在干擾環境下應用於不等差錯保護低密度奇偶校驗碼之影像傳輸系統

Image Transmission for Unequal Error Protection LDPC Coded System under PBNJ

朱培宏(PEI-HONG JHU)

指導教授 ： 鄭立德

中原大學/電機資訊學院/電子工程研究所/碩士(2017年)

https://doi.org/10.6840/cycu201700889

摘要

在本論文中，我們提出了一個無線影像在部分頻帶干擾的傳輸系統，因為減少傳輸過程所消耗的通訊資源，所以將傳輸影像進行壓縮後再做傳送。傳輸的通道是用部分頻帶干擾(Partial Band Noise Jamming，PBNJ)來做模擬。
為了抵抗傳輸過程中的干擾，我們使用跳頻展頻系統(Frequency-Hopping，FH)來傳輸影像以及低密度奇偶校驗碼(Low-density parity-check code，LDPC Code)搭配非均等保護機制(Unequal Error Protect，UEP)來保護傳輸資料。我們在後端接收的部分使用了多樣性結合的技術來更為降低資料的失真度。在模擬結果的部分會比較不同的多樣性結合方式在不同傳輸環境下的影像接收品質。

關鍵字

離散小波轉換 ； 影像壓縮 ； 部分頻帶干擾 ； 多樣性結合 ； 跳頻 ； 低密度奇偶校驗碼 ； 非均等保護機制

並列摘要

Frequency-hopping technique has been widely used in wireless communication systems owing to the advantages of anti-jam and multiple access, especially, in military communication system. To acquire a satisfactory capability, a FH system usually need an extra mechanism of protection by appealing to the so-called Unequal Error Protection coding (UEP). To attain the near optimum performance, a more powerful coding scheme is demanded. Therefore, we take into account the use of low density parity check code (LDPC).In this project, two types of jammer - partial-band noise jammer (PBNJ) and Additive white Gaussian noise (AWGN) are discussed. We decode the LDPC code by applying the sum-product algorithm (SPA). We employ different diversity combining schemes to compute the codeword bit decision reliability, and propose a modified detection rule to determine whether the hop is jammed or not as well as the optimum decoding metric for each received symbols. .
Low-Density Parity Check codes (LDPC) become popular because of its flexibility in codeword length and better performance than those of other channel codes. This study, we propose a image transmission system which empolyed LDPC code to replace RS code under partial band noise jamming (PBNJ). Besides, we also propose Image compression and Different levels Unequal Error Protect which integrated the information after image process and channel information.

並列關鍵字

DWT、compressed image ； partial band noise jamming ； Frequency-Hopping ； diversity combining ； LDPC code ； Unequal Error Protection

參考文獻

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