Laguerre盲均衡器的设计与仿真

现代高速卫星通信、遥感,以及远程侦查无人机的数据传输速率可达Mb/s甚至Gb/s,码间干扰和群延时不可忽视。针对卫星通信的应用,提出了一种易于实现的Laguerre算法,和有利于消除码间干扰和群时延的分数间隔结构,设计出了一种高效地盲均衡器。Laguerre算法采用有限的滤波阶数,就可以达到IIR长脉冲滤波的效果;而分数间隔均衡器（FSE）能够降低采样相位敏感性,可以有效改善由于位同步相位误差造成的性能损失,分数间隔均衡器的设计目标立足于具有较好性能和易于工程上FPGA的实现。文中通过仿真均衡前后误码增益,得到几种不同信道下的均衡器的性能理论曲线,可以为高速数传均衡器设计提供有益参考。     

10Gb/s光通信系统中EDC均衡器的性能研究

采用数值仿真的方法对几种使用在10Gb/s光通信系统中的电色散补偿(EDC)均衡器的性能进行了研究,包括判决反馈均衡器、线性均衡器、最大似然序列估计器(MLSE).仿真结果表明MLSE的性能最好,但由于它不易实现,可以采用判决反馈均衡器替代,这对实际系统的设计具有参考价值.     

一种基于65 nm CMOS工艺的3抽头前馈均衡器

高速串行接口技术是当前高速数据传输的关键技术之一,而前馈均衡器(FFE)是高速串行接口中的重要模块电路。设计了一款工作在40 Gb/s、用于高速串口发送端的前馈均衡器;分析了FFE求和模块、延时模块对均衡效果的影响;采用LC网络作为延时单元,并通过设计闭环反馈控制来控制延时时间,解决了高速均衡电路的延时实现问题。电路采用TSMC 65 nm CMOS工艺进行设计和仿真,后仿真结果表明,在40 Gb/s数据传输时,该3抽头FFE电路具有20 dB的均衡能力;在TT_27 ℃工艺角、1.0 V电源电压下,电路功耗为51.52 mW。     

基于DVB-C的自适应均衡电路优化实现

采用经典的常数模和面向判决的最小均方误差算法,并使用判决反馈的结构,实现了DVB-C对均衡器的性能要求.所设计的均衡器支持64/256的正交幅度解调且易于VLSI实现.通过采用误差的2次幂量化,乘法器复用以及流水线等优化技术,大大减少了均衡电路的硬件规模和功耗.所设计的均衡器经过算法级仿真和带0.25μm标准工艺库仿真,结果表明能有效消除码间干扰(ISI).     

一种用于数字QAM接收机的盲均衡器实现

提出了一种适用于数字QAM接收机的自适应盲均衡器实现方案。该均衡器采用多模算法(MMA)和最小均方算法(LMS)，称为MMA—LMS算法结合判决反馈结构(DFE)，即采用前向滤波器和反馈滤波器两级滤波器组实现，提高了信道的适应性能和降低均衡器的阶数。仿真结果表明，该均衡器比一般采用恒模算法(CMA)的横式均衡器有更好的性能，更易于硬件实现。     

一种宽带阵列数字下变频与均衡器一体化设计

从基本FIR均衡器的原理出发,讨论了不同系统采样率对均衡性能的影响。为适应宽带阵列中高速信号处理的要求,讨论一种经典的数字下变频和均衡器的设计方法。该方法虽然实现简单,但没有充分考虑采样率对均衡器设计的影响,需要大量的乘法资源。为了在保证均衡性能的同时降低系统对乘法资源的消耗,提出了一种数字下变频与均衡器的一体化设计方法。与传统方法相比,所提方法在阵列通道个数较大时能明显降低对乘法资源的损耗。通过仿真和实测数据分析,验证了所提方法的正确性。     

稀疏水声信道判决反馈盲均衡算法研究

针对高速水声通信中信道的稀疏特性,提出了一种基于常数模准则的稀疏水声信道判决反馈盲均衡算法。该算法将改进的常数模算法与一种变化的判决反馈均衡器结构(部分反馈均衡器)有机结合,利用水声信道的稀疏特性,不但很好地实现了稀疏水声信道的盲均衡,而且简化了计算,易于算法的硬件实现。用典型稀疏水声信道进行了计算机仿真。结果表明,该算法性能稳定,计算量小,稳态均方误差低,整体性能与基于自适应LMS的稀疏迭代算法接近。该研究为高速水声通信中稀疏信道的均衡提供了一种可实现的方法。     

