广义空间调制系统的低复杂度检测算法

针对广义空间调制( GSM)系统接收端最大似然( ML)检测算法计算复杂度极高的缺点,提出了一种基于压缩感知( CS)信号重构理论的低复杂度信号检测算法。首先,在多输入多输出( MI-MO)信道模型下,通过改进正交匹配追踪( OMP)算法,得到一个激活天线索引备选集;然后,利用ML算法在该备选集中进行遍历搜索,检测出激活天线索引和星座调制符号。仿真结果表明所提算法的检测性能接近于ML算法,且复杂度约为ML算法的2%。因此,所提算法在保证检测性能的同时也大大降低了计算复杂度,实现了检测性能与复杂度之间的平衡。     

OFDM系统中基于迭代和门限理论降低PAPR的改进PTS方法

传统的部分传输序列法（PTS）中,如果要得到最佳的相位旋转因子,需要遍历所有的可选相位,这样的计算量随分割的子序列数按指数增长。本文提出两种减少计算复杂度的改进PTS方法（经迭代的IPTS和经门限的IPTS）。这两种方法都利用快速傅立叶变换（FFT）的时域循环移位特性增加备选信号,改善PAPR降低的性能。首先提出了一种利用反复迭代移位的IPTS方法(经迭代的IPTS),该方法的计算量随子序列数按线性增长。接着提出了一种利用预先设定的门限值以降低计算复杂度的IPTS方法(经门限的IPTS)。最后理论分析、比较了PTS、PTS/CSS方法与本文方法的计算复杂度。Matlab软件仿真显示,当使用相同的分割子序列数和相位旋转因子时,两种IPTS方法能够以较小的运算量达到了PTS/CSS方法性能;两种IPTS方法降低PAPR的性能要优于PTS方法,但计算复杂度并没有增加。      

基于逼近噪声子空间的求根时延估计算法

多重信号分类(MUSIC)时延估计算法需要多径数估计,且其特征分解和谱峰搜索的计算复杂度较高。针对此问题,给出了一种基于逼近噪声子空间的求根时延估计算法。该算法利用协方差矩阵逆的高次幂逼近噪声子空间与其自身共轭转置的积,并构造多项式等式,以多项式求根的方式避免谱峰搜索,从而降低了计算复杂度。仿真结果表明,在无需多径数估计和复杂度低于MUSIC算法的条件下,所提算法的性能与MUSIC算法的性能相当,并且逼近克拉美罗界。     

时频双选信道OFDM系统的低复杂度MMSE-SD算法

在时频双选信道OFDM系统中,针对最小均方误差连续检测(MMSE-SD)算法求逆运算导致计算复杂度过高的问题,该文提出一种改进的低复杂度MMSE-SD算法.该算法首先对信道矩阵和检测矩阵进行扩展处理,然后建立扩展矩阵和原矩阵之间的关系,每次检测用扩展矩阵的迭代求逆代替原矩阵的直接求逆.理论分析和仿真结果表明:和原MMSE-SD算法相比,该改进算法在保持原算法性能的基础上,大幅度降低其计算复杂度;与其它算法相比,该改进算法兼顾了系统性能与计算复杂度,当归一化多普勒频移增大时,其计算复杂度保持不变而性能更优.     

广义RASK系统的回溯StOMP检测算法

本文提出了一种基于压缩感知（compressive sensing,CS）理论的低复杂度的检测算法:回溯分段正交匹配追踪（backtracking stagewise orthogonal matching pursuit,BStOMP）次优检测算法,较好地解决了广义接收天线移位键控（generalized receive antenna shift keying,GRASK）系统中最优最大似然（maximum likelihood,ML）检测算法会随着激活接收天线数的增多而计算复杂度大幅度增长的问题。该算法首先依据当前迭代残差和等效信道矩阵的内积选择出大于设定阈值的项作为候选激活天线索引;然后通过最小二乘法对候选激活天线索引进行初步估计;最后引入回溯过程进行筛选,剔除一些多余的索引,提高重构精度。仿真结果表明,在相同条件下,所提算法与传统StOMP检测算法相比,能在增加少量计算复杂度的情况下检测性能得到较大的提升,因此保证了在检测性能与计算复杂度间获得良好的平衡。      

A partitioning technique for reducing the computational complexity of probabilistic fault detection in general combinational circuits

This paper examines the impacts of different types of circuit partitioning on reducing the computational complexity for computing the fault detection probability, which usually grows exponentially with the number of input lines in the given circuit. Partitioning a large combinational circuit into arbitrary subcircuits does not, in general, reduce the computational time complexity of the fault detection probability. In fact, partitioning a given circuit into general subcircuits is expected to increase the time complexity by the amount of time spent in the partition process itself. Nevertheless, it will be shown that decomposing a general combinational circuit into its modules (supergates) such that these modules constitute the basic elements of a tree circuit (network) considerably reduces the computational complexity of the fault detection probability problem. Toward this goal, two algorithms are developed. The first partitions a given circuit into maximal supergates whenever this is possible. Its computational complexity depends linearly on the number of edges (or lines) and nodes (or gates) of the circuit. The second computes the exact detection probabilities of single faults in the tree network and its computational complexity grows exponentially with the largest number of input lines in any of the network maximal supergates rather than the total number of inputs. The case of multi-output circuits is also discussed.     

