多元位置3值VMAP调制解调器

为同时改善不对称的随机极性甚小幅相(ARP-VMAP)调制信号的频谱利用率和能量利用率,提出了一种多元位置3值VMAP调制方式,设计了基于BP神经网络或支持向量机解调器的接收机。对比和分析了ARP-VMAP调制、3值VMAP调制、多元位置ARP-VMAP调制和多元位置3值VMAP调制信号的功率谱特性、?60 dB带宽、频谱利用率和解调性能。仿真结果表明,新的调制方式不仅提高了频谱利用率,而且显著改善了解调性能。     

一种随机极性MCP-EBPSK调制解调器

为改善随机极性的连续相应的扩展二元相移键控(CP-EBPSK)调制信号的频谱结构,该文提出一种带功率谱形状调节系数的随机极性修正CP-EBPSK (Modified CP-EBPSK, MCP-EBPSK)调制解调器。阐述了随机极性MCP-EBPSK调制的基本原理,给出了无随机极性的MCP-EBPSK调制理论功率谱表达式。同时,设计了合适的数字冲击滤波器用于解调,给出了无编码的随机极性MCP-EBPSK通信系统框图,分析和验证了该类调制信号的功率谱特性和解调性能,并对多径信道上的解调性能进行了仿真。仿真结果表明:新的调制方式通过对功率谱形状的调节,不仅频谱利用率更高,解调性能也更好;现阶段,该系统不适合在无线信道传输,有望在有线信道上率先获得应用。     

LDPC编码的随机极性CP-EBPSK系统

随机极性的连续相位扩展二元相移键控（CP-EBPSK）是一种高频谱效率的调制技术,特殊的冲击滤波器使得门限判决解调成为可能,为了进一步改善其在低信噪比下的误码率性能,引入低密度奇偶校验（LDPC）码作为信道编码。精确的后验概率估计对于译码性能至关重要,但解调方式的特殊性给获取后验概率带来困难。本文引入并分析了贝叶斯方法和支持向量机（SVM）以及两种基于判决门限的后验概率估计法。仿真结果表明,基于SVM和贝叶斯方法较基于判决门限的后验概率估计法更加精确,解调性能可提升8dB-9dB,但在解调之前对需要对码元进行训练,因而复杂度也相对较高;而基于判决门限的后验概率估计法不需要这一过程,因而实现较为简单,性能也可提升7dB以上。所以,在随机极性的CP-EBPSK系统中利用后验概率估计法作为LDPC码译码初始化较为有效。      

HSDPA中QAM软解调算法实现和性能分析

正交幅度调制(QAM)方式可以提高系统的频谱利用率,因此受到高速通信体制的广泛青睐,3GPP在HS-DPA中也引入了16QAM和64QAM.为了提高QAM系统性能,解调时一般采用软判决译码方式,对数似然比(Log Likelihood Ratio,LLR)软判决准则就是为计算QAM信号软判决译码度量值发展而来的.本文在介绍LLR求取原理的基础上,引入了简单的LLR求取算法,并进行了相关仿真工作.     

不对称的随机极性甚小幅相调制系统

为了紧缩随机极性MCP-EBPSK调制信号的频谱,消除边带线谱,同时易于电路实现和芯片集成,提出了一种不对称的随机极性甚小幅相调制(ARP-VMAP)。该方法是对随机极性MCP-EBPSK调制的波形表达式进行了简化和近似,消除了超越函数,使得调制器更容易硬件实现,工作频率更高。仿真结果表明:即使在-74dB边带功率带宽的苛刻要求下,ARP-VMAP调制能完全去除已调信号功率谱中的线谱分量,获得比随机极性MCP-EBPSK更高的频谱利用率,且解调性能也显著提高,对于发射能量的利用率更高,有利于节能环保。      

