过采样广义调制滤波器组在B3G移动通信系统中的实现

本文在GMC-TDD-xDMA系统背景下从广义多载波并行传输的基本原理出发,讨论广义多载波调制解调的数字实现,得到多载波调制解调的广义DFT调制滤波器组实现结构,并给出了一种普遍适用的滤波器组快速实现方法.解决了DFT调制滤波器组在GMC-TDD-xDMA系统中运用时存在的问题.     

用于多路MCP-EBPSK信号解调的冲击滤波器组设计

修正的随机极性连续相位扩展的二元相移键控调制（MCP-EBPSK）通过随机化调制指数的符号,并加入功率谱调节系数,进一步降低了连续相位扩展的二元相移键控(CP-EBPSK)调制信号功率谱中的线谱分量,使得功率谱占用带宽更窄,信息传输更加的高效高速。多载波作为高频谱利用率的复用调制方式,与MCP-EBPSK结合势必会带来更高的系统性能,因此本文对用于解调单路MCP-EBPSK信号的冲击滤波器进行初步改进,通过添加陷波零点来抑制旁路干扰,设计出带陷波的冲击滤波器组。引入量子粒子群优化算法对加入陷波的冲击滤波器组进行优化得到滤波器组系数,仿真显示即使时频混叠的子载波间不满足正交关系,利用各冲击滤波器中心频率处极陡峭的陷波选频特性依然可以实现各子载波的正确解调。因此, 设计的冲击滤波器组可以用于子载波无保护间隔的多路MCP-EBPSK信号解调。      

CMFB-DWMT多载波系统与DMT多载波系统的比较

本文首先讨论了基于余弦调制滤波器组（cosine modulation filter-banks-CMFB)的多载波调制解调结构的快速实现。然后在性能和抗噪方面对CMFB多载波结构与DMT（discretemulti-tone)作了分析和比较。计算机仿真结果显示，CMFB－DWMT(discrete wavelet multi-tone）在左频域特性、抑制噪声和抑制突发错误方面比DMT有较大的优势。     

一种宽带信号数字下变频的实现方法

在宽带、超宽带应用中,单一信号带宽达几百兆赫兹;或者在不同中频同时调制多个信号产生的宽带信号也达数百兆赫兹,用常规的数字下变频方法很难实现。文章提出了一种基于DFT滤波器组的高效数字下变频结构,分析了该解调算法的特点和实现性能。对已知信号带宽和中频的宽带信号,对比了DFT滤波器组和多相分解算法的性能。对信号带宽和中频均在变化的信号,给出了实现思路。最后,给出了该DFT滤波器组的硬件实现方案。     

通用载波同步模块的设计与实现

通信系统能否有效、可靠地工作,很大程度上依赖于有无良好的载波同步模块。阐述了某通用解调器中载波同步模块的设计与实现,主要由相位旋转器、鉴相器、环路滤波器、NCO（数字振荡器）等组成,可适用于MPSK（多进制相移键控）、MQAM（多进制正交幅度调制）等多种调制信号。然后针对特定的环路滤波器参数进行了计算机仿真,并给出了相应的FPGA（现场可编程门阵列）设计与硬件实现结果。     

基于滤波多音改进的F-OFDM方案

针对滤波OFDM（F-OFDM）系统对子带内定时同步要求严格的问题,提出了一种基于滤波器组的滤波多音（FMT）调制技术来实现F-OFDM的改进方案。通过滤波器组结构实现子载波级的滤波处理,采用载波频谱不重叠的FMT调制,改进方案降低了子带内严格的定时同步要求。仿真结果表明,所提方案可进一步将带外发射（OOBE）抑制到-65 dB深度,且在加性高斯白噪声（AWGN）信道和瑞利衰落信道下,具有较好的抗载波频率偏移（CFO）性能。相比于F-OFDM的直接实现,改进方案具有更低的运算复杂度。     

