模擬LDPC碼正交分頻多工系統再移動通訊環境下利用軟式資訊交換進行多載波偵測與解碼

Simulation of Soft-inout Soft-output Multicarrier Detector and Decoder for LDPC Codes OFDM System in Mobile Channels

彭以榮(Yi-Rung Peng)

指導教授 ： 曾恕銘

國立臺北科技大學/機電學院/電腦與通訊研究所/碩士(2006年)

摘要

近年來低密度同位元檢查碼(Low-Density Parity-Check codes)受到了許多關注。在文中吾人利用渦輪架構(Turbo scheme)針對通道的偵測(ICI消除)與通道編碼的解碼(Sum-product algorithm)對介於行動通道的LDPC-OFDM系統進行效能的探討，並與相同架構但使用不同的編碼與解碼機制的convolutional coded-OFDM系統進行比較。最後我們也考慮通道為完美或非完美知道的情況進行比較。
模擬結果顯示，本論文提出的方法比渦輪架構ICI消除和BCJR解旋旋碼的CC-OFDM系統，當codeword長度夠長時可達到相似的效能，也可以有較低的解碼計算複雜度。

關鍵字

內部載波干擾 ； 正交分頻多工 ； 多重接取干擾 ； 渦輪原理 ； 軟式輸入軟

並列摘要

Recently, low-density parity-check (LDPC) codes have attracted a lot of attention. In this thesis, we apply turbo inter-carrier interference (ICI) cancellation (channel detecting) and sum-product decoding to the LDPC-OFDM system in the mobile channel.
The simulation results show that the proposed Turbo ICI cancellation and sum-product algorithm decoding of LDPC coded OFDM systems can achieve the comparable error rate performance with Turbo ICI cancellation and BCJR decoding of convolutional coded-OFDM systems when codeword length is not too short. LDPC_OFDM also have lower computational complexity. We also consider the perfected known and unperfected known channel conditions.

並列關鍵字

ICI ； OFDM ； MAI ； LDPC ； Turbo Principle ； Soft-In Soft-Out

參考文獻

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[5] H. Futaki, T. Ohtsuki, “Low-Density Parity-Check (LDPC) Coded OFDM Systems” Vehicular Technology Conference, 2001, IEEE VTS 54th, pp. 82 - 86 vol.1, VTC 2001 Fall.

[6] W. G. Jeon, et al, “An equalization technique for orthogonal frequency-division multiplexing systems in time-variant multipath channels,” IEEE Trans. Commun., vol. 47, no. 1, pp. 27 - 32, July 2001.