802．11无线局域网中AP放置与信道配置的联合算法

在多小区无线局域网规划中,接入访问点(AP)放置与信道配置是两个重要的任务。在给定用户业务需求的条件下,谋求最大系统吞吐率和资源分配的公平性是网络规划的目标,其中公平性由吞吐率均衡因子表征。在传统的规划策略中,AP放置与信道配置被分割为两个先后的步骤;而该文提出的目标函数则将这两个问题联合解决以得到更好的系统性能。当采用全局遍历时,对目标函数寻求全局最优解计算量庞大;因此该文又提出了一种有效的局部最优解搜索算法补丁算法,此算法计算量小,同时能较好地逼近全局最优解。     

结合深度信息的多视点视频编码快速模式选择算法

多视点视频加深度(MVD,multi-view video plus depth)的编码格式包含多个纹理视频序列及其对应的深度图,深度图与对应的纹理视频具有相似的边缘信息。传统的编码模式不考虑两者的联系,单独编码导致复杂度高、编码时间过长。因此,合理利用深度图与纹理图的相似性进行编码,可以有效降低编码复杂度,同时应该确保编码质量不受影响。本文利用深度图的这一特点辅助纹理视频的编码,提出一种帧间快速模式选择算法,充分利用深度图与纹理图之间的相似性,建立一种联合复杂度模型,根据模型得到每个宏块的复杂度。对于复杂度低的宏块,在计算率失真代价之前跳过编码中一些不必要的模式,从而降低编码复杂度。实验表明,本文提出的快速模式选择算法,在保证率失真性能基本不变的情况下,能减少60.57%的编码复杂度,并最高能减少80.64%的编码时间。     

Prime-factor algorithms for generalised discrete Hartley transform

A prime factor fast algorithm for the type-II generalised discrete Hartley transform is presented. In addition to reducing the number of arithmetic operations and achieving a regular computational structure, a simple index mapping method is proposed to minimise the overall implementation complexity     

A Computationally Efficient Tree-PTS Technique for PAPR Reduction of OFDM Signals

The high peak-to-average power ratio (PAPR) of time domain signals has been a major problem in orthogonal frequency division multiplexing (OFDM) systems, and thus various PAPR reduction algorithms have been introduced. Partial transmit sequence (PTS) is one of the most attractive solutions because of its good performance without distortion. However, it is considered as an impractical solution for the realization of high-speed data transmission systems due to its high computational complexity. In this paper, a novel PAPR reduction algorithm based on a tree-structured searching technique is proposed to reduce the PAPR with low complexity. In the proposed scheme, the computational complexity of searching process is decreased by adjusting the size of tree with two parameters, width and depth, while preserving good performance. The simulation results show that proposed scheme provides similar performance with optimum case with remarkably reduced computational complexity.     

基于量子计算方法的多址DCSK通信系统的研究

为了降低多用户之间的干扰问题,提出了一种新的混沌多址通信系统（多比特MA-DCSK）,并设计了该系统的多用户检测算法。通过仿真实验,比较了该多比特MA-DCSK系统与可变延时MA-DCSK系统的误码率性能,证明了该系统具有更低的误码率。利用量子并行运算的特性,采用Grover量子算法解决多用户检测算法的计算复杂度,这种算法可以将复杂度从 降低到 。仿真结果表明,在不影响系统性能的同时,量子算法可以有效地降低计算复杂度。     

一种基于对称性的双向双二进制卷积Turbo码译码结构研究

该文提出了一种基于对称性的双向并行译码方案,用于提高802.16 m标准中双二进制卷积Turbo码(DB CTC)的译码速度。定义了分支度量矩阵以降低译码计算复杂度,定义了前向、后向因子矩阵,推导了前、后向度量递归计算中的对称性,并将其应用于前向、后向度量及后验概率对数似然比的双向并行计算中。构造了采用该方案的DB CTC译码器结构图,详细分析了迭代过程。以计算复杂度,存储空间,译码速度为指标考察了方案的性能,并给出了译码性能仿真曲线。分析表明,该双向并行的译码方法较常规方法提高了一倍的译码速度,而没有增加计算复杂度和存储空间。     

Split-Radix Algorithms for Arbitrary Order of Polynomial Time Frequency Transforms