全数字正交幅度调制器(QAM)的实现

提出了如何用全数字方法实现QAM调制器。第一部分概述了全数字正交幅度调制器和模拟调制器相比的优点。第二部分论述了数字调制器各个关键部分的实现方法和注意要点,尤其是数字滤波器和数字信号合成技术,正是由于DDS技术应用的普及,全数字调制器的实现变为了现实可行的。第三部分为结论,认为该方法易于大规模集成,性能稳定,功耗低,成本低,而且可以根据需要配置成不同的QAM调制方式,载波频率也可以随意改变。     

一种基于带通RAKE接收机的多载波解调方法

ＣＤＭＡ２０００采用多载波和直接序列扩频两种方式来达到提供宽带数据业务的目的。针对ＣＤＭＡ２０００前向信道的三载波调制方式,提出了一种基于带通ＲＡＫＥ接收机的多载波解调方法。这种方法避开了设计多比特的基带数字滤波器,从而大大降低了实现的复杂度。文章首先分析了三载波的调制结构。根据ＲＡＫＥ接收机的原理,推导出相应的带通ＲＡＫＥ接收机模型并给出解调结构,最后,用ＳＰＷ软件对此模型进行仿真并给出了传真结     

滤波多音调制技术的应用

文章详细介绍了滤波多音调制(FMT)这种基于滤波器组调制的新兴多载波调制技术,并将其与现有的其他多载波传输技术(如OFDM)作了对比,指出了有待研究的有关课题,最后对FMT在宽带无线数据传输中的应用作了初步展望。     

非相干重采样技术及应用

从基本原理、实现方法两个方面对多速率信号处理中的重采样技术进行了详细分析,说明了几种内插滤波器的特点及选择依据,最后介绍了非相干重采样技术在多载波调制和在时钟恢复中的应用。相对于利用DA和AD转换芯片实现采样率变换的方法,采用数字重采样技术实现采样率变换的方法具有性能稳定可靠、灵活性好、功耗低、复杂度低等特点。     

Rational sampling filter banks based on IIR filters

The problem of splitting the spectrum of a digital signal by using nonuniform infinite impulse response (IIR) filter banks is addressed. Near perfect reconstruction (NPR) is considered. The method uses the modulation of different IIR prototypes. The cancellation of the main aliasing components constrains the prototypes to be dependent on each other. By using this approach, linear-phase prototypes are needed, and noncausal filtering is required. Numerical examples of filter bank design are given, and the computational complexity is compared with the finite impulse response (FIR) case     

Filter banks in digital communications

Digital signal processing has played a key role in the development of telecommunication systems over the last two decades. In recent years digital filter banks have been occupying an increasingly important role in both wireless and wireline communication systems. In this paper we review some of these applications of filter banks with special emphasis on discrete multitone modulation which has had an impact on high speed data communication over the twisted pair telephone line. We also review filter bank precoders which have been shown to be important for channel equalization applications.     

Filter Bank Channelizers for Multi-Standard Software Defined Radio Receivers

The ability to support multiple channels of different communication standards, in the available bandwidth, is of importance in modern software defined radio (SDR) receivers. An SDR receiver typically employs a channelizer to extract multiple narrowband channels from the received wideband signal using digital filter banks. Since the filter bank channelizer is placed immediately after the analog-to-digital converter (ADC), it must operate at the highest sampling rate in the digital front-end of the receiver. Therefore, computationally efficient low complexity architectures are required for the implementation of the channelizer. The compatibility of the filter bank with different communication standards requires dynamic reconfigurability. The design and realization of dynamically reconfigurable, low complexity filter banks for SDR receivers is a challenging task. This paper reviews some of the existing digital filter bank designs and investigates the potential of these filter banks for channelization in multi-standard SDR receivers. We also review two low complexity, reconfigurable filter bank architectures for SDR channelizers based respectively on the frequency response masking technique and a novel coefficient decimation technique, proposed by us recently. These filter bank architectures outperform existing ones in terms of both dynamic reconfigurability and complexity.     

