Adaptive acquisition of PN code in multipath fading mobile channels

The adaptive acquisition processor (AAP), which controls false alarms and reduces miss detection of multipath signals by estimating the threshold level after censoring some highest samples in the sliding window, was introduced by the present author. In addition, an AAP was analysed in a single path situation. Here, the detection performance of an AAP in multipath situations, which may exist in the sliding window, is investigated. Results show that the AAP has good performance if the number of excision samples, Ne, is greater than or equal to the number of multipath signals in the window     

基于路面约束的行人检测感兴趣区域提取

针对行人检测存在识别精度不高,实时性较差等问题进行相关研究.分析了基于多尺度滑动窗口法提取行人检测窗口的缺点,为解决行人检测中检测窗口数量过多的问题,提出在图像分割和路面提取的基础上实现对行人检测窗口的提取.先利用FCM聚类算法训练得到分割阈值,其次提取路面区域,根据路面区域筛选可能存在的行人位置,进而提取感兴趣区域,并对相应的感兴趣区域提取HOG特征进行进一步精确分类.实验结果表明,采用基于路面约束的图像分割方法来提取感兴趣区域,有效减少了遍历窗口的数量,从而提高了行人检测速度和检测精度.     

Efficient Recursive IDFT Scheme for Complex-valued Signals in Tap-selective Maximum-likelihood Channel Estimation

This paper presents several efficient, recursive inverse discrete Fourier transform (IDFT) schemes for complex-valued input data in tap-selective maximum-likelihood channel estimation; the results of their implementation are also presented. The proposed schemes employ only real-valued arithmetic, which reduces the number of required real multiplication operations in comparison with conventional IDFT approaches; however, the number of real additions increases significantly due to the sliding window scheme. The results show that the schemes can reduce the computational complexity and enhance flexibility when only several subsets of the IDFT output bins are required.     

数字调幅广播系统中基于滑动窗口的二维信道估计

针对DRM数字广播系统,提出一种基于滑动窗口的二维信道估计方法.该方法首先对接收到的导频信号所在信道进行最小二乘估计,然后进行时间方向插值估计导频子载波上所有位置处的信道频率响应,最后通过一个滑动窗口在多径扩展域和多谱勒扩展域分别进行处理.对于快速时变信道,通过调整窗口的滑动步数,可以有效处理窗口内信道路径数和路径延迟可能变化的情况,从而显著降低了子载波间干扰和高斯白噪声的影响.理论分析和仿真表明,与现有信道估计相比,该方法具有估计精确、易于实现的优点.     

Arbitrary Frame Rate Transcoding Through Temporal and Spatial Complexity

In this paper, an arbitrary frame rate transcoding joint considering temporal and spatial complexity of frames in the adaptive length sliding window is proposed. The length of a sliding window can be adjusted according to bandwidth variation in order to decide the number of skipped frames. The proposed method preserves significant frames and drops non-significant ones using the complexity measurements. Moreover, the motion vector composition algorithm is proposed to reduce the computations of motion estimation process by adopting the coding feature of variable block sizes in H.264/AVC video transcoder. Experimental results show that the proposed method achieves higher visual quality compared to other existing methods. After combining with the proposed fast motion composition algorithm, our proposed algorithm reduces encoding time significantly with slight visual quality degradation.      

基于Markov链的椭圆曲线标量乘法算法性能分析

在椭圆曲线密码系统中,采用规范重编码、滑动窗口等优化技术可以有效提高椭圆曲线上点的标量乘法k·P的运算性能,但在实现中,需要对不同优化技术的算法性能进行定量分析,才能确定标量乘法的最优实现.本文运用Markov链对标量k规范重编码表示的滑动窗口划分过程进行了建模,提出了一种对椭圆曲线标量乘法的平均算法性能进行定量分析的方法,并运用该方法分析了不同参数下标量乘法运算的平均性能,计算了滑动窗口的最优窗口大小.最后,通过比较说明,采用规范重编码和滑动窗口技术的椭圆曲线标量乘法的运算开销比用m-ary法少10.32~17.32％,比单纯采用滑动窗口法也要少4.53~8.40％.     

Rate control for consistent visual quality of H.264/AVC encoding

In this paper, a novel rate control scheme with sliding window basic unit is proposed to achieve consistent or smooth visual quality for H.264/AVC based video streaming. A sliding window consists of a group of successive frames and moves forward by one frame each time. To make the sliding window scheme possible for real-time video streaming, the initial encoder delay inherently in a video streaming system is utilized to generate all the bits of a window in advance, so that these bits for transmission are ready before their due time. The use of initial encoder delay does not introduce any additional delay in video streaming but benefits visual quality as compared to traditional one-pass rate control algorithms of H.264/AVC. Then, a Sliding Window Buffer Checking (SWBC) algorithm is proposed for buffer control at sliding window level and it accords with traditional buffer measurement of H.264/AVC. Extensive experimental results exhibit that higher coding performance, consistent visual quality and compliant buffer constraint can be achieved by the proposed algorithm.     