HSDPA中QAM软解调算法实现和性能分析

正交幅度调制（QAM）方式可以提高系统的频谱利用率,因此受到高速通信体制的广泛青睐,3GPP在HS-DPA中也引入了16QAM和64QAM。为了提高QAM系统性能,解调时一般采用软判决译码方式,对数似然比（Log Likelihood Ratio,LLR）软判决准则就是为计算QAM信号软判决译码度量值发展而来的。本文在介绍LLR求取原理的基础上,引入了简单的LLR求取算法,并进行了相关仿真工作。     

高阶调制系统中Viterbi译码的改进算法

本文分析了高阶调制通信系统中将解调和卷积码的译码联合的解码方法,并与传统的Viterbi软判决译码和Viterbi硬判决译码算法进行了比较.仿真结果表明,在不增加复杂度和保持相同的误码率的条件下系统所需信噪比比Viterbi软判决译码降低0.2-0.3dB.本文给出的方法也可推广到更高阶调制通信系统中.     

一种基于调制m序列的直接序列扩频信号调制方法

为提高直接序列扩频通信系统的频谱利用率,该文提出在m序列周期等于信息比特位宽整数倍情况下的直接序列扩频信号——调制m序列的信号调制与解调方法(m-DSSS)。首先结合调制m序列相关性数值仿真结果验证m-DSSS信号捕获可行性,然后根据信息比特的排列组合情况,设计一种基于多通道的m-DSSS信号调制和解调方法,并对m-DSSS信号通过加性高斯白噪声信道后的抗干扰能力建立数学模型。最后在相同频谱利用率条件下,与码移键控(CSK)调制方式进行了仿真对比试验。仿真结果表明,m-DSSS信号不仅比CSK信号具有更低的副峰,且当载波采用BPSK调制时,m-DSSS还可通过判断极性来辅助信号捕获,在误码率优于1e-3条件下,m-DSSS信号比CSK信号有2 dB以上优势,验证了m-DSSS调制用于直扩系统的可行性。     

一种基于调制m序列的直接序列扩频信号调制方法

为提高直接序列扩频通信系统的频谱利用率,该文提出在m序列周期等于信息比特位宽整数倍情况下的直接序列扩频信号——调制m序列的信号调制与解调方法(m-DSSS).首先结合调制m序列相关性数值仿真结果验证m-DSSS信号捕获可行性,然后根据信息比特的排列组合情况,设计一种基于多通道的m-DSSS信号调制和解调方法,并对m-DSSS信号通过加性高斯白噪声信道后的抗干扰能力建立数学模型.最后在相同频谱利用率条件下,与码移键控(CSK)调制方式进行了仿真对比试验.仿真结果表明,m-DSSS信号不仅比CSK信号具有更低的副峰,且当载波采用BPSK调制时,m-DSSS还可通过判断极性来辅助信号捕获,在误码率优于1e-3条件下,m-DSSS信号比CSK信号有2?dB以上优势,验证了m-DSSS调制用于直扩系统的可行性.     

联合解调与Viterbi译码算法的改进

本文分析了在第三代移动通信系统中，将数据解调和卷积码译码结合的译码方法，并与传统的Viterbi软判决译码和硬判决译码算法进行了比较。在3GPP所规定使用的调制和编码方式下进行了仿真，结果表明，在不增加复杂度和保持相同的误码率的条件下系统所需信噪比比Viterbi软判决译码降低1—2dB。本文给出的方法也可推广到其它通信系统中。     

Design of digital impacting filter in CP-EBPSK with random-polar communication system

To solve the difficulty of designing digital impacting filter in the receiver of random-polar modulated Extended Binary Phase Shift Keying with Continuous Phase (CP-EBPSK), a design method based on Quantum-behaved Particle Swarm Optimization (QPSO) algorithm is proposed. Firstly, QPSO is introduced elaborately, and the basic flow of QPSO is also given. Then, the demodulation principle of digital impacting filter in the communication system of CP-EBPSK with random-polar is demonstrated, and QPSO is utilized to design the digital impacting filter, which also takes the effect of finite word length into consideration when implemented by hardware. Finally, the proposed method is simulated. Simulation results show that the digital impacting filter designed by new method can derive satisfied demodulation performance.     

