息,自适应选择调制模式和发射权矢量,并自动重传数据,形成三重反馈的闭环MIMO跨层系统。推导了不完美反馈下的系统频谱效率和中断概率闭合表达式,分析了时延对跨层系统性能的影响。仿真结果表明:对比单发/单收(SISO)跨层系统以及开环MIMO跨层系统,自适应闭环MIMO跨层系统的性能有明显提高。     

基于压缩感知的圆阵自适应数字波束形成算法

根据目标在空间的稀疏性,在圆形面阵的接收端,提出了一种基于压缩感知的自适应数字波束形成算法.该算法在不改变波束性能与天线口径的前提下,可以大大减少实际的阵元数目,是一种新的稀布阵方法.在阵元稀布的情况下,根据压缩感知的压缩采样理论,先用重构算法恢复缺失通道的回波信息,然后利用恢复得到的信号计算自适应权系数,得到理想的自适应数字波束方向图.不同信噪比和干噪比情况下的仿真结果验证了所提算法的正确性和有效性.     

HBP: improvement in BP algorithm for an adaptive MLP decision feedback equalizer

Though the decision feedback equalizer (DFE) with multilayer perceptron (MLP) structure can be trained effectively by the backpropagation (BP) algorithm, it is always accompanied by the problem of local minimum. In order to solve some problems of the local minimum in the BP algorithm and to improve the performance of the BP algorithm under the same MLP structure, we combine the hierarchical approach and the BP algorithm to implement the MLP DFE, and we call the new scheme hierarchical BP (HBP) algorithm. Based on the hierarchical approach, from the input layer to the output layer of the MLP, every two layers of neural nodes (with one hidden layer) will be trained with an individual BP algorithm. Therefore, the entire MLP can be trained by several independent BP algorithms, unlike the standard BP algorithm, which utilizes only one BP algorithm to train the whole MLP structure. The results of performance evaluation indicate that the HBP algorithm not only strongly reduces the mean squared error but also yields a much lower bit-error rate than the standard BP algorithm does for equal computational cost and conditions.     

基于自适应决策融合的合作频谱感知方法

频谱感知是认知无线电(CR)的关键技术之一。在该机制中,对主用户(PU)信号的可靠检测是实现CR的前提。提出一种基于自适应决策融合的合作频谱感知算法用于频谱感知,该算法通过估计PU的先验概率与各个CR用户(SU)的漏检及虚警概率,然后运用Chair-Varshney准则对局部判决进行决策融合以得到全局判决。仿真结果表明,采用该方案的全局虚警和漏检概率明显低于单个SU,可有效提高CR系统频谱感知的可靠性。     

基于效用距离的分层多播反馈控制算法

源自适应的分层多播存在着因反馈信息爆炸而导致的缩放性问题，反馈信息合并是一个较好的解决办法。本文给出一个以效用最优为目标的自适应分层多播模型UALM，分析了在反馈树的支持下，通过反馈合并策略实现反馈控制的方法，提出了一种基于加权效用距离的分层多播反馈合并算法。仿真结果表明，该算法能够有效地控制反馈信息数目，同时使得在此基础上完成的动态分层效用接近于不进行反馈合并时的系统效用，满足分层多播的缩放性要求。     

基于决策树算法的研究生遴选质量评价

本文针对如何提高研究生遴选质量、选拔出更多优秀生源的问题,提出一种基于决策树算法的研究生遴选质量评价方法。首先通过分析研究生生源学校以及初试和复试等招生信息,同时结合对研究生的课程学习成绩、参与科研项目情况、硕士毕业论文质量的跟踪,建立了适合于计算机专业研究生质量的评价指标。然后采用经典的ID3决策树算法对相关数据进行分析挖掘,以评价现有研究生招生体系中各项指标对研究生培养质量的影响,并通过统计学方法对结论进行逆向分析验证。结果表明在研究生入学考核的各项指标中,面试成绩和上机考试成绩在区分考生能力、优秀研究生遴选中具有关键作用。     

New gradient decision feedback equaliser algorithm

An efficient algorithm for a least-squares gradient lattice decision feedback equaliser is described. Simulation results for telephone channel and HF radio channel models are presented. Performance is compared with other decision feedback algorithms.     

A gain optimizing algorithm for adaptive arrays

An algorithm for optimizing the gain of an adaptive antenna on an incoming signal is discussed. The gain optimization is based on a constrained gradient-search technique. The algorithm is presented, and some examples are given. The convergence and stability of the algorithm are also discussed.     

（英）基于多帧配准的红外焦平面阵列非均匀性自适应校正

提出了一种场景自适应的非均匀性校正固定图案噪声去除方法.基于多帧配准和相邻帧之间的全局位移估计,利用最小均方算法迭代计算均方误差函数,同时结合误差函数均方差以及互相关峰值,从而能够自适应场景变化.所提出的算法充分利用相邻多帧之间的相关性,对模拟和实际红外图像序列非均匀性的校正效果突出.实验结果表明本方法能够精确估计非均匀性参数,收敛速度较快,几乎不残留鬼影.     

基于空间相关性的H.264快速自适应模式选择算法

为了减小H.264编码器的复杂度,提出了一种帧间预测模式快速自适应选择算法。该算法首先利用运动补偿后残差宏块的统计信息,将需要计算率失真代价函数的候选模式减少为一个模式组中包含的模式子集;然后根据相邻的左块和上块的模式,从所选择的模式子集中选出出现概率最高的两种模式来计算并比较率失真代价函数,选出代价最小的模式作为最佳模式。实验表明,本算法平均可以节省编码时间约65%,同时PSNR下降约为?0.24dB,有利于实时应用。     

Wavelet based decision feedback equaliser

A decision feedback equaliser (DFE) structure based on wavelets (WBDFE) is presented. The WBDFE shows faster convergence than the conventional DFE, with a very small increase in computation. In addition, the WBDFE has good time-frequency localisation, and is suitable for time-varing channels     

基于PR—QMF理论的判决反馈均衡器

根据完全重构正交镜像滤波器（PR-QMF）的理论,我们构造了一类正交变换并且用于交换域判决反馈均衡器（OFE）的设计。在此基础上我们进一步讨论了该类DFE的优化设计。通过与卡胡南一洛也夫变换（KLT）和离散余弦变换（DCT）比较得出这样的结论：经过最优化设计,本文提出的算法具有更快的收敛速度,同时,它还具有复杂程度低和设计灵活的优点。     

Blind adaptive decision feedback CDMA receivers for dispersive channels

Blind adaptive decision feedback (DF) receivers for direct sequence code division multiple access (DS-CDMA) systems in dispersive channels are proposed. Blind adaptive stochastic gradient algorithms are developed for use with the constrained minimum variance and constrained constant modulus receivers along with successive and parallel DF structure.