等价于MAP的SOVA译码方法

不同于MAP(Maximum A Posteriori)算法,SOVA(Soft-Output Viterbi Algorithm)算法的软输出不是真正意义上的后验概率,很少有文献给出SOVA算法的完整数学解释。该文给出了一种完整的SOVA的数学表达形式,并从SOVA的数学表达出发推导出了两种等价于MAP,具有SOVA形式的译码方法,一种是Li等人(1995)给出的适用于连续传输的最佳软输出算法(Optimal Soft output Algorithm, OSA);后一种是对OSA算法的改进,后者可以得到与前者等价的软输出,但是降低了运算复杂度。     

Incorporation of fractional-order dynamics into an existing PI/PID DC motor control loop

The problem of changing the dynamics of an existing DC motor control system without the need of making internal changes is considered in the paper. In particular, this paper presents a method for incorporating fractional-order dynamics in an existing DC motor control system with internal PI or PID controller, through the addition of an external controller into the system and by tapping its original input and output signals. Experimental results based on the control of a real test plant from MATLAB/Simulink environment are presented, indicating the validity of the proposed approach.     

Joint data detection and channel estimation for coded and uncoded continuous phase modulation signals

The performance of decision‐directed approach for joint data detection and channel estimation for continuous phase modulation (CPM) signal is limited because of an inevitable decision delay, which results in a trade‐off between data detection and channel estimation. In this paper, a novel hard output demodulation that solves the conflict requirement on the decision delay by predicting the channel coefficients over a given observation interval through a Kalman filter is proposed for uncoded CPM signal. The prediction guarantees high channel tracking capability and meanwhile maintains the accuracy of data detection. The proposed hard output demodulator is further extended to design a soft‐input soft‐output demodulator for serially concatenated CPM signal, which allows iterative processing. The convergence behavior of the proposed iterative receiver is presented. Simulation results show that the proposed demodulators provide improved performance in terms of bit error rate over some existing algorithms. Copyright © 2014 John Wiley & Sons, Ltd.     

An alternative structure for next generation regulatory controllers: Part I: Basic theory for design, development and implementation

Even though employed widely in industrial practice, the popular PID controller has weaknesses that limit its achievable performance, and an intrinsic structure that makes tuning not only more complex than necessary, but also less transparent with respect to the key attributes of the overall controller performance, namely: robustness, set-point tracking, and disturbance rejection. In this paper, we propose an alternative control scheme that combines the simplicity of the PID controller with the versatility of model predictive control (MPC) while avoiding the tuning problems associated with both. The tuning parameters of the proposed control scheme are related directly to the controller performance attributes; they are normalized to lie between 0 and 1; and they arise naturally from the formulation in a manner that makes it possible to tune the controller directly for each performance attribute independently. The result is a controller that can be designed and implemented much more directly and transparently, and one that outperforms the classical PID controller both in set-point tracking and disturbance rejection while using precisely the same process reaction curve information required to tune PID controllers. The design, implementation and performance of the controller are demonstrated via simulation on a nonlinear polymerization process.     

多径信道Turbo均衡技术性能分析

Turbo均衡技术将Turbo原理和均衡技术结合起来，通过对接收信号在均衡器和译码器之间迭代处理，提高系统抗符号间干扰（ISI）的能力。文中介绍了几种Turbo均衡技术，讨论了其计算复杂度，并给出了系统在Proakis信道下的误码性能。文中提出将应用于设计短波接收机。     

MC-CDMA系统迭代检测中的均衡

本文研究在同步MC- CDMA系统中的上行链路中的均衡技术。接收机采用多用户检测和译码相结合的迭代检测技术;其中,串行干扰消除用于多用户检测,一个SISO译码器用于信道译码。仿真给出在不同的均衡策略下如ORC、EGC、MRC、MMSE,迭代检测接收机的性能     

基于SISO的LDPC码盲译码算法研究

针对传统BP译码算法需要初始条件的缺点,本文提出了一种基于软输入软输出(SISO)的LDPC码盲译码算法,所提算法采用类似BP迭代译码算法步骤,通过对距离信息进行迭代处理,实现无需接收信号的信噪比和信道状态即可译码;同时,还将所提盲译码算法推广到多进制LDPC码的译码应用中。本文所提盲译码算法在初始状态难以确定以及接收信号信噪比难以估计的通信信道中具有重要价值。仿真结果表明,所提算法不论是在AWGN信道还是在瑞利衰落信道上都能取得优良的性能,不论是与标准BP译码算法还是与分层BP译码算法相比,在性能相近的情况下,计算复杂度都有所降低。     

SCCPM的非相干接收机设计与仿真

串行级联连续相位调制(SCCPM)的相干迭代接收机需要知道载波相位信息和精确的信道信息,然而这些信息在低信噪比下难以获得.针对此问题,研究了SCCPM非相干接收机,通过连续观察多个码元计算得到非相干解调的CPM信道转移概率,利用修正的CPM软输入软输出(SISO)算法实现迭代的解调和解码.仿真了码元速率为1/2外卷积码,通过随机交织器级联调制指数h=1/2的二进制 CPM组成的SCCPM系统.仿真结果表明,在AWGN信道中,所提出的非相干接收机比相干接收机的性能在误比特率为10-3时大约仅下降0.4dB.与SCCPM相干迭代接收机相比,此非相干接收机有着相似的迭代接收机结构,实现较容易.     

OFDM系统中一种新的迭代信道估计算法

本文提出了OFDM系统中一种新的基于软信息迭代处理的信道估计算法。该算法将面向判决最小二乘估计算法和盲估计算法相结合,在估计器中构造了一种新的置信度量函数,根据解码和软映射重构的反馈信号置信度大小在两种估计算法中自适应选择,这样估计的信道频响可以有效提高软信息迭代接收性能,大大降低信道估计训练开销。仿真结果表明,本文提出的算法能有效跟踪信道时变,限制传统面向判决估计的错误传播,达到好的系统性能。     

一种极点配置算法在SISO系统中的应用

极点配置问题是线性系统综合中的一类重要问题 ,尤其是SISO系统的极点配置 ,它在整个极点配置问题中发挥着重要作用 ,在很大程度上促进着MIMO系统极点配置问题的解决 .为了能对实际中一些不可控或不可观的SISO系统也进行极点配置 ,采用了将状态反馈和从输出至 x反馈相结合的配置方法 ,并引入了惟一确定状态反馈阵时先进的ValasekM和AckermannJ算法 ;最后结合工程实际 ,说明了该算法在控制系统中的具体应用 .