RS码与LDPC码的联合迭代译码

针对RS码与LDPC码的串行级联结构,提出了一种基于自适应置信传播(ABP)的联合迭代译码方法.译码时,LDPC码置信传播译码器输出的软信息作为RS码ABP译码器的输入;经过一定迭代译码后,RS码译码器输出的软信息又作为LDPC译码器的输入.软输入软输出的RS译码器与LDPC译码器之间经过多次信息传递,译码性能有很大提高.码长中等的LDPC码采用这种级联方案,可以有效克服短环的影响,消除错误平层.仿真结果显示:AWGN信道下这种基于ABP的RS码与LDPC码的联合迭代译码方案可以获得约0.8 dB的增益.     

串行级联LDPC码及其传输性能分析

提出了一种简化的LDPC译码算法,以减小译码算法的复杂度.以非规则LDPC码作为内码,串联一个高码率规则LDPC码作为外码,可降低或消除错误平层.将此串行级联LDPC码在M-QAM调制信道上进行了仿真分析,结果表明其性能优于RS码,可有效利用带宽,同时保证数据可靠传输.     

基于LDPC码的CPQPSK编码调制方案

为提高CPQPSK (Continuous Phase QPSK)调制的抗噪声性能,提出了LDPC(Low Density Parity Check)码与CPQPSK的串行级联方案.重点研究了全响应CPQPSK与一种基于有限几何LDPC码的级联,该LDPC码具有高性能的同时,其编译码器都非常简单.CPQPSK信号采用基...     

一种LDPC编码高阶调制系统的联合解调解码方法

该文用一种级联码模型描述了LDPC编码高阶调制系统。该级联码模型以LDPC码为外码,二-十进制转换码为内码,再加一个删余模块构成。基于这种级联码模型,该文给出了其联合校验方程和二分图,并提出了级联码置信度传播算法,实现了LDPC编码高阶调制系统的联合解调解码。仿真表明,该文提出的联合解调解码算法有效地改进了LDPC编码高阶调制系统的性能。     

基于CCSDS规范LDPC码的FPGA实现

低密度奇偶校验(Low Density Parity Check,LDPC)码具有优异的误码性能,但目前卫星数传系统主要采用RS+卷积级联编码,为此,在现场可编程门阵列(Field Programmable Gate Array,FPGA)上实现基空间数据系统咨询委员会(Consultative Committee for Space Data Systems,CCSDS)的LDPC码编码是必要的。介绍了基于CCSDS规范的LDPC码,包括校验矩阵形式和生成矩阵形式。依据(8 176,7 154)LDPC码的矩阵结构,分析了矩阵信息的存储设计。在FPGA上实现了LDPC码串行编码,并详细介绍了编码过程。结合吞吐量的因素,实现了LDPC码并行编码。     

LDPC码的级联译码算法的改进与实现

针对中短码长中LDPC码的OSD串行级联译码算法,给出了一种FPGA实现方案。该方案基于FPGA芯片中的块RAM资源,实现了OSD译码中GF(2)上的高斯消元算法,避免了其对逻辑资源的大量消耗。结果表明,该实现方案可在中低端FPGA上实现500 kbit·s^-1吞吐量的LDPC码OSD串行级联译码器。     

降低SCL译码错误的级联极化码

串行抵消列表(SCL)算法是极化码的一种近似最大似然(ML)译码算法,基于该算法的循环冗余校验(CRC)级联极化码、校验(PCC)级联极化码纠错性能优良,已成为5G极化码标准编码方案。总结了SCL译码错误类型,并从降低SCL译码错误的角度揭示了CRC级联极化码、PCC级联极化码,以及CRC辅助的PCC级联极化码,三者提升SCL译码性能的原理。仿真结果表明:CRC辅助的校验级联极化码可以显著降低SCL译码错误,并在较高信噪比(SNR)范围内,呈现出最佳的纠错性能。     

多元LDPC码串行译码算法在光纤通信中的应用

将串行BP译码算法用在多元LDPC码中,降低了在光纤传输系统中的译码延时.详细介绍了在多元LDPC码中的串行BP译码算法和光纤通信系统的仿真模型.给出了在采用串行BP算法的LDPC译码器中,译码最大迭代数量对译码性能的影响,比较了采用传统的BP算法扣串行BP算法时LDPC译码器的性能.结果表明,采用串行BP算法确实能够提升LDPC译码器的收敛速度.     

