Multi-h CPM信号的减少状态多符号差分非相干检测

针对多指数连续相位调制(Multi-h CPM)载波恢复困难且实现复杂度高的难题,提出了一种适用于Multi-h CPM信号的减少状态多符号差分非相干检测算法。该算法利用多符号差分信息进行分支度量计算的同时引入参考相位信号,实现了具有残留载波频偏校正的非相干序列检测,并且结合逐幸存处理技术,利用幸存路径上的假设判决信息减少了网格状态数。通过计算和搜索接收信号所有可能调制指数序列所对应的分支度量信息实现了调制指数的估计与同步。计算机仿真结果表明,与相干最大似然序列检测相比,该算法能够以较小的性能损失获得其实现复杂度的降低,而且当存在残留载波频偏时,该算法的检测性能也较为稳健。     

一种新颖的全响应CPM信号载波频偏同步法

连续相位调制(CPM)具有许多线性调制法难以比拟的优势,但是其接收机实现复杂度高,信号同步困难。通过对CPM信号相位的分析研究找到相位变化特殊点,在这些点上相位的影响仅由频偏决定。据此提出了一种基于2P幂-滑动观测窗的快速收敛频偏估计算法。仿真表明,在系统开销较小的情况下该算法能很快实现精度足够的载波同步。     

一种低复杂度的CPM信号最大似然块检测算法

为了降低连续相位调制(Continuous Phase Modulation,CPM)信号多符号非相干检测的运算复杂度,提出了一种低复杂度的最大似然块检测算法。该算法充分利用已判决输出的符号对检测过程中的符号向量取值进行约束,有效减少判决统计量计算时的运算量,进而降低算法复杂度。另外,该算法引入判决长度变量,通过调整单次检测时判决符号数使算法能够在检测性能与运算量之间灵活折中。仿真结果表明,提出的低复杂度检测算法能够适用于全响应和部分响应CPM信号,相比原最大似然块检测算法能够在不损失检测性能的前提下降低算法运算量至少50〖WT《Times New Roman》〗%〖WTBZ〗,并且能够通过选择不同的判决长度提高算法应用的灵活性。     

一种CPM信号与PSK类信号的调制识别算法

提出了一种基于分形盒维数及二次方谱特征的方法,对由CPM与PSK类信号组成的信号集进行调制识别分类。首先提取信号集内各待识别信号的分形盒维数特征,将CPM和OQPSK识别出来;然后对信号集中剩余信号提取相应的二次方谱离散谱线特征依次区分出BPSK、UQPSK和QPSK;最后根据决策树原理设计分类器,实现信号集内信号的识别。仿真结果表明,该算法对信号集内的信号在信噪比达到3 d B以上条件下正确识别率可达到90%以上。     

一种新的2CPFSK信号极化合成方法

针对低信噪比下连续相位调制信号的极化合成,提出了一种基于多符号检测技术的极 化合成新方法。通过把解调和极化合成作为一个整体进行处理,在基带上完成了通常在中频 上实现的极化合成过程,避免了连续相位调制信号在低信噪比下载波相位跟踪困难的问题。 仿真结果表明,该方法的合成效果与理论值之间的差距小于0.3 dB。     

一种CPM信号的符号速率估计算法

在非合作通信中,调制参数估计是信号盲解调的必要前提,符号速率就是其中的一个重要参数。对于连续相位调制(Continuous Phase Modulation,CPM)信号,符号速率的精确估计对于信号的盲识别、参数估计及盲解调等都具有重要的意义。针对符号速率估计中存在的问题,提出了一种基于瞬时频率的符号速率估计算法,通过相位差分求取信号的瞬时频率,对瞬时频率值进行快速傅里叶变换得到瞬时频率谱,并根据瞬时频率谱求出符号速率的估计值。仿真实验结果表明,该算法不需要较大的数据量,且识别速度快,具有很好的抗噪声性能。     

一种CPM信号频率成形脉冲盲估计算法

频率成形脉冲是连续相位调制(CPM)信号解调所必需的调制参数,由脉冲形状和脉冲长度两个参数共同决定。该文利用CPM信号的自相关特性,深入分析了CPM信号调制参数与自相关函数之间的内在联系,并在此基础上提出了一种频率成形脉冲的盲估计算法。该算法首先实现脉冲形状的盲识别,然后将CPM信号的调制指数调整为整数,最后通过自相关函数中非零值的个数来实现脉冲长度的盲估计。计算机仿真结果与分析表明,该算法实现简单,能够在任意调制阶数和调制指数下有效估计出频率成形脉冲。     

CPM信号的微积分解调算法分析

连续相位调制（Continuous Phase Modulation）是一类包络恒定且相位连续的调制方式,具有很高的带宽和功率利用率,优良的包络和相位特性使其适用于空间通信。在分析CPM信号的模型基础上,研究了基于微积分的代数运算方法来完成对CPM信号的解调,该方法几乎不需要任何的先验信息和参数信息就能实现信号的盲解调,目的能够降低接收机的复杂度,是一种优秀的CPM信号解调方式。     

一种串行级联CPM的简化迭代译码方法

针对如何降低串行级联CPM系统接收译码复杂度这一问题,提出一种简化迭代译码方法.该方法利用PAM分解,将CPM信号网格状态数减少至2,有效地降低了接收端解码器的复杂度.此外,与现有方法不同,由于解调器可与基于PAM分解的符号检测器共用前端匹配滤波器,系统接收机的复杂度显著降低.仿真表明,当误比特率为10-5时,系统的复杂度显著降低,而误码性能损失仅约为0.1 dB.     