The polynomial time frequency transform is one of important tools for estimating the coefficients of the polynomial-phase signals (PPSs) with the maximum likelihood method. The transform converts a one-dimensional (1-D) data sequence into a multidimensional output array from which the phase coefficients of the data sequence are estimated. A prohibitive computational load is generally needed for high-order polynomial-phase signals although the 1-D fast Fourier transform (FFT) algorithm can be used. Based on the split-radix concept, this paper derives a fast algorithm for arbitrary order of polynomial time frequency transforms to significantly reduce the computational complexity. Comparisons on the computational complexity needed by various algorithms are also made to show the merits of the proposed algorithm     

Computational power of neural networks: a characterization in termsof Kolmogorov complexity

The computational power of recurrent neural networks is shown to depend ultimately on the complexity of the real constants (weights) of the network. The complexity, or information contents, of the weights is measured by a variant of resource-bounded Kolmogorov (1965) complexity, taking into account the time required for constructing the numbers. In particular, we reveal a full and proper hierarchy of nonuniform complexity classes associated with networks having weights of increasing Kolmogorov complexity     

On fundamental tradeoffs between delay bounds and computational complexity in packet scheduling algorithms

We clarify, extend, and solve a long-standing open problem concerning the computational complexity for packet scheduling algorithms to achieve tight end-to-end delay bounds. We first focus on the difference between the time a packet finishes service in a scheduling algorithm and its virtual finish time under a GPS (General Processor Sharing) scheduler, called GPS-relative delay. We prove that, under a slightly restrictive but reasonable computational model, the lower bound computational complexity of any scheduling algorithm that guarantees O(1) GPS-relative delay bound is /spl Omega/(logn). We also discover that, surprisingly, the complexity lower bound remains the same even if the delay bound is relaxed to O(n/sup a/) for 0相似文献   

OFDM系统中基于PM的时延估计算法

在正交频分复用(OFDM)系统的超分辨时延估计中,针对多重信号分类(MUSIC)算法的特征分解计算复杂度较高的问题,给出一种基于传播算子(PM)的时延估计算法。对OFDM系统进行信道估计,根据信道估计结果计算协方差矩阵,并利用协方差矩阵计算PM,然后根据PM构造出噪声子空间并将其标准正交化,最后利用伪谱函数进行时延估计。仿真结果和复杂度分析表明,在复杂度大幅度下降的条件下,所提算法与MUSIC性能相当,且逼近克拉美罗界。     

一种基于时域处理的低复杂度HACO-OFDM系统

针对计算复杂度高和误码率(BER)受限幅噪声估计精度影响的问题,提出一种低复杂度的混合非对称限幅光正交频分复用(HAC0-0FDM)系统及基于时域处理的接收解调方法,详细介绍了HAC0-0FDM系统的组成及其时域信号的结构特点,通过简单的时域信号处理实现限幅噪声消除.实验结果表明:该方案显著降低了计算复杂度;当限幅噪声...     

A computationally efficient iterative solution of themultidestination optimal dynamic routing problem

The dynamic routing problem for multiple destination networks is considered. The minimum time rather than total delay cost functional is employed. The problem is solved through an iterative link-by-link optimization. Each link capacity is optimally partitioned by examining the upper bounds for the evacuation time imposed through different capacity allocations for each origin/destination pair traffic. The computational complexity per iteration is polynomial in the number of network nodes. This is due to the examination of origin/destination pairs rather then destinations alone as in previous work where a similar approach led to exponential complexity. Sufficient conditions for the convergence of the iterative algorithm to the optimum are given. If these are not satisfied supplementary steps are described which conduct the algorithm to the desired solution. These involve exponential computational complexity     

省略B帧运动补偿的转码算法实现 MPEG-2到MPEG-4视频流转码

MPEG-2和MPEG-4作为最流行的通用编码国际标准,将长期并存于不同的系统和网络服务中.为实现不同视频系统和网络间对以上两种压缩标准的兼容性,本文在详细分析它们压缩算法运算复杂度的基础上,提出三种压缩视频流转码算法.重点讨论了两种高性能转码算法的原理与实现过程,它们均是运算复杂性和视频质量之间的折衷方案:一是针对演播室和后处理环境的最高目标视频质量要求的运动参数重用算法;另一个是针对网络服务器和用户终端系统处理性能有限,具有最小延时要求的实时低复杂度转码算法.大量测试序列的仿真结果证明了算法的良好性能.     

Multiuser detection for DS-CDMA systems using evolutionary programming

This article introduces a new multiuser detection scheme which uses evolutionary programming (EP) to detect the user bits based on the maximum-likelihood decision rule. The major advantage of the proposed detector is that it has a lower computational complexity compared to other popular evolutionary-algorithm-based detectors. The simulation results show that the EP has always converged to the optimum solution with a small number of generations. The simulated average computational time performance demonstrates that this approach achieves practical ML performance with polynomial complexity in the number of users.