2002 Fiscal Year Final Research Report Summary
An Application of Digital Filters to Spread Spectrum Communications
| Project/Area Number |
13650410
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
情報通信工学
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| Research Institution | Shimane University |
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Principal Investigator |
NISHIMURA Shotaro Shimane University, Interdisciplinary Faculty of Science and Engineering, Professor, 総合理工学部, 教授 (50031092)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUMA Shinji Shimane University, Interdisciplinary Faculty of Science and Engineering, Assistant Professor, 総合理工学部, 助手 (50313565)
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| Project Period (FY) |
2001 – 2002
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| Keywords | 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 |
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| Research Abstract |
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.
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Research Products
(12 results)
