An Application of Digital Filters to Spread Spectrum Communications

数字滤波器在扩频通信中的应用

基本信息

批准号：
13650410
负责人：
NISHIMURA Shotaro
金额：
$ 1.41万
依托单位：
Shimane University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650410/
关键词：
Adaptive Digital Filter IIR Notch Filter Gradient Method Spread Spectrum Communication Narrow-Band Interference Rejection Bit Error Rate Region of Interest Image Coding Optimum Bit Rate Allocation 定常特性 PN系列

项目摘要

1. We proposed a method to analyze the steady-state performance of a complex coefficient adaptive infinite impulse response (IIR) notch filter which is useful for the rejection of multiple narrow-band interference in quadrature phase shift keying (QPSK) spread spectrum communication systems. The signal-to-noise ratio (SNR) improvement factor has been obtained from which the validity of the use of the notch filter can be concluded.2. We have investigated the problem of narrow-band interference (NBI) suppression in a direct-sequence code-division multiple-access (DS CDMA) communication system using adaptive IIR notch filter algorithms.We first proposed a second-order lattice-based adaptive IIR notch filter with a normalized algorithm. We found out from the convergence analysis that for large NBI power or interference-to-signal power ratio (ISR), the convergence speed of the normalized algorithm is independent of the number of DS CDMA system active users and power of the NBI which is a desirable result.Secondly, we analyzed the performance gain of the DS CDMA system afforded by the proposed second-order lattice-based adaptive IIR notch filter algorithms using SNR improvement factor of the decision variable and bit error rate (BER) as figures of merit. We found out that the SNR improvement factor increases with the power of the NBI and decreases with the number of DS CDMA system active users.3. We proposed a region-of-interest (ROI) image coding based on multiple wavelet transforms. The proposed method can avoid much information loss for non ROI at lower constrained bit rate caused in JPEG-2000, therefore the subjective image quality for whole of restored image will be improved, maintaining the quality of ROI higher than that of non-ROI.

1. 我们提出了一种分析复系数自适应无限脉冲响应（IIR）陷波滤波器稳态性能的方法，该方法可用于抑制正交相移键控（QPSK）扩频通信系统中的多个窄带干扰。得到了信噪比(SNR)改善因子，由此可以得出陷波滤波器使用的有效性。 2．我们使用自适应IIR陷波滤波器算法研究了直接序列码分多址（DS CDMA）通信系统中的窄带干扰（NBI）抑制问题。我们首先提出了一种基于二阶格的自适应IIR具有归一化算法的陷波滤波器。通过收敛分析发现，对于较大的北向接口功率或干扰信号功率比（ISR），归一化算法的收敛速度与DS CDMA系统活跃用户数和北向接口功率无关。其次，我们使用决策变量的信噪比改进因子和误码率（BER）作为品质因数，分析了所提出的基于二阶格的自适应IIR陷波滤波器算法所提供的DS CDMA系统的性能增益。我们发现，SNR改善因子随着北向接口功率的增加而增大，随着DS CDMA系统活跃用户数的增加而减小。 3．我们提出了一种基于多重小波变换的感兴趣区域（ROI）图像编码。该方法可以避免JPEG-2000在较低的受限比特率下造成的非ROI的大量信息丢失，因此整个恢复图像的主观图像质量将得到改善，保持ROI的质量高于非ROI的质量。