在干擾環境下應用多種影像修復法於慢跳頻里德所羅門編碼系統之研究

跳頻展頻(Frequency-Hopping Spread Spectrum，FH-SS) 技術因具有抗干擾、多重進接等特性，已經廣泛地被應用於無線通訊系統中，尤其是在軍事用途上。近年來，跳頻技術結合M-ary頻率鍵移(M-ary Frequency Shift Keying，MFSK)的系統已經廣泛地被運用在一般的通訊系統上。一般而言，跳頻系統可分為兩種：一種稱快跳頻(Fast Frequency-Hopping，FFH)系統，而另一種則是慢跳頻(Slow Frequency-Hopping，SFH)系統。對於慢跳頻系統的話，為了達到符合規格的抗干擾能力，通常會加入一樣額外的機制來強化它，常用的一種方式就是利用正向錯誤更正碼(forward error-correction coding，FEC)。近年來，部分頻帶干擾(Partial Band Noise Jamming，PBNJ)以及帶頻多波道單音干擾環境結合禮德－所羅門(Reed-Solomon)碼的應用在慢跳頻系統裡的效能已被廣泛研究，不過主要都僅限於錯誤率的分析，均只是利用一般的通訊方法或結合正向錯誤更正碼來提升抗干擾效能，完全沒有運用到傳送資料本身的相關特性，例如影像的像素點之間具有高度的相關性。　　因此，本論文希望整合一般通訊及影像處理兩大技術領域，透過影像修復及正向錯誤更正碼的結合，來提升抗干擾的效能。在正向錯誤更正碼的解碼部分，本論文選用禮德－所羅門碼及Berlekamp-Massey演算法，希望藉由此演算法來找出錯誤碼字，並紀錄其錯誤碼字來對應到影像中的錯誤像素點，最後再針對這些錯誤像素點，以多種影像修復的濾波器來進行還原的目地，以達到抗干擾功效。模擬結果顯示，本論文所提出的方法，確實能有效地提升抗干擾效能。

關鍵字

里德所羅門碼；跳頻；影像處理；部分頻帶雜訊干擾

並列摘要

Owing to the advantage of anti-jam (AJ) capability and multiple access property, frequency-hopping spread spectrum (FH-SS) combined with (M-ary Frequency Shift Keying，MFSK) has been widely applied in wireless communication systems. The initial application of FH-SS techniques are developed in military communication systems. In general, there are two classes of frequency-hopping systems. One is the fast frequency-hopping (FFH) system, and the other is the slow frequency-hopping (SFH) system. For SFH systems, a good forward error correcting coding (FEC) is essential to acquire a satisfactory AJ capability. In the recent years, SFH systems and Reed-Solomon code systems under Partial Band Noise Jamming (PBNJ) and Band Multi-tone Jamming (BMTJ) environment are studied extensively. But most of them only focused on the error probability in the general communication systems. None of them has utilized the property of transmitted data, such as the correlations among image pixels. In this paper, we proposed the scheme of combining image restoration and FEC to enhance AJ capability. We use the Reed-Solomon code systems and Berlekamp-Massey Algorithms to decode the RS codewords and decide which codewords can be corrected. Finally, the error pixels were corresponded to the error pixels in the image and be processed by several image filters for image restoration. The simulation results show that our system which combines FEC and image processing technique is better than those only use FEC in wireless communication.

並列關鍵字

RS code ； frequency-hopping ； image processing ； partial-band noise jamming

參考文獻

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[3] C. D. Frank and M. B. Pursley, “Concatenated coding for frequency-hop spread-spectrum with partial-band interference.” IEEE Trans. Commun., vol. 44, pp.377-387, Mar. 1996.

[4] A. J. Viterbi, “A robust ratio-threshold technique to mitigate tone and partial-band jamming in coded MFSK systems.” In IEEE Milcom 82., 1982, IEEE Cat. No. 82CH1734-3, pp. 22.4.1-5.

[6] B. K. Levitt, “Use of diversity to improve FH/MFSK performance in worst case partial band noise and multitone jamming.” In IEEE Milcom 82., 1982, IEEE Cat. No. 82CH1734-3 ,pp.28.2.1-5.

[7] S. Haykin, Communication Systems, John Wiley & Sons, Inc 4th ed.

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在干擾環境下應用多種影像修復法於慢跳頻里德所羅門編碼系統之研究

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