Interactive Kalman Filtering for Differential and Gaussian Frequency Shift Keying Modulation with Application in Bluetooth

Some applications are constrained only to implement low cost receivers. In this case, designers are required to use less complex and non-expensive modulation techniques. Differential Quadrature Phase Shift Keying (DQPSK) and Gaussian Frequency Shift Keying (GFSK) can be non-coherently demodulated with simple algorithms. However, these types of demodulation are not robust and suffer from poor performance. This paper proposes a new method to enhance the performance of DQPSK and GFSK using Interactive Kalman Filtering (IKF) technique, in which a one Unscented Kalman Filter (UKF) and two Kalman Filters (KF) are coupled to optimize the demodulated signals. This method consists of simple but very effective algorithms without adding complexity to the demodulators comparing to other very complex methods. UKF is used in this method due to its superiority in approximating and estimating nonlinear systems and its ability to handle non-Gaussian noise environments. The proposed method has been validated by creating a MATLAB/SIMULINK Bluetooth system model, in which the IKF is integrated into the receiver, which implement both DQPSK and GFSK, and run simulation in Gaussian and Non-Gaussian noise environments. Results have shown the effectiveness of this method in optimizing the received signals, and that the UKF outperforms the Extended Kalman Filter (EKF).

BLIND CHANNEL ESTIMATION OF SPACE-TIME FREQUENCY-SHIFT KEYING

The decoupled coherent Maximum Likelihood (ML) detection algorithm presented in this letter can sharply reduce the complexity of the receiver as well as provide better error performance under the precondition that channel should be estimated first. Considering the bandwidth inefficiency of Frequency Shift Keying (FSK), the acquisition of channel state information through training sequences will further decrease the transmission efficiency. This letter presents a blind channel estimation algorithm based on noise subspace theory which can acquire channel information without any training symbols. The simulation shows that the algorithm brings about fewer channel estimation errors while the frequency efficiency can be increased.

Adaptive compensating method for Doppler frequency shift using LMS and phase estimation

The novel compensating method directly demodulates the signals without the carrier recovery processes, in which the carrier with original modulation frequency is used as the local coherent carrier. In this way, the phase offsets due to frequency shift are linear. Based on this premise, the compensation processes are： firstly, the phase offsets between the baseband neighbor-symbols after clock recovery is unbiasedly estimated among the reference symbols; then, the receiving signals symbols are adjusted by the phase estimation value; finally, the phase offsets after adjusting are compensated by the least mean squares （LMS） algorithm. In order to express the compensation processes and ability clearly, the quadrature phase shift keying （QPSK） modulation signals are regarded as examples for Matlab simulation. BER simulations are carried out using the Monte-Carlo method. The learning curves are obtained to study the algorithm＇s convergence ability. The constellation figures are also simulated to observe the compensation results directly.

Shaped Offset Quadrature Phase Shift Keying Based Waveform for Fifth Generation Communication

Fifth generation(5G)wireless networks must meet the needs of emerging technologies like the Internet of Things(IoT),Vehicle-to-everything(V2X),Video on Demand(VoD)services,Device to Device communication(D2D)and many other bandwidth-hungry multimedia applications that connect a huge number of devices.5G wireless networks demand better bandwidth efficiency,high data rates,low latency,and reduced spectral leakage.To meet these requirements,a suitable 5G waveform must be designed.In this work,a waveform namely Shaped Offset Quadrature Phase Shift Keying based Orthogonal Frequency Division Multiplexing(SOQPSK-OFDM)is proposed for 5G to provide bandwidth efficiency,reduced spectral leakage,and Bit Error Rate(BER).The proposed work is evaluated using a real-time Software Defined Radio(SDR)testbed-Wireless open Access Research Platform(WARP).Experimental and simulation results show that the proposed 5G waveform exhibits better BER performance and reduced Out of Band(OOB)radia-tion when compared with other waveforms like Offset Quadrature Phase Shift Key-ing(OQPSK)and Quadrature Phase Shift Keying(QPSK)based OFDM and a 5G waveform candidate Generalized Frequency Division Multiplexing(GFDM).BER analysis shows that the proposed SOQPSK-OFDM waveform attains a Signal to Noise Ratio(SNR)gain of 7.2 dB at a BER of 10�3,when compared with GFDM in a real-time indoor environment.An SNR gain of 8 and 6 dB is achieved by the proposed work for a BER of 10�4 when compared with QPSK-OFDM and OQPSK-OFDM signals,respectively.A significant reduction in OOB of nearly 15 dB is achieved by the proposed work SOQPSK-OFDM when compared to 16 Quadrature Amplitude Modulation(QAM)mapped OFDM.