基于MSK和LT码的联合迭代译码算法

传统的简单级联编码调制系统在译码时会造成软信息损失.提出了一种基于MSK和LT码的联合软迭代译码算法,设计了算法的系统模型.利用LT码的软译码和MSK调制的SISO算法,进行联合软迭代译码,提高了编码调制系统的性能.仿真结果表明:在误码率为10-4时,提出的算法比传统的简单级联编码调制算法约有1.5 dB的编码增益.     

基于并行级联LDPC码的递增冗余HARQ方案及性能分析

并行级联LDPC码是由多个码率不同的子码,经并行级联后得到的码率可变的LDPC码.本文提出了基于并行级联:LDPC码的递增冗余HARQ方案,给出了这种方案的吞吐量性能封闭解.在AWGN信道和Rayleigh衰落信道下,通过仿真将新方案的性能和随机LDPC码的性能进行了比较.结果显示,并行级联LDPC码的递增冗余HARQ方案性能接近随机LDPC码,但编、译码更简单,参数选择范围更广.     

Nakagami衰落信道上组合SC/MRC的性能分析

研究Nakagami衰落信道上组合发射机选择合并(SC)/接收机最大比合并(MRC)天线分集系统的性能.使用矩生成函数方法,推导采用组合SC/MRC天线分集和相干检测的MPSK(M进制相移键控)、MQAM(M进制正交幅度调制)、MPAM(M进制脉冲幅度调制)、BFSK(二进制频移键控)、最小相关BFSK(BFSKmin)、差分编码BPSK(DE-BPSK)和预编码MSK(最小频移键控)等几种M进制数字调制方式在Nakagami衰落信道上的误符号率性能,获得了M进制数字调制系统误符号率性能的精确数学表达式.数值计算结果阐明了发射天线和接收天线数目以及衰落参数对数字调制系统误符号率性能的影响.     

Space-time MSK Codes for Quasi-Static Fading Channels

In this paper, 4-state and 8-state space-time trellis codes with full rate, full diversity and high coding gain are proposed for MSK modulation, based on a technique similar to the super-orthogonal space-time trellis code (SOSTTC) design. Since the phase continuity requirement of MSK is the main constraint in space-time MSK code design not all the signal matrices corresponding to the trellis branches are orthogonal. The paper shows that the SOSTTC design technique can be extended to nonorthogonal coding structures. The new space-time MSK codes have frame error performances very close to those of their space-time QPSK counterparts given in [1]     

最小移频键控信号的检测和误码性能分析

首先介绍了MSK信号差分检测原理。其次,分析了存在相关高斯噪声和信道有瑞利衰落时MSK的抗噪声性能。结果表明,在高斯噪声时的差分MSK的误码率与DPSK相同;而当信道存在瑞利衰落时将严重影响系统的抗噪声性能。所得结论能为系统的设计提供重要依据。     

基于谱逼近的瞬态极化雷达最优波形设计

针对瞬态极化雷达(IPR)两路极化波形相关度较高而导致的目标极化参数估计误差大的问题,该文提出纯相位谱逼近算法(POSAA)来设计具有低相关水平的波形对。首先,以积分旁瓣电平准则构建目标函数;然后利用相关与谱的傅里叶变换对关系,基于谱逼近的思想,推导了目标函数的频域表示;最后获得目标函数的梯度和Hess矩阵,并采用信赖域方法优化求解目标函数以获得理想波形。仿真结果表明优化后的波形对具有极低的相关水平,且利用该优化波形获得的目标参数误差远小于当前常见波形。     

