首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 578 毫秒
1.
A simple lower bound, an upper bound and a simple approximation to the upper bound on the probability of error for coherent phase-shift-keyed (CPSK) systems operating in the presence of intersymbol interference and additive noise are obtained. The additive noises in the in-phase channel and the quadrature channel are assumed to be independent, and are independent of the signal, but not restricted to be Gaussian. The approximation to the upper bound is four times the lower bound, hence the tightness of these bounds is uniform for all cases. This fact and the simplicity of the bounds make these bounds a useful system design tool. Numerical examples for quaternary and octonary systems are presented and compared to known results.  相似文献   

2.
An upper bound and a lower bound to the probability of error for data transmission systems using a decision-feedback equalizer, with error propagation effects taken into account, are presented. Numerical examples show that they are tight bounds.We introduce the concept of a generalized decision-feedback equalizer suggested by the form of the derived bounds. A subclass is studied and optimized numerically with the aid of the derived error probability bounds. The solution represents the best compromise achievable by that class between the output noise power and the output intersymbol interference due to error propagation. A numerical example is carried out in detail to illustrate the concept.  相似文献   

3.
研究了一种扩谱载波数字脉冲间隔调制SSC—DPIM(Spread spectrum carrier digital pulse interval modulation)技术并用于电力线载波扩谱通信系统．采用线性扫频SSC扩谱载波对DPIM符号进行编码，引入脉冲前导码作为传输数据块的同步信号以防止差错传播．介绍了数据传输速率及数据块传送差错率的理论分析结果．并采用单片机实现了SSC-DPIM电力线载波通信系统．实验结果表明，在同样的电力线网络环境下，其通信效果明显优于已有的电力线载波通信系统。  相似文献   

4.
This paper is dedicated to the stochastic bipartite consensus issue of discrete-time multi-agent systems subject to additive/multiplicative noise over antagonistic network, where a stochastic approximation time-varying gain is utilized for noise attenuation. The antagonistic information is characterized by a signed graph. We first show that the semi-decomposition approach, combining with Martingale convergence theorem, suffices to assure the bipartite consensus of the agents that are disturbed by additive noise. For multiplicative noise, we turn to the tool from Lyapunov-based technique to guarantee the boundedness of agents’ states. Based on it, the bipartite consensus with multiplicative noise can be achieved. It is found that the constant stochastic approximation control gain is inapplicable for the bipartite consensus with multiplicative noise. Moreover, the convergence rate of stochastic MASs with communication noise and antagonistic exchange is explicitly characterized, which has a close relationship with the stochastic approximation gain. Finally, we verify the obtained theoretical results via a numerical example.  相似文献   

5.
The problem of the estimation of a discrete probability density from independent observations is considered. For a wide class of noises, a method is given for estimating a probability density when the measurements are corrupted by additive noise. This method is shown to be consistent, and several bounds on the error are given. An application to the detection of a (nonparametric) random signal is discussed. Finally, the estimation of a probability density is considered where the measurements are noisy and some of the measurements are incorrect. This situation may arise when a machine collecting the data fails part of the time.  相似文献   

6.
In this paper, the state estimation problem for discrete-time networked systems with communication constraints and random packet dropouts is considered. The communication constraint is that, at each sampling instant, there is at most one of the various transmission nodes in the networked systems is allowed to access a shared communication channel, and then the received data are transmitted to a remote estimator to perform the estimation task. The channel accessing process of those transmission nodes is determined by a finite-state discrete-time Markov chain, and random packet dropouts in remote data transmission are modeled by a Bernoulli distributed white sequence. Using Bayes’ rule and some results developed in this study, two state estimation algorithms are proposed in the sense of minimum mean-square error. The first algorithm is optimal, which can exactly compute the minimum mean-square error estimate of system state. The second algorithm is a suboptimal algorithm obtained under a lot of Gaussian hypotheses. The proposed suboptimal algorithm is recursive and has time-independent complexity. Computer simulations are carried out to illustrate the performance of the proposed algorithms.  相似文献   

7.
The detection of a deterministic signal in additive noise is considered. The log-likelihood ratio is studied for three cases: stationary white noise process, stationary Markov noise process, and noise process with independent increments. Procedures leading to realizable optimum detection schemes and related examples are given. An approximation to the log-likelihood ratio, which leads to the locally optimum detector, is also presented for the white noise case.  相似文献   