基于分块和滑动窗口的车牌定位方法

车牌定位是车牌识别系统的关键环节.提出了一种利用分块和滑动窗口快速定位车牌的新方法.首先,进行垂直边缘的检测;然后利用分块和滑动窗口的方法进行搜索,产生车牌候选区域;最后经过判别得到车牌区域,并对边界加以调整.实验结果证明这种算法具有定位准确、效率高、适应性强的特点.     

消息复用下的空间耦合LDPC码窗译码优化算法

空间耦合低密度奇偶校验（Spatially Coupled Low Density Parity Check,SC-LDPC）码由于其奇偶校验矩阵呈现对角带非零项的特点,采用窗译码可获得较低的时延及复杂度。针对SC-LDPC码窗译码性能损失、译码复杂度依然较高的问题,提出了消息复用（Message Reuse for Window Decoding,MR-WD）算法和动态多目标符号输出（Dynamic Multi-target-symbol Output for Window Decoding,DMO-WD）算法。消息复用算法以外部对数似然比值作为边信息传入窗口,与传统窗译码相比,译码性能得到了提升,译码复杂度降低。动态多目标符号输出算法在连续若干个窗口均满足奇偶校验方程判定为零时,增加目标符号的输出数量,反之减少目标符号的输出数量。该算法在误码率损失可忽略不计的情况下降低译码复杂度最大达20%,且在动态多目标符号窗译码中使用消息复用更新边信息时,相比于传统窗译码性能提升约0.2 dB,复杂度下降约35%。     

有效的模(2n+1)乘算法及其VLSI设计

模乘运算在剩余数值系统、数字信号处理系统及其它领域都具有广泛的应用,模乘法器的硬件实现具有重要的作用。提出了一种改进的模(2~n 1)余数乘法器的算法及其硬件结构,其输入为通常的二进制表示,因此无需另外的输人数据转换电路而可直接用于数字信号处理应用。通过利用模(2~n 1)运算的周期性简化其乘积项并重组求和项,以及采用改进的进位存储加法器和超前进位加法器优化结构以减少路径延时和硬件复杂度。比较其它同类设计,新的结构具有较好的面积、延时性能。     

Linear multi-state sliding-window systems

This paper proposes a new model that generalizes the consecutive k-out-of-r-from-n:F system to the multi-state case. In this model (linear multi-state sliding window system), the system consists of n linearly ordered multi-state elements. Each element can have various states: from complete-failure up to perfect-functioning. A performance rate is associated with each state. The sliding window system fails if the sum of the performance rates of any r consecutive multi-state elements is lower than a minimum allowable level. An algorithm for system reliability evaluation is based on an extended universal moment-generating function. Examples of system reliability evaluation are presented.     

一种与缓冲区紧耦合的环形循环滑动窗口的数据流抽取算法

 许多应用领域产生数据流的流量不断增大,需要挖掘系统提供更有效的数据流抽取策略来应对数据处理能力与流速之间的矛盾.本文构造了基于环形缓冲区循环的逻辑滑动窗口(环形循环滑动窗口),将环形缓冲区和环形循环滑动窗口紧耦合,提出了基于环形循环滑动窗口的数据流抽取算法.实验表明这是适合数据流流动和方便数据流挖掘的数据流抽取模型,能够提升数据流抽取速度和保证数据流的挖掘持续正常实施.     

DMBT系统中利用FWT快速实现信道估计

根据PN码的结构特性,针对DMB-T系统多载波模式,本文提出了一种新的理论上与滑窗相关法等价的信道估计方法,利用FWT(快速沃尔什变换)实现快速多径捕获.通过干扰抵消进一步消除了径间干扰.该方法具有很强的抗多径效应和抗强窄带干扰的能力,将运算复杂度从传统滑动互相关法的N~2降低到(N+1)log_2(N+1).     

基于自适应滑窗递归稀疏主成分分析的工业过程故障监测

本文提出一种自适应滑窗递归稀疏主成分分析方法,用于时变工业过程的在线故障监测.首先,通过滑窗提取正常过程数据空间的特征信息,并对当前窗口数据块矩阵进行稀疏主成分分析,构建稀疏主成分分析故障监测模型;然后,根据相邻窗口的相似度实时调整遗忘因子以自适应更新滑窗大小,使得所建立的稀疏主成分故障监测模型可以有效追踪复杂的时变过程;最后,通过递归更新滑窗稀疏载荷矩阵来动态更新故障监测模型.非线性数值仿真系统与田纳西-伊斯曼过程的故障监测结果表明,所提方法可以有效提高故障检测的准确率,适应于长流程时变工业过程在线故障监测.     