一种高速串行信号线性均衡电路

设计了一种高速串行信号连续时间线性均衡器。采用有源电感负载结构,结合高频与全频通路信号求和技术来实现高速串行信号均衡。电路具有面积小、功耗低、利于集成等优点。采用65 nm CMOS工艺进行设计,1.2 V电源供电,可对经过80 cm长的衰减信道、且传输速率为14 Gbit/s的信号进行补偿,实现6.24 dB@10.96 GHz的补偿。该均衡器将输出端信号眼图水平方向抖动减小至0.25UI,功耗数据率比低至0.399 mW·s/Gbit,设计版图面积为0.09 mm²。     

DLMS算法的脉动阵结构设计及FPGA实现

为了减小无人机数据链中的码间干扰,适应数据链对传输速度的要求,利用Verilog HDL设计DLMS算法,并在其中加入脉动阵结构,完成了均衡器的高速实现。仿真表明所设计的均衡器的最高频率可达298.063 MHz,这为以后设计更高频率或其他类型的高速均衡器指明了方向。     

基于遗传算法的微波均衡器仿真和工程设计

研究了用于均衡行波管增益的微波均衡器的计算机仿真和工程设计问题。理论分析并建立了均衡 器的一般微波网络模型,该网络模型具有数十个优化变量,能够使均衡器实现任意有理函数类的均衡曲线。利用遗 传优化算法完成多变量的单目标或多目标优化,最终根据优化结果来具体实现均衡器的工程设计并为后期调试提 供指导。设计了一种C 波段10 阶同轴均衡器,实物调节和测试表明该设计对该波段的各种均衡曲线均有很好的适 应性,均衡误差1dB 以内,其中均衡枝节还具有温度补偿特性,高低温温飘小于5MHz。     

基于Kalman滤波的水声混合双向迭代信道均衡算法

水声信道均衡中基于信道估计的均衡方法理论上具有更优的均衡性能,但较高的计算复杂度限制了算法的实际应用。针对这一问题,该文首先基于Kalman滤波和Turbo均衡提出一种迭代Kalman均衡器,实现了基于软符号的迭代信道估计与迭代Kalman均衡,且复杂度较常规方法降低约1个数量级。其次,针对单一均衡算法和单一方向Turbo均衡器存在的误差传递现象,设计了基于迭代Kalman均衡器与改进成比例归一化LMS (IPNLMS)自适应均衡器相结合的混合双向Turbo均衡器,提高了自适应均衡器的收敛速度和均衡性能,并通过双向均衡结构带来的增益改善了符号估计误差传递的现象。理论分析与仿真实验验证了该文算法的有效性。     

On the use of tapered linearly chirped gratings asdispersion-induced distortion equalizers in SCM systems

We report on the use of tapered linearly chirped fiber gratings to equalize dispersion-induced distortion in long distance/broad-band subcarrier multiplexed (SCM) systems. Different apodization functions for the coupling factor of the fiber grating have been considered and their equalizing capability of fiber-induced distortion in a subcarrier system have been compared. The results of the theoretical analysis show that both harmonic and intermodulation distortions are significantly reduced when the equalizer parameters have been properly designed. Higher reduction of the nonlinear distortion is obtained when the length of the filter increases, even though a saturation effect on this reduction figure appears when the equalizer length is about four or five times its minimum value to achieve equalization, which is derived theoretically based on the SCM optical system parameters. The performance of a Tanh-type tapered linearly chirped grating equalizer on a realistic broadband SCM system is also considered. The results reveal that the dispersion-induced distortion can be neglected when the equalizer is employed     

盲均衡器高速运算单元的优化设计

在自适应盲均衡器的设计过程中,符号数的乘加（MAC）运算是关键路径。文中对自适应均衡器的核心运算单元——Booth编码算法进行了详细描述,并采用Booth编码算法对高性能乘累加（MAC）运算单元进行了优化和现场可编程门阵列设计。系统仿真结果证明,优化设计后可以获得良好的均衡效果,在此基础上设计的均衡器能够很好地消除码间...     