滤波器组在相干激光测风雷达信号处理中的应用

首先简要介绍了相干激光测风雷达和数字滤波器组的工作原理,然后重点分析了余弦调制滤波器组。余弦调制滤波器组具有实现简单、占用资源少等特点。信号通过滤波器组后可分解成若干个窄带子信号,目标的多普勒频率将落入其中一个子带信号中,针对这一子信号进行处理可获得较高的信噪比。利用Matlab设计出了8通道余弦调制滤波器组,然后对回波信号进行处理,从仿真结果和实测信号处理结果可以看出:该方法可以判断并抽取出多普勒频率所在的子带信号。     

A general formulation of modulated filter banks

This paper presents a general framework for maximally decimated modulated filter banks. The theory covers the known classes of cosine modulation and relates them to complex-modulated filter banks. The prototype filters have arbitrary lengths, and the overall delay of the filter bank is arbitrary, within fundamental limits. Necessary and sufficient conditions for perfect reconstruction (PR) are derived using the polyphase representation. It is shown that these PR conditions are identical for all types of modulation-modulation based on the discrete cosine transform (DCT), both DCT-III/DCT-IV and DCT-I/DCT-II, and modulation based on the modified discrete Fourier transform (MDFT). A quadratic-constrained design method for prototype filters yielding PR with arbitrary length and system delay is derived, and design examples are presented to illustrate the tradeoff between overall system delay and stopband attenuation (subchannelization)     

基于二进小波变换的实信号的多尺度Hilbert变换和瞬时频率提取

该文着重讨论了使用二进小波变换方法实现数字Hilbert滤波,特别是使用滤波器组实现多尺度Hilbert滤波所要考虑的各尺度滤波器的设计问题。将多尺度Hilbert方法应用到求信号的瞬时参数中,并利用小波变换的去噪思想,取得了比使用DWT方法去噪更好的去噪效果。     

Multiplication-free adaptive digital filters

The authors update delta modulation digital filter weights using the LMS (least-mean-squares) and the SIGN algorithms to realize an adaptive digital filter without multiplication operations. It is shown that using the SIGN algorithm results in an adaptive filter that can be implemented using the simple up/down counting operations. Learning curves demonstrating convergence properties of the algorithms for a system identification problem are presented     

An efficient digital implementation of multicarrier CDMA system based on generalized DFT filter Banks

In this paper, an efficient digital implementation of multicarrier transmission scheme based on generalized discrete Fourier transform (DFT) filter banks is presented for multicarrier code-division multiple-access (MC-CDMA) systems. Generalized DFT filter banks has been traditionally discussed for very high-speed digital subscriber lines (VDSL) wireline systems, received interest also for wireless applications. The design of the generalized DFT modulated filter banks is investigated and its fast implementation is derived in the time-domain for arbitrary integer sampling rate. Through the utilization of the generalized DFT modulated filter banks, one or more subcarriers, even noncontiguous subcarriers can be easily supported by system in both uplink and downlink, which facilitates the users to access the network in a frequency-division multiple-access manner. Simulation results show that the overall bit-error-rate performance of the proposed multicarrier transmission scheme well approaches that of a single-carrier system due to the negligible intercarrier interference introduced by an appropriate design of the generalized DFT modulated filter banks.     

基于加权总体最小二乘正则化方法的混合滤波器组最优化设计

模拟分析滤波器组的实现欠理想、系统噪声以及数字综合滤波器有效阶数实现所带来的系统误差均有可能造成混合滤波器组的设计出现解不稳定、无唯一解等病态问题,影响混合滤波器组的准确重构效果。本文首先给出了满足准确重构条件下,以综合滤波器组频域响应为求解变量的混合滤波器组线性求解模型。针对线性方程中系数矩阵以及目标向量受扰动误差影响特点,提出一种新的基于加权总体最小二乘正则化算法的IIR形式综合滤波器设计方法。算法以系统扰动误差最小化为目标函数,根据随机误差变量的二阶统计特性,采用加权总体最小二乘算法抑制滤波器实现误差以及随机噪声等扰动因素影响,使得到的综合滤波器组频域响应解的加权误差平方和最小化,并通过Tikhonov正则化方法优化病态情况下方程组解的稳定性。提出一种IIR类型的综合滤波器系数的求解算法,并利用正则化方法优化滤波器系数,提高系统稳定性。该方法可应用于过采样混合滤波器组的设计。仿真结果表明该算法的有效提高系统鲁棒性和改善重构性能。