8.
Transmit antenna selection with maximal ratio combining at the receiver (TAS/MRC) is a promising technique that can be used to avoid the hardware complexity of multiple input multiple output (MIMO) system without jeopardizing the diversity gain. The generalized Gaussian distribution (GGD) is used to model different kinds of additive noise including Gaussian, Laplacian, uniform, and impulsive. In this paper, we study the bit error performance of TAS/MRC system assuming flat Rayleigh fading channels perturbed by additive white generalized Gaussian noise (AWGGN). To this end, we provide a closed form expression for the average bit error rate of coherent modulation techniques in terms of Mejier’s G function that is readily available in many commercial mathematical software packages like MATLAB and Mathematica. Moreover, we study the asymptotic behavior of the BER at high signal to noise ratio (SNR). Analytical results are verified by simulation.  相似文献   

9.
This paper investigates the modified tracking performance limitation of the networked time-delay systems with two-channel constraints. We consider both the white Gaussian noise and packet dropout constraints in the communication channels. In the plant, the non-minimum phase, unstable poles and time-delay are considered. The modified tracking performance limitation expressions will be achieved using the co-prime factorization and the spectral decomposition technique, and the two-parameter controller is adopted. The results show that the modified tracking performance limitation is related to the intrinsic properties of the given plant, including the non-minimum phase zeroes, the unstable poles and the time-delay. Furthermore, the network communication parameters, e.g. the white Gaussian noise, the packet-dropouts probability and the modified factor affect the modified tracking performance limitation of the networked time-delay systems. Finally, some particular examples are provided to illustrate the efficiency of the proposed method.  相似文献   

10.
The multi-taper spectrum (MTS) estimator enjoys a relatively low computational complexity and high estimation accuracy making it an attractive method for spectrum sensing in cognitive radio (CR) networks. However, it is difficult to guarantee both detection and false alarm probabilities when its design is based on fixed threshold, especially when the noise power fluctuates due to channel conditions. In this paper, a new adaptive threshold method to guarantee both detection and false alarm probabilities for MTS based spectrum sensing is proposed. By means of estimating noise power and signal power, the decision of adaptive threshold is able to adapt the noise fluctuation and achieve efficient trade-off between detection and false alarm probabilities. A closed form expression for the adaptive threshold is derived for both additive white Gaussian noise (AWGN) channel and multipath fading channel. Several metrics are employed to compare the performance of the proposed adaptive threshold method with that of the fixed threshold methods such as: error decision probability, detection probability, false alarm probability and throughput. The obtained results show that the proposed method achieves better spectrum efficiency and high throughput in comparison with the conventional fixed and adaptive threshold methods presented in the literature.  相似文献   

11.
  相似文献   

12.
In this paper, a novel event-triggered adaptive fault-tolerant control scheme is proposed for a class of nonlinear systems with unknown actuator faults. Multiplicative faults and additive faults are taken into account simultaneously, both of which may vary with time. Different from existing results, our controller fuses static reliability information and dynamic online information, which is helpful to enhance the fault-tolerant capability. With the aid of an event-triggering mechanism, an actuator switching strategy and a bound estimation approach, the communication burden is significantly reduced and the impacts of the actuator faults as well as the network-induced error are effectively compensated for. Moreover, by employing the prescribed performance control technique, the system tracking error can converge to a predefined arbitrarily small residual set with prescribed convergence rate and maximum overshoot, which implies that the proposed scheme is able to ensure rapid and accurate tracking. Simulation results are presented to illustrate the effectiveness of the proposed scheme.  相似文献   

13.
This paper is concerned with the event-based fault detection for the networked systems with communication delay and nonlinear perturbation. We propose an event-triggered scheme, which has some advantages over existing ones. The sensor data is transmitted only when the specified event condition involving the sampled measurements of the plant is violated. An event-based fault detection model is firstly constructed by taking the effect of event-triggered scheme and the network transmission delay into consideration. The main purpose of this paper is to design an event-based fault detection filter such that, for all unknown input, communication delay and nonlinear perturbation, the error between the residual signal and the fault signal is made as small as possible. Sufficient conditions for the existence of the desired fault detection filter are established in terms of linear matrix inequalities. Based on these conditions, the explicit expression is given for the designed fault detection filter parameters. A numerical example is employed to illustrate the advantage of the introduced event-triggered scheme and the effectiveness of the proposed method.  相似文献   