一种基于循环平稳性的CPM信号调制阶数盲识别算法

本文利用CPM信号的循环平稳性,深入分析了M进制CPM信号循环谱密度函数与信号调制阶数之间的内在联系,并在此基础上提出了一种基于信号循环平稳性的CPM信号调制阶数盲识别算法.实现了任意调制指数和频率成形脉冲的CPM信号调制阶数盲识别,为CPM信号的盲解调奠定了基础.计算机仿真结果与分析表明,该算法具有较高的正确识别率,并且受高斯噪声影响较小,实现简单,有实用意义.     

A BEM-based detector for CPM signals transmitted over frequency-flat fading channels

In this paper, the expectation-maximization (EM) algorithm for maximum a posteriori (MAP) estimation of a random vector is applied to the problem of symbol detection for continuous phase modulation signals transmitted over time-selective Rayleigh-fading channels. This results in a soft-in-soft-out detection algorithm suitable for iterative detection/decoding schemes. Simulation results show that the error performance provided by the proposed solution is very close to that of a MAP detector endowed with an ideal knowledge of the channel state both in uncoded and coded transmissions.     

2CPFSK的减少状态格状图

本文在不减少２ＣＰＦＳＫ的自由平方欧氏距离的前提下，提出了２ＣＰＦＳＫ的减少状态格状图，从而减少了维特比译码的复杂度。     

On Walsh filtering method for decoding of CPM signals

Walsh filtering has been used as a method to reduce receiver complexity in several coding and modulation systems, especially in continuous phase modulation systems. In this paper, we show that its lowpass filtering ability is poor and alias components arising from an adjacent channel can significantly degrade the maximum-likelihood decoding. Instead, a lowpass filtering method is more robust against adjacent channel interference and thus gives less decoding errors than the Walsh filtering method.     

Soft-decision phase detection with Viterbi decoding for CPM signals

It is known that continuous phase modulation (CPM) signals can be optimally detected by using coherent demodulation followed by Viterbi decoding. However, such a receiver is generally complicated, particularly at higher numbers of states, as it requires many correlators and many reference signals in the demodulator. In this study, a much simpler receiver, which employs a soft-decision phase detector followed by a Viterbi decoder, is proposed for the detection of CPM signals. The phase detector makes a decision in favor of one of the preselected phase subregions at the end of every interval, which is then used to calculate metrics for decoding. As in optimal detection, the Viterbi decoder decodes according to the trellis structure of CPM signals. The proposed receiver is analyzed in a narrow-band Gaussian channel with 2REC, 2-h, and trellis-coded continuous-phase frequency-shift keying signals. Numerical results show that the proposed receiver performs close to optimal detection with all types of signals considered in this study. The effect of the number of subregions in the phase detector is examined     

基于瞬时幅度特征的连续相位调制信号识别

针对非合作通信系统中连续相位调制（CPM）信号识别难的问题,提出一种CPM信号识别新方法。算法以信号的瞬时幅度谱为特征,结合谱线检测,实现了CPM信号与幅移键控（ASK）、正交幅度调制（QAM）、相移键控（PSK）、频移键控（FsK）信号的区分。算法无需各种参数估计及同步等预处理过程,仿真实验结果表明,在信噪比不小于4dB时,CPM信号正确识别率达到95％以上。与已有算法相比,本文所提算法具有计算量小、实现简单和低信噪比下识别率高等优点。     

Training-based time-delay estimation for CPM signals over time-selective fading channels

In this paper, we consider training-based symbol timing synchronization for continuous phase modulation over channels subject to flat, Rayleigh fading. A high signal-to-noise-ratio maximum-likelihood estimator based on a simplified channel correlation model is derived. The main objective is to reduce algorithm complexity to a single-dimensional search on the delay parameter, similar to that of the static-channel (slow fading) estimator. The asymptotic behavior of the algorithm is evaluated, and comparisons are made with the Cramer-Rao lower bound for the problem. Simulation results demonstrate highly improved performance over the conventional, static-channel delay estimator.     

一种新颖的Multi-h CPM信号符号速率盲估计算法

针对非合作条件下Multi-h连续相位调制(CPM)信号符号速率的盲估计问题,提出了一种新颖的预滤波二次谱算法,通过对接收信号滤波然后搜索其二次谱的峰值实现Multi-h CPM信号符号速率的估计,并利用CPM信号的PAM展开表达式解释了算法的原理.仿真实验结果表明,该算法是无偏的,与基于循环谱分析的算法相比具有运算量小的优点,并且适用于各种类型的Multi-h CPM信号,同时不需要载波频率和调制指数的先验信息,具有很强的鲁棒性.     

CPFSK调制解调算法研究及其DSP实现

简单介绍了CPFSK的基本原理,对其调制和解调算法进行了讨论.通过对过零检测、FFT频谱幅值法和非相干解调算法的比较,可以看出采用非相干解调方法具有较好的误码特性.     

On optimum detection of linearly filtered CPM signals

A novel structure of the MLSE receiver for linearly filtered CPM (continuous phase modulation) signals is derived. It is shown that the correlator bank required in the works of Svensson (1987) can equivalently be replaced by a reduced correlator bank, preceded by a linear filter with impulse response h*(-t) [channel matched filter]. The reduced correlator bank only incorporates characteristics of the CPM signals and is independent of the channel impulse response. This implies that the complexity of the modified correlator bank depends only linearly on the channel filter impulse response length. The proposed receiver structure permits considerable complexity reduction when compared to the currently known solution     

Joint phase and timing recovery with CPM signals

We describe joint carrier phase and timing recovery algorithms for CPM signaling. They may be employed with any CPM format, and with either full or reduced state detectors. Their implementation is fully digital, and involves a limited computational complexity. Simulation results show that these algorithms have excellent tracking performance. When operated in their simplest form, however, they may exhibit false locks. In particular, this occurs with multilevel and partial response formats. A simple solution to the false lock problem is proposed