利用自适应均衡滤波器改善大气湍流信道OWC性能

光无线通信是近年来无线通信领域的研究热点之一。大气湍流是影响光无线通信的重要因素,特别是在高速数字通信中会产生严重的码间干扰。本文分析了大气湍流信道的特性,提出采用自适应LMS均衡技术改善大气湍流信道的性能,对采用OOK调制方式的OWC系统均衡前后的误码率性能进行了分析比较。仿真结果表明自适应LMS均衡技术可以将系统的性能提高约10dB。     

A Simplified Two-Stage Equalizer with a Reduced Number of Multiplications for Data Transmission over Voiceband Telephone Links

The paper presents an equalization scheme based on the two-stage equalizer originally introduced by Proakis. Mostly additions are required for implementation of the equalizer structure and the adaptation algorithm. The equalizer can be applied to data transmission Systems which use four-phase modulation, especially in 1200/2400 bit/s modems, thus replacing the fixed equalizer recommended by CCITT. The results presented in the paper deal with the analog and digital implementation of the proposed equalizer. Its performance is compared to the performance of the conventional transversal equalizer, a decision-feedback equalizer, an ideal linear canceller, and an ideal QPSK system.     

A 5 Gb/s CMOS adaptive equalizer for serial link

A 5 Gb/s adaptive equalizer with a new adaptation scheme is presented here by using 0.13μm CMOS process.The circuit consists of the combination of equalizer amplifier,limiter amplifier and adaptation loop.The adaptive algorithm exploits both the low frequency gain loop and the equalizer loop to minimize the inter-symbol interference (ISI) for a variety of cable characteristics.In addition,an offset cancellation loop is used to alleviate the offset influence of the signal path.The adaptive equalizer core occupies an area of 0.3567 mm2 and consumes a power consumption of 81.7 mW with 1.8 V power supply.Experiment results demonstrate that the equalizer could compensate for a designed cable loss with 0.23 UI peak-to-peak jitter.     

无线传感网OFDM系统中信道均衡器的电路实现

信道均衡器是无线传感网OFDM系统的关键部分,传统均衡器设计在信道估计精度或电路复杂度上效果不佳。为使均衡器更精确、复杂度更低,采用快速LMMSE算法进行信道估计与均衡,定制了精简的20位浮点数进行均衡器电路设计。电路经过综合、仿真与FPGA验证,结果表明,均衡器电路复杂度低,性能显著提高。相比于传统LS算法均衡器,在资源消耗仅增加27.27%的情况下,16dB载噪比下误码率降低了89.8%,实现了低复杂度高性能的均衡器电路。     

A Lumped Circuit for Wideband Impedance Matching of a Non-Resonant, Short Dipole or Monopole Antenna

A new technique is proposed for wideband impedance matching of short dipole- or monopole-like antennas in the VHF-UHF bands. Instead of constructing the network topology for every particular antenna, we propose a simple network of one fixed topology. This network is an inductive L-section cascaded with a high-pass T-section. The network includes five discrete components—three inductors and two capacitors. Although the approach is not general, the paper proves that matching with the present network is close to the theoretical limit impedance matching confirmed by Bode-Fano theory. The matching performance also approaches the performance of the Carlin's equalizer for short dipoles and monopoles. The dipoles and monopoles may have different shape and different matching bandwidths. By using the matching circuit of fixed topology we avoid greater difficulties related to the practical realization of the Carlin's equalizer. The key point is to minimize the antenna's matching network complexity (and loss) so that the circuit can be designed and constructed in a straightforward manner.      

Equalization for PSK signals over non-linear channels with non-symmetrical frequency response

In this paper, a minimum mean square error equalizer (MMSE) for receiving quadrature phase shift keyed (QPSK) signals over band-limited non-linear satellite channels is designed. The effect of intersymbol interference due to non-symmetrical frequency response followed by AM/AM and AM/PM conversions are taken into account while optimizing the performance in the presence of down-link additive white Gaussian noise. The taps gain coefficients of the equalizer are obtained using numerical methods. The average probability of error is computed for two systems: the one sample detector and the (MMSE) equalizer. It is shown that significant improvement in performance is possible by replacing the one sample detector by an MMSE equalizer.     

A Method of Self-Recovering Equalization for Multilevel Amplitude-Modulation Systems

A self-recovering equalization algorithm, which is employed in multilevel amplitude-modulated data transmission, is presented. Such a self-recovering equalizer has been required when time-division multiplexed (TDM) voice or picturephone PCM signals must be transmitted over the existing frequency-division multiplexed (FDM) transmission channel. The present self-recovering equalizer is quite simple, as is a conventional binary equalizer. The convergence processes of the present self-recovering equalizer are shown by computer simulation. Some theoretical considerations on this convergence process are also added.