基于差分进化的FSK信号频率检测仿真

针对通信信号检测中FSK信号频率的快速检测问题,提出一种基于多次差分进化搜索FSK信号的快速频率检测方法。该方法将信号的幅度谱作为差分进化的初始目标函数,通过多次差分进化搜索目标函数的最大值,并更新目标函数,获得最优极值坐标向量;针对最优极值坐标向量所对应的目标函数值向量,提出定义其差分比值,来确定有效的峰状谱线位置,最终完成FSK信号的频率检测。仿真实验验证了其有效性和可行性。

An innovative detection method of high frequency BPSK signal with low signal-to-noise ratio

Based on chaotic oscillator system, this paper proposes a novel method on high frequency low signal-to-noise ratio BPSK(Binary Phase Shift Keying) signal detection. Chaotic oscillator system is a typical non-linear system which is sensitive to periodic signals and immune to noise at the same time. Those properties make it possible to detect low signal-to-noise ratio signals. The BPSK signal is a common signal type which is widely used in modern communication. Starting from the analysis of advantages of chaotic oscillator system and signal features of the BPSK signal, we put forward a unique method that can detect low signal-to-noise ratio BPSK signals with high frequency. The simulation results show that the novel method can detect low signal-to-noise ratio BPSK signals with frequency in an order of magnitude of 108 Hz, and the input Signal-to-Noise Ratio threshold can be -20 dB.

Frequency Hopping Spread Spectrum Security Improvement with Encrypted Spreading Codes in a Partial Band Noise Jamming Environment

Frequency Hopping Spread Spectrum (FHSS) system is often deployed to protect wireless communication from jamming or to preclude undesired reception of the signal. Such themes can only be achieved if the jammer or undesired receiver does not have the knowledge of the spreading code. For this reason, unencrypted M-sequences are a deficient choice for the spreading code when a high level of security is required. The primary objective of this paper is to analyze vulnerability of linear feedback shift register (LFSRs) codes. Then, a new method based on encryption algorithm applied over spreading codes, named hidden frequency hopping is proposed to improve the security of FHSS. The proposed encryption security algorithm is highly reliable, and can be applied to all existing data communication systems based on spread spectrum techniques. Since the multi-user detection is an inherent characteristic for FHSS, the multi-user interference must be studied carefully. Hence, a new method called optimum pair “key-input” selection is proposed which reduces interference below the desired constant threshold.

QPSK DS-CDMA System over Rayleigh Channel with a Randomly-Varying Frequency Narrow-Band Interference: Frequency Tracking Analysis

This paper analyses frequency tracking characteristics of a complex-coefficient adaptive infinite-impulse response (IIR) notch filter used for suppression of narrow-band interference (NBI) with a randomly-varying frequency in a quadriphase shift keying (QPSK) modulated direct-sequence code-division multiple-access (DS-CDMA) communication system. The QPSK DS-CDMA signals are transmitted over a frequency non-selective Rayleigh fading channel. The analysis is based on a first-order real-coefficient difference equation with respect to steady-state instantaneous frequency tracking error from which a closed-form expression that relates frequency tracking mean square error (MSE) with number of DS-CDMA active users and NBI power is obtained. Closed-form expressions for optimum notch bandwidth coefficient and step size constant that minimize the frequency tracking MSE are also derived. Computer simulations are included to substantiate the accuracy of the analyses.

基于FPGA的2CPFSK全数字中频调制器的设计与实现

针对飞行器数据链中高码速率要求,需要使用数字技术实现传统模拟调制,以得到更好的调制性能,增加系统作用距离。本文介绍了二进制连续相位频移键控(2CPFSK)调制原理,提出了基于软件无线电架构的2CPFSK正交调制算法。该算法利用2CPFSK相位累加特性实现了基带数据的分数倍内插,从而适应宽范围码速率的调制。设计了提高频谱纯度的数字滤波器、基于FPGA+DAC架构的数字调制器硬件平台并实现算法。通过与传统模拟频率调制(FM)比较,该设计提升了1.7 dB调制性能,增加了系统作用距离。

A NOVEL SEMI-BLIND TIME-FREQUENCY DOMAIN TRACKING ALGORITHM SUITABLE FOR MPSK-OFDM

This paper presents a semi-blind tracking algorithm used for Multiple Phase Shift Keying based Orthogonal Frequency Division Multiplexing(MPSK-OFDM) system. By using special pream-bles to assist the decision of a feedback loop and to solve the problem of phase ambiguity,the tracking performance of the algorithm has been improved greatly. Only a few preambles are needed in the al-gorithm since the preambles are not used to estimate the frequency offset but used to provide the variation information of the phase due to the presence of frequency offset. Simulations verify that the algorithm has low SNR bound for tracking as well as high tracking accuracy and the tracking range is expanded to 30% of one subcarrier spacing.

一种FSK来电显示软调制的设计与实现

提出了一种基于GD32实现的FSK来电显示软发号的设计。该设计以GD32为核心控制器,通过软件调制的方式实现频移键控(Frequency-Shift Keying,FSK)来电显示号码的发送,在初步介绍来电显示基础上,阐述该设计的原理过程,并给出相应软件设计的源代码。该设计的实现对于程控用户交换机、程控集团电话的设计以及FSK来电显示号码的发送,均具有一定的参考实用价值,从根本上理解FSK来电显示有积极的意义和价值。