A single-chip MSK coherent demodulator for mobile radio transmission

Design and performance of a single-chip minimum shift keying (MSK) coherent demodulator fabricated by complementary metal oxide semiconductor-integrated circuit (CMOS-IC) technology is described. The demodulator consists of a phase detection circuit, carrier recovery circuit, data recovery circuit, and timing-clock recovery circuit. For the carrier recovery circuit, three types of Costas-loop are reviewed from the viewpoint that MSK modulation format has a close relationship to binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK). Among these loops, a loop of center-frequency locking scheme modified from a BPSK Costas-loop, termed MSK Costas-loop in this paper, is adopted for IC implementation. Digital IC design techniques are next described. Utilizing the sample-and-hold operation of the digital devices, a divided-frequency locking scheme of the quadrature coherent demodulation is proposed. Finally, IC demodulator performance is experimentally shown in the static and Rayleigh fading environments. The bit error rate performance and error-burst characteristic are measured. It is concluded that the single-chip coherent demodulator is suitable for digital mobile radio application.     

MSK信号的最大似然非相干检测算法研究

针对最小频移键控(MSK)信号,本文研究了一种性能优异的低复杂度最大似然非相干检测(MLNCD)接收模型,通过利用有限的几个符号构成的观测序列检测中间符号解调信息。本文给出了MLNCD模型的判决表达式,并推导了基于MLNCD算法的MSK信号软解调简化表达式,降低了实现复杂度。本文还仿真分析了采用MLNCD算法的无编码MSK系统和有编码MSK系统的误码率(BER)性能,结果表明MLNCD算法比传统MSK非相干解调算法具有显著的BER性能优势,与MSK相干解调性能接近,而且软信息的简化几乎没有造成系统性能损失。      

Decision feedback detection of minimum shift keying

A new decision feedback (DF) receiver for minimum shift keying (MSK) is derived, which uses the previously detected symbols to estimate the initial phase in the current symbol for optimum coherent detection. Some of theoretical and simulated bit error rate (BER) performance results are presented. The results show that the DF detection provides good bit error performance in the AWGN channel, and is also an efficient detection method for MSK in a fast Rayleigh fading mobile channel     

基于深度学习的抗窄带干扰MSK非相干接收机

窄带干扰(Narrowband Interference,NBI),作为一种敌意的频域干扰,会严重地恶化最小频移键控(Min-imum Shift Keying,MSK)非相干检测的误码率(Bit Error Rate,BER)性能.为降低窄带干扰对BER性能的影响,MSK非相干接收机一般首先对接收信号进行干扰抑制.然...     

Error rate performance of noncoherent detection of duobinary coded MSK and TFM in mobile radio communication systems

Two continuous phase constant envelope modulation schemes are considered for use in digital mobile radio communication systems. These two schemes, duobinary coded minimum shift keying (MSK) and tamed frequency modulation (TFM), use partial response signaling to achieve efficient power spectrum. Therefore, they are suitable candidates for the application of digital data transmission via mobile radio where spectrum efficiency is an important consideration. The mobile communication channel is characterized by fast Rayleigh fading and cochannel interference resulting from the reuse of the channels. The error rate performance of duobinary coded MSK and TFM has been studied under these environments with noncoherent detection. A closed form expression for the probability of error of duobinary coded MSK with discriminator detection has been derived and evaluated for different cases of fast and slow fading and cochannel interference. The probability of error of duobinary coded MSK and TFM with differential detection has been calculated by numerical integrations for different cases of slow and fast fading and cochannel interference.     

A differentially coherent receiver for minimum shift keying signal

The author extends to the case of minimum-shift-keying (MSK) modulation the differentially coherent reception theory established for phase-shift-keying modulation. A novel differentially coherent detector for MSK is thus derived. The receiver filter is equivalent to the cascade of a matched filter and an equalizer in order to suppress inherent intersymbol interference. It is shown that performance can be improved when the delay between signals, multiplied by the differential detector, is increased from one to M bit time intervals. This decreases the effect of noise correlation and, thus, the bit error probability. The bit error probability of the proposed receiver is calculated. It is found that almost all potential improvement due to the delay M is obtained with M=3