Single sideband quadrature amplitude modulation

Anew modulation scheme—single sideband quadrature amplitude modulation (SSB QAM) is proposed. This scheme allows to decrease the spectral width of the transferred signal by two times as opposed to the traditional quadrature amplitude modulation, while maintaining its spectral efficiency. This allows transmitting the modulated signal with the spectral width, which is equal to the spectral width of the modulating signal, and providing an energy gain of about 3 dB.     

联合正交调制与网络编码的协作HARQ方案

为了提高正交调制协作系统的传输效率,提出联合网络编码与正交调制协作混合自动重传请求方案。所提方案在重传中引入了网络编码,使得系统可以在相同的时间内能够重传更多的信息,从而节约了重传时间,进而改善系统吞吐量。接着,建立了Markov状态转移模型,并推导了所提方案在各种脉冲幅度调制(PAM)方式下的误帧率和延时性能,进而获得其吞吐量闭式近似解。仿真结果表明,与传统正交调制协作HARQ方案相比,所提方案在信噪比为5 dB、10 dB、15 dB处分别采用2PAM、4PAM、8PAM调制时都有近8%的吞吐量增益。     

An adaptive modulation scheme for simultaneous voice and datatransmission over fading channels

We propose a new adaptive modulation technique for simultaneous voice and data transmission over fading channels and study its performance. The proposed scheme takes advantage of the time-varying nature of fading to dynamically allocate the transmitted power between the inphase (I) and quadrature (Q) channels. It uses fixed-rate binary phase shift keying (BPSK) modulation on the Q channel for voice, and variable-rate M-ary amplitude modulation (M-AM) on the I channel for data. For favorable channel conditions, most of the power is allocated to high rate data transmission on the I channel. The remaining power is used to support the variable-power voice transmission on the Q channel. As the channel degrades, the modulation gradually reduces its data throughput and reallocates most of its available power to ensure a continuous and satisfactory voice transmission. The scheme is intended to provide a high average spectral efficiency for data communications while meeting the stringent delay requirements imposed by voice. We present closed-form expressions as well as numerical and simulation results for the outage probability, average allocated power, achievable spectral efficiency, and average bit error rate (BER) for both voice and data transmission over Nakagami-m fading channels. We also discuss the features and advantages of the proposed scheme. For example, in Rayleigh fading with an average signal-to-noise ratio (SNR) of 20 dB, our scheme is able to transmit about 2 bits/s/Hz of data at an average BER of 10 ^-5 while sending about 1 bit/s/Hz of voice at an average BER of 10^-2     

Bandwidth compressive 64-state sqam modems for non-linearly amplified satcom systems

A new class of spectral and power efficient offset modes of the M-ary QAM modulation technique, 64SQAM (superposed QAM), is analysed. The power spectrum of 64SQAM reveals a fast spectral roll-off and a low out-of-band energy. P(e) performance is analysed with different baseband wave shapes of 64SQAM in AWGN linear channels. For the operation of M-ary QAM at the highest power efficiency (i.e. at the saturation mode of HPA), a new bandwidth compressive NLA (non-linearly amplified) 64SQAM is investigated. Retaining a compact power spectrum and allowing a simple filtering strategy, NLA-64SQAM operates within 0–75 dB C/N degradation at P(e) = 10^?6.     

Intelligent Decision Making System for Digital Modulation Scheme Classification in Software Radio Using Wavelet Transform and Higher Order Statistical Moments

This paper proposes a neural network (NN) based intelligent decision making system for digital modulation classification using wavelet transform, histogram peak and higher order statistical moments. The decision making system is developed to classify the modulation schemes buried in additive white Gaussian noise and channel interference utilizing NN classifier. The performance is verified and validated for M-ary PSK, M-ary FSK, M-ary QAM and GMSK modulation schemes by examining the receiver operating characteristics, confusion matrix and probability of correct identification for various signal-to-noise ratios (SNR) and also for various decision parameters. The performance of the proposed system also has been compared with existing methods and found that this method can be considered as reliable classification method for Digital Modulation Scheme with lower SNR upto  − 5 dB.