A sliding window PDA for asynchronous CDMA, and a proposal for deliberate asynchronicity

The probabilistic data association (PDA) method is extended to multiuser detection over symbol-asynchronous code-division multiple access (CDMA) communication channels. A direct extension as well as a sliding window processing method are introduced. While achieving near-optimal performance with O(K/sup 3/) computational complexity in synchronous CDMA, K being the number of users, it is shown that, in asynchronous CDMA, the probability of group detection error of the proposed PDA method is very close to the performance lower bound provided by an ideal clairvoyant optimal detector, and the computational complexity is only marginally increased to O([h/s]K/sup 3/) per symbol, where h and s are the width and the sliding rate of the processing window, respectively. Due to the outstanding performance of the PDA detector in heavily overloaded asynchronous systems, it is observed that an optimally designed synchronous system can be easily outperformed by an arbitrarily designed asynchronous system. Hence, it is proposed to use asynchronous transmission deliberately, even when synchronous transmission is possible - asynchronous is better than synchronous!.     

一种低复杂度的降低MIMO—OFDM峰平比的CARI方法

天线旋转取反算法(CARI)是降低MIMO-OFDM系统峰平功率比(PAPR)的一种性能较优的算法,不足之处是其迭代次数很大。CARI的次最优算法逐次次最优天线旋转取反(SS-CARI)算法虽然可以减小迭代次数,但性能损失又比较大。针对这一问题,提出了一种用滑动窗搜索旋转取反组合的次最优CARI方法,利用滑动窗搜索局部最优的旋转取反组合,既可以避免整体的遍历搜索大大减小CARI算法的计算复杂度,又可以改善SS-CARI的PAPR减小性能。仿真结果表明,该方法能够在系统复杂度与PAPR降低性能上取得很好的折衷。     

Resonators in Open-Loop Sigma–Delta Modulators

In this paper, we introduce the modulo resonator for use in analog-to-digital open-loop sigma-delta modulators (OLSDMs). The OLSDM presented in this paper is intended for use in high-accuracy (14-bit) high-speed analog-to-digital converters. The modulo resonator is used with a modulo notch filter to insert a zero in the noise transfer function at a nonzero frequency. The effect of finite gain in modulo integrators and resonators is described and verified through simulation. The modulo resonator and a previously published modulo integrator are used in a behavioral model of a switched-capacitor fifth-order OLSDM with more than 13-bit effective number of bits for an oversampling ratio of four. We prove for the N -order OLSDM that the number of bits in the quantizer (B) must be larger than N to ensure equivalence between open-loop sigma-delta modulation and sigma-delta modulation.     

空间耦合LDPC码的分层译码算法

针对长码长空间耦合低密度奇偶校验(SC-LDPC)码译码时延较长的问题,该文提出了分层滑动窗译码(LSWD)算法。该算法利用SC-LDPC子码码块的准循环特性和滑动窗内校验矩阵的层次结构,通过在滑动窗内对校验矩阵进行分层处理,优化层与层之间消息传递,从而加快窗内译码的收敛速度,减少了译码迭代次数。仿真和分析结果表明:在相同的信噪比(SNR)条件和相同的误码性能要求下,LSWD算法所需的迭代次数少于滑动窗译码(SWD)算法,特别在高信噪比下,LSWD算法的迭代次数约为SWD算法的一半,从而有效缩短全局译码时延;在相同译码迭代次数下,LSWD算法的译码性能优于SWD算法,而其计算复杂度增加不大。     

基于工地场景的深度学习目标跟踪算法

针对施工现场环境复杂,难以高效管理的问题.提出了基于工地场景的深度学习目标跟踪算法,辅助施工顺利进行.根据工地现场目标的连续性,构建增强群跟踪器,提升目标成功跟踪的概率.然后从滑动窗口、Stacked Denoising Auto Encoder（SDAE）和Support Vector Machine（SVM）三方面组建深度检测器.在滑动窗口方面：从梯度角度建立模型实现窗口自适应.在SDAE算法方面：构建反向算法微调网络参数.优化SVM算法降低跟踪时目标漂移和跟踪失败的概率,最终实现目标高精度跟踪.通过实验表明本文提出的算法可有效对目标进行跟踪,实现动态管理.     

一种OFDM系统信道密钥生成方法

提出了一种在正交频分复用(OFDM)系统中提取信道频率响应(CFR)表征信道特征,经过探测、量化、协商、一致性确认以及隐私放大生成信道密钥的方法。首先,利用OFDM系统多载波的优势,在各个子信道提取信道特征,并进行量化;然后,采用滑窗密钥生成机制以及分段校验,通过一次位置信息交互,高效地完成协商,生成初始信道密钥;最后,利用隐私放大函数生成信道密钥。所提方法通过滑窗生成大量密钥比特,以一轮协商代替多轮协商;只限定初始密钥最大长度,使得初始密钥在长度及信息两个维度保持随机化。