14.
In this paper, the problem of fuzzy model-based leader-following consensus control for multi-agent systems (MASs) under deception attacks is investigated. For the sake of alleviating the communication burden, a novel memory-based event-triggered scheme (METS) is first proposed for the considered MASs to reduce redundant data transmission, and the leader-following consensus can be achieved faster with a smaller adjustment error by applying the historical released packets. Considering the designed METS and upper-bounded attacks synthetically, the closed-loop fuzzy system model is well established. Furthermore, with the help of Lyapunov-Krasovskii technique, some sufficient conditions are derived to ensure the consensus of MASs subject to deception attacks. Finally, a simulation example is introduced to manifest the effectiveness of the proposed method.  相似文献   

15.
This paper investigates the state estimation problem for networked systems with colored noises and communication constraints. The colored noises are considered to be correlated to itself at other time steps, and communication constraints include two parts: (1) the information is quantized by a logarithmic quantizer before transmission, (2) only one node can access the network channel at each instant based on a specified media access protocol. A robust recursive estimator is designed under the condition of colored noises, quantization error and partially available measurements. The upper bound of the covariance of the estimation error is then derived and minimized by properly designing estimator gains. An illustrative example is finally given to demonstrate the effectiveness of the developed estimator.  相似文献   

16.
王玮 《大众科技》2012,(12):26-28
MPEG-2是目前在视频通信中广泛应用的视频标准,由于其使用了VLC编码,增加了每个码流比特的重要性,而在某些复杂的传输环境中会引入很多噪声,这对视频解码的质量和完成都是有很大影响的。所以错误检测与掩盖技术在MPEG-2视频解码中非常重要。文章主要讨论MPEG-2解码器的噪声检测与错误掩盖的方法及其实现。  相似文献   

17.
The probabilistic-constrained tracking control issue is investigated for a class of time-varying nonlinear stochastic systems with sensor saturation, deception attacks and limited bandwidth in an unified framework. The saturation of sensors is quantified by a sector-bound-based function satisfying certain conditions, and the random deception attacks are considered and modeled by a random indicator variable. To gain more efficient utilization of communication channels, a Round-Robin (RR) protocol is utilized to orchestrate the transmission order of measurements. The main purposes of this study aim to plan an observer-based tracking controller to achieve the following goals: (1) the related performance indicators of the estimation error is less than given bound at each time step; and (2) the violation probability of the tracking error confined in a predefined scope is supposed to be higher than a prescribed scalar and the area is minimized at each instant. In order to reach these requirements, a group of recursive linear matrix inequalities (RLMIs) are developed to estimate the state and design the tracking controller at the same time. Finally, two simulation examples are exploited to illustrate the availability and flexibility of the proposed scheme.  相似文献   

18.
徐婷  彭亚红  罗建宝  刘俞伯 《大众科技》2012,14(4):82-83,88
在短波通信中,为了克服信道中的多径干扰、衰落和多普勒频移等对接收信号的影响,实现低信噪比下,信号高速传输,文章提出了一种基于压缩感知的短波多天线分集合并接收系统设计方法。该系统有效地将OFDM调制方式和压缩感知相结合,充分利用了OFDM调制方式频谱效率高、抗多径衰落能力强等优势以及压缩感知抗干扰能力强、能以低采样率高精度重建待测信号的特性。实验结果表明:与现有的短波通信系统相比,在信号受强噪声干扰且高速传输的情况下,重建性能最优。  相似文献   

19.
This paper addresses the estimation problem for the steady state and error covariances of continuous systems subjected to additive and multiplicative noise. Several upper and lower matrix bounds of these covariances are developed. Comparing to existing results, these obtained bounds are more general. Furthermore, it is also shown that they are sharper for some case(s).  相似文献   

20.
By utilizing the theory of moment spaces, upper and lower bounds are obtained for error probability of digital communication systems, based on the use ofquadratic- exponential moments of the inter-symbol interference random variables. Some bound can be evaluated numerically with minimal computational effort, while other bounds require more effort. Even the computationally simple bounds can be extremely tight.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号