一种FPGA控制DDS实现4FSK&FM调制载波的国产化设计

文章主要介绍一种现场可编程逻辑门阵列(Field Programmable Gate Array,FPGA)控制数字频率合成器(Direct Digital Synthesizer,DDS)实现四进制移频键控(Quaternary Frequency Shift Keying,4FSK)&频率调制(Frequency Modulation,FM)调制载波的设计方案,给出技术指标参数、硬件组成框图以及信号处理流程,对4FSK的调制信号和FM信号产生的实施方法进行探讨,并对电路框图中的关键器件进行国产化设计选型。

高速置换索引差分混沌移位键控通信系统

为了提高置换索引差分混沌移位键控系统的数据传输速率和能量效率,提出了高速置换索引差分混沌移位键控通信系统。该系统采用置换矩阵索引多元信息,并携带一个调制位。发射端将参考信号复制P次作为信息承载信号,通过希尔伯特变换,每个信息时隙中多传输N个用户的信息,将信号级联到正交频分复用系统进行正交载波调制,大大提高了系统的数据传输速率;同时推导了该系统在高斯白噪声信道和多径瑞利衰落信道下的误码率表达式。理论分析及仿真结果证明,该系统相比其他置换索引类系统具有高速率、低误码率的良好特性,有更好的应用前景。

FSK/BPSK复合调制信号识别与参数估计

该文提出了一种有效的频率键控-二相编码(FSK/BPSK)复合调制信号的识别和参数估计算法。首先给出FSK/BPSK复合调制信号的模型,并分析了其相位特征。然后采用二叉树方法,基于相位展开和瞬时频率特征实现FSK/BPSK复合调制信号,BPSK信号和FSK信号的识别,并详细讨论了基于Neyman-Pearson准则的识别门限选定原则。最后采用Haar小波法和正弦波频率估计算法实现FSK/BPSK复合调制信号的参数估计。仿真结果表明,该算法在较低信噪比下仍具有较好的识别性能和参数估计精度。

基于HHT变换的时频分析法及其在2FSK系统解调中的应用

该文用一种非平稳信号时频分析方法(HHT变换)。该方法立足于信号本身特征,着重分析信号的瞬时频率分布,实现2FSK系统的解调。通过与传统解调方法的比较,论述了该方法在2FSK信号解调中的合理性和可行性。仿真结果给出了该方法在解调过程中的抗噪声性能,表明了该方法的有效性。

采用FSK调制的直接序列扩频水声通信技术

水声信道的时变相位起伏使得实现可靠的相位跟踪比较困难,从而造成基于相位检测的水声通信接收机结构复杂。提出基于FSK调制的直接序列扩频(DSSS-FSK)水声通信系统。它采用FSK调制和非相干检测,对DSSS-FSK信号的相关解扩和RAKE解调方法进行了研究。数值仿真和湖试数据处理表明,DSSS-FSK信号兼有扩频信号抗多径、低截获概率和非相干检测简单可靠两方面的优点,特别适用于低信噪比、强多径的水声信道中。

远动通道FSK信号载频检测方法的研究及其应用

为了实现对基于 FSK(频移键控 )调制方式的远动信道的监控 ,必须首先准确检测 FSK信号的载波频率。 FSK信号的频谱成分比较复杂 ,包含基带信号引入的连续谱和载波信号引入的离散谱两部分 ,传统的信号处理方法难以准确测量。针对以上特点 ,提出了一种新的非线性变换——时域拼接变换 ,通过对 FSK信号的分割和重新组合 ,消除了两个载波信号之间的相关性 ,抑制了基带信号对功率谱的影响 ,将离散谱从功率谱中分离 ,并结合现代功率谱估计方法 ,实现了对信号载波频率的高精度测量。计算机仿真与实验证明 ,该方法是一种有效的

基于DFT的2FSK信号解调自适应门限同步检测算法

传统的基于离散傅立叶变换(DFT)的频移键控(FSK)信号解调在同步检测中采用了固定门限,无法适应时变信道环境中信号衰减和噪声干扰的动态变化,实际应用中效果不佳。为了解决这个问题,首先在分析传统方法固有缺陷的基础上,提出了自适应门限同步检测的思路,然后应用随机信号检测与估计相关理论对检测算法进行了详细推导,并给出了自适应门限的计算公式,最后对算法的有效性及性能进行了仿真与分析,结果表明该方法所得的同步检测门限在不同信噪比情况下均能适应信道环境的动态变化,其虚警概率和检测概率的性能与理论相符,有效解决了时变信道环境下门限选择的问题。

铁路专用2FSK调制信号生成方法的研究

铁路信号车载和地面列控设备是确保列车高速安全运行的重要基础装备 ,针对我国铁路信号地面系统制式多、设备不兼容的现状 ,如何基于相同硬件及专用软件 ,模拟产生现有不同制式轨道电路信号是新型列车自动控制系统研制过程中亟待解决的技术难题。分析了我国铁路主要制式信号的典型参数特征 ,通过MAT LAB仿真软件建立了主要制式信号的数学模型 ,在重点解决了边频精度、相位连续、波形转换等关键问题的前提下 ,提出了我国铁路专用 2FSK (二进制频移键控 )调制信号的全新生成方法 ,并给出了相关硬件、软件的设计思路。由实验结果分析表明 ,该设计的精确度和稳定度完全满足现场应用的要求 ,具有通用、简便。