WiMAX通道編碼效能分析與模擬

The Efficiency Analysis and Simulation of WiMAX Channel Coding

莊恆毅(Heng-Yi Juang)

指導教授 ： 劉玉蓀

國立臺北科技大學/電資學院/電腦與通訊研究所/碩士(2008年)

https://doi.org/10.6841/NTUT.2008.00097

摘要

本論文旨在於模擬WiMAX規格中通道編碼 (channel coding)功能，並針對特定的錯誤更正碼進行分析及探討。在文中主要分為兩部份：第一部份是使用軟體實現802.16d OFDM (Orthogonal Frequency-Division Multiple , OFDM)規格中通道編碼功能，此規格的錯誤更正碼包含了里德索羅門碼 (Reed-Solomon codes)及摺積碼 (convolutional codes)，並且在錯誤更正碼前後分別使用亂數化 (randomization)及交錯 (interleave)來保護其資料。第二部份則是針對802.16e OFDMA(Orthogonal Frequency-Division Multiple Access , OFDMA)規格中 TBCCs (tail-biting convolutional codes, TBCCs)進行模擬探討。傳統摺積碼解碼方法都是使用威特比演算法進行解碼，若使用硬體實現時，則需要使用改良的滑動視窗 (sliding window)解碼器進行解碼。但應用在TBCCs中，並沒有相關參考文獻針對其解碼器的滑動視窗大小進行分析，因此本文運用滑動視窗概念應用在TBCCs硬式決策 (hard-decision)解碼方法，並使用白色高斯雜訊 (Additive White Gaussian Noise , AWGN)作為通道環境，探討滑動視窗大小對於解碼效能的影響。最後在文末提出，滑動視窗應用在TBCCs解碼器的最佳長度。

關鍵字

通道編碼 ； 摺積碼 ； 硬式決策 ； 威特比演算法 ； 滑動視窗

並列摘要

The substance of this paper is simulating channel coding function of WiMAX standard and discussing one specific error-correction codes of these. We separate this paper into two parts. In first part, we realize the channel coding of standard 802.16d OFDM via software. The functions of error-correction code include Reed-Solomon codes and convolutional codes on channel coding. It also has randomization and interleave functions. The second part, we discuss the effect of sliding window size when applying on TBCCs (tail-biting convolutional codes) decoder. On traditional convolutional codes, it’s always decoded by Viterbi algorithm , and also uses sliding window method when realizing via hardware. But there is no references discussing about sliding window method applying on TBCCs decoder. Base on this reason, we will talk about how much size of sliding window will affect the efficiency of TBCCs decoders. In the experiment, we use AWGN (Additive White Gaussian Noise) as channel environment and hard-decision as determining path. Finally, we proposed the best size of sliding window among experimented result.

並列關鍵字

channel coding ； convolutional codes ； hard-decision ； Viterbi algorithm ； sliding window

參考文獻

[7]Jia-Wei Wu “Software Implementation of Channel Coding for WiMAX Physical Layer” Institute of Computer and Communication, National Taipei University of Technology, July, 2007.

[3]T. K. Moon, Error Correction Coding — Mathematical Methods and Algorithms, Wiley, 2005.

[4]T.-K. Troung, J.-H. Jeng, and T. C. Cheng, “A new decoding algorithm for correcting both erasures and errors of Reed-Solomon codes,” IEEE Transactions on Communications, vol.51, no.3, March 2003.

[6]T.-K. Troung, et al, “Simplified procedure for correcting both errors and erasures of Reed-Solomon code using Euclidean algorithm,” IEE Proceedings, vol.135, pt.E, no.6, November 1988.

[8]Wonjin Sung ’Minimum decoding trellis lengths for tail-biting convolutional codes’, ELECTRONICS LETTERS , 30th March 2000 , Vol.36 